JP2002374039A - Optical transmitting/receiving system and optical communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmitting/receiving system or optical communication system, using a plane light emitting laser diode to be operated over 1.1 to 1.7 μm bands. SOLUTION: In the construction of the optical transmitting/receiving system or optical communication system, this system is provided with an active layer emitting a light in the range of 1.1 to 1.7 μm, in a GaInNAs system or GaInAs system and a resonator structure composed of reflecting mirrors provided on the upper part and lower part of the active layer, each of reflecting mirrors is composed of a semiconductor distribution Bragg reflection mirror cyclically repeating the first material layer of small refraction factor in the AlGaAs system and the second material layer of large refraction factor in the AlGaAs system, the planar light-emitting laser diode provided with the hetero-spike buffer layer of the AlGaAs system having an intermediate composition of thickness 20 to 50 nm between the first and second material layers is used as a light source. Then, an optical fiber transmission line is coupled to the emitting light source, and a light-receiving unit is provided at the other end of the optical fiber transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to optical communications, and more particularly to a so-called surface emitting laser diode for forming a laser beam emitted in a direction substantially perpendicular to a substrate surface, and light using the surface emitting laser diode. The present invention relates to a transmission / reception system and an optical communication system.

[0002]

2. Description of the Related Art A surface-emitting laser diode emits a laser beam in a substantially vertical direction from the surface of a substrate, is capable of two-dimensional parallel integration, and has a spread angle of output light. Is relatively narrow (approximately 10 °) so that coupling with an optical fiber is easy, and further, there is a characteristic that element inspection is easy. Therefore, the surface emitting laser diode is particularly suitable for forming an optical transmission module (optical interconnection device) of a parallel transmission type, and research and development are being actively conducted. The immediate application of the optical interconnection device is parallel connection between housings of computers, etc. and between boards, short-distance optical fiber communication, etc. In the future, large-scale computer networks and long-distance large-capacity It is expected to be applied to telecommunication backbone systems.

Generally, a surface emitting laser diode is Ga
An active layer composed of a III-V group compound semiconductor such as As or GaInAs, and an optical resonator composed of an upper semiconductor distributed Bragg reflector and a lower semiconductor distributed Bragg reflector arranged so as to sandwich the active layer vertically. However, since the length of the optical resonator is significantly shorter than that of the edge emitting laser diode, the reflectivity of the reflecting mirror is extremely high (9).
It is necessary to make laser oscillation easy by setting the value to 9% or more. For this reason, a low refractive index material usually made of AlAs and a high refractive index material
Semiconductor distributed Bragg reflectors formed by alternately laminating at quarter-wave periods are used.

[0004] However, in the conventional semiconductor distributed Bragg reflector having the above-described structure, spikes are generated in the band due to discontinuity of the band at the hetero interface because the materials having different band gaps are grown alternately. There has been a problem that it acts as a barrier and the electrical resistance in the semiconductor multilayer film portion becomes extremely high. For this reason, a relatively high operating voltage of about 2.5 V is required to operate a general GaAs surface emitting laser, and a laser diode driving IC made of CMOS is required.
(Laser diode driving voltage is 2 V or less). The breakdown of the operating voltage 2.5V is 1.5V in the diode part and 1V in the element resistance.
In order to operate at 2 V or less, the element resistance must be reduced to half or less. This is a very difficult task at present.

On the other hand, in the case of a laser having a long wavelength band having a laser wavelength of 1.1 μm or more, such as a laser used for optical communication, for example, a long wavelength band laser having a laser wavelength of 1.3 μm or 1.55 μm, Since only a voltage of 1 V or less is applied to the diode portion, low-voltage operation is expected, but low-voltage operation is not actually realized. In a conventional long wavelength band laser, InP is used for a production substrate, and InGa is used for an active layer.
Although AsP is used, the lattice constant of InP constituting the substrate is large, and a large difference in the refractive index cannot be obtained with a reflecting mirror material that matches this. Therefore, it is necessary to increase the number of layers to 40 or more. However, when the number of stacked reflectors is increased as described above, the resistance in the reflector portion increases, and it is difficult to use the laser diode in combination with a laser diode drive IC composed of CMOS.

A surface emitting laser formed on an InP substrate
Another problem with the diode is that the characteristics change significantly with temperature. Therefore, such I
In the case of a laser diode using an nP substrate, it is necessary to additionally use a device for keeping the temperature constant, and it has been difficult to use a laser diode for a consumer device which requires strict formation at low cost. As described above, the surface emitting laser diode using the InP substrate has a problem of the number of layers and the temperature characteristics.
Practical long-wavelength surface-emitting semiconductors have not yet been put to practical use.

To solve the above problem, Japanese Patent Laid-Open No. 9-237
No. 942 discloses that a GaAs substrate is used, and that at least one of the upper and lower semiconductor distributed Bragg reflectors has a GaAs low refractive index layer.
A semiconductor layer made of AlInP lattice-matched to the s substrate is used, and a semiconductor layer made of GaInNAs is used as a high refractive index layer of at least one of the upper and lower semiconductor distributed Bragg reflectors, thereby realizing a larger refractive index difference than before. Thus, there are described a semiconductor distributed Bragg reflecting mirror that achieves high reflectance with a smaller number of stacked layers, and a surface emitting laser diode having such a semiconductor distributed Bragg reflecting mirror.

In the conventional surface emitting laser diode, GaInNAs is used as a material for the active layer. By introducing N into the GaInAs-based III-V compound semiconductor constituting the active layer, the band gap (forbidden band width) of the active layer can be reduced by 1.4 eV. It is possible to emit a long wavelength. In the above prior art, GaIn
An NAs-based material can be lattice-matched with a GaAs substrate, so that a semiconductor layer made of GaInNAs has a thickness of 1.3 μm.
m-band and 1.55 μm long-wavelength surface emitting laser diodes
Preferred points for the material for the metal are also described.

[0009]

However, although there is a description suggesting the possibility of such a surface emitting laser diode having a wavelength band longer than 0.85 μm, such a device is actually used. Things have not been realized. This is presumably because, although the basic configuration has been almost theoretically determined, a more specific configuration for actually obtaining stable laser emission is still unknown.

As an example, a semiconductor distributed Bragg reflector formed by alternately laminating a low-refractive-index material made of AlAs and a high-refractive-index material made of GaAs at a period of 1/4 wavelength as described above is used. Laser laser
Or a laser diode using a semiconductor layer made of AlInP, which is lattice-matched to a substrate, as a low refractive index layer of a semiconductor distributed Bragg reflector, as disclosed in JP-A-9-237942. Even if you make it in
The actual situation is that the laser element does not emit light at all, or even if it emits light, its luminous efficiency is low, which is far from a practical level.

This is considered to be because the material containing Al is chemically very active, and crystal defects caused by Al are likely to occur. In order to solve this problem, Japanese Patent Application Laid-Open Nos. 8-340146 and 7-307525 propose a technique of forming a semiconductor distributed Bragg reflector using GaInNP and GaAs not containing Al. . However, the refractive index difference between GaInNP and GaAs is about half of the refractive index difference between AlAs and GaAs. Therefore, in this proposal, it is necessary to greatly increase the number of stacked reflectors. Is difficult to reduce.

That is, at present, there is no long-wavelength surface emitting laser diode having a laser oscillation wavelength of 1.1 to 1.7 μm which can be used for optical fiber communication expected in computer networks and the like. However, a communication system using this cannot be constructed.

Further, in the conventional surface emitting laser, as described above, a laser diode drive IC using a CMOS circuit cannot be used, so that an expensive special drive circuit must be used. However, CMOS lasers that can be easily mass-produced
It is considered that if the diode drive IC can be used, a low-cost system can be easily realized. Further, if a CMOS circuit can be used, the power supply voltage of the laser driving IC is changed from 5V to 3.
It can be reduced to 3V. If the power supply voltage can be reduced in this way, the power consumption of the system can be reduced to nearly half, and a very large power consumption reduction effect can be obtained.

As described above, at present, optical fiber communication is expected in computer networks and the like. In particular, realization of a low-cost system is required for popularization. However, it can be used for this purpose, and C
It can be used in combination with a MOS laser diode drive IC, and there is no surface emitting laser diode that oscillates in a long wavelength band of 1.1 to 1.7 μm. There is no system.

In the above-described semiconductor distributed Bragg reflector, substances having different band gaps are alternately grown, so that band discontinuity at the hetero interface causes a spike in the band, which acts as a barrier to carriers.
There arises a problem that the electric resistance becomes extremely high in the semiconductor multilayer film portion. Due to this effect, the operating voltage of a general GaAs surface emitting laser is set to 2.5 as described above.
As high as about V, it has been difficult to drive with a laser diode drive IC composed of CMOS (laser diode drive voltage is 2 V or less). Since the breakdown of the operating voltage of 2.5 V is 1.5 V in the diode portion and 1 V in the element resistance, the element resistance must be reduced to half or less in order to operate at 2 V or less. It is a difficult task.

In recent years, private optical transmission / reception systems are being constructed, and optical fiber communication in computer networks and the like, including such private optical transmission / reception systems, is expected. In particular, it is necessary to realize a low-cost system for widespread use. However, it can be used in combination with a CMOS laser diode drive IC that can be used for such a system. 1 to
As described above, a 1.7 μm long-wavelength band surface emitting laser diode does not exist, and therefore, a communication system using the same does not exist.

The laser oscillation wavelength is 1.1 to 1.7 μm.
In an optical communication system using a long-wavelength surface-emitting laser diode having a wavelength of m, the light receiving element made of ordinary Si is 1.1.
Since the wavelength of 1.7 to 1.7 μm cannot be detected, 1.1 to 1.
A light receiving element sensitive to a wavelength of 7 μm must be used. However, a light-receiving element having a sensitivity at a wavelength of 1.1 to 1.7 μm is more expensive than a relatively low-priced Si light-receiving element, and simply using a 1.1 to 1.7 Si light-receiving element.
Simply replacing the photodetector with a sensitivity to a wavelength of μm would increase the price of the entire optical communication system. Therefore, an optical communication system using a long-wavelength surface emitting laser diode of 1.1 to 1.7 μm is expected to realize a system that is not a simple replacement of a light receiving element.

Further, as shown below, GaInNAs
In long-wavelength surface emitting lasers using
Although an InNAs active layer is sometimes used, in such a laser, there is a concern that the characteristics may be degraded due to a thermal stress generated due to a difference from a linear expansion coefficient of the mounting substrate.

In an optical communication system using a surface emitting laser diode, since the surface emitting laser diodes can be arranged at a high density, the optical communication system is more luminous than when a conventional edge emitting laser diode is used. The distance at which the fibers are mounted, that is, the distance between the optical fibers, is reduced. Generally, an optical fiber core wire incorporated in an optical cable is provided with a colored layer for identifying a communication line and a plastic ring (marker band) for giving an identification code (ID code). However, as the distance between the optical fibers becomes shorter, the space for providing these protective layers and rings becomes smaller, and it becomes practically difficult to form them. However, as the distance between the optical fibers becomes shorter, the space for providing these protective layers and rings becomes smaller, and it is practically difficult to form them.

In a manufacturing process for manufacturing a module having an array of surface emitting laser diodes as a product, if the quality of a predetermined number of lasers constituting the array cannot be ensured, the array is treated as a defective product. And loses its value as a product. This is related to the yield in the laser diode manufacturing process. Particularly, in the manufacturing process of a module product that requires an array arrangement, it is possible to effectively use a module that functions normally and to improve the yield of the entire manufacturing process. There is a strong need to establish a manufacturing process that can be performed.

In summary, at present, a long-wavelength surface emitting laser diode having a laser oscillation wavelength of 1.1 to 1.7 μm.
And optical transmission and reception systems using it do not exist,
Its appearance is longing.

Accordingly, it is a general object of the present invention to provide an optical transmission / reception system and an optical communication system using a new and useful surface emitting laser diode element which have solved the above-mentioned problems.

A more specific object of the present invention is to provide an optical transmission / reception system using a long-wavelength surface emitting laser diode having a laser oscillation wavelength of 1.1 to 1.7 μm in which an operating voltage, an oscillation threshold current and the like are controlled. It is an object of the present invention to provide an optical transmission / reception system that can be easily constructed by using a surface emitting laser diode element chip that can be reduced.

A second object of the present invention is to provide an optical transmission / reception system which can be easily constructed especially in a building by using a surface emitting laser diode element chip capable of reducing an operating voltage, an oscillation threshold current and the like as a light source. Is to provide.

[0025] A third object of the present invention is to provide an image processing apparatus comprising:
An object of the present invention is to provide an optical transmission / reception system that can operate stably by using a long wavelength surface emitting laser diode element chip that operates stably in a laser oscillation wavelength band of m as a light emitting light source.

A fourth object of the present invention is to solve a specific problem which occurs when such an optical transmission / reception system is actually incorporated in a device.

A fifth object of the present invention is to use a surface emitting laser diode element chip capable of lowering an operating voltage, an oscillation threshold current and the like as a light emitting light source, to reduce energy consumption,
An object of the present invention is to provide an optical transmitting and receiving system that can be manufactured at low cost.

A sixth object of the present invention is to use a surface-emitting laser diode device capable of lowering an operating voltage, an oscillation threshold current and the like as a light-emitting light source, and to further use the surface-emitting laser diode.
An optical communication system that can improve productivity during assembly of the package and can be easily constructed by setting the length of an optical fiber cable drawn out of a packaged device or a module package containing the device to a certain length or more. To provide.

A seventh object of the present invention is to provide a low-cost, large-capacity light transmission device using a surface-emitting laser diode device capable of reducing operating voltage, oscillation threshold current, and the like as a light-emitting light source. A communication system is provided.

An eighth object of the present invention is to reduce the power consumption by using a surface-emitting laser diode device capable of lowering an operating voltage, an oscillation threshold current and the like as a light-emitting light source.
It is an object of the present invention to provide a highly reliable optical communication system which can reduce fluctuations in the characteristics of a laser diode and prevent a reduction in life.

A ninth object of the present invention is to use a surface emitting laser diode device capable of lowering an operating voltage, an oscillation threshold current and the like as a light emitting light source, thereby providing a good space between the laser device and the optical fiber. Another object of the present invention is to provide an optical communication system capable of realizing an optical coupling.

A tenth object of the present invention is to use a surface-emitting laser diode element chip capable of lowering an operating voltage, an oscillation threshold current, and the like as a light-emitting light source, thereby reducing power consumption and the number of parts. An object of the present invention is to provide an optical communication system capable of achieving good optical coupling efficiency.

An eleventh object of the present invention is to use a surface emitting laser diode element chip capable of lowering an operating voltage, an oscillation threshold current and the like as a light emitting light source so that a laser beam can be efficiently coupled to an optical fiber. An object of the present invention is to provide a ring optical communication system.

A twelfth object of the present invention is to provide an optical communication system which can be used without damaging a laser element by using a surface emitting laser diode element capable of lowering an operating voltage, an oscillation threshold current and the like as an emission light source. Is to provide.

[0035]

The present invention solves the above problems,
A surface emitting laser diode including an active layer and a resonator structure including a reflector provided above and below the active layer.
A reflection element having a reflection wavelength of 1.1.
a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of at least μm and having a small refractive index and a second material layer having a large refractive index are periodically repeated, wherein the first material layer and the second material layer are formed. Between the first material layer and the second material layer.
A hetero-spike buffer layer having a value between
above λ, the design reflection wavelength of the distributed Bragg reflector is λ
A surface emitting laser diode element constituting a light emitting light source, and one end optically coupled to the light emitting light source. A ringed optical fiber transmission line, and a light receiving unit optically coupled to the other end of the optical fiber transmission line, wherein a light emitting light source is installed at a location A and a light receiving unit is installed at a location B. In the meantime, the optical transmission / reception system solves the problem by changing the direction of the optical fiber transmission line by bending the optical fiber transmission line itself so that a local angle is not formed.

The present invention also provides a surface-emitting laser diode device chip comprising an active layer and a resonator structure comprising a reflector provided above and below the active layer. The reflecting mirror comprises a semiconductor distributed Bragg reflecting mirror in which a first material layer having a reflection wavelength of not less than 1.1 μm and having a small refractive index and a second material layer having a large refractive index are periodically repeated. Between the first material layer and the second material layer, a hetero-spike buffer layer having a refractive index between the first material layer and the second material layer having a refractive index of 5 nm or more. A surface emitting laser diode element constituting a light emitting light source, having a configuration in which the design reflection wavelength of the reflecting mirror is set to λ [μm] and (50λ−15) [nm] or less, Optical fiber transmission line optically coupled at one end to a light source A light receiving unit optically coupled to the other end of the optical fiber transmission line, between a point A in the building provided with the light emitting source and a point B in the building provided with the light receiving unit. The problem is solved by an optical transmitting and receiving system, wherein a reflecting member is provided, and the direction change of the optical fiber transmission line is performed by the reflecting member.

The present invention also provides an optical transmission / reception system for performing communication within an apparatus, comprising: an apparatus; a laser light source provided in the apparatus for forming an optical signal; A light receiving unit that receives the optical signal, and a cover member that covers the light emitting element unit and the light receiving element unit of the laser light source and the light receiving unit, wherein the laser light source is an active layer,
A surface emitting laser diode element chip having a resonator structure comprising reflectors provided above and below the active layer, wherein the reflector has a reflection wavelength of 1.1 μm or more and a refractive index of not less than 1.1 μm. A semiconductor distributed Bragg reflector in which a small first material layer and a second material layer having a large refractive index are periodically repeated, and a semiconductor distributed Bragg reflector is provided between the first material layer and the second material layer. A hetero-spike buffer layer having a refractive index between the first material layer and the second material layer having a value of 5 nm or more and a design reflection wavelength of the distributed Bragg reflector being λ [μm] (50λ− 15) An optical transmission / reception system having a structure provided with a thickness of [nm] or less and comprising a surface emitting laser diode element constituting a light emitting light source.

The present invention also solves the above-mentioned problem by applying an optical transmission / reception system provided with a cover member for covering the light emitting element section and the light receiving element section to a recording apparatus using the principle of electrophotography.

The present invention also provides a laser device, a first optical fiber coupled to the laser device and receiving a laser beam formed by the laser device, and a first optical fiber coupled to the first optical fiber. A second optical fiber that transmits an optical signal in the first optical fiber; and a third optical fiber that is coupled to the second optical fiber and receives light in the second optical fiber. A light receiving element coupled to the third optical fiber and receiving light in the third optical fiber, the laser element comprises: an active layer; and an upper part and a lower part of the active layer. A surface emitting laser diode element chip having a resonator structure comprising a reflecting mirror provided, wherein said reflecting mirror has a reflection wavelength of 1.1 μm or more and a first material layer having a small refractive index and a refractive index. Second material with high rate And a periodically distributed semiconductor Bragg reflector, and a refractive index between the first material layer and the second material layer between the first material layer and the second material layer. The hetero-spike buffer layer having a value of 5 nm or more is provided at a thickness of (50λ−15) [nm] or less, where the design reflection wavelength of the distributed Bragg reflector is 5 nm or more and λ [μm]. The problem is solved by an optical transmission / reception system comprising a surface emitting laser diode element constituting a light emitting light source.

The present invention also provides a laser device, a first optical fiber coupled to the laser device and receiving a laser beam formed by the laser device, and a first optical fiber coupled to the first optical fiber. A second optical fiber that transmits an optical signal in the first optical fiber; and a third optical fiber that is coupled to the second optical fiber and receives light in the second optical fiber. A light receiving element coupled to the third optical fiber and receiving light in the third optical fiber, the laser element comprises: an active layer; and an upper part and a lower part of the active layer. A surface emitting laser diode element chip having a resonator structure comprising a reflecting mirror provided, wherein said reflecting mirror has a reflection wavelength of 1.1 μm or more and a first material layer having a small refractive index and a refractive index. Second material with high rate And a periodically distributed semiconductor Bragg reflector, and a refractive index between the first material layer and the second material layer between the first material layer and the second material layer. The hetero-spike buffer layer having a value of 5 nm or more is provided at a thickness of (50λ−15) [nm] or less, where the design reflection wavelength of the distributed Bragg reflector is 5 nm or more and λ [μm]. The first optical fiber is 1
The problem is solved by an optical communication system having a length of at least mm.

According to another aspect of the present invention, there is provided an optical communication system including a laser element and an optical transmission line coupled to the laser element, wherein the laser element includes an active layer,
A surface emitting laser diode element chip having a resonator structure comprising reflectors provided above and below the active layer, wherein the reflector has a reflection wavelength of 1.1 μm or more and a refractive index of not less than 1.1 μm. A semiconductor distributed Bragg reflector in which a small first material layer and a second material layer having a large refractive index are periodically repeated, and a semiconductor distributed Bragg reflector is provided between the first material layer and the second material layer. A hetero-spike buffer layer having a refractive index between the first material layer and the second material layer having a value of 5 nm or more and a design reflection wavelength of the distributed Bragg reflector being λ [μm] (50λ− 15) The optical transmission line is composed of an optical fiber having a core and a clad, and has a diameter of D and a length of the optical fiber L. when, characterized in that the relationship ^{10 5 ≦ L / D ≦ 10} 9 is established The optical communication system, resolve.

According to the present invention, there is provided an optical communication system comprising a laser element, a mounting substrate on which the laser element is mounted, and an optical waveguide coupled to the laser element, wherein the laser element has an active state. A surface emitting laser diode element chip comprising a layer and a resonator structure comprising a reflector provided above and below said active layer,
The reflecting mirror comprises a semiconductor distributed Bragg reflecting mirror in which a first material layer having a reflection wavelength of 1.1 μm or more and having a small refractive index and a second material layer having a large refractive index are periodically repeated. A hetero-spike buffer layer having a refractive index having a value between the first material layer and the second material layer is provided between the material layer and the second material layer. Assuming that the design reflection wavelength of the mirror is λ [μm], (50
.lambda.-15) a surface emitting laser diode element having a thickness of not more than [nm], comprising a surface emitting laser diode element constituting a light emitting light source, and having a linear expansion coefficient between the laser element and the substrate material. Is within 2 × 10 ⁻⁶ / K.

According to the present invention, there is provided an optical communication system comprising a laser device and an optical fiber coupled to the laser device, wherein the laser device includes an active layer, and an upper portion and a lower portion of the active layer. A surface emitting laser diode element chip having a resonator structure comprising a reflecting mirror provided, wherein said reflecting mirror has a reflection wavelength of 1.1 μm or more and a first material layer having a small refractive index and a refractive index. 2nd with high rate
And a semiconductor distributed Bragg reflector in which the material layer is periodically repeated. The refractive index between the first material layer and the second material layer is between the first material layer and the second material layer. A hetero-spike buffer layer having a value between the material layers of the distributed Bragg reflector having a value of λ [μ
m] and a thickness of (50λ−15) [nm] or less, comprising a surface-emitting laser diode element constituting a light-emitting light source, wherein the optical fiber is the laser element of the laser element. The problem is solved by an optical communication system in which the fiber axis direction is pressed toward the light emitting unit and mechanically connected.

The present invention also provides an optical communication system comprising a laser element and an optical fiber or an optical waveguide optically coupled to the laser element, wherein the laser element includes an active layer, A surface emitting laser diode element chip having a resonator structure comprising reflectors provided above and below an active layer, wherein the reflector has a reflection wavelength of 1.1 μm or more and a small refractive index. A semiconductor distributed Bragg reflector in which a first material layer and a second material layer having a large refractive index are periodically repeated, and a refractive index is provided between the first material layer and the second material layer. A hetero-spike buffer layer having a ratio between the first material layer and the second material layer having a value of 5 nm or more and a design reflection wavelength of the distributed Bragg reflector being λ [μm] (50λ−15) ) [N
m] and a surface emitting laser diode element constituting a light emitting light source, wherein the core diameter of the optical fiber or the optical waveguide is X, and the opening of the laser diode is Assuming that the aperture is d and the light emission angle of the laser diode is θ, the optical path length l from the laser diode to the end of the optical fiber or the optical waveguide is expressed by the relation d + 2 tan (θ / 2) ≦ X
Is solved by an optical communication system characterized by the following.

According to the present invention, there is provided an optical communication system comprising a laser device and an optical waveguide coupled to the laser device, wherein the laser device comprises: an active layer;
A surface emitting laser diode element chip having a resonator structure comprising reflectors provided above and below the active layer, wherein the reflector has a reflection wavelength of 1.1 μm or more and a refractive index of not less than 1.1 μm. A semiconductor distributed Bragg reflector in which a small first material layer and a second material layer having a large refractive index are periodically repeated, and a semiconductor distributed Bragg reflector is provided between the first material layer and the second material layer. A hetero-spike buffer layer having a refractive index between the first material layer and the second material layer having a value of 5 nm or more and a design reflection wavelength of the distributed Bragg reflector being λ [μm] (50λ− 15) A surface-emitting laser diode element having a thickness of not more than [nm] and comprising a surface-emitting laser diode element constituting a light-emitting light source, and having a light emitting portion in the surface-emitting laser diode element. Assuming that the diameter of the tangent circle is d and the core diameter of the optical fiber is F, the relationship is The optical communication system .5 ≦ F / d ≦ 2, characterized in that the established, resolve.

According to the present invention, there is provided an optical communication system comprising a laser element and an optical waveguide coupled to the laser chip, wherein the laser element includes an active layer, and an upper portion and a lower portion of the active layer. A surface emitting laser diode element chip having a resonator structure comprising a reflecting mirror provided, wherein said reflecting mirror has a reflection wavelength of 1.1 μm or more and a first material layer having a small refractive index and a refractive index. 2nd with high rate
And a semiconductor distributed Bragg reflector in which the material layer is periodically repeated. The refractive index between the first material layer and the second material layer is between the first material layer and the second material layer. A hetero-spike buffer layer having a value between the material layers of the distributed Bragg reflector having a value of λ [μ
m] (50λ−15) [nm] or less, comprising a surface-emitting laser diode element constituting a light-emitting light source, wherein the surface-emitting laser diode element is provided. Assuming that the area of the light emitting portion of the chip is S (mm ² ) and the operating voltage of the laser element is V (V), V / S is 15000 to 30
The problem is solved by an optical communication system having a range of 000.

According to the present invention, the laser oscillates at a wavelength in the 1.1 to 1.7 μm band suitable for optical fiber communication, such as a computer network or a trunk system of long-distance large-capacity communication. Low heat generation
Surface emitting laser diode capable of performing stable oscillation
However, according to the present invention, by devising a semiconductor distributed Bragg reflector, laser oscillation can be performed in the above-mentioned wavelength range, the operating voltage and oscillation threshold current can be reduced, and the heat generated by the laser element can be reduced. A surface-emitting laser diode that achieves stable oscillation has been realized, and by using such a surface-emitting laser diode, it has become possible to realize a practical point-to-point optical transmission / reception system at low cost. .

In constructing such a point-to-point optical transmission / reception system, in this embodiment, the direction of the transmission line is changed by bending the optical fiber so that a local angle is not formed. An optical transmission / reception system that connects two points easily and at low cost can be realized without damaging the fiber.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] First, a light emitting element applied to an optical communication system according to the present invention, which emits light at a wavelength of 1.1 to 1.7 .mu.m with a small transmission loss. An example of a laser diode will be described with reference to FIG.

As described above, a long-wavelength surface-emitting laser diode that oscillates at a wavelength of 1.1 to 1.7 μm to which the present invention is applied conventionally has only a suggestion of the possibility. However, the materials and the specific and detailed configuration for realization were unknown.

On the other hand, in the present invention, G is used as the active layer.
A clear and specific configuration of a long wavelength surface emitting laser diode using a material such as aInNAs is provided.

In the present invention, n-Ga having a plane orientation of (100) is used.
On the As substrate 11, the composition is Al _x G with a thickness of 1/4 (λ / 4 thickness) of the oscillation wavelength λ in each medium.
n-type AlGaAs represented by a _{1 -x} As (x = 1.0)
and a low refractive index layer made of s, composition _Al y _{Ga 1-y} As
An n-type semiconductor distributed Bragg reflector (AlAs / GaAs lower semiconductor distributed Bragg reflector) 12 is formed by alternately stacking high-refractive-index layers of n-type AlGaAs represented by (y = 0) for 35 periods. composition in a thickness of the above lambda / 4 is _{Ga x in 1-x P y} As 1-y (x = 0.5, y
= 1), an n-type GaInPAs layer 13 was stacked. Wherein in this example n-type _{Ga x In 1-x P y} As
_{The 1-y} (x = 0.5, y = 1) layer 13 is also one of the low-refractive index layers constituting the lower reflecting mirror.

A lower spacer layer 14 of undoped GaAs is formed on the GaInPAs layer 13, and the lower spacer layer 14 has a composition of Ga _x In _{1 -x}
An active layer 15 having a multiple quantum well structure is formed by laminating a quantum well layer 15a represented by As three times via a GaAs barrier layer 15b having a thickness of 20 nm.
5 is an upper spacer layer 1 made of undoped GaAs.
6 are laminated, and the active layer 15 is
Together with 4 and 16, a resonator 15R having a thickness of one oscillation wavelength λ (thickness of λ) in the medium is formed. The resonator 15R forms an active region of the surface emitting laser diode.

In the structure shown in FIG.
On top, the composition doped with C (carbon) is Ga_xIn
_1-xP_yAs_1-y(X = 0.5, y = 1)
A p-type GaInPAs layer 17 is formed.
Zn is doped on the GaInPAs layer 17 and the composition is
Al_xGa_1-xGaAs layer represented by As (x = 0)
And Zn doped and the composition is Al_xGa_1-xAs (x =
1.0) in each medium.
Layers alternately stacked with a thickness of 1/4 of the lasing wavelength λ
The periodic structure (one period) is stacked, and C-doped
The composition is Al_xGa _1-xAs (x = 0.9)
P-type AlGaAs layer and Zn-doped Al
_xGa_1-xP-type GaAs represented by As (x = 0)
Is 1/4 times the oscillation wavelength λ in each medium.
A half having a periodic structure (25 periods) alternately stacked with a thickness
A conductor distributed Bragg reflector 18 is formed. This example
Then, the p-type GaInPAs layer 17 is also a part of the upper reflecting mirror.
And constitutes one of the low refractive index layers.

FIG. 2 shows that the AlAs / GaAs structural unit is composed of 2
4 shows a reflection spectrum of a reflecting mirror formed by stacking four pairs. In the example of FIG. 2, the thickness of the AlAs layer is 93.8 nm.
The thickness of the GaAs layer is set to 79.3 nm, and each of them corresponds to a ｎn wavelength of light having a wavelength in vacuum of 1.1 μm in each layer. . Here, n indicates the refractive index in the AlAs layer or the GaAs layer. Thus, by setting the thickness of each layer of the distributed Bragg reflector to 1 / 4n times the wavelength λ, a high reflectance can be realized in a wide band near the wavelength λ. In the present invention, the λ is called a design reflection wavelength.

Here, the reason why the AlGaAs-based semiconductor material is shown as an example of the semiconductor material of the distributed Bragg reflector is that this material system has the following excellent properties as the material of the distributed Bragg reflector. Because they do. That is, the AlGaAs-based semiconductor material is capable of crystal growth on a GaAs substrate that is inexpensive and easily available, with substantially lattice matching, and has excellent heat dissipation as compared with other semiconductor material systems. In addition, G of a binary material that forms a mixed crystal
The refractive index difference between aAs and AlAs is, for example, 1.3 μm.
In the m band, it is as large as about 0.5, and a high reflectance can be obtained with a smaller number of stacked pairs than other semiconductor material systems.

FIG. 3 shows the configuration of the distributed Bragg reflected light constituting the upper reflecting mirror 18 or the lower reflecting mirror 12.

Referring to FIG.

In this embodiment, each of the upper reflecting mirror 18 and the lower reflecting mirror 12 has a configuration in which the low refractive index layers 18a and the high refractive index layers 18b are alternately laminated. In the meantime, as shown in FIG. 3, Al having a refractive index between the low refractive index layer 18a and the high refractive index layer 18b.
_A hetero-spike buffer layer 18c made of zGa1 _- zAs (0≤y <z <x≤1) is provided.

Referring now to FIG. 3, the reflection wavelength of the surface emitting laser diode applied to the present invention is 1.1 μm.
The configuration of the above reflecting mirror will be described more specifically.

FIG. 3 shows the semiconductor distributed Bragg reflector 18.
Are shown. However, although a similar configuration is also formed for the semiconductor distributed Bragg reflector 12, the configuration of the semiconductor distributed Bragg reflector 12 is substantially the same as the configuration of the semiconductor distributed Bragg reflector 18, and a description thereof will be omitted.

Referring to FIG. 3, in the reflecting mirror having a reflection wavelength of 1.1 μm or more applied to the present invention, the low refractive index layer 18 is used.
between a high refractive index layer 18b, hetero spike buffer layer _{Al z Ga 1-z As (} 0 ≦ y the refractive index takes an intermediate value of the low-refractive index layer 18a and the high refractive index layer 18b <z < x ≦
1) 18c is provided.

Conventionally, it has been studied to provide such a hetero-spike buffer layer for a laser diode having a laser wavelength of 0.85 μm band. , Has not been considered in detail. Further, the laser oscillation wavelength as in the present invention is 1.1 to 1.
No proposal has been made to provide such a heterospike buffer layer for a long-wavelength surface emitting laser diode of 7 μm. This is a new field of long-wavelength surface-emitting laser diodes having an oscillation wavelength of 1.1 to 1.7 μm.
This is probably because little research has been conducted yet.

The present inventor has swiftly recognized that this field, that is, a long-wavelength surface emitting laser having an oscillation wavelength band of 1.1 to 1.7 μm.
He noticed the usefulness of the diode and the optical communication technology using it, and made intensive studies to realize it.

Such a hetero spike buffer layer 18c
In the formation of the semiconductor distributed Bragg reflector 12 or 18, the Al composition in the AlGaAs film constituting the hetero-spike buffer layer 18c is continuously adjusted by controlling the flow rate of the source gas, particularly when using the MOCVD method. Or change it step by step. Along with this, the refractive index of the film also changes continuously or stepwise.

More specifically, the AlGaAs film 18
c during the formation _{of, Al z Ga 1-z As} (0 ≦ y <z <x
≦ 1) The value of the composition parameter z in the layer changes from 0 to 1.0, that is, the film composition is GaAs → AlGa
The supply rates of Ga and Al are changed so as to gradually change from As to AlAs. Such a change in the supply speed
It is created by controlling the gas flow rate during the formation of the film 12c as described above. At this time, the same effect can be obtained by changing the ratio of Al and Ga continuously or stepwise as described above.

The reason for providing such a hetero-spike buffer layer is to solve one of the problems of the semiconductor distributed Bragg reflector, in particular, the problem that the electrical resistance tends to increase in the p-type semiconductor distributed Bragg reflector 18. That's why.
This increase in electric resistance is caused by a hetero barrier at the interface between the two types of semiconductor layers constituting the semiconductor distributed Bragg reflector. It is possible to suppress the generation of the hetero-barrier by changing the Al composition gradually from the composition to the other composition and also changing the refractive index.

Such a hetero spike buffer layer will be described more specifically with reference to FIG.

FIG. 4 shows a semiconductor distributed Bragg reflector 1 in which a hetero-spike buffer layer 18c is provided between two types of semiconductor layers 18a and 18b constituting a semiconductor distributed Bragg reflector.
8 is shown. 4, AlGaAs-based semiconductor material as an example of the material of the semiconductor distributed Bragg reflector _(Al z Ga
_{The case where 1-z} As (0 ≦ y <z <x ≦ 1) is used is shown.

The two types of semiconductor layers 18a and 18b constituting the distributed Bragg reflector 18 of FIG. 4 are AlAs and GaAs, and serve as a hetero-spike buffer layer having a valence band energy intermediate between AlAs and GaAs. A composition gradient layer in which the Al composition is changed is provided between them. _{That, Al z Ga 1-z As} (0 ≦ y <z <x ≦ 1)
The ratio of Al and Ga is gradually changed so that the value of z of the layer changes from 0 to 1.0, that is, GaAs → AlGaAs → AlAs.

In an AlGaAs-based semiconductor material, the band gap energy increases as the Al composition increases, and the refractive index decreases. At this time, in the conduction band, the Al composition x is 0.1.
After the energy increases until reaching 43, the energy starts decreasing, but in the valence band, the valence band energy decreases monotonically in substantially proportion to the increase amount of the Al composition x. As a whole, the band gap energy increases with respect to the composition.

In the case of an AlGaInP-based quaternary material, A
As the lInP composition increases, the A
1 shows the same tendency as the increase in the composition. The conduction band energy is
After the AlInP composition increases to 0.7, it begins to decrease. However, the valence band energy monotonically decreases as the AlInP composition increases.

In the example of FIG. 4, the composition gradient (band-gap energy increase rate) in the region near the GaAs layer (region I in FIG. 4) is calculated using the region gradient near the AlAs layer (region II in FIG. 4). ) Is set to be larger than the composition gradient in ()). For comparison, FIG. 5 shows a structure in which a linear composition gradient layer in which the Al composition is simply changed linearly is used as the hetero-spike buffer layer 18c.

FIG. 6 shows that the interface between the AlAs layer 18a and the GaAs layer 18b having a reflection wavelength of 1.3 μm has a thickness of 20 nm.
m, and the AlAs layer 18 is provided.
a and the GaAs layer 18b are repeated four times (4
It is a result of estimating the electric resistance of the p-type distributed Bragg reflector 18 (stacked pair).

In FIG. 6, the carrier density of each layer 18a to 18c of the distributed Bragg reflector 18 including the hetero-spike buffer layer is 1 × 10 ¹⁸ cm ⁻³ of p-type, and the vertical axis represents the differential sheet resistance near zero bias. Indicates the value. On the other hand, the horizontal axis in FIG. 6 shows the Al composition gradient in the region I, and shows the case where the thickness of the region I is variously changed. However, the sum of the region I and the region II is always 20 nm, and the thickness and the composition gradient of the region II are
It is determined from the thickness of the region I and the composition gradient. Simply GaAs
When a linear composition gradient layer is provided between the AlAs layer and the AlAs layer
The composition gradient is 0.05 nm ⁻¹ , which corresponds to point A in the figure.

FIG. 6 shows that the resistance value can be further reduced by increasing the Al composition gradient in the region I as compared with the case where the composition gradient is simply made linear as shown in FIG. It can also be seen that there is an optimum Al composition gradient that is minimal. For example, the thickness of the region I is 10 nm.
(The same thickness as the region II), the Al composition gradient was 0.09.
In nm ⁻¹ , the resistance is reduced to about 80% of the conventional resistance (and this tendency does not depend on the applied voltage). Next, the reason will be described.

FIG. 7 shows a band structure in a thermal equilibrium state near a heterointerface in a distributed Bragg reflector having an AlAs / GaAs structure.

Referring to FIG. 7, heterospikes caused by band discontinuity mainly appear conspicuously on the AlAs layer side having a wide bandgap, and the occurrence of notches is slight on the GaAs layer side. Since the notch generated on the GaAs layer side does not cause a high resistance, it is necessary to efficiently flatten spikes mainly generated on the AlAs layer side with a limited thickness of the hetero spike buffer layer. It is important for reducing the resistance of the distributed Bragg reflector.

In the structure shown in FIG.
The composition is rapidly increased on the s side, which corresponds to a gradual change in the composition gradient on the AlAs side where spikes occur. This makes it possible to reduce the occurrence of spikes as compared with the case where the composition change of the hetero spike buffer layer is simply linear. Conversely, Al in region I
When the composition gradient is smaller than that in the region II, the resistance value is rather increased.

FIG. 8 schematically shows the band structure of the structure of FIGS. 4 and 5 in a state of thermal equilibrium.

Referring to FIG. 8, by adopting the composition gradient profile of FIG. 3, the composition gradient rate on the AlAs side can be reduced with the same thickness as compared with the case of using the simple composition gradient layer shown in FIG. Can be From the above, region I
It can be understood that the electrical resistance can be reduced as compared with the conventional one by increasing the composition gradient of the sample.

In FIG. 4, the Al composition is changed linearly, and it can be considered that the hetero-spike buffer layer 18c is composed of the regions I and II. However, as shown in FIG. It is also possible to change to. In such a case, the boundaries of regions I and II are:
As shown in FIG. 9, the tangent line to the valence band at the boundary between the hetero spike buffer layer 18c and the GaAs layer 18b, the hetero spike buffer layer 18c and the AlAs layer 18
It can be defined by the intersection with the tangent to the valence band at the boundary with a.

In the hetero spike buffer layer 18c, the Al composition does not need to change continuously.
As shown in FIG. 0, another region may be interposed between the region I and the region II.

According to FIG. 6, the differential sheet resistance of the Bragg reflector decreases as the thickness of the region I decreases. The value of the differential sheet resistance is most reduced when the region I is not provided as shown in FIG. 11 or when the thickness of the region I is sufficiently small as shown in FIG. ) And the hetero-spike buffer layer 18c (wide band gap layer) have discontinuous valence band energy.
Or, it can be understood that this is the case where it can be regarded as having occurred.

FIG. 13 shows the differential sheet resistance of a distributed Bragg reflector similar to FIG. 6 as a function of the Al composition gradient in region II. However, the Al composition gradient in the region II depends on the thickness of the hetero-spike buffer layer 18c and the region I
And the Al composition gradient in the region I.

FIG. 13 shows that, regardless of the thicknesses of the regions I and II, the differential sheet resistance is minimized when the specific composition gradient is within the region II.

FIG. 14 shows the same relationship as in FIG. 13 when the sum of the region I and the region II is 40 nm.
It can be seen that this occurs at the composition gradient.

As shown in FIG. 13 or FIG. 14, in the distributed Bragg reflector having a hetero-spike buffer layer, the gap between the narrow gap layer (GaAs layer 18b in FIG. 3) and the hetero-spike buffer layer 18c constituting the reflector is shown. , The optimum valence band energy discontinuity can be determined.

As described above, in the semiconductor distributed Bragg reflector having the hetero-spike buffer layer, the narrow gap layer 18
By rapidly changing the Al composition in the region I so that the valence band energy becomes discontinuous or can be regarded as discontinuous between the region b and the hetero-spike buffer layer 18c, the Al composition gradient in the region II is reduced. By optimizing, the resistivity can be minimized. For example, by setting the thickness of the region I in the hetero spike buffer layer having a thickness of 20 nm to 1 nm, the distributed Bragg reflector having the same thickness and a hetero spike buffer layer in which the Al composition changes linearly is obtained. On the other hand, the resistance value can be reduced by as much as 75%.

Further, even in such a case, the change in the Al composition in the hetero-spike buffer layer 18c need not be linear, but may be non-linear as shown in FIG.

The above consideration is not limited to the distributed Bragg reflector of the AlGaAs type, but also applies to the distributed Bragg reflector made of another material, for example, the AlGaInP type material. In an AlGaInP-based distributed Bragg reflector, a similar effect can be obtained by changing the AlInP composition in the hetero-spike buffer layer.

Next, such a hetero-spike buffer layer A
The optimum thickness of l _z Ga _1-z As (0 ≦ y <z <x ≦ 1) will be discussed.

FIG. 16 shows the relationship between the reflectivity and the layer 18c in the 0.88 μm band and the 1.3 μm band of the distributed Bragg reflector having the linear composition gradient hetero spike buffer layer 18c shown in FIG. Here, the reason why the designed reflection wavelength of the reflecting mirror is set to 0.88 μm, which is the same as the conventional one, is to compare the characteristics by configuring the same reflecting mirror in each band. GaAs absorbs light having a wavelength shorter than 0.87 μm. In FIG. 16, a GaAs layer is used for the high refractive index layer, and an AlAs layer is used for the low refractive index layer. In each wavelength band, the number of laminated pairs whose reflectance value exceeds 99.9% is 18 pairs or more in the 0.88 μm band and 23 pairs or more in the 1.3 μm band, and FIG. Have
The relationship between the composition gradient layer thickness and the reflectance for a distributed Bragg reflector tuned to each band is shown.

Table 1 shows the reflectance values of FIG.

[0095]

[Table 1] As described above, in the 1.3 μm band, the reflectance is hardly reduced until the thickness of the composition gradient layer 18c reaches 5 nm. However, in the 0.88 μm band, the thickness of the composition gradient layer 18c is 5 mm.
From around nm, a decrease in the reflectivity value begins to be seen. Since the surface-emitting laser element has a short cavity length and is greatly affected by the reflection loss due to the mirror, even a slight decrease in the reflectance value has a large effect on the threshold current value.

FIGS. 17 and 18 show 1.3 μm having the same linear composition gradient layer hetero-spike buffer layer 18c as in FIG.
Near the zero bias of the AlAs / GaAs distributed Bragg reflector tuned to the reflection wavelength (dV / dJ: current density J [A / c] of voltage V [V])
m ² ]] [Ωcm ² ]. However, in the illustrated example, the number of stacked pairs is four. Note that FIG.
Is a logarithmic display, and FIG. 18 is a linear display. FIG. 17, FIG.
In, the broken line indicates the resistivity estimated from the bulk resistance value without considering the effect of band discontinuity. The p-type doping density of the distributed Bragg reflector is 1 × 10 ¹⁸ [cm ⁻³ ] for each layer.

FIG. 17 shows that the resistivity decreases with the thickness of the composition gradient layer 18c. However, since the relative proportion of the composition gradient layer 18c is small in the 1.3 μm band, Table 1 and FIG. When the thickness of the composition gradient layer is 5 nm, the electric resistance is 2 without substantially affecting the reflectance.
It can be reduced by an order of magnitude. When the reflection wavelength is longer, a thicker composition gradient layer can be provided, so that the resistance can be reduced without affecting the reflectance. However, when the thickness is smaller than this, as can be seen from FIG. 17, the effect of reducing the resistance is hardly obtained, so that the composition gradient layer is insufficient.

As shown in FIG. 17, a distributed Bragg reflector having no composition gradient layer 18c (the composition gradient layer has a thickness of 0n).
m), the resistivity is as high as 1 Ωcm ^2, and as a practical problem, for example, when used as a reflector mirror of a surface emitting laser element, a laser diode is connected via a distributed Bragg reflector stacked in 20 pairs or more. It is difficult to drive. Also, a very high drive voltage is required. Therefore, it is difficult to apply such a distributed Bragg reflector to a current driven optical device such as a surface emitting laser device.

However, when the composition gradient layer having a thickness of 5 nm is provided as described above, the electric resistivity is reduced by about two digits as compared with the case where the composition gradient layer is not provided. As a result, energization of the laser diode becomes easy, and laser oscillation becomes possible. Also, since the voltage required for energization is reduced,
Various problems related to reliability, such as destruction and failure of elements, are also greatly improved. Further, as shown in Table 1, since there is almost no decrease in reflectance, oscillation can be obtained with a low threshold current density.

As described above, the thickness of 5 nm can be considered as the lower limit of the thickness of the composition gradient layer that can reduce the resistance without affecting the reflection characteristics in the long wavelength band. Therefore, it is appropriate that the thickness of the hetero spike buffer layer 18c be 5 nm or more.

When the thickness of the composition gradient layer is further increased, the resistivity sharply decreases, and accordingly, the operating voltage of the device and the heat generation of the device also decrease. Therefore, the temperature at which oscillation can be maintained and the output obtained are increased.

For example, when 99.8% is taken as the allowable value of the reflectance, the thickness of the composition gradient layer that can be provided in the distributed Bragg reflector tuned to the 0.88 μm band is limited to 20 nm. On the other hand, in the distributed Bragg reflector tuned to the 1.3 μm band, the thickness of the composition gradient layer can be set to 50 nm.

As shown in FIG. 6, the resistance value of the distributed Bragg reflector is 50 n in thickness of the hetero buffer layer 18c.
m, effectively decreasing with the thickness of layer 18c,
8c is 50 nm thick and the resistivity is 1.0 of the bulk resistivity.
Although it is about five times, even if the thickness of the hetero buffer layer 18c is further increased, the resistivity starts to show a saturation tendency.

However, the reflectivity of the distributed Bragg reflector starts to decrease rapidly as the thickness of the hetero-spike buffer layer 18c increases, and drops to 99.8% or less when the thickness is 50 nm or more. Therefore, it is considered that the thickness of the hetero-spike buffer layer 18c that satisfies both of these characteristics at the same time has a practical significance within 50 nm.

FIG. 19 shows how the reflectivity decreases in detail. However, FIG. 19 shows the hetero spike buffer layer 18c.
Of the reflectivity R (| dR / dt |) with respect to the thickness t of FIG.

As compared with the tangent line shown in FIG. 19, when the thickness of the hetero spike buffer layer exceeds about 50 nm,
It can be seen that the reflectance changes abruptly. The oscillation threshold current of the laser diode starts to increase correspondingly sharply.

As described above, for example, 5 nm or more, 50
In a distributed Bragg reflector having a designed reflection wavelength of 1.3 μm provided with a hetero-spike buffer layer having a thickness of not more than nm, it is possible to effectively reduce the resistance due to the influence of the hetero interface, and to simultaneously achieve a high reflectance. Obtainable. In a surface emitting laser element using this, it is possible to easily obtain oscillation at a low threshold current under realistic driving conditions.

Further, for example, in order to increase the output of a surface emitting laser, it is necessary to set the mirror reflectivity on the light output side to a small value and to design the light output easily. In addition, in order to stably oscillate up to a high output (high injection region), it is necessary to suppress heat generation of the element and set an output saturation point due to heat as high as possible. A distributed Bragg reflector provided with a relatively thick material layer such as 50 nm (in this example, a heterospike buffer layer) satisfies these conditions and is suitable for high-power applications.

As described above, in the long-wavelength surface emitting laser diode of the present embodiment, by appropriately selecting the thickness of the hetero-spike buffer layer 18c in the range of 5 nm to 50 nm according to the purpose, the reflection characteristics of the reflector can be improved. And electrical properties can be optimized.

In the example shown in FIG. 3, the low refractive index layer 1
Although 8a is an AlAs layer and the high refractive index layer 18b is a GaAs layer, two types of AlGaAs layers having different Al compositions can be used. However, in the distributed Bragg reflector, the higher the refractive index difference between the low refractive index layer and the high refractive index layer constituting the reflecting mirror, the higher the reflectance can be obtained with a smaller number of laminated pairs. In order to obtain the refractive index, it is preferable to make the difference in Al composition between the low refractive index layer and the high refractive index layer as large as possible. The structure of FIG.
FIG. 9 shows a combination in which the difference in refractive index is largest due to As.

By the way, in such a combination having a large difference in Al composition, as described above, the amount of valence band discontinuity that causes a hetero-spike also increases, so that good reflection characteristics can be obtained. On the other hand, there is a problem that the element resistance is likely to increase. In particular, when such a large refractive index difference can be realized between the high refractive index layer and the low refractive index layer, the valence band discontinuity is large. It is necessary to provide a hetero spike buffer layer having a large thickness. However, the conventional 0.
This was difficult with a distributed Bragg reflector tuned to the 85 μm band. On the other hand, in the distributed Bragg reflector of the present invention, even when a material such as GaAs / AlAs is used, a high reflectance and a low resistance can be obtained at the same time.

In the distributed Bragg reflector shown in FIG. 3, especially when the reflector is tuned to a long wavelength band of 1.1 μm or more, the hetero-spike buffer layer 18c
Can be set in a range from 20 nm to 50 nm.

By the way, when looking at FIG. 17 in detail, the resistivity of the distributed Bragg reflector initially shows that the hetero-spike buffer layer 1
It can be seen that the thickness rapidly decreases with an increase in the thickness of 8c, and then gradually approaches the bulk resistivity. In the example of FIG. 17, the thickness of the composition gradient layer at which the decrease in resistivity starts to saturate is about 20 nm. When the thickness of the hetero spike buffer layer 18c is 20 nm, the resistivity is about 2 times the bulk resistance value.
It has been reduced to about twice. Therefore, by setting the thickness of the composition gradient layer in the range of 20 nm or more and 50 nm or less, it is possible to obtain a distributed Bragg reflector whose resistivity is reduced to about the bulk.

FIG. 20 is a band structure diagram showing a configuration example of another distributed Bragg reflector according to the present invention.

In the example shown in FIG. 20, in the distributed Bragg reflector having the structure shown in FIG. 3, a GaAs layer is used as the high refractive index layer 18b, and Al _0.8 Ga _0.2 As is used as the low refractive index layer 18a.
A layer having a composition gradient of 30 nm in thickness is used as the hetero-spike buffer layer 18c. FIG.
In the example, the composition gradient layer is formed as a parabolic composition gradient layer (for example, an AlGaAs parabolic composition gradient layer) in which the valence band energy changes parabolically with the thickness. That is, the parabolic composition gradient layer changes so that the valence band side energy becomes convex downward toward the Al _0.8 Ga _0.2 As layer having a wide band gap.

In the configuration shown in FIG. 20, the design reflection wavelength (λ) of the distributed Bragg reflector, that is, the tuning wavelength is 1.5 μm, and Al _0.8 G for a wavelength of 1.5 μm.
a _0.2 n / 4 (effective wavelength) of As layer and GaAs layer
And thickness were 110.8 nm and 12 mm, respectively.
5.5 nm. Here, n is the refractive index of each semiconductor layer for a wavelength of 1.5 μm. In the distributed Bragg reflector of FIG. 20, the thickness of each semiconductor layer is
The optical length of the parabolic composition gradient layer 18c (50 nm in thickness) is adjusted so as to have an optical thickness reduced. Here, the low refractive index layer is formed, for example, of Al _0.6 Ga _0.4
If it is an As layer, it will be equivalent to an example described later.
In this case, the λ / 4n thickness of the Al _0.6 Ga _0.4 As layer with respect to 1.5 μm is 121.7 nm.

Further, each semiconductor layer constituting the distributed Bragg reflector has an Al _0.8 Ga _0.2 As layer, a GaAs layer, and a parabolic composition gradient layer each having a carrier density of 5 × 10 ¹⁷ cm ^-3 . P-type doping is performed uniformly.

In the embodiment shown in FIG. 20, a distributed Bragg reflector is used.
Doping density is 5 × 10¹⁷cm ^-3And conventional distribution bra
The value is lower than that of the mirror, but is relatively thick, 50n.
m as a hetero-spike buffer layer 18c.
The resistance value is reduced to about the resistance value of the bulk layer
Has been reduced. Also, the doping density was set low.
As a result, light absorption between valence bands is small,
A distributed Bragg reflector with low loss can be obtained.
In addition, the design reflection wavelength is 1.5 μm and the conventional 0.85 μm band
Is very long compared to a distributed Bragg reflector,
Very thick parabola of 50nm easily with high emissivity
A linear composition gradient layer can be provided. As a result, the light
The chemical characteristics are also good. As described above,
To obtain a distributed Bragg reflector with low resistance and high reflectivity
it can.

In the embodiment of FIG. 20, a parabolic composition gradient layer is used as the hetero-spike buffer layer 18c.
8c may be another one. Further, the design reflection wavelength of the distributed Bragg reflector may be other than 1.5 μm, and the Al composition of the low refractive index layer may be another value. Further, a different doping density may be set for each semiconductor layer.

In this embodiment, the designed reflection wavelength is 1.1 μm
In the long-wavelength band distributed Bragg reflector described above, the thickness of the hetero-spike buffer layer 18c is set to 30 nm to 50 nm. As the thickness of the layer 18c increases as shown in FIG. 17, the resistivity of the distributed Bragg reflector rapidly decreases to a certain thickness. The thickness of the composition gradient layer where the sharp decrease in resistivity is observed is related to the doping density of the distributed Bragg reflector.

For example, FIG. 21 shows AlAs / Ga of FIG.
The case where the doping concentration of each layer is set to 7 × 10 ¹⁷ cm ⁻³ in the As distributed Bragg reflector is shown.

When the doping density is low as shown in FIG. 21, the range in which the resistivity of the hetero-spike buffer layer 18c rapidly decreases is as large as about 30 nm. It changes linearly.
In particular, in a p-type distributed Bragg reflector, light absorption increases as the hole density (doping density) increases due to light absorption between valence bands in addition to free carrier absorption. This may cause an increase in the threshold current. Therefore, it is preferable that the carrier density is low in terms of optical characteristics. In addition, since absorption between valence bands becomes remarkable for light having a long wavelength, particularly in a wavelength band of 1.1 μm or more,
It is important to keep absorption losses low. Further, in a conventional distributed Bragg reflector including a layer having a doping density exceeding 1 × 10 ¹⁸ cm ⁻³ , it is difficult to reduce absorption loss.

For such a reason, the first semiconductor layer (having a large refractive index) and the second semiconductor layer (having a small refractive index) or a material layer (compositionally graded layer) constituting a distributed Bragg reflector are used. In some cases, the doping density of any or all of the layers may be intentionally low (1 × 10 ¹⁸ cm ⁻³ or less). However, in the distributed Bragg reflector having the reduced doping density, the effect of the hetero interface becomes more remarkable due to the increase in the width of the vacancy layer, and the electric resistance tends to increase. For example, when the doping density is slightly lowered for such a reason, a thicker composition gradient layer is necessary to reduce the influence of the hetero interface and reduce the resistance value. The effect is remarkably exhibited from a thickness of 30 nm or more. In the case where the doping density is further reduced, a composition gradient layer having a larger thickness is required. However, by providing a composition gradient layer having a thickness within the above range such as 40 nm or 50 nm, the hetero interface can be reduced. The effect can be effectively reduced. The same can be said for the case where the layer constituting the distributed Bragg reflector is made of AlGaAs or the like in addition to AlAs.

FIG. 22 is a graph showing the relationship between Al _0.8 Ga _0.2 As / GaAs.
22 is a diagram in which the resistance value of the four-pair distributed Bragg reflector is calculated in the same manner as in FIG. In FIG. 22, the doping density of each layer is set further lower, and is set to 5 × 10 ¹⁷ cm ⁻³ .

Also in this case, when the thickness of the hetero-spike buffer layer 18c is 30 m or more, the resistivity of the distributed Bragg reflector is almost equal to the bulk resistivity. For example, for the above-described reason, the doping density of one or all of the high refractive index layer 18b, the low refractive index layer 18a, and the hetero-spike buffer layer 18c (composition gradient layer) constituting the distributed Bragg reflector is conventionally reduced. Smaller (1 × 10 ¹⁸ cm ^-3
In the distributed Bragg reflector set below, when the thickness of the hetero-spike buffer layer 18c is 30 nm, the resistivity of the distributed Bragg reflector starts to saturate. Therefore, when the doping density of at least one layer constituting the distributed Bragg reflector is 1 × 10 ¹⁸ cm ⁻³ or less, as described above, the composition gradient layer having a thickness in the range of 30 nm to 50 nm should be used. Thereby, the resistance value can be effectively reduced.

Of course, the thickness of the hetero-spike buffer layer 18c in the above range is such that the resistance can be effectively reduced even in a distributed Bragg reflector having a higher doping density, and includes the distributed Bragg reflector. All layers are 1
It may be used when it is doped to at least × 10 ¹⁸ cm ⁻³ . However, especially with a doping density of 1 × 10 ¹⁸ cm ⁻³ or less and a heterospike buffer layer thickness of 30 nm to 50 nm, by properly selecting them, both absorption loss and electrical resistance can be reduced. At the same time, it can be reduced.

Further, by using the distributed Bragg reflector of the embodiment shown in FIG. 22 as a reflector mirror of a surface emitting laser element, a surface emitting laser element having excellent element characteristics can be obtained. Also, as described above, 30 nm to 5 nm
The thickness of the hetero-spike buffer layer of 0 nm is difficult to realize with the conventional distributed Bragg reflector used in the 0.85 μm band or the like, and the wavelength targeted by the present invention is 1.1 μm or longer. For the first time, the distributed Bragg reflector can be provided without deteriorating the optical characteristics.

In the distributed Bragg reflector of the present invention, the low refractive index layer 18a and the high refractive index layer 18b constituting the distributed Bragg reflector are made of AlAs, GaAs, or AlGaAs.
It is also possible to form a mixed crystal and make the Al composition difference between the high refractive index layer and the low refractive index layer less than 0.8.

In such a distributed Bragg reflector made of an AlGaAs-based semiconductor material, if the Al composition difference between the high refractive index layer and the low refractive index layer is less than 0.8: The electrical resistance can be effectively reduced while keeping the reflectance of the semiconductor distributed Bragg reflector having a designed reflection wavelength in a wavelength band longer than 1 μm high.

In an AlGaAs mixed crystal semiconductor, the valence band energy decreases monotonously with an increase in the Al composition. The AlGaAs mixed crystal having a larger Al composition has a larger band discontinuity with the GaAs single crystal, and has a larger potential at the hetero interface. A barrier is formed. This causes a high resistance. The decrease in valence band energy is substantially proportional to the Al composition, and the band discontinuity between semiconductor layers having different Al compositions corresponds to the Al composition difference.

FIGS. 23 and 24 show the resistivity of four pairs of p-type distributed Bragg reflectors whose design reflection wavelength is 1.3 μm.
It is the figure which changed and showed the thickness of the hetero spike buffer layer.
23 and 24, in the distributed Bragg reflector, the high refractive index layer 18b is made of GaAs, and the low refractive index layer 18a is made of AlA.
s, Al _0.8 Ga _0.2 As, Al _0.6 Ga _0.4 As
Seed for species. The thickness of each semiconductor layer is set to １ ／ optical thickness of the design wavelength according to the refractive index of the material. The doping density of the semiconductor layer was 5 × 10 ¹⁷ cm ⁻³ in FIG. 23 and 1 in FIG.
× 10 ¹⁸ cm ^-3 . The doping concentration of 1 × 10 ¹⁸ cm ⁻³ is a typical value used for doping a p-type distributed Bragg reflector.

FIGS. 23 and 24 show that the AlGaAs layer
It can be seen that a distributed Bragg reflector having a larger composition has a higher resistivity when the heterospike buffer layer is thinner, and also requires a thicker heterospike buffer layer to realize a low resistance value such as bulk. For example, in a distributed Bragg reflector using an Al _0.6 Ga _0.4 As layer and a GaAs layer as the low refractive index layer 18a and the high refractive index layer 18b, respectively, the band discontinuity in the valence band is about 300 meV, The band discontinuity of the valence band is about 400 meV between Al _0.8 Ga _0.2 As and GaAs.

In the case of a distributed Bragg reflector made of AlAs and GaAs, the thickness of the hetero-spike buffer layer required to effectively reduce the resistivity depends on the doping density, but the results shown in FIGS. When considered together, 2
It can be seen that a heterospike buffer layer having a thickness of 0 nm or more may be provided. Looking at the band discontinuity of the semiconductor material forming the distributed Bragg reflector in this way,
When the band discontinuity is less than 400 meV, that is, when the Al composition difference is less than 0.8, the resistivity of the distributed Bragg reflector can be effectively reduced by setting the thickness of the hetero-spike buffer layer to 20 nm or more. .

In practice, the increase in the resistance of the distributed Bragg reflector due to the band discontinuity depends not only on the height and thickness of the barrier but also on the effective mass of holes as carriers. However, the effective mass of heavy holes is limited by AlGaAs, AlGaInP, GaI, which are usually used as distributed Bragg reflectors.
There is no significant difference between nAsP-based materials as much as the effective mass of electrons, and the band discontinuity can be considered as a measure of the resistance at the heterointerface. Therefore, when the band discontinuity of the valence band is less than 400 meV, that is, when the Al composition difference is less than 0.8, the use of a hetero-spike buffer layer having a thickness of 20 nm or more enables more effective electric power. It is possible to reduce the resistivity.

As described above, the upper limit thickness of the composition gradient layer is selected in a range where the reflectance does not decrease significantly in consideration of the design reflection wavelength of the distributed Bragg reflector. In addition, a distributed Bragg reflector having excellent electrical and optical characteristics can be obtained.

In the distributed Bragg reflector having the structure shown in FIG. 3, the second semiconductor layer constituting the distributed Bragg reflector having a small refractive index and the first semiconductor layer having a large refractive index are composed of AlAs, GaAs, Alternatively, a difference in Al composition between a first semiconductor layer having a large refractive index and a second semiconductor layer having a small refractive index, which is formed of an AlGaAs mixed crystal, is 0.8 or more.

In this embodiment, in a distributed Bragg reflector made of an AlGaAs-based semiconductor material,
The Al composition difference between the low-refractive-index layer 18a and the high-refractive-index layer 18b constituting the distributed Bragg reflector can be set to 0.8 or more. Also in this case, in a semiconductor distributed Bragg reflector having a design reflection wavelength in a wavelength band longer than 1.1 μm, the resistance can be effectively reduced while keeping the reflectance high.

In AlAs and GaAs, the band discontinuity of the valence band is about 500 meV, and the AlAs layer and the GaAs
To effectively reduce the resistivity of a distributed Bragg reflector consisting of an s layer, a thick heterospike buffer layer is required (depending on the doping density). In such a case, considering the results of FIGS.
It is understood that a composition gradient layer having a thickness of 30 nm or more may be provided. When attention is paid to the band discontinuity of the semiconductor material constituting the distributed Bragg reflector, if the band discontinuity is 400 meV or more, the thickness of the hetero-spike buffer layer should be 30 nm or more. Thereby, the resistance can be effectively reduced.

The relationship between the Al composition difference and the valence band discontinuity has the relationship described in the embodiments of FIGS. 23 and 24. The valence band discontinuity of 400 meV corresponds to the Al composition difference of 0.1 meV.
8 or more. Therefore, when the Al composition difference is 0.8 or more, the thickness of the hetero-spike buffer layer is 3
When the thickness is 0 nm or more, the thickness can effectively reduce the resistance. By providing the composition gradient layer having this thickness, the resistivity can be effectively reduced.

Further, as described above, the upper limit thickness of the composition gradient layer is selected by taking the design reflection wavelength of the distributed Bragg reflector into consideration and selecting a thickness within a range where the reflectance does not decrease significantly. In addition, a distributed Bragg reflector having excellent electrical and optical characteristics can be obtained.

In the distributed Bragg reflector of the present invention, when the designed reflection wavelength is longer than 1.1 μm, the thickness of the hetero-spike buffer layer is adjusted to the designed reflection wavelength λ [μm] of the distributed Bragg reflector. And (50λ-15) [n
m] or less. Even in such a case, the heterospike buffer layer has a function of effectively reducing the resistance while keeping the reflectance of the distributed Bragg reflector high.

FIG. 25 shows the relationship between the thickness of the hetero-spike buffer layer and the reflectivity for a distributed Bragg reflector having a designed reflection wavelength of 1.1 μm to 1.7 μm. The distributed Bragg reflector has the structure of FIG. 3 described above, and GaAs is used as the high refractive index layer 18b, and the low refractive index layer 1
An AlAs layer is used as 8a. Further, the number of pairs of the distributed Bragg reflector is such that the reflectance at each wavelength exceeds 99.9% for the first time. That is, there are 18 pairs at 0.88 μm, 22 pairs at 1.1 μm, 23 pairs at 1.3 μm, 23 pairs at 1.5 μm, and 24 pairs at 1.7 μm.

FIG. 26 shows the change rate (| dR / dt) of the reflectance of FIG. 25 with respect to the thickness of the hetero-spike buffer layer.
|) Are indicated. From FIG. 25, it can be seen that the reflectance of the reflecting mirror decreases as the thickness of the hetero-spike buffer layer increases. FIG. 26 also shows that the rate of decrease in reflectance sharply increases at a certain thickness of the hetero-spike buffer layer. In FIG. 26, the slope of the reflectance change rate is indicated by a straight line in order to make this situation easier to understand. That is, the straight line in FIG. 26 represents a tangent drawn to the thickness at which the reflectance starts to decrease. For example, focusing on a distributed Bragg reflector having a designed reflection wavelength of 1.3 μm, FIG.
6, it can be seen that the rate of change of the reflectance sharply increases when the thickness of the hetero-spike buffer layer exceeds 50 nm. In FIG. 25, in response to this, the reflectance of the distributed Bragg reflector starts to decrease sharply. Therefore, in a surface emitting laser device using such a distributed Bragg reflector as a reflector, the oscillation threshold current sharply increases at this point. Further, as shown in FIG. 26, the thickness of the hetero-spike buffer layer at which the rate of change of the reflectance sharply increases differs depending on the design wavelength band of the semiconductor distributed Bragg reflector. That is, the longer the distributed Bragg reflector having the designed reflection wavelength of longer wavelength, the thickness of each semiconductor layer constituting the reflector becomes thicker, so that the influence of the thickness of the hetero-spike buffer layer is reduced.

As described above, the thickness (threshold thickness) of the hetero-spike buffer layer at which the rate of change starts to increase sharply differs depending on the design reflection wavelength of the distributed Bragg reflector, but the threshold of the rate of change at which the rate of change starts to increase sharply. Does not depend much on the wavelength, and is approximately 0.09 as shown in FIG.

Table 2 shows the threshold thickness for each wavelength shown in FIG.

[0146]

[Table 2] From Table 2, the design reflection wavelength and the threshold thickness have a substantially linear relationship, and when the relationship between the threshold thickness t [nm] and the design reflection wavelength λ [μm] of the distributed Bragg reflector is obtained, the equation t = It can be seen that there is a relationship of 50λ-15 (Equation 1).

Therefore, for a distributed Bragg reflector having a design reflection wavelength λ of not less than 1.1 μm, a material layer having a thickness of not more than t determined by the equation 1 is provided as a hetero-spike buffer layer, thereby increasing the height. It is possible to obtain a low-resistance distributed Bragg reflector having a low reflectance. In the above-described example, the hetero-spike buffer layer is assumed to be a linear composition gradient layer, but the above-described nonlinear layer may be used. Also in this case, similar results and effects can be obtained.

In the present invention, the designed reflection wavelength is 1.1.
In a distributed Bragg reflector having a wavelength longer than μm, the thickness of the hetero-spike buffer layer can be set to 20 nm or more. Also in this case, the material layer can effectively reduce the resistance of the reflector while keeping the reflectance high.

As described above, there is a relationship represented by the following equation (1) between the heterospike buffer layer that can keep the reflectance of the distributed Bragg reflector high and the designed reflection wavelength.

Regarding the electrical characteristics of the distributed Bragg reflector, as described above, as the thickness of the hetero-spike buffer layer is increased, the influence of the semiconductor hetero interface can be reduced, and the distribution of the distributed resistance is lower. A Bragg reflector can be obtained. Further, the resistance reduction effect of the hetero-spike buffer layer is determined by the material of the distributed Bragg reflector, the doping density and the profile, and is essentially independent of the reflection wavelength band. Therefore, there is a lower limit to the composition gradient layer from which the effect of lowering the resistance can be sufficiently obtained. In order to obtain a distributed Bragg reflector having sufficiently low resistance, it is necessary to provide a composition gradient layer having a certain thickness or more.

For example, as shown in FIG. 24, 1 × 10 ¹⁸ cm
^For a distributed Bragg reflector uniformly doped to a density of ^-3 , if the thickness of the heterospike buffer layer is less than 20 nm,
It can be seen that the resistivity of the distributed Bragg reflector is orders of magnitude larger than the bulk resistivity, but that it decreases to the same order as the bulk resistivity above 20 nm. Therefore, when the doping density is as described above, it is preferable in terms of electrical characteristics that the thickness of the hetero-spike buffer layer be set to 20 nm or more.

From the above results, by selecting the thickness t [nm] of the hetero-spike buffer layer within the range of 20 ≦ t ≦ 50λ−15 with respect to the design reflection wavelength λ [μm] of the distributed Bragg reflector, It can be seen that a distributed Bragg reflector excellent in characteristics having sufficiently low electrical resistance and high optical reflectivity can be obtained.

In the distributed Bragg reflector of the present invention, the thickness of the hetero-spike buffer layer can be set to 30 nm or more. Even in such a case, the heterospike buffer layer has a function of effectively reducing the resistance of the distributed Bragg reflector while maintaining the reflectance of the distributed Bragg reflector having a design reflection wavelength longer than 1.1 μm high. ing.

In a semiconductor material, even for a photon having an energy smaller than the forbidden band width, light absorption tends to increase with an increase in free carriers. In addition, in a p-type semiconductor, an increase in holes as carriers is caused. Accordingly, light absorption due to valence band absorption occurs remarkably. Further, since the valence band absorption increases as the wavelength becomes longer, the designed reflection wavelength becomes 1.
This is a particular problem with distributed Bragg reflectors having longer wavelengths than 1 μm, and their light absorption causes a reduction in the reflectivity of the distributed Bragg reflector. Further, in a laser diode using this as a reflecting mirror, an increase in threshold current, a decrease in efficiency, and the like occur due to light absorption. Therefore, in terms of reducing light absorption, it is preferable that the doping density of the semiconductor layer be as low as possible. However, as the doping density is reduced, the thickness of the depletion layer at the hetero interface increases, so that the influence of the potential barrier at the interface increases,
This causes the resistivity to increase.

Therefore, for example, in a semiconductor distributed Bragg reflector in which the doping density is reduced for the purpose described above, a thicker heterospike buffer layer is required to reduce the resistivity. When such a distributed Bragg reflector is doped to, for example, about 5 × 10 ¹⁷ cm ⁻³ , the results of FIG. 23 show that the heterospike buffer layer has a thickness of 30 nm or more and a resistivity of 30 nm or more. It can be seen that it is reduced to the same level as bulk.

Various combinations are conceivable as the doping density and profile of the semiconductor layer, and the types are enormous. However, when the doping density of at least one semiconductor layer is less than 1 × 10 ¹⁸ cm ⁻³ , a similar tendency appears. This is because the height and barrier thickness of the potential barrier formed at the hetero interface are determined by the doping density of the semiconductor layer in contact with the hetero interface.
The lower the doping density is, for example, 1 × 10 ¹⁸ cm ⁻³ , the greater the influence of the hetero interface. In addition, the electrical characteristics are mainly determined by the hetero interface having a low doping density. The present invention has a great effect on the semiconductor layer constituting at least one of the distributed Bragg reflectors in which the doping density of at least one semiconductor layer is less than 1 × 10 ¹⁸ cm ^−3. .

Further, here, the results of the above-described doping densities are shown as an example, but a distributed Bragg reflector doped in the order of 1 × 10 ¹⁷ cm ⁻³ shows substantially the same results. Of course, the doping density may be in a lower range, and in this case, the resistance can be similarly reduced by setting the thickness of the hetero-spike buffer layer to 30 nm or more within the above upper limit. Can be.

As described above, with respect to the design reflection wavelength λ [μm] of the distributed Bragg reflector, the thickness t [nm] of the material (gradient composition layer) is selected in the range of 30 ≦ t ≦ 50λ−15. Accordingly, it is possible to obtain a distributed Bragg reflector excellent in characteristics having sufficiently low electrical resistance and high optically high reflectance.

As described above, the conventional wavelength is 0.85.
The provision of such a hetero-spike buffer layer for a laser diode in the .mu.m band has been studied. However, a long-wavelength surface emitting laser diode having a laser oscillation wavelength of 1.1 to 1.7 .mu.m as in the present invention is proposed. -Is more effective in the case of. Because, for example, the equivalent reflectance (for example, 99.5% or more)
In order to obtain a value of 1.1 to 1.7 from the 0.85 μm band,
In the case of the μm band, the thickness of such a material layer can be approximately doubled, so that the resistance value of the semiconductor distributed Bragg reflector can be reduced. As a result, the operating voltage,
The oscillation threshold current and the like are reduced, and advantages can be obtained in terms of prevention of heat generation of the laser element, stable oscillation, and low-energy driving.

As described above, the provision of such a hetero-spike buffer layer in a semiconductor distributed Bragg reflector requires a long-wavelength surface emitting laser diode having a laser oscillation wavelength of 1.1 to 1.7 μm as in the present invention. Can be said to be an especially effective device.

As an example of a more detailed examination result for obtaining an effective reflectivity, for example, in a 1.3 μm band surface emitting laser device, Al _x Ga is used as a low refractive index layer.
_1-x As (x = 1.0) and A as a high refractive index layer
_{l y Ga 1-y As (} y = 0) when the 20-period stacking, the reflectivity of the semiconductor distributed Bragg reflector is 99.7% or less _{Al z Ga 1-z As (} 0 ≦ y <z <x ≦ 1)
The thickness of the layer is 30 nm. The reflectivity is 99.5%
The thickness of the hetero spike buffer layer described above is 53 nm. Therefore, when the reflectance is designed to be 99.5% or more, ±
It is sufficient if the film thickness can be controlled by 2%. Then, when prototypes having a film thickness of 10 nm, 20 nm and 30 nm which are equivalent to and thinner than this were produced, it was possible to keep the reflectivity to a practically negligible level. A 1.3 μm band surface emitting laser device with reduced laser emission was realized, and laser oscillation was also successful. Other configurations of the prototyped laser device are as described below. In the multilayer mirror, there is a band having a high reflectance including the design wavelength (assuming that the film thickness control is completely performed). This is called a high reflectance band (including a region where the reflectance is equal to or higher than a required value for a target wavelength). In the high reflectance band, the reflectance is the highest at the design wavelength, and the reflectance decreases very little as the wavelength increases. Beyond a certain area, the reflectivity drops sharply.

Therefore, it is necessary to completely control the thickness of the multilayer mirror at the atomic layer level so that the reflectance higher than the required reflectance is obtained at the target wavelength. However, actually, since a film thickness error of about ± 1% occurs, the target wavelength and the wavelength having the highest reflectance usually shift. For example, when the target wavelength is 1.3 μm, if the film thickness control is shifted by 1%, the wavelength having the highest reflectance is shifted by 13 nm. Therefore, it is desirable that the high reflectivity band (here, defined as a region where the reflectivity is equal to or more than a required value with respect to the target wavelength) is wide.

As described above, the oscillation wavelength of the present invention is 1.1 to 1.0.
In a 1.7 μm long-wavelength surface emitting laser diode, by devising and optimizing the configuration of such a semiconductor distributed Bragg reflector, it is possible to reduce the resistance value while maintaining a high reflectance. Therefore, the operating voltage, the oscillation threshold current, and the like can be reduced, and the heat generation of the laser element can be prevented, and stable oscillation and low-energy driving can be performed.

Referring again to FIG. 1, the composition is Al _x Ga _{1 -x} A on the upper semiconductor distributed Bragg reflector 18.
The p-type GaAs layer 19 represented by s (x = 0) is formed as a contact layer (p-contact layer) for making contact with the p-side electrode electrode 20.

In the structure shown in FIG. 1, the I
The n composition x was 39% (Ga _0.61 In _0.39 As). The thickness of the quantum well active layer was 7 nm. The quantum well active layer has a compressive strain of about 2.8% with respect to the GaAs substrate.

In the surface emitting laser diode shown in FIG. 1, each semiconductor layer is formed by MOCVD. In this case, no lattice relaxation phenomenon was observed. Raw materials constituting each layer of the laser diode include TMA (trimethyl aluminum), TMG (trimethyl gallium), TMI (trimethyl indium), AsH ₃ (arsine), PH ₃
(Phosphine) was used. The carrier gas is H
₂ was used. In the case where the active layer (quantum well active layer) has a large strain as in the device of FIG. In this case, the GaInAs layer 15a (quantum well active layer) is grown at 550 ° C. The MOCVD method used here has a high degree of supersaturation and is suitable for crystal growth of a high strain active layer. In addition, high vacuum is not required as in the MBE method, and the supply flow rate and supply time of the source gas may be controlled.

In the illustrated laser diode, a portion outside the current path forms a high-resistance region 15F by proton (H ⁺ ) ion implantation to form a structure in which the current is narrowed.

Further, in the structure of FIG. 1, the p-type contact layer formed on the uppermost layer of the upper reflecting mirror 18 and constituting a part of the upper reflecting mirror 18 except for the light emitting portion 20A has the p-type structure.
A side electrode 20 is formed, and an n-side electrode 21 is formed on the back surface of the substrate.

In this embodiment, the upper and lower reflecting mirrors 12 and 18 are used.
Active region (in this embodiment, upper and lower spacer layers 16 and 14) in which carriers are injected and recombination occurs.
And a multiple quantum well active layer 15), do not use a material containing Al (1% or more of the group III) in the active region, and further use the lower reflector 12 and the upper reflector 18 most layer near the active layer _Ga x _{an in} of the low refractive index layer of _{1-x P y As 1-} y (0 <x ≦ 1,0 <y
.Ltoreq.1). That is, by appropriately selecting the value of x or y, GaInP, GaInPAs, or GaInP
PAs are used as a non-radiative recombination prevention layer. Note that this layer, there is a case where a material other than Al is added small amount, the main _{material, Ga x In 1-x P} y As
_1-y (0 <x ≦ 1, 0 <y ≦ 1).

In such a structure, carriers are confined between the low-refractive index layers of the upper and lower reflectors, which are closest to the active layer and have a wide gap, so that only the active region is made of Al.
Not containing (1% or less of group III elements)
However, if the low refractive index layer (wide gap layer) of the reflector in contact with the active region is made to contain Al, non-radiative recombination occurs at this interface when carriers are injected and recombined. Luminous efficiency is reduced. Therefore, not only the active region, but also the low refractive index layer in contact with
Is desirably constituted by a layer containing no.

The main composition is Ga _x In _{1 -x
P y As 1-y (0} <x ≦ 1,0 <y ≦ 1) non-radiative recombination prevention layer made of are accumulated small and thus tensile strain than the lattice constant GaAs substrate.

In the epitaxial growth, the growth is performed by reflecting the information of the base, and if there is a defect on the substrate surface, it goes up to the growth layer. When the defect reaches the active layer, the luminous efficiency is reduced. However, it is known that the presence of such a strained layer is effective in suppressing the rise of such defects.

On the other hand, in the case of an active layer having a strain, problems such as a decrease in the critical thickness and an inability to grow the layer to a required thickness are likely to occur. In particular, when the amount of compressive strain of the active layer is large, for example, 2% or more, or when the strained layer is grown thicker than the critical film thickness,
Even when non-equilibrium growth such as low-temperature growth is performed, problems may occur such that film growth does not occur due to defects. On the other hand, the presence of the strained layer can suppress such defects from climbing up, so that the luminous efficiency can be improved, a layer having a compressive strain of 2% or more of the active layer can be grown, or the thickness of the strained layer can be increased. The thickness can be grown to be larger than the critical film thickness.

The Ga _x In _{1-x Py} As _1-y (0
<X ≦ 1, 0 <y ≦ 1) The layer 13 or 17 is in contact with the active region and also has a role of confining carriers in the active region, but the Ga _x In _1-x P _y As
_1-y (0 <x ≦ 1, 0 <y ≦ 1) layer 13 or 17
Have a feature that the band gap energy can be increased as the lattice constant decreases. For example, Ga _x In
_{In the case of a 1-x} P (when y = 1) film, the composition parameter x
Increases, and as the film composition approaches GaP, the lattice constant increases and the band gap also increases. The band gap energy Eg is Eg (Γ) = 1.351 +
0.643x + 0.786x ^2, Eg by indirect transition (X)
= 2.24 + 0.02x. Therefore the said active region _{Ga x In 1-x P y} As 1-y (0 <
x ≦ 1, 0 <y ≦ 1) The height of the hetero-barrier between the layer 13 and the layer 13 or 17 is increased, the carrier confinement is improved, the threshold current is reduced, and the temperature characteristics are improved.

Further, the Ga _x In _1-x P _y As
_The non-radiative recombination preventing layer 13 or 17 composed of _1-y (0 <x ≦ 1, 0 <y ≦ 1) layers has a lattice constant larger than that of a GaAs substrate, and the active layer has a lattice constant of Ga _x.
In _{1−x Py} As _1−y (0 <x ≦ 1, 0 <y ≦ 1)
It is larger than the layer 13 or 17 and stores compressive strain. The _{Ga x In 1-x P y} As 1-y (0 <x ≦
1,0 <y ≦ 1) Since the direction of the strain accumulated in the layer is the same as the direction of the strain accumulated in the active layer, the substantial amount of compressive strain felt by the active layer is reduced. Since the larger the strain is, the more easily the external factors are affected, the configuration of the present invention is particularly effective when the amount of compressive strain of the active layer is, for example, as large as 2% or more, or when the critical thickness is exceeded. .

A surface emitting laser diode having an oscillation wavelength of 1.3 μm band is preferably formed on a GaAs substrate, and a semiconductor multilayer reflector is often used as a resonator. In this case, it is necessary to grow 50 to 80 semiconductor layers having a total thickness of 5 to 8 μm before growing the active layer (in contrast, in the case of the edge emitting laser diode, the total thickness before growing the active layer is required). Is about 2 μm, and it is sufficient to grow about three semiconductor layers.) In this way, when a large number of semiconductor layers are grown before forming the active layer, a high-quality GaAs substrate is used. For various reasons, the defect density on the surface immediately before the active layer growth is inevitably higher than the defect density on the GaAs substrate surface. Once a defect has occurred,
Basically, it rises in the crystal growth direction, and a new defect may occur at the hetero interface. On the other hand, if a strained layer is inserted before the active layer is grown or a process of substantially reducing the amount of compressive strain felt by the active layer is performed, the influence of defects on the surface immediately before the active layer is grown can be reduced.

In this embodiment, Al is not contained in the active region and at the interface between the reflecting mirror and the active region. Therefore, non-radiative recombination caused by crystal defects caused by Al during carrier injection is eliminated. And non-radiative recombination is reduced.

As described above, the configuration in which the non-radiative recombination preventing layer containing no Al is provided at the interface between the reflector and the active region is as follows.
Although it is preferable to apply to both the upper and lower reflecting mirrors 12 and 18, the effect can be obtained by applying to only one of the reflecting mirrors. In the illustrated example, the upper and lower reflectors are semiconductor Bragg reflectors, but it is also possible to use one semiconductor reflector as a semiconductor Bragg reflector and the other reflector as a dielectric reflector.

In the above example, the reflecting mirror 12 or 1
8, only the low refractive index layer closest to the active layer was Ga_xI
n_1-xP_yAs_1-y(0 <x ≦ 1, 0 <y ≦ 1)
Although the light-emitting recombination preventing layer 13 or 17 is used,
Ga_xIn_1-xP_yAs _1-y(0 <x ≦ 1,0 <
y ≦ 1) the non-radiative recombination preventing layer 13 or
17 may be configured.

In this embodiment, this concept is applied to the lower reflector 12 between the GaAs substrate and the active layer, and crystal defects caused by Al, which are problematic at the time of growing the active layer, crawl into the active layer. The adverse effects caused by this can be suppressed. As a result, it is possible to grow a crystal of the active layer with high quality, to obtain a surface emitting laser diode having high luminous efficiency and sufficient reliability for practical use. Moreover, not all in this embodiment of the low refractive index layer of the semiconductor distributed Bragg reflector, the closest to the at least the active region does not include the _{Al Ga x In 1-x P} y As 1-y (0 <x ≤1,0 <
Since only y ≦ 1) layers, the above effect can be obtained without particularly increasing the number of stacked reflectors.

The surface emitting laser diode thus manufactured oscillated at a wavelength of about 1.2 μm. Ga
Although the wavelength of GaInAs on an As substrate increases with an increase in the In composition, it is accompanied by an increase in the amount of strain.
μm was considered to be the limit of longer wavelengths (see “I
EEE Photonics. Technol. Let
t. Vol. 9 (1997) pp. 1319-132
1)). However, as the inventor made this time, 6
By using a growth method with a high degree of non-equilibrium, such as a low-temperature growth of 00 ° C. or less, a GaInAs quantum well active layer with a high strain can be grown coherently thicker than before. It is considered that this was achieved. This wavelength is transparent to the Si semiconductor substrate. Therefore, when a circuit chip in which an electronic element and an optical element are integrated on a Si substrate is formed, light transmission through the Si substrate becomes possible.

As is clear from the above description, it has been found that a surface emitting laser diode in a long wavelength band can be formed on a GaAs substrate by using GaInAs having a high In composition and a high compression strain as the active layer. Was.

As described above, such a surface emitting laser
The diode can be grown by MOCVD, but other growth methods such as MBE can also be used. In the embodiment, the triple quantum well structure (TQW) has been described as an example of the stacked structure of the active layer. However, a structure (SQW, MQW) using various quantum wells having different numbers of quantum wells may be used.

The structure of the laser may be another structure. Although the resonator length is set to the thickness of λ, it can be set to an integral multiple of λ / 2. Desirably, it is an integral multiple of λ. Also, an example in which GaAs is used as the semiconductor substrate has been described.
The above concept can be applied even when another semiconductor substrate such as P is used. The period of the reflecting mirror may be another period.

In this example, a layer mainly composed of Ga, In and As, ie, Ga _x In, is used as the active layer.
_{Although an example of 1-} xAs (GaInAs active layer) is shown, in order to perform laser oscillation of a longer wavelength, a layer (GaInN) in which N is added and the main element is Ga, In, N, As is used.
(As active layer).

By actually changing the composition of the GaInNAs active layer, it was possible to perform laser oscillation in each of the 1.3 μm band and the 1.55 μm band.
By selecting the composition of the active layer, a surface emitting laser having a longer wavelength, for example, in the 1.7 μm band is considered to be possible.

Also, even if GaAsSb is used for the active layer,
A 1.3 μm band surface emitting laser can be realized on a GaAs substrate. As described above, a laser diode having a wavelength of 1.1 to 1.7 .mu.m has not been conventionally suitable, but the active layer has a G layer having a high strain.
By using aInAs, GaInNAs, and GaAsSb, and providing a non-radiative recombination prevention layer, a high-performance surface emitting laser in a long wavelength region of 1.1 to 1.7 μm band where stable oscillation has conventionally been difficult. Can be realized. Second Embodiment Next, another configuration of a long-wavelength surface emitting laser diode which is a light emitting element applied to the optical transmitting / receiving system of the present invention will be described with reference to FIG. However, FIG.
In FIG. 2, the same reference numerals are given to the parts described above, and the description is omitted.

Referring to FIG. 27, in this embodiment, similarly to the case of FIG. 1, n-type GaAs of (100) plane orientation is used.
The substrate 11 is used. On the GaAs substrate 11, the composition is Al _x Ga _1-x As with a thickness of の times the thickness of the oscillation wavelength λ (thickness of λ / 4) in each medium.
(X = 0.9) n-type AlGaAs and a composition of Al _x Ga
An n-type semiconductor distributed Bragg reflector (Al _0.9 ) in which n-type GaAs of _{1− x} As (x = 0) is alternately stacked for 35 periods.
Ga _0.1 As / GaAs lower reflector) 12 is formed,
The thickness of lambda / 4 thereon composition _Ga x _{In 1-x P y}
N-type I given by As _1-y (x = 0.5, y = 1)
An nGaP layer 13 was stacked. In this example, n-type Ga _x In
_{The 1-x Py} As _1-y (x = 0.5, y = 1) layer 13 is also a part of the lower reflecting mirror 12 and constitutes one of the low refractive index layers.

On the InGaP layer 13, an undoped lower GaAs spacer layer 14 and three layers of Ga _x In
And _{1-x N y As 1-} y MQW active layer 15 quantum well active layer 15a, is the thickness between is formed by laminating with intervening GaAs barrier layer 15b of 15 nm,
The undoped upper GaAs spacer layer 16 formed on the multiple quantum well active layer 15 forms a resonator 15R having a thickness (λ thickness) corresponding to one oscillation wavelength in the medium.
Are formed. In the illustrated example, the multiple quantum well active layer 15 has a triple quantum well (TQW) structure. The resonator 15R forms an active region of the surface emitting laser diode.

A p-type semiconductor distributed Bragg reflector (upper reflector) 18 is formed on the resonator 15R.

[0191] The upper reflector 18, and the GaInP layer 17 AlAs layer 18 ₁ serving as the selective oxidation layer AlGa
Including a low refractive index layer having a thickness of 3λ / 4 sandwiched between As layers. Wherein the GaInP layer 17 is doped with C composition _{Ga x In 1- x P y As} 1-y (x =
0.5, y = 1).
/ 4-15 nm thick. On the other hand, the AlAs layer constituting the selective oxidation layer is C-doped and has a composition of A.
thickness represented by _{l z Ga 1-z As (} z = 1) is 30n
m, and the AlGaAs layer has a thickness of (2λ /
Composition in 4-15Nm) is _{Al x Ga 1-x As (} x =
0.9)).

Further, a thickness of λ /
4 GaAs layers are formed for one period.
_Al the composition doped with C in the layer x _{Ga 1-x} As
A p-type AlGaAs layer represented by (x = 0.9) and a p-type GaAs layer doped with C and having a composition represented by Al _x Ga _{1 -x} As (x = 0) are formed in each medium. Twenty-two periods are alternately laminated with a thickness of 1/4 times the oscillation wavelength to form a periodic laminated structure constituting a main part of the upper reflecting mirror 18.

Also in this example, although it is not shown in FIG. 27 because it becomes complicated in FIG. 27, the semiconductor distributed Bragg reflector 18 has a low refractive index layer 18a and a high refractive index as shown in FIG. between the rate layer 18b, the refractive index is provided _{Al z Ga 1-z as (} 0 ≦ y <z <x ≦ 1) hetero spike buffer layer 18c made of a layer that takes an intermediate value.

In the present embodiment, the semiconductor distributed Bragg
The composition at the top of the mirror 18 is Al_xGa _1-xAs (x =
The p-type GaAs layer represented by 0)
Contact layer (p-contact layer) for securing
And play a role.

In the surface emitting laser diode of this embodiment,
The In composition x of the quantum well active layer 15a is 37%, N
(Nitrogen) composition is set to 0.5%. The thickness of the quantum well active layer is 7 nm.

In this embodiment, the surface emitting laser diode is used.
The growth of each semiconductor layer constituting the gate was performed by the MOCVD method. As a raw material constituting each layer of the laser diode,
TMA (trimethylaluminum), TMG (trimethylgallium), TMI (trimethylindium), As
H ₃ (arsine) and PH ₃ (phosphine) were used as raw materials for Al, Ga, In, As, and P, respectively, and DMHy (dimethylhydrazine) was used as a nitrogen raw material. Since DMHy decomposes at low temperature, it is suitable for low-temperature growth at a temperature of 600 ° C. or lower, and is particularly preferable when growing a quantum well layer having a large strain that requires low-temperature growth. Note that H ₂ was used as a carrier gas. The growth of the GaInNAs layer (quantum well active layer) was performed at 540 ° C.

The MOCVD method has a high degree of supersaturation and is suitable for crystal growth of a material containing both N and other group V elements.
In addition, high vacuum is not required as in the MBE method, and the supply flow rate and supply time of the source gas may be controlled.

In this embodiment, a predetermined portion of the thus-formed laminated structure is replaced with the p-type Ga _x I
_{n 1-x P y As 1} -y (x = 0.5, y = 1) layer 17
Etched to reach the _{p-Al z Ga 1-z}
As the (z = 1) the selective oxidation layer ₁₈₁ to form the exposed monkey mesa structure on the side surface. Further this way the exposed mesa structure side on the walls _Al z _Ga 1-z As the (z = 1) layer 18 ₁ is oxidized from the side surface with water vapor, the composition is _Al x _{O y}
In forming the current confining layer 18 ₂ represented.

Finally, using an insulating film such as a polyimide film,
It flattened by embedding the previously removed in the mesa etching portion, by removing the polyimide on the top mirror, to form a polyimide region 18 _3. Further, a p-side electrode 20 is formed on the p-type contact layer except for the light emitting portion, and an n-side electrode 21 is formed on the back surface of the GaAs substrate 11.

In this embodiment, the selectively oxidized layer 18 ₁
Below the Ga as a part of the upper reflecting mirror 18.
_x In _{1−x Py} As _1−y (0 <x ≦ 1, 0 <y ≦
1) Layer 17 is inserted. When a GaInPAs-based material uses a sulfuric acid-based etchant, it can be used as an etching stop layer for an AlGaAs-based material. Therefore, when a wet etching is used in the step of forming the mesa structure, a sulfuric acid-based etchant is used. _{Ga x In 1-x P y} As 1-y (0 <x ≦ 1,0
<Y ≦ 1) Etching stops spontaneously in the layer 17, and the height of the mesa structure can be strictly controlled. Therefore, the uniformity and reproducibility of the surface emitting laser diode simultaneously formed on the substrate are improved, and the manufacturing cost can be reduced. In particular, in the case of manufacturing a laser diode array in which the surface emitting laser diodes (elements) of this embodiment are integrated one-dimensionally or two-dimensionally, the controllability at the time of manufacturing the elements is improved. The uniformity and reproducibility of element characteristics of the element are improved.

In the present embodiment shown in FIG. 27, Ga _x In _{1-x Py} As _1-y (0
<X ≦ 1, 0 <y ≦ 1) A layer 17 is provided on the side of the upper reflecting mirror 18.
Is also provided on the lower reflecting mirror 12 side.

Also in this embodiment, the upper and lower reflecting mirrors 12, 1
In the active region 15 formed by being sandwiched between the active regions 8 and undergoing recombination by injecting carriers, A
No material containing l is used. Further among the low refractive index layer of the lower reflector 12 and the upper reflecting mirror 18, the composition of the layer closest to the active layer 15 is _{Ga x In 1-x P y} As 1
_The non-radiative recombination preventing layer 13 or 17 represented by _−y (0 <x ≦ 1, 0 <y ≦ 1). Therefore, in this embodiment, Al is not contained in the active region 15 and in the interface between the reflecting mirror 12 or 18 and the active region 15, and non-radiative recombination caused by crystal defects caused by Al during carrier injection. Can be reduced.

Incidentally, such a configuration in which Al is not contained in the interface between the reflecting mirror and the active region is preferably applied to both the upper and lower reflecting mirrors 12 and 18 as in the present embodiment, but either one is preferable. The effect can be obtained simply by applying the present invention to a reflector. In this example, both the upper and lower reflectors 12 and 18 are semiconductor distributed Bragg reflectors, but only one reflector may be a semiconductor distributed Bragg reflector and the other reflector may be a dielectric reflector. .

Further, in this embodiment, since the lower reflector 12 provided between the GaAs substrate 11 and the active layer 15 is constructed in the same manner as in the example of FIG.
The adverse effect of the crystal defects caused by Al, which is a problem during the growth of Al, caused by creeping into active layer 15 can be effectively suppressed, and active layer 15 can be formed with high quality.

The non-radiative recombination preventing layer 13
Alternatively, 17 constitutes a part of the semiconductor distributed Bragg reflector 12 or 18 in any of the configurations shown in FIGS. 1 and 27, and its thickness is １ ／ of the oscillation wavelength λ in the medium ( (thickness of λ / 4). It is also possible to provide a plurality of these non-radiative recombination preventing layers.

In the above description, the semiconductor Bragg reflector 1
Although the example in which the non-radiative recombination preventing layer 13 or 17 is provided on a part of 2 or 18 has been described, such a non-radiative recombination preventing layer may be provided in the resonator 15. For example, the resonator 15 may be replaced with a GaInNAs quantum well layer 15a.
And a GaAs barrier layer 15b, the GaAs layer is used as a first barrier layer.
There is a structure in which a non-radiative recombination preventing layer made of aInPAs, GaAsP or GaInP is used as the second barrier layer. At that time, the thickness of the resonator portion can be set to a thickness for one wavelength. In this case, the non-radiative recombination preventing layer is G
Since the band gap is larger than that of the aAs first barrier layer, the active region into which carriers are injected substantially extends to the GaAs barrier layer.

Further, the remaining Al raw material, Al reactant,
In the case where the step of removing the compound or Al is provided during the manufacturing process of the laser diode, the step of forming the non-radiative recombination preventing layer may be provided in the middle of the step of forming the non-radiative recombination preventing layer. And a step of forming a GaAs layer is provided between them, and the step can be performed in the middle of the GaAs layer forming step.

According to the structure of this embodiment, the luminous efficiency is high,
A highly reliable surface emitting laser diode was obtained. At that time, among the semiconductor distributed Bragg reflector 12 or 18, not all of the low refractive index layer, the closest to the least active regions, not including _{Al Ga x In 1-x P} y
Since only the non-radiative recombination preventing layer composed of As _1-y (0 <x ≦ 1, 0 <y ≦ 1) was obtained, the above-described effect was able to be obtained without particularly increasing the number of laminated mirrors. .

Even with such a structure, since the polyimide can be easily embedded, the wiring does not break at the step portion or the like when forming the wiring forming the p-side electrode. Is further improved.

The surface emitting laser diode manufactured as described above
The laser was confirmed to oscillate at a wavelength of about 1.3 μm.

In this embodiment, the main elements are Ga, In,
Since a GaInNAs layer made of N and As was used for the active layer, it was possible to form a long-wavelength surface emitting laser diode on the GaAs substrate 11. Al and A
s has performed the current constriction by the selected selective oxidation of oxide layer 18 ₁ as a main component, the threshold current at the time of laser oscillation was also sufficiently suppressed. According the current constriction structure using the current constriction layer formed of the selective oxidation layer 18 ₁ Al oxide film 18 ₂ selected oxidized, suppress the diffusion of electric current by forming close the current constriction layer ₁₈₂ to the active layer And
Carriers can be efficiently confined in a minute region that does not come into contact with the atmosphere. Further, the current confinement layer 18 ₂ is the result Al oxide film of oxide, Al oxide film has a small refractive index, it becomes possible to confine light efficiently to the small area that is confined with the carrier. As a result, the efficiency of the laser diode is further improved, and the threshold current is reduced. In addition, since the current narrowing structure can be easily formed, the manufacturing cost can be reduced.

As is apparent from the above description, even in the configuration as shown in FIG. 10, 1.3 μm
A surface emitting laser diode which oscillates in a band, consumes little power, and can be manufactured at low cost can be realized.

The surface emitting laser diode shown in FIG.
Although growth can be performed by MOCVD as in the case of FIG. 1, other growth methods such as MBE can be used. In the above embodiment, DMHy was used as a nitrogen source, but activated nitrogen or another nitrogen compound such as NH ₃ may be used.

Further, in this embodiment, an example of a triple quantum well structure (TQW) has been described as a laminated structure of the active layer 15, but another structure having a different number of quantum well layers, for example, an SQW structure or a DQW structure has been proposed.
A QW structure, an MQW structure, or the like can also be used. Further, other structures can be used for the laser structure.

In the surface emitting laser diode of FIG. 27, by adjusting the composition of the GaInNAs active layer 15a, the 1.55 μm band, and further, the longer wavelength 1.7 μm.
It is also possible to realize a band surface emitting laser diode. At that time, the GaInNAs active layer may contain other III-V elements such as Tl, Sb, and P. Also, even when GaAsSb is used for the active layer, a 1.3 μm band surface emitting laser diode can be formed on a GaAs substrate.

In the above description, as the active layer, the main element is a layer made of Ga, In, As (GaInAs active layer) or N is added, and the main element is Ga, I
Although the case of using a layer made of n, N, and As (GaInNAs active layer) has been described, other than GaNAs, GaP
N, GaNPAs, GaInNP, GaNASSb, G
aInNAsSb can also be used. In particular, when nitrogen is contained in the active layer as in these examples, the non-radiative recombination preventing layer of the present invention is particularly effective.

FIG. 28 is a view showing a structure produced by the MOCVD method.
The result of measuring the room temperature photoluminescence spectrum of an active layer having a GaInNAs / GaAs double quantum well structure including a GaInNAs quantum well layer and a GaAs barrier layer is shown. FIG. 29 shows the structure of the sample.

Referring to FIG. 29, a GaAs substrate 201
A lower clad layer 202, an intermediate layer 203A, an active layer 204 containing nitrogen, another intermediate layer 203B, and an upper clad layer 205 are sequentially stacked thereon.

Referring to FIG. 28, the curve A shows the AlGaAs
The s layer is used as the cladding layer 202, and the GaAs intermediate layer 2
The results are shown for a sample in which a double quantum well structure was formed by sandwiching 03A or 203B.
The measurement results are shown for a sample in which a double quantum well structure is continuously formed by using an aInP layer as the cladding layer 202 and sandwiching a GaAs intermediate layer.

As shown in FIG. 28, it can be seen that the photoluminescence intensity of sample A is lower than that of sample B by less than half. This is because, when a single MOCVD apparatus is used to continuously form an active layer containing nitrogen such as GaInNAs on a semiconductor layer containing Al as a constituent element such as AlGaAs, the emission intensity of the active layer deteriorates. It shows that the problem arises. For this reason, AlGaAs
The threshold current density of the GaInNAs-based laser diode formed on the cladding layer
It is more than twice as high as when formed on the P clad layer.

The inventor of the present invention has clarified the cause of this problem and has obtained the following knowledge.

FIG. 30 shows cladding layers 202 and 205.
Is formed of an AlGaAs layer, a GaAs layer is used as the intermediate layers 203A and 203B, and the active layer is GaInN.
FIG. 5 shows the depth distribution of nitrogen and oxygen concentrations in an element having an As / GaAs double quantum well structure formed using a single MOCVD film forming apparatus. FIG. However, the measurement in FIG. 30 was performed by SIMS under the measurement conditions shown in Table 3.

[0223]

[Table 3] Referring to FIG. 30, it can be seen that two nitrogen peaks appear in the active layer 204 corresponding to the GaInNAs / GaAs double quantum well structure. On the other hand, the results in FIG. 13 show that an oxygen peak is also detected in the active layer 204. On the other hand, the oxygen concentration in the intermediate layers 203A and 203B containing no N and Al
The concentration is about one order of magnitude lower than the oxygen concentration in FIG.

On the other hand, as the cladding layer 202, GaInP
When the element in which the GaAs is used as the intermediate layers 203A and 203B and the GaInNAs / GaAs double quantum well structure is used as the active layer 204 is used to measure the oxygen concentration in the depth direction, the oxygen concentration in the active layer 204 is measured. Concentrations were found to be background levels.

That is, the nitrogen compound raw material and the organic metal Al
When a semiconductor light emitting device in which a semiconductor layer 202 containing Al is provided between a substrate 201 and an active layer 204 containing nitrogen is continuously grown by one epitaxial growth apparatus using a raw material, the active layer 204 It has been experimentally demonstrated that oxygen is incorporated. Oxygen incorporated in the active layer forms a non-radiative recombination level, which lowers the luminous efficiency of the active layer. Thus, from the results of FIG. 30, it can be seen from the results of FIG. 30 that the oxygen taken in the active layer causes a reduction in the luminous efficiency of the semiconductor light emitting device having the semiconductor layer containing Al between the substrate and the active layer containing nitrogen. Was newly found to be. The origin of this oxygen is considered to be a substance containing oxygen remaining in the apparatus or a substance containing oxygen contained as an impurity in the nitrogen compound raw material.

Next, the cause of oxygen being taken into active layer 204 will be discussed.

FIG. 31 is a diagram showing the distribution of Al in the depth direction obtained for the same sample as in FIG. The measurement is shown in FIG.
Was performed by SIMS. Table 4 shows the measurement conditions.

[0228]

[Table 4] Referring to FIG. 31, it can be seen that Al is detected even in the active layer 204 into which the Al material is not originally introduced. On the other hand, the cladding layer 202 or 205 containing Al
In the GaAs intermediate layer 203A or 203B adjacent to the active layer, the Al concentration is about one digit lower than that of the active layer. This is because Al in the active layer 204 diffuses from the cladding layer 202 or 205 containing Al,
4 shows that Ga is not substituted.

On the other hand, when an active layer containing nitrogen was grown on a semiconductor layer containing no Al such as GaInP, no Al was detected in the active layer.

[0230] From the above, Al detected in the active layer 204 is composed of Al raw material and Al reactant remaining in the growth chamber or the gas supply line, or Al compound or Al compound.
And the like are combined with the nitrogen compound raw material or impurities (such as moisture) in the nitrogen compound raw material and taken into the active layer 204.
When one semiconductor epitaxial growth apparatus having a structure having a semiconductor layer containing Al between a substrate and an active layer containing nitrogen is continuously crystal-grown by one epitaxial growth apparatus using the raw materials, the active layer containing nitrogen contains It has been newly clarified by the study of the present inventors that Al is naturally taken up into the glass.

FIG. 31 is a comparison of the nitrogen and oxygen concentration distributions in the depth direction obtained for the same device shown in FIG. 30. In FIG. 30, two oxygen peak profiles in the double quantum well active layer are shown. 31 does not match the nitrogen concentration peak profile, but rather matches the Al concentration profile in FIG. From this, GaIn
It can be seen that oxygen in the NAs quantum well layer is not taken in together with the nitrogen source, but is taken in in combination with Al taken in the quantum well layer. That is, MO
When the Al raw material, Al reactant, Al compound or Al remaining in the growth chamber of the CVD apparatus comes into contact with the nitrogen compound raw material, the Al contains water contained in the nitrogen compound raw material or water remaining in the gas line or the reaction chamber. It is supposed that Al is taken into the active layer as a result. As described above, according to the study of the present inventor, it is clear for the first time that in the conventional GaAs-based surface-emitting laser diode, oxygen was taken into the active layer and the luminous efficiency of the active layer was reduced by the taken-in oxygen. It became.

From the above findings, in order to improve the luminous efficiency of a GaAs surface emitting laser diode, at least the nitrogen compound raw material in the growth chamber or the nitrogen compound From the part where impurities contained in the raw material may touch,
It is concluded that it is necessary to remove the Al raw material, the Al reactant, the Al compound or Al.

Therefore, after the growth of the semiconductor layer containing Al,
Until the start of the growth of the active layer containing nitrogen, such residual A
When a nitrogen compound raw material is supplied to the growth chamber for growing an active layer containing nitrogen by providing the l removal step, the residual Al raw material, the Al reactant, and the concentration of the Al compound and Al are reduced. , Residual Al, nitrogen compound raw material or impurities contained in the nitrogen compound raw material, MOCVD
Reaction with substances containing oxygen remaining in the device is suppressed,
It has become possible to significantly reduce the concentrations of Al and oxygen impurities taken into the active layer. Further, the residual Al
Is removed by the end of the growth of the non-radiative recombination preventing layer, a favorable effect of suppressing non-radiative recombination in the active layer when carriers are injected into the active layer by current injection can be obtained. .

For example, by reducing the Al concentration in the active layer containing nitrogen to 1 × 10 ¹⁹ cm ⁻³ or less, Ga
The continuous oscillation at room temperature of the As-based surface emitting laser diode became possible. Further, the Al concentration in the active layer containing nitrogen is set to 2 ×
By reducing the active layer to 10 ¹⁸ cm ⁻³ or less, light emission characteristics equivalent to those obtained when the active layer was formed on a semiconductor layer containing no Al were obtained.

In the film formation chamber, the step of removing the Al raw material, the Al reactant, the Al compound, and the Al remaining in the portion where the nitrogen compound raw material or the impurities contained in the nitrogen compound raw material can touch can be performed, for example, by using a carrier gas. A purging step is possible. However, here, the time of the purge step is
The time from when the growth of the Al-containing semiconductor layer is completed and the supply of the Al source to the growth chamber is stopped to when the nitrogen compound source is supplied to the growth chamber to start the growth of the nitrogen-containing semiconductor layer. Define. As the above-mentioned purging step, a method in which the growth is interrupted during the growth of the intermediate layer containing neither Al nor nitrogen, and purging with a carrier gas is also possible. When purging is performed with the growth interrupted in this way, the growth interruption is performed by A
It can be performed during the period from the start of the growth of the semiconductor layer containing 1 to the middle of the growth of the non-radiative recombination preventing layer.

FIG. 32 shows an example of a sectional structural view of a semiconductor light emitting device formed by providing a step of purging with the carrier gas. However, in FIG. 32, portions corresponding to the portions described above are denoted by the same reference numerals. Therefore, in FIG. 32, the first semiconductor layer 202 containing Al as a constituent element on the substrate 201 and the first lower intermediate layer 60 are formed.
1, a second lower intermediate layer 602, and an active layer 2 containing nitrogen.
04, an upper intermediate layer 203, and a second semiconductor layer 205 are sequentially stacked.

In forming the structure shown in FIG. 32, crystal growth is performed by an epitaxial growth apparatus using an organic metal Al material and an organic nitrogen material. At this time, after the growth of the first lower intermediate layer 601, the crystal growth is performed. 2 lower intermediate layer 602
The growth interruption step is provided before starting the growth of.
In the growth interrupting step, the remaining Al raw material, Al reactant, A
The l-compound or Al is purged with hydrogen gas used as a carrier gas.

FIG. 33 shows the semiconductor light emitting device obtained by suspending the growth between the first lower intermediate layer 601 and the second lower intermediate layer 602 and performing the purge step for 60 seconds.
The result of measuring the distribution of Al concentration in the depth direction is shown.

Referring to FIG. 33, it can be seen that the Al concentration in the active layer 204 has been reduced to 3 × 10 ¹⁷ cm ⁻³ or less as a result of the growth interruption step and the purge step. This value is almost the same as the Al concentration in the intermediate layer 601 or 602.

FIG. 34 shows the results of measuring the distribution of the nitrogen and oxygen concentrations in the depth direction for the same device shown in FIG.

Referring to FIG. 34, it can be seen that the oxygen concentration in active layer 204 has been reduced to a background level of 1 × 10 ¹⁷ cm ⁻³ . The reason why the peak of the oxygen concentration appears in the lower intermediate layer 601 or 602 in FIG. 34 is considered that oxygen segregated at the growth interruption interface. Therefore, when the purge is performed after the growth is interrupted, it is preferable that the position where the growth is interrupted is provided after the growth of the Al-containing semiconductor layer is completed and before the growth of the non-radiative recombination preventing layer is completed. The non-radiative recombination preventing layer can have a larger band gap energy than the quantum well active layer and the barrier layer. When carriers are injected into the active layer by current injection, non-luminescent due to oxygen segregated at the growth interruption interface. The adverse effects of recombination can be suppressed. The configuration in which the non-radiative recombination preventing layer is provided is effective when the active layer containing nitrogen is used as described above.

In the semiconductor light emitting device shown in FIG. 32, the growth is interrupted between the first lower intermediate layer 601 and the second lower intermediate layer 602, and the purging step is performed for 60 minutes. , The concentration of impurities such as Al and O contained in the active layer 204 was reduced, whereby the luminous efficiency of the active layer 204 could be improved.

In the step of purging the film forming chamber with the carrier gas, the susceptor is purged while being heated, so that the Al adsorbed on the susceptor or around the susceptor is purged.
The raw materials and reaction products can be removed, and efficient removal can be performed. However, when the substrates are simultaneously heated in the purge step, AsH ₃ or PH may be used even during the interruption of the growth to prevent the semiconductor layer on the outermost surface from being thermally decomposed.
It is necessary to keep supplying a group V source gas such as H ₃ into the film formation chamber.

When purging the film forming chamber of the MOCVD apparatus with the carrier gas, the substrate can be transferred from the film forming chamber to another chamber. When the substrate is transported from the film formation chamber to another chamber, the substrate is transferred to the another chamber. Therefore, even when purging while heating the susceptor, a V-group source gas such as AsH ₃ or PH ₃ is used. There is no need to supply to the film formation chamber. Therefore, the thermal decomposition of the reaction product containing Al deposited on the susceptor or around the susceptor can be further promoted, whereby the Al concentration in the growth chamber can be efficiently reduced.

It is also possible to perform a purge while growing the intermediate layer. For example, in the configuration of FIG. 10, since the non-radiative recombination preventing layer 13 is provided between the AlGaAs-based reflecting mirror 12 containing Al and the active layer 15 containing nitrogen, the layer containing Al and the nitrogen are removed. Since the distance between the active layer 15 and the active layer 15 is increased, the purge time can be increased even when purging is performed simultaneously with growth. In this case, it is preferable to slow the growth rate and lengthen the time.

It is also possible to form the reflecting mirror 12 made of AlGaAs containing Al and the active layer 15 containing nitrogen by separate devices. Even in this case, by providing the regrowth interface below the non-radiative recombination preventing layer 13, the concentration of impurities such as Al and O in the active layer 15 containing nitrogen can be reduced.

When a crystal growth method using no organic metal Al raw material and nitrogen compound raw material is used as in the ordinary MBE method, a semiconductor layer containing Al is provided between the substrate and the active layer containing nitrogen. No report has been made on the decrease in luminous efficiency of the semiconductor light emitting device. On the other hand, in the MOCVD method, a decrease in luminous efficiency of a GaInNAs active layer formed on a semiconductor layer containing Al has been reported.

For example, Electron. Lett. , 2
000,36 (21), pp1776-1777, even when an intermediate layer made of GaAs is provided on an AlGaAs cladding layer in the same MOCVD film forming chamber,
It has been reported that when GaInNAs quantum well layers are continuously grown, the photoluminescence intensity is significantly degraded. In the above report, in order to improve the photoluminescence intensity, an AlGaAs cladding layer and a GaI
nNAs active layers are grown in different MOCVD growth chambers. Therefore, in the case of a crystal growth method using an organic metal Al raw material and a nitrogen compound raw material as in the MOCVD method, the above problem is considered to occur to a greater or lesser extent.

In the MBE method, crystal growth is performed under ultra-low pressure (in a high vacuum). On the other hand, in the MOCVD method, the processing pressure in the film formation chamber is usually from several tens Torr to about atmospheric pressure,
It is considered that the mean free path of gas phase molecules is much shorter than that of the E method, and the supplied raw material and carrier gas come into contact with and react with others in a gas line or a reaction chamber. That is, in the case of a growth method in which the pressure in the reaction chamber or the gas line is high, such as the MOCVD method, after the growth of the semiconductor layer containing Al and before the start of the growth of the active layer containing nitrogen, it is more preferable. By the end of the growth of the non-radiative recombination preventing layer, the Al raw material or the Al reactant remaining in the film forming chamber at a position where the nitrogen compound raw material or the impurities contained in the nitrogen compound raw material may touch. By providing the step of removing the Al compound or Al, the incorporation of oxygen into the active layer containing nitrogen can be effectively prevented.

For example, after growing a semiconductor layer containing Al,
Before growing the active layer containing nitrogen, it is also possible to evacuate the gas line and the growth chamber. In this case, it is highly effective to perform vacuum evacuation while heating the substrate.

It is also possible to remove the remaining Al by flowing an etching gas after growing the semiconductor layer containing Al and before growing the active layer containing nitrogen. Examples of the gas that can react with and remove such an Al-based residue include an organic-based compound gas.

For example, when a DMHy gas, which is one of the organic compound gases, is supplied using a DMHy cylinder during the growth of the active layer containing nitrogen as described above, it is apparent that the gas reacts with the Al-based residue. . Therefore, by supplying the organic compound gas using the organic compound gas cylinder after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, the reaction chamber side wall, the heating zone, and the substrate are held. These Al-based residues can be removed by reacting with Al-based residues remaining in a jig or the like. Such a method can also suppress the incorporation of oxygen into the active layer. In particular, when the same gas as that containing nitrogen and used as the nitrogen source for the active layer is used, it is not necessary to add a special gas line. This step may be performed with the growth interrupted, and may include GaNAs, GaInNAs, Ga
This may be performed by growing a layer containing nitrogen such as an InNP layer as a dummy layer separately from the active layer by crystal growth. When the Al removing step is performed at the same time in the crystal growing step as described above, there is no time loss as compared with the case where the growth is interrupted, and a favorable effect of improving the semiconductor device manufacturing throughput is obtained.

GaInAs is used for the active layer of the laser diode.
Conventionally, 1.1 μm was considered to be the upper limit of the laser oscillation wavelength. However, according to the present invention, a GaInAs quantum well active layer with high strain is grown thicker than before by low-temperature growth at 600 ° C. or lower. 1.2 μm
Laser wavelengths can be realized. As described above, a laser diode having a wavelength of 1.1 to 1.7 μm has not been conventionally suitable, but the active layer has a high strain GaIn.
By using As, GaInNAs, and GaAsSb, and by providing a non-radiative recombination preventing layer, a high-performance surface-emitting laser in a long wavelength region of 1.1 to 1.7 μm in a wavelength range in which stable oscillation has conventionally been difficult. Can be realized,
The possibility of application to optical communication systems has been opened. [Third Embodiment] FIG. 35 is the same as FIG. 1 or FIG.
The laser diode chip 32 including the long-wavelength surface-emitting laser diode element of 0 is n-type GaAs having a plane orientation of (100).
The example formed on the s wafer 31 is shown.

Referring to FIG. 35, 1 to n laser diode elements are formed on the laser diode chip 32, and the number n and the arrangement thereof are determined according to the use of the laser diode chip 32. .

FIG. 36 shows an example of an optical transmission / reception system using a long-wavelength surface emitting laser diode having a laser oscillation wavelength of 1.1 μm to 1.7 μm. In FIG. 36, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 36, a surface emitting laser diode chip 32 as a light emitting light source is installed at a point A so that a light emitting portion 32A in the laser diode chip 32 is coupled to an optical fiber. The optical signal emitted from the light emitting section 32 of the diode chip 32 is
It is injected into the optical fiber 33 and transmitted in the direction indicated by the thick arrow in the figure. The terminal end of the optical fiber 33 is provided at a point B. At the point B, a light receiving element 34 such as a photodiode constituting a light receiving unit optically couples its optical detector 34A to the optical fiber 33. And an optical transmission / reception system is configured.

In this example, the installation location A of the light emitting light source and the installation location B of the light receiving unit are linearly connected by the optical fiber 33.

FIG. 37 schematically shows the structure of FIG.

Referring to FIG. 37, black circles A and B in the figure indicate the installation locations of the light emitting light source 32 and the light receiving unit 34, respectively, and the thick black line indicates the optical fiber 33.

Normally, the light emitting light source 32 and the light receiving unit 34 are optically coupled by the optical fiber 33 as a transmission line and function as an optical transmitting and receiving system. In an optical transmission / reception system using a long-wavelength surface emitting laser diode in the 1.7 μm band, a transmission path is formed over several tens of meters to several tens of kilometers, and there is not necessarily no obstacle between them.

For example, FIG. 38 shows that obstacles 35A and 35B are present between the points A and B, and the location A of the light-emitting light source and the location B of the light-receiving unit are connected by a straight transmission path 33. In this example, the transmission line is bent at a right angle.

In the case of FIG. 38, when the optical fiber 33 is bent at a right angle at a portion where the transmission line is bent at a right angle, the optical fiber 33 is bent.
Will be damaged and will not function as a transmission path. In other words, if the optical fiber 33 is bent in such a manner that an angle is locally formed, the fiber 33 is damaged and does not function as a transmission path. In addition, a reflection member for bending the transmission path can be provided in this portion to bend the traveling direction of the light beam, but the cost increases.

In view of the above, the present invention proposes a method of bending a transmission line without providing a reflection member and not impairing the function of the transmission line.

FIG. 39 shows a third embodiment of the present invention. 39. However, in FIG. 39, the same reference numerals are given to the previously described portions, and description thereof will be omitted.

Referring to FIG. 39, in the case shown in the figure, an obstacle 35C exists between the point A and the point B, and the installation location A of the light emitting light source and the installation location B of the light receiving unit are linear transmission paths. h cannot be connected. However, in the present invention, as shown in this example, the optical fiber 33 constituting the transmission path is bent without giving a local angle, so that the light-emitting light source 32 and the light-receiving unit 34 are placed at the place A and B, respectively. And are connected. With such a configuration, the optical fiber 33 constituting the transmission path is not damaged, and the obstacle 3
5C can be avoided, and a good optical transmission / reception system can be constructed.

FIG. 40 shows another example of the present invention. Also in this case, obstacles 35D and 35E exist between the points A and B, and the installation location A of the light emitting light source 32 and the light receiving unit 34
Cannot be connected in a straight line with the installation location B of the transmission line.

However, according to the present invention, as shown in this example, the optical fiber of the transmission line is bent without forming a local angle, and the light-emitting light source installation location A and the light-receiving unit installation location B are bent.
Are connected. In the present invention, as a result, the transmission path is continuously bent, and is not formed in a stepwise angle.

In the above description, the laser oscillation wavelength is 1.1
The description is based on medium-to-long distance communication to which an optical transmission / reception system using a long-wavelength surface emitting laser diode using the μm band to 1.7 μm band is suitably applied. Or in a building, for example, several cm to several meters
, It can be suitably applied. Even in this case, by bending the optical fiber of the transmission path without forming a local angle, the transmission direction of the light beam can be changed without providing a reflecting member. At this time, the function of the transmission path is not impaired.

In the case where the transmission line is continuously bent as described above, the bending curvature is not completely free from any condition. The inventor of the present invention has made intensive studies on this point, and as a result, the transmission path shown in FIGS. 39 and 40 must be a transmission path having a curvature that forms a part of a circle having a diameter of 20 cm or more. It has been found that the laser light may be damaged and that the laser light cannot be transmitted satisfactorily. In other words, when constructing such an optical transmission / reception system, if the transmission path is a transmission path having a curvature that forms a part of a circle having a diameter of 20 cm or more, a reflection member or the like for changing the direction is used. Even without special provision, transmission lines can be arranged while avoiding obstacles as shown in FIG. 40, and a good optical transmission / reception system that functions reliably at low cost can be constructed. [Fourth Embodiment] Next, a fourth embodiment of the present invention will be described.

FIG. 41 shows that the laser oscillation wavelength ranges from 1.1 to 1.0.
Another example of an optical transmission / reception system using a long-wavelength surface emitting laser diode of the 7 μm band is shown. However, in FIG. 41, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 41, in this example, laser element light emitting section 32A is optically coupled to optical fiber F1, and the laser beam emitted from laser element light emitting section 32A is transmitted in the transmission direction indicated by the thick arrow in the figure. You. The optical fiber F1
The laser beam transmitted through the inside is then reflected by the reflecting member R 9.
The beam is bent at 0 ° and enters the optical fiber F2. The end of the optical fiber F2 is optically coupled to the optical detector 34A of the light receiving element 34 such as a photodiode, so that an optical transmitting and receiving system is configured.

This example is for explaining the features of the optical transmission / reception system of the present invention.
Although only one 2A is shown, a plurality of laser elements 32A are formed on one chip 32 by utilizing the features of the long-wavelength surface emitting laser diode suitably applied to the present invention. A multi-laser array type system capable of transmitting and receiving large-capacity light can also be provided using a plurality of optical fibers F1 and a plurality of light receiving elements 34 optically coupled thereto.

FIG. 42 shows a configuration in which the optical transmission / reception system of FIG. 41 is arranged in a premises. In the example of FIG. 42, the optical transmission / reception system of FIG. 41 is arranged inside a wall of a building. FIG.
In FIG. 2, the same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 42, a room 42 defined by a wall 41 is formed in a building. In a space 41A inside the wall 41, a laser oscillation wavelength which is a light emitting light source at a point A is provided. A long-wavelength surface emitting laser diode chip 32 having a band of 1.1 to 1.7 μm is disposed, and a photodiode constituting a light receiving unit 34 is disposed at a point B. In the space 41A, a reflection member R for changing the direction of the transmission path between the point A and the point B is provided. FIG. 42 shows a plan view of a room, and illustrates an optical transmission / reception system in a large scale for explanation. For this reason, the scales of the room or the wall and the optical transmission / reception system do not match.

Further, although not shown, each of the optical transmission / reception units 32 and 34 at both the points A and B has other connection devices or connectors. These are walls 4
1 may be in the internal space 41 </ b> A, from which terminals and the like may be drawn into the room 42.

FIG. 43 is a plan view showing a case where a conventional optical transmitting / receiving system is arranged in a premises. 43. However, in FIG. 43, the same reference numerals are given to the previously described portions, and description thereof will be omitted.

Referring to FIG. 43, the laser element 32 and the photodiode 34 are connected in a straight line by an optical fiber F12, and the optical fiber F12 is disposed across the inside of the room 42. Since such an optical fiber F12 is arranged so as to cross the room 42, it is arranged on the floor, under the floor, or on the ceiling of the room.

FIG. 44 also shows an example in which a conventional optical transmission / reception system is arranged in a premises. 44. However, in FIG. 44, the same reference numerals are given to the previously described portions, and description thereof will be omitted.

Referring to FIG. 44, also in this case, the laser element 32 and the photodiode 34 are connected by the optical fiber F12. In this example, the optical fiber F12 is curved by utilizing the flexibility of the optical fiber. Are arranged in a way.

However, even if the flexibility of the optical fiber is utilized, only the direction of the transmission path can be changed with a large curvature, and the optical fiber F12 must also be arranged so as to cross the room 42. Therefore, it is arranged on the floor of the room 42, under the floor, or on the ceiling.

In the conventional arrangements shown in FIGS. 43 and 44, the optical fibers are arranged so as to cross the room, so that the optical fibers on the floor, under the floor or in the ceiling of the room are arranged very complicatedly and randomly. When a plurality of these are arranged, there is a problem that they are entangled with each other, become entangled, and subsequent maintenance becomes difficult. In particular, when it is placed on the floor, it is very dangerous that pedestrians can catch their feet.

On the other hand, in the configuration of the present invention as shown in FIG. 42, the direction of the transmission path can be bent by 90 ° by the reflection member. An optical fiber transmission line can be arranged in an order along a pillar or the like. For this reason, even if it arrange | positions in the place which is visible rather than the inside of the wall 41, it arrange | positions also visually beautifully. Further, even if a plurality of wires are arranged, they do not become entangled with each other and entangled with each other, so that subsequent maintenance or the like can be easily performed.

In this embodiment, when such a private optical transmission / reception system is constructed, the reflection member R for changing the direction of the transmission line is provided, so that the transmission line is efficiently arranged according to the shape of the building. It is possible to effectively design buildings without unnecessary transmission lines being exposed where they can be seen, and without excessively occupying areas on the ceiling, under the floor, or inside the walls of the building. And the degree of freedom for aesthetic design increases.

When the direction of the transmission path is bent by the reflection member R, the angle is not necessarily limited to 90 °.
However, when a building is usually designed / constructed, its columns, walls, floors and ceilings should be designed and constructed based on a plane that intersects a straight line at 90 °, unless there is a special design requirement. The optical fiber transmission lines F1 and F2 are pillars,
When placing along a wall, floor, ceiling, etc., the direction
It is more preferable to change the angle by 0 ° in terms of efficiency and aesthetic appearance.

If the direction of the transmission line is changed by 90 ° in this manner, unnecessary transmission lines may be exposed to the eyes when constructing such an optical transmission / reception system, or the ceiling and floor of a building may be exposed. Alternatively, the transmission line does not occupy the area inside the wall more than necessary, so that the building can be effectively designed and the degree of freedom in aesthetic design increases.

FIG. 45 shows another example of the optical transmitting / receiving system of this embodiment. In this example, the light emitting unit 3 of the laser element 32
The optical signal emitted from 2A is transmitted spatially, travels straight in the direction of the arrow in the figure, and is received by the optical detector 34A of the light receiving element 34 such as a photodiode.

As the laser element that can be suitably used, as described in the previous embodiment, the semiconductor distributed Bragg reflector 1
A surface emitting laser diode having a laser oscillation wavelength in the 1.1 to 1.7 μm band, which has not been realized conventionally, is obtained by improving the configurations of Nos. 2 and 18 and providing a non-radiative recombination preventing layer. In terms of reliability, low-energy driving, and lower manufacturing costs,
preferable.

In the following description of the embodiment, an example in which one laser element is used will be described.
Since a large number of long-wavelength surface emitting laser diodes in the band can be formed easily and inexpensively on a single chip, a multi-laser array system can be easily realized, and a large amount of information communication can be realized.

FIG. 46 shows another example of the optical transmission / reception system of this embodiment. 46. However, in FIG. 46, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 46, the optical signal emitted from the light emitting portion 32A of the laser element 32 is spatially transmitted and goes straight in the direction of the arrow in the figure. The light is received by the light detector 34A of the light receiving element 34 such as a diode. Fifth Embodiment Conventionally, in an electronic device,
Signal transmission is performed by electric signals using a conductor cable. Therefore, in various electronic devices, an infinite number of conductor cables are connected inside the devices, but the arrangement and processing of the conductor cables are complicated, which has been a problem at the design stage or the assembly stage of a factory.

Therefore, according to the present invention, signals are not exchanged by using such a conductor cable, but by using FIG.
6, the electrical signal is converted to an optical signal by an optical transmission / reception system, and the converted optical signal is transmitted spatially, and the number of conductor cables is omitted or reduced. To simplify.
By simplifying the internal wiring of the electronic device in this way, it is considered that the complexity of the layout process of the conductor cable can be eliminated and the degree of freedom in the layout of each component / unit inside the device can be increased.

Examples of the electronic equipment into which the optical transmission / reception system of the present invention is incorporated include a recording apparatus using the electrophotographic principle, such as a copying machine and a laser printer, an ink jet recording apparatus, and a recording apparatus for a silver halide photographic process. And the like. The present invention can also be used for computers, video equipment, television receivers, and the like in addition to the above.

FIG. 47 is a view showing an electrophotographic copying machine 541 to which the present invention is suitably applied. FIG. 48 is an enlarged view of FIG.
It is the figure which showed the internal structure schematically. However, in the figure, parts corresponding to the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIGS. 47 and 48, the electronic copying machine 541 has a sheet feed cassette 542 and a sheet collection tray 543, and further includes a sheet supply mechanism 548 and a photosensitive member in a main body housing closed by a cover 547a. Drum 5
Further, a circuit board 5 carrying an electronic circuit is provided in the housing 547 in which an image forming mechanism 549 including
50 are held.

In the electrophotographic copying machine 541 shown in FIGS. 47 and 48, the laser diode 32 described above is provided at the point A and the photodiode 34 described above is provided at the point B in the housing 547. The laser diode 3
2 and the photodiode 34 are optically coupled by the configuration using the optical fiber F1, the mirror R, and the optical fiber F2 described above with reference to FIG.

FIG. 49 shows an ink jet recording apparatus 551 as another example to which the present invention is suitably applied. FIG.
49 is an enlarged view of FIG. 49, showing a schematic internal structure.

Referring to FIGS. 49 and 50, the ink jet recording apparatus 551 has a lower housing 554b and an upper housing 5
54a, and the upper housing 55
A paper feed mechanism 555 and an ink jet recording head 556 are provided in 4a.

Referring to FIG. 50, an ink jet recording head 556 is provided on a carriage 556A so as to be movable left and right, and forms an image on a recording sheet held on a platen roller 558 in a recording section 557. .

A circuit board 559 for holding an electronic circuit is provided in the lower housing 554b. In the circuit board 559, an optical fiber similar to that of the previous embodiment is provided between point A and point B. An optical fiber F12 is provided, and the optical fiber F12 transmits an optical signal formed by a light source 32 formed of a laser diode chip provided at point A to a light receiving element 34 formed of a photodiode provided at point B.

As described above, in the present invention, the conductor cables are removed or the number thereof is reduced inside various electronic devices, and the signals inside the devices are exchanged by the optical transmission / reception system. 47 to 50 show examples of an electrophotographic copying machine and an ink jet recording apparatus as applied electronic devices, but the present invention is not limited to these. [Sixth Embodiment] In a recording apparatus using an electrophotographic principle, an ink jet recording apparatus, a recording apparatus for a silver halide photographic process, and the like, a characteristic property of these apparatuses is that toner or liquid ink or liquid development is performed inside the apparatus. There is a problem that the liquid floats as fine particles, floats together with paper powder, or floats in a mist state. Therefore, the inside of the device is not a very favorable environment for the optical transmitting and receiving system of the present invention.

In consideration of the above, in the sixth embodiment of the present invention, as shown in FIG.
And cover members 32B and 34B for covering the laser diode chip 32 and the photodiode 34 in the light receiving unit 34, respectively. These cover members 32B and 34B are formed of a transparent member such as glass, for example. However, in the figure, the same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted.

As the cover members 32B and 34B, other than glass, a high-precision plastic member from which internal distortion has been removed can be used. Such a cover member plays a role of physically and chemically protecting the laser element and the light receiving element of the present invention manufactured by a high technology.

Further, foreign matters such as toner, ink or paper powder should not adhere to the laser diode chip of the present invention and impair the function of the optical transmission / reception system. Preferably, these cover members are detachable. With this configuration, when foreign matter adheres, it can be immediately removed and cleaned at any time. FIG. 5
In No. 1, the cover is not provided on the reflection member R, but a cover can be provided on the reflection member R if necessary.

In view of the above points, it is necessary to provide such a cover because the use of toner or paper is less than that of a computer, a video device, a television receiver, or the like, which has less chance of contamination. The device is considered to be a device in which toner powder or paper powder flies due to this, or a device in which liquid is used inside.
B, 34B are particularly effective in such devices. Seventh Embodiment FIG. 52 shows that the laser oscillation wavelength is 1.1 to
Another example of an optical transmission / reception system using a long-wavelength surface emitting laser diode in the 1.7 μm band is shown. However, in FIG. 52, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 52, in the present embodiment, in the configuration of FIG. 36, a plurality (3 in this example)
This is an example in which optical fibers are connected in cascade to enable communication over a longer distance.

Conventionally, an optical communication system has been studied even with a wavelength in the 0.85 μm band, but the transmission loss of the optical fiber is large and it is not practical. On the other hand, it has been difficult to construct a stable surface emitting laser element in a practical long wavelength band where transmission loss in an optical fiber is small.

On the other hand, according to the present invention, as described above, the semiconductor distributed Bragg reflector 12 or 18 is improved, and the non-radiative recombination preventing layers 13 and 17 are provided so as to obtain a 1.1 to 1.7 μm. A surface emitting laser diode that oscillates in the band wavelength range can be constructed, and a practical long wavelength band optical communication system has become possible.

In the example shown in the figure, the laser element light emitting portion 32A of the long wavelength surface emitting laser diode chip 32 as described above is used.
A first optical fiber FG1 for receiving the laser beam emitted from the first optical fiber FG1 and transmitting the same; a second optical fiber FG2 for receiving the laser beam emitted from the first optical fiber FG1 and transmitting the same; A third optical fiber F for receiving the laser beam emitted from the second optical fiber FG2 and transmitting the laser beam.
G3 is disposed along the optical signal transmission path, and the third
A photodiode chip 34 having an optical detector 34A for receiving the emitted laser beam is coupled to the optical fiber FG3.

An optical connection module MG1 for connecting a laser diode and an optical fiber is provided between the laser diode chip 32 and the first optical fiber FG1, and optically couples both. . Similarly, the optical connection modules MG2, MG3 and MG4 are also provided between each optical fiber and between the optical fiber and the photodiode chip.
Are provided to realize optical coupling.

FIG. 53 shows a bidirectional optical transmission / reception system having a configuration in which a transmission system FGB obtained by inverting the system of FIG. 52 is arranged in a transmission system FGA corresponding to the system of FIG. In FIG. 53, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 53, the transmission system FGB
Are, in order from the right, a third optical fiber FR3 acting as a transmission path for transmitting a laser beam emitted from the laser element light emitting portion 32A of the surface emitting laser diode chip 32, and an emission from the third optical fiber FR3. A second optical fiber FR2 acting as a transmission path for transmitting the laser beam, and a first optical fiber FR2 acting as a transmission path for transmitting the laser beam emitted from the second optical fiber FR2.
And the first optical fiber F1.
The light detector 34A of the photodiode chip 34 is optically coupled to R1.

[0312] In the transmission system FGB, a connection module MR4 is provided between the laser diode chip 32 and the third optical fiber FR3.
R4 optically couples both. Similarly, between the optical fibers FR3 and FR2, and between the optical fibers FR2 and FR2.
1 and between the optical fiber FR1 and the photodiode chip 34 in the same manner.
MR2 and a connection module MR1 are provided for optical coupling.

FIG. 54 shows an example of an optical communication system in which a plurality (n) of the optical transmission / reception systems of FIG. 52 are arranged in parallel.

Referring to FIG. 54, a plurality of laser light emitting portions 32A are provided on the laser diode chip 32, and the first and the second light emitting portions are provided by a plurality of optical fibers corresponding to each of the plurality of light emitting portions 32A. Second and third optical fiber groups MFG1, MFG2, and MFG3 are configured. Further, the photodiode chip 34 also has a plurality of photodetector sections 34A corresponding to the plurality of laser light emitting sections 32A.

Since a surface emitting laser diode chip is used in the present invention, it is easy to provide a single laser diode chip 32 with a plurality of laser light emitting portions 32A. By providing the plurality of laser light emitting units 32A on the laser diode chip 32, a large-capacity communication system can be easily realized.

Although not shown, the optical transmission / reception system of FIG. 54 is modified according to the configuration of the bidirectional optical transmission / reception system of FIG. 53 to construct a bidirectional large-capacity optical transmission / reception system using a plurality of optical fibers in parallel. You can also. [Eighth Embodiment] Next, another feature of the present invention will be described.

FIG. 55 shows the surface emitting laser diode chip 32 and the first optical fiber group MF in the left part of FIG.
The configuration of an optical connection module MG1 used for optically coupling G1 is shown. However, the optical connection module MG1 is conceptually shown by a rectangular dotted line. Hereinafter, a more specific configuration of the optical connection module will be described with reference to FIGS. In the figure, the same reference numerals are given to the parts described above, and the description is omitted.

FIGS. 56 and 57 show the surface emitting laser diode chip 32 and the optical fiber group MFG1 respectively.
The state before and after optical coupling are shown.

Referring to FIG. 56, the optical connection module MG1 shown by the conceptual rectangular dotted line portion in FIG. 55 is, specifically, a laser chip holder 61 and the optical fiber group FG.
1 is inserted into the chip holder 61 as shown by an arrow in FIG. 57 so that each laser element light emitting portion 32A is Corresponding to the end face of the optical fiber fg1,
The desired optical coupling is achieved.

At that time, in the present invention, the laser element light emitting section 3
The holders 61 and 62 are used to identify their orientations such that the 2A and the end surface (light receiving surface) of the optical fiber fg1 face each other one-to-one in the left-right and up-down directions without leaving any ambiguity. Means are provided. For this purpose, in the illustrated example, arrows are marked on the LD chip holder 61 and the fiber holder 62, respectively.
By providing such an identification means, the direction of the holders 61 and 62 can be instantaneously and correctly identified when the laser diode chip 32 and the optical fiber group FG1 are connected when constructing an optical transmission / reception system as in the present invention. Therefore, the optical connection can be performed efficiently.

Note that the identification means is not limited to such visible arrow marks, and it is also possible to use a difference in color. Further, the discriminating means is not necessarily limited to those which can be visually recognized, and need not be such that it can be recognized by tactile sensation by utilizing the unevenness of the shape. Is also possible. When the identification means that can be identified by touch is used, it is possible to easily identify the orientation of the holders 61 and 62 even when the construction is performed in the dark or at night.

FIGS. 58 and 59 show the LD chip holder 6.
Another example of the optical connection module MG1 composed of the combination of the optical connection module MG1 and the fiber holder 62 is shown.

Referring to FIGS. 58 and 59, also in this embodiment, the identification means is provided in each of the LD chip holder 61 and the fiber holder 62 as in the case shown in FIGS. 56 and 57. In the example, in addition to the above, a flange surface (FIG. 5) which engages with the end (flange surface 61A of FIG. 58) of the laser diode chip holder 61 so that the two can be accurately positioned and coupled.
8 flange surface 62B).

Next, other features of the present invention will be described.
This corresponds to the identification means shown in FIGS.
The coupling means relates to an optical connection module MG1 for optically coupling the surface emitting laser diode chip and the first optical fiber group MFG1. However, this idea of the present invention,
Surface emitting laser diode chip and first optical fiber group M
The first optical fiber group MFG1 is not applied only to the optical connection module MG1 for optically coupling with the FG1.
The present invention is also applied to an optical connection module MG2 that optically couples the second optical fiber group MFG2 with the second optical fiber group MFG2.

FIG. 60 shows an example of an optical connection module MG2 for optically coupling such an optical fiber group to another optical fiber group.

Referring to FIG. 60, also in this case, the first
Of each optical fiber fg1 in the optical fiber group MFG1
Is properly coupled with the corresponding optical fiber fg2 in the second optical fiber group MFG2.
In the fiber holders 64 and 65 constituting G2, means for identifying the directions are formed in the form of arrow marks. By providing such identification means,
When constructing an optical transmitting / receiving system as in the present invention, the first optical fiber group MFG1 and the second optical fiber group MFG
2 can be instantaneously distinguished from each other at the time of connection, and the optical coupling operation can be performed efficiently.

Note that the identification means is not limited to the arrow mark as in the examples of FIGS. 56 to 59, but may be one utilizing the difference in color, and further limited to one which is always visible. Instead, it may be one that can be recognized by tactile sensation using unevenness of the shape. By using such a structure that can be recognized by tactile sensation as the identification means, there is an advantage that the orientation of the fiber holder can be easily recognized even when working in the dark or when performing construction at night.

In the configuration shown in FIG. 60, not only the first fiber group holder 64 and the second fiber holder 65 are provided with identification means but also both are positioned with high precision and optical coupling can be performed with high efficiency. When the end of the first fiber group holder 64 (part A in FIG. 60) and the flange surface of the second fiber holder 65 (part B in FIG. 60) are in a state where optimal optical coupling is obtained. , Are configured to engage with each other. In this case, the end portion and the flange surface serve as stoppers, and it is possible to accurately perform positioning in the left-right direction in FIG.

Further, such an identification means and a positioning / coupling means optically couple the second optical fiber group MFG2 and the third optical fiber group MFG3 to form the optical connection module MG.
3 is also applied to the optical connection module MG4 for optically coupling the third optical fiber group MFG3 and the photodiode chip 34, and is connected to each other when constructing an optical transmitting / receiving system as in the present invention. Between the optical fiber groups or between the photodiode chip and the optical fiber group can be instantaneously identified, and the positioning and optical coupling can be achieved with higher accuracy. Ninth Embodiment A large-capacity optical transmission / reception system that extends over a distance of several cm to several hundred km by connecting a plurality of fibers in parallel and in series using an optical connection module like the present invention. Can be easily constructed because, as described above, according to the present invention, the oscillation wavelength 1.1.
This is because stable oscillation of the surface emitting laser diode device having a thickness of about 1.7 μm has become possible. Further, according to the present invention, a surface emitting laser diode device having an oscillation wavelength of 1.1 to 1.7 μm, which could not be realized conventionally, can be realized by devising the device structure of the present invention, and furthermore, the inspection of the laser device. And productivity is remarkably improved. Although it was difficult to construct such an optical transmission / reception system with a conventional 0.85 μm laser device, the emergence of a surface emitting laser diode device having an oscillation wavelength of 1.1 to 1.7 μm according to the present invention, For the first time, it has become possible to realize a commercial optical transmission / reception system.

FIG. 61 shows another example of a communication system using a long-wavelength surface emitting laser diode. However, FIG.
An optical fiber 72 drawn from a surface emitting laser diode element chip or a module package 71 accommodating the chip and a communication optical fiber 73 connected thereto are shown. In the figure, the same reference numerals are given to the parts described above, and the description is omitted.

Referring to FIG. 61, an optical fiber 72 pulled out from a module package 71 via a connector 71A is connected to a communication optical fiber 73 connected thereto at a fiber connecting portion 74 by, for example, fusion or the like. However, in that case, a certain connection margin is required. In particular, with respect to the optical fiber cable 72 drawn out from the module package 71, if the length Lg of the guide optical fiber shown in FIG. Would. It is also disadvantageous in producing a highly accurate module package.

Usually, an optical fiber used in a communication system such as the present invention is very fine, and its diameter is
Typically, it is only about 50 μm or 62.5 μm. When assembling the module package 71 using such an optical fiber, the optical fiber 72 extending from the module package 7 is held using a tool such as tweezers, and necessary work is performed. At this time, if the length Lg of the optical fiber 72 does not exceed a certain value, it becomes difficult to hold the optical fiber 72 with a tool.

[0333] Such an assembling operation can be performed by an automatic device, but even in this case, a work for gripping such a fine optical fiber is required. The length Lg of the optical fiber 72 needs to be equal to or more than a certain value in consideration of the ease with which the tip of the work, that is, the portion that actually grips the optical fiber, holds the optical fiber.

The present inventor has noticed the importance of performing such an assembling operation smoothly, and as a result of intensive studies on the assembling process, at least 1 mm is required as the length Lg shown in FIG. I found something. That is, in a communication system using a long-wavelength surface-emitting laser diode as in the present invention, the length of the surface-emitting laser diode element chip or the optical fiber cable 72 drawn out of a module package containing the chip. Lg (Length L of optical fiber for guiding in FIG. 61)
It has been found that g) needs to be 1 mm or more.

If the length of this part is shorter than 1 mm,
If the diameter is on the order of microns, as in the case of the optical fiber diameter, the assembling operation is expensive, highly accurate, requires highly mechanized equipment, and must be performed under a microscope, resulting in very low productivity. Such work is industrially unrealistic.

Note that such a guide optical fiber 72 is used.
Is connected to the optical fiber 73 constituting the optical communication system shown in FIG. 61 by, for example, fusion. At this time, the end face of the guide optical fiber 72 is actually melted. A length on the order of millimeters is required as the margin Gm).

The present inventor actually conducted a fusion experiment, and
The length required as the welding margin Gm was examined.

As a result, when the guide optical fiber length Lg is on the order of microns, for example, 200 μm, 500 μm
Alternatively, in the case of 900 μm, the end face of the optical fiber 71 was excessively melted, and good bonding was not obtained. on the other hand,
When the length Lg of the guide optical fiber was set to 1 mm or more, for example, when it was set to 1 mm or 3 mm, it was confirmed that good joining was obtained.

In summary, the fiber length Lg of the guide optical fiber 72 is required to be 1 mm or more from the viewpoint of assembly of the module package 71 and from the viewpoint of connection with the optical fiber of the optical communication system. It is concluded that there is.

The upper limit of the guide optical fiber 72 is sufficient if it is 20 mm from the viewpoint of the module assembling work and the connection with the optical fiber 73 of the optical communication system. If the optical fiber 7 is too long, it may be cut appropriately after assembling the module 71 to a required length.

Next, another aspect of this embodiment will be described.

In the above description, the relationship between the surface emitting laser diode element 32, which is a light source, and the guide optical fiber 72 directly coupled to the surface emitting laser diode element 32 is discussed. Holds for the side.

Although not shown, if the surface emitting laser diode 32 shown in FIGS. 61 and 62 is replaced with a light receiving element 34 such as a photodiode, the light receiving element 34 is provided on the light receiving side.
An optical fiber directly coupled to the light receiving element (FIG. 61,
(Corresponding to 62 guide optical fibers 72).

[0344] As with the light-emitting-side module package 71, the light-receiving unit requires the same concept from the viewpoint of module assembly and the connection with the optical fiber of the optical communication system.

In the present invention, the length of the optical fiber (corresponding to the guide optical fiber 72 in FIGS. 61 and 62) which is first optically coupled to the light receiving element 34 is set to 1 mm or more. Thus, practical assembly of the light receiving unit and highly reliable connection with the optical fiber of the optical communication system are realized.

It is sufficient that the upper limit is 20 mm as in the case of the module package on the light emitting side. [Tenth Embodiment] FIG. 63 shows that the laser oscillation wavelength is 1.1 to 1.0.
1.7 μm band long wavelength surface emitting laser diode chip 3
2 shows an example of a communication system using two and a plurality of optical fibers. However, in FIG. 63, the same reference numerals are given to the parts described above, and the description will be omitted.

In the configuration shown in FIG. 63, the laser diode element 32A in the laser diode chip 32 is driven by the communication control device 81 via the laser diode driving circuit 82, and the optical fiber 72 and During 73, an optical signal is provided in the form of a light beam.

Conventionally, an optical communication system has been studied when the laser oscillation wavelength is in the 0.85 μm band, but the optical fiber has a large transmission loss and is not practical for long distances. Further, in a communication system using a plurality of optical fibers using a conventionally known edge emitting type laser diode, it is necessary to individually adjust the optical fibers corresponding to each light emitting unit, and the Not only is it complicated, but also it is difficult to directly join laser diodes to each other or to arrange them two-dimensionally. In addition, the emission angle of the light emitting section is large, and the aspect ratio of the emitted light beam is shifted from 1.
In order to increase the optical coupling efficiency, a coupling lens needs to be provided between the light emitting unit and the optical fiber.

On the other hand, 1.1 to 1.7 μm
In the long-wavelength surface emitting laser diode of the band, stable driving can be performed with low energy as described above, and heat generation is suppressed.

FIG. 64 shows the structure of the surface emitting laser diode in the 1.3 μm band. The emission angle of such a surface emitting laser diode is about 15 degrees in both the vertical and horizontal directions, which is smaller than that of the edge emitting laser diode. , The shape is also circular,
There is no need to perform beam shaping.

Therefore, if the irradiation surface is smaller than the core diameter of the optical fiber 72, each laser diode element 32A can be connected to the corresponding optical fiber 72 without the coupling lens.
Can be combined with The same applies to other long wavelength bands.

As described above, by using the surface emitting laser diode, the difference between the diameter of the laser diode element 32A and the diameter of the fiber core becomes a margin, and a plurality of optical fibers are collectively adjusted. It becomes possible.

As shown in FIG. 63, the laser light emitted from each light emitting portion, that is, the laser diode element 32A is injected into the core at a high efficiency at the end face of the corresponding optical fiber. Since the optical signal injected into the optical fiber in this manner has a long wavelength, the transmission loss is small and the optical signal is transmitted over a long distance. As a result, according to this embodiment, an optical communication system with extremely high practicality is realized by using a plurality of optical fibers. As described above, in the surface emitting laser diode chip 32, the laser diode element 32A can be formed at any two-dimensional position as long as it does not interfere with the adjacent laser diode element.

In order to fix a plurality of optical fibers collectively, each of the plurality of optical fibers 72 is temporarily fixed with a jig 91 as shown in FIGS.
The resin 92 may be injected into the jig 91 as shown in FIG. At this time, by providing a positioning guide in the connector joint portion 71A, adjustment at the time of system construction can be omitted. That is, according to the present embodiment,
It is possible to construct an optical communication system that is easy to maintain while using a plurality of optical fibers.

Since the number of optical fibers in an optical communication system differs for each system, if the number of fibers can be freely changed, the system can be designed flexibly.

Therefore, as shown in FIG. 66 (B), a number of openings having substantially the same diameter as the optical fiber are formed in the connector joint portion 71a, and the surface emitting laser diode chip 32 shown in FIG. 66 (C) is formed. On the upper side, the connector joint portion 71a is adhered after adjustment in advance. Further, FIG.
As shown in the figure, several types of optical fibers holding a required number of optical fibers by the connector 71b are prepared in advance, and the necessary connector 7 is prepared.
1b is selected and inserted into the connector joint 71a.
With such a configuration, useless use of the optical fiber in the optical connector 71A is eliminated, and the number of optical fibers can be added later as needed, thereby increasing the degree of freedom in designing the optical communication system. It becomes possible.

Further, in the long-wavelength surface emitting laser diode chip 32 of the present invention, the light emitting section 3 is provided.
Since the laser diode elements constituting 2A can be two-dimensionally arranged, a hexagonal cross-sectional shape is formed on each optical fiber 95 so as not to be in contact with an adjacent fiber as shown in FIG. By applying the resin coating 96 and arranging the optical fibers 95 having the resin coating 96 two-dimensionally, it is possible to realize an optical fiber cable having a structure in which the optical fibers are closest packed as shown in FIG. FIG.
In the optical fiber cable of No. 8, since the optical fibers are closest packed, the area of the connector connection portion 71A can be minimized.

In the structure shown in FIG. 67, the optical fiber 9
A close-packed optical fiber is realized by forming a resin coating 96 on the outside of the optical fiber 5. However, instead of the resin coating 96, a fixing member such as a resin having a hole having a hexagonal cross-section formed close to the resin coating 96. It is also possible to use. [Eleventh Embodiment] FIG. 69 shows a long wavelength surface emitting laser diode.
1 shows an example of an optical fiber 101 used for a communication system using a cable. However, in the figure, the same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 69, the optical fiber 10
Reference numeral 1 denotes a core 101A into which a laser beam emitted from the laser element light emitting unit 32A is injected and which transmits the injected laser beam, and a clad 101B surrounding the core 101A.
The diameter of the core 101A is D, the optical fiber 101 is
The length L is set so as to satisfy the condition 10 ⁵ ≦ L / D ≦ 10 ⁹ where L is the length.

Conventionally, an optical communication system which operates in a laser oscillation wavelength band of 0.85 μm has been studied, but the transmission loss of the optical fiber is large and is not practical. In a practical long wavelength band where transmission loss is small, a stable laser element cannot be obtained. On the other hand, in the present invention, as described above, the semiconductor distributed Bragg reflecting mirrors 12 and 18 are improved,
By providing the non-light-emitting recombination preventing layers 13 and 17, a surface-emitting laser diode that can be driven stably with low energy in a laser oscillation wavelength band of 1.1 to 1.7 μm is realized. As a result, A practical long wavelength band optical communication system has become possible.

FIG. 70 shows the configuration of a long-distance optical communication system using the long-wavelength surface emitting laser diode chip 32 and the optical fiber 101.

Referring to FIG. 70, the long-distance optical communication system includes a long-wavelength surface emitting laser diode chip 32.
A first optical fiber having a core diameter D of 50 μm, a length L of 5 km, and a first optical fiber 101A for injecting and transmitting a laser beam emitted from the laser element light emitting portion 32A of the laser diode chip 32; 1 optical fiber 1
A second optical fiber 101B having a core diameter D of 50 μm and a length L of 5 km for transmitting the laser beam emitted from the first optical fiber 101A;
And a photodiode chip 34 having a photodetector section 34A into which the laser beam emitted from B is injected.

A connection module 71 is provided between the laser diode chip 32 and the first optical fiber 101A.
And a similar connection module 75 is similarly provided between the second optical fiber 101B and the photodiode chip 34. Further, a repeater 1 is provided between the first optical fiber 101A and the second optical fiber 101B.
01C is installed to amplify and reproduce an optical signal.

In the configuration shown in FIG. 70, the first and second optical fibers 101A and 101B are usually manufactured in units of several thousand km, but finally, due to defects such as air bubbles generated in the manufacturing process, ultimately. A length of about several hundred km is a unit of a product. Considering the propagation loss and the like, the repeater 101C
The transmission length up to is generally, for example, a core diameter of 50 μm
In the case of the optical fiber described above, 5 m to 50 km is a practical range, and an optical fiber of this length is used for optical communication.

If the transmission distance is longer than 50 km, transmission cannot be performed substantially due to transmission loss. Therefore, it is necessary to provide a relay point and amplify the signal. On the other hand, if the transmission distance is shorter than 5 m, other communication means are possible without necessarily using such an optical communication system.

As the optical fiber 101 used in this embodiment, a silica glass optical fiber having a core diameter D of several μm or a plastic optical fiber having a core diameter D of several hundred microns can be used. It is also possible to use them alone or in bundles.

FIG. 71 shows a quartz glass optical fiber 101-A having a core diameter D of 50 μm and a transmission length L of 500 m.
1B illustrates an optical communication system in which bidirectional optical communication is performed by separating these optical fibers at a light receiving end and a light emitting end.

Referring to FIG. 71, in this embodiment, optical transmitting / receiving sections 102A and 102A in which a long-wavelength surface emitting laser diode chip 32 and a photodiode chip 34 are paired.
B, the first optical fiber 101A is coupled to the light emitting unit 32A of the laser diode chip 32 in the optical transmitting and receiving unit 102A, and the optical fiber 101A is further connected to the optical transmitting and receiving unit 102B by It is optically coupled to the light receiving section 34A of the photodiode chip 34. Similarly, in the optical transmitting / receiving section 102B, the second optical fiber 101B is coupled to the light emitting section 32A of the laser diode chip 32, and the optical fiber 101B
Is optically coupled to the light receiving section 34A of the photodiode chip 34 in the optical transmitting / receiving section 102A.
At this time, the laser diode chip 32 and the photodiode chip 34 constituting the optical transmitting / receiving section 102A constitute a connection module 71, and the optical transmitting / receiving section 102A
The laser diode chip 32 and the photodiode chip 34 forming B constitute a connection module 75.

A long-wavelength surface-emitting laser diode chip 32, a photodiode chip 34, and an optical fiber are combined as a set, and a large number of laser diode elements 32A are formed on the laser diode chip 32. A large number of photodiode elements 34A on the diode chip 34
By expanding the case where is formed, a large-capacity communication system can be realized.

FIG. 72 shows a transmission length of 100 m using a fluorinated plastic optical fiber having a core diameter of 100 μm.
1 shows an application example of the present invention to a high-speed multimedia network of less than.

Referring to FIG. 72, a first optical fiber 111 having a core diameter D of 50 μm and a length of 50 km extends from the optical line terminal 110. The optical fiber 111 further has a core diameter D of 50 μm. 50 optical fibers with a length of 1 km
The second optical fiber 112 having a length of 50 km, which is formed by the fusion splicing, is coupled to the optical fiber 112 so that the total extension is 1 km.
A high-speed optical transmission system capable of transmitting information at a high speed of the order of Gbps over a distance of 00 km has been formed. In the example of FIG. 72, an optical repeater 111R is provided between the optical fiber 111 and the optical fiber 112 in order to compensate for signal attenuation due to the propagation loss of the silica glass optical fiber.

The optical signal transmitted through the second optical fiber 112 once enters the network terminator 115, is converted into an electric signal, and the number of lines 1 corresponding to the required number of terminals.
15a to 115c, and each line 115a to 115c
The optical transmission / reception units 102A and 102A described with reference to FIG.
B is transmitted again in the form of an optical signal by the optical communication system 116 including B. The transmitted optical signal is supplied to a corresponding optical output port. In the optical communication system 116, for optical transmission to the optical output port corresponding to the line 115a, an optical fiber 117a having a core diameter of 100 μm and a length of 10m includes an optical fiber 117a having an optical output port corresponding to the line 115b. For transmission, the core diameter is 100 μm and the length is 5
0m optical fiber 117b is connected to the line 115c.
For optical transmission to the optical output port corresponding to
An optical fiber 117c having a length of 0 μm and a length of 100 m is used. The optical signal transmitted in this manner is converted into an electric signal by the optical transmission / reception unit 102B at each optical output port and supplied to the corresponding terminal device 102C.

Also, transmission from each terminal device is transmitted in the form of an optical signal from the optical transmitting / receiving section 102B to the optical transmitting / receiving section 102A via the optical fibers 117a to 117c. To reach.

In this embodiment, the optical fiber 117 used is
Since the core diameters a to 117c are as large as 100 μm, alignment with a high-precision lens system is not required, and optical connection to equipment in an office or home can be extremely easily performed.

[0375] Also in this embodiment, between the length L of the core diameter D and the optical fiber, the relationship of ^{10 5 ≦ L / D ≦ 10} 9 is maintained. If the transmission distance is longer than 100 km, substantial transmission cannot be performed due to transmission loss. In such a case, a relay point is provided to amplify and reproduce the signal.
When the length is shorter than 10 m, other means exist even if the optical communication system is not necessarily used.

FIGS. 73A and 73B are a plan view and a cross-sectional view, respectively, showing an example of application to a hybrid optical integrated circuit device using a long-wavelength surface emitting laser diode of the present invention.

Referring to FIGS. 73A and 73B, in this embodiment, the long-wavelength surface-emitting laser diode chip 32 and the photodiode chip 3 are disposed on a ceramic substrate 51.
Further, on the ceramic substrate 51, a first light guide having a rectangular cross section of 7 × 7 μm and having a length of 1 cm and transmitting a laser beam emitted from the laser element 32A in the laser diode 32 is provided. The optical waveguide 52 is optically coupled to a light detector section 34A in the photodiode chip 34, and is 7 μm × similar to the first optical waveguide 52.
A second optical waveguide 5 having a rectangular cross-sectional shape of 7 μm and a length of 1 cm and supplying an optical signal to the optical detector unit 34B.
3 is formed. Further, on the ceramic substrate 51, a preamplifier 51A for amplifying an output electric signal formed by the photodiode chip 34 is formed.

Furthermore, the core diameter D is 100 μm and the length is 1
The first optical fiber 54 having a core diameter D of 1
A second optical fiber 55 having a length of 100 μm and a length of 100 m is provided so as to be optically coupled to the first optical waveguide 52 and the second optical waveguide 53 via a connection module 56, respectively. .

Further, a connection module 57 having the surface emitting laser diode chip 32 and the photodiode chip 34 is provided at the other end of the optical fibers 54 and 55, and the optical fiber 54 is an optical detector of the photodiode chip 34. In the portion 34A, the optical fiber 5
5 is a laser diode of the laser diode chip 32.
It is provided so as to be coupled to the storage element 32A.

The optical waveguides 53 and 54 are formed by forming respective cores and a clad layer enclosing the cores on a silicon substrate 58 by photolithography. Above, it is provided alongside the preamplifier 51A. [Twelfth Embodiment] FIGS. 74A and 74B show an example of a laser diode chip 120 used in an optical communication system using a long-wavelength surface emitting laser diode according to the present invention. However, FIG. 74A is a plan view, and FIG. 74B is a cross-sectional view taken along AA ′. Note that FIG.
4 (A) and FIG. 74 (B) are not the same scale. In the figure,
The same reference numerals are given to the parts described above, and the description will be omitted.

Referring to FIGS. 74 (A) and (B), FIG.
On the diode chip 120, a long wavelength surface emitting laser diode element 32A and a corresponding light receiving element 34A are monolithically formed.

The light receiving element 34A has a semiconductor laminated structure similar to that of the long wavelength surface emitting laser diode element 32A, and is formed collectively in the same process as the surface emitting laser diode element 32A. . By using the semiconductor laminated structure of the surface emitting laser diode element with a reverse bias or no bias, it can be used as a light receiving element. The light receiving element 34A is a surface emitting laser diode element 32A.
It has sensitivity to the oscillation wavelength and can detect light.

As can be seen from the plan view of FIG.
The light receiving element 34A is formed so as to surround the long wavelength surface emitting laser diode element 32A. The ray
An upper electrode 121 is formed on the upper surface of the diode element 32A, and a lower electrode 123 is formed on the lower surface of the laser diode chip 120. Another upper electrode 122 is formed on the upper surface of the light receiving element 34A. Upper electrode 121 of laser diode element 32A
Has a window for extracting light output, but such a window is not formed in the upper electrode 122 of the light receiving element 34A.

FIG. 75 shows the laser diode shown in FIG.
FIG. 4 is a diagram for explaining the operation of the chip 120.

Referring to FIG. 75, the laser diode element 32A in the surface emitting laser diode chip 120 is
Opposite to the end face of the optical fiber 125, it is positioned so that the light emitted from the surface emitting laser diode element 32A enters the core of the optical fiber. Surface emitting laser
From the side surface of the diode element 32A, light leaks in a direction transverse to the main light emitting direction, and such leak light is detected by the adjacent light receiving element 34A. Although the amount of light leaking from the side surface of the surface emitting laser diode 32A is not large, the light receiving element 34A is close to the surface emitting laser diode element 32A so as to surround the surface emitting laser diode element 32A in the configuration of FIG. Since it is formed, leakage light can be detected. In FIG. 75, since the semiconductor distributed Bragg reflector 18 and the upper electrode 122 are formed on the light receiving element 34A, an optical signal or the like transmitted through the optical fiber 125 from a partner (not shown) is indicated by an arrow in the figure. Are reflected by the upper surface of the light receiving element 34A, and are not detected.

As is clear from the above description of the configuration and operation, according to this embodiment, the light-receiving element for detecting the output of the surface-emitting laser diode is integrally formed on the surface-emitting laser diode chip. By forming and integrating such a laser diode chip on the ceramic substrate 111, an optical communication system having a hybrid configuration can be configured.

FIGS. 76A and 76B show another example of a semiconductor laser diode chip used in an optical communication system using a long wavelength surface emitting laser diode according to the present invention. However, FIG. 76A is a plan view, and FIG.
The cross-sectional views along -A 'are shown respectively. Note that the scales of FIG. 76A and FIG. 76B are not the same.

Referring to FIGS. 76 (A) and (B), FIG.
On the diode chip, a long wavelength surface emitting laser diode element 32A and a light receiving element 34A are monolithically integrated. The light receiving element 34A is a long wavelength surface emitting laser.
It has the same semiconductor lamination structure as the diode element 32A, and is formed collectively in the same process as the surface emitting laser diode element 32A. The light receiving element 34A has sensitivity to the wavelength of the surface emitting laser diode element 32A and can detect light. However, in this embodiment, the upper semiconductor distributed Bragg reflector 18 in the light receiving element 34A is removed by etching, and as shown in the plan view of FIG. 76A, surrounds the long wavelength surface emitting laser diode element 32A. It is formed in such a shape. The upper electrode 12 having a light input / output window opened on the upper surface of each of the elements 32A and 34A.
1 and 122 are formed respectively, and a lower electrode 123 is formed on the lower surface of the laser diode chip 120.

FIG. 77 shows the laser diode shown in FIG.
FIG. 4 is a diagram illustrating the operation of the chip.

Referring to FIG. 77, in the surface emitting laser diode chip 120, a laser diode element 32A is provided so as to face an end face of an optical fiber 125, and the laser diode element 32A is Positioning is performed so that light emitted from the surface emitting laser diode element 32A enters the core of the optical fiber.

In this embodiment, the surface emitting laser diode
The side surfaces of the storage element 32A and the light receiving element 34A are
Alternatively, since it is covered with 122, no light leaks from the side surface of the element.

Then, when a light beam carrying an optical signal from a partner (not shown) enters through the optical fiber 125, the light beam emitted from the end face of the optical fiber 125 is as shown by an arrow in the figure. The light enters the surface of the light receiving element 34A while spreading and is detected by the light receiving element 34A formed so as to surround the surface emitting laser diode 32A. On the other hand, a semiconductor distributed Bragg reflector 18 is formed on the upper surface of the surface-emitting laser diode 32A, so that an incident light beam hardly enters the inside of the surface-emitting laser diode 32A.

As is clear from the above configuration and operation, according to the present embodiment, the surface emitting laser diode element 3
The light-receiving element 34A for output detection of 2A is integrally formed on the surface emitting laser diode chip 120, and the laser diode chip 120 is integrated on the ceramic substrate 111, so that the optical transmission / reception of the hybrid configuration is achieved. It is possible to configure an optical communication system including the unit. The combination of the surface emitting laser diode and the light receiving element shown in the above embodiment is merely an example, and a plurality of these are arranged to form an array or to detect the output of the surface emitting laser diode element 32A. A configuration in which the light receiving element 34A and the light receiving element 34A for detecting incident light are combined also falls within the scope of the present invention. Needless to say, the present invention is not limited to the positional relationship and the shape of the surface emitting laser diode element and the light receiving element shown in the above embodiment. [Thirteenth Embodiment] Next, still another embodiment of the present invention will be described.

By the way, in the present invention, 1.1 to 1.7.
In order to realize a long-wavelength surface emitting laser having a long wavelength of
It is important to use nAs, GaInNAs, and GaAsSb active layers, for which it is necessary to minimize the mechanical stress applied to the laser diode. Examples of such mechanical stress include a thermal stress generated between the laser diode and the mounting substrate due to the operating temperature environment of the system, heat generation of the laser diode, the drive circuit, and the like. Such a thermal stress occurs when a temperature change occurs in a structure in which materials having different coefficients of linear expansion are fixed to each other, and the structure tries to maintain its original shape, and its magnitude is large. Depends on the temperature change, the coefficient of linear expansion of the constituent materials, the Young's modulus, and the like. In order to prevent such thermal stress from occurring, it is conceivable to control the temperature of the entire module including the laser diode. However, providing such a temperature control mechanism increases the cost, In practice, it is difficult to control the temperature completely constant.

Therefore, in order to provide a low-cost and highly-reliable system, a material having a similar linear expansion coefficient to that of a laser diode is used as the material of the mounting substrate, and the laser diode is connected to the laser diode by thermal stress. It is desirable to reduce the influence of.

In view of this point, in the present embodiment, mounting boards were manufactured from materials having various linear expansion coefficients, and the thermal stress generated during actual laser oscillation and the output characteristics of the laser associated therewith were examined. The surface emitting laser used is that shown in FIG. 1 and has an oscillation wavelength of 1.3 μm.
Was used. The chip size is 5mm x 1
A laser having 0 mm (thickness: 0.6 mm) and 20 laser elements formed in one row at a pitch of 300 μm was used. On the other hand, the size of the mounting board is 10 mm x 20 mm (2 mm thick)
And

[0397] Table 5 shows the results. In the table, ○ is 0-7
The symbol "x" indicates that a stable output was obtained in a use environment of 0 ° C, and the symbol "x" indicates that a stable output was not obtained and was not practically used.

[0398]

[Table 5] The linear expansion coefficient of the laser diode of the present invention is 6 × 10 ^−6.
/ K. Therefore, from the above results, if the difference between the linear expansion coefficients of the laser diode and the mounting substrate is within about 2 × 10 ⁻⁶ / K, the thermal stress generated at the time of laser oscillation and the output characteristics of the laser associated therewith will be stable. It is clear that it is practical. Among them, Si, SiC, GaAs, AlN
Is a material that can be particularly preferably used from the viewpoint of easy availability of materials and ease of manufacturing and processing as a mounting substrate.

Also, for the heat dissipating member fixing the mounting substrate, selecting a material close to the linear expansion coefficient of the laser diode reduces distortion to the mounting substrate, and consequently reduces the laser diode. The applied mechanical stress is also reduced. Further, the material constituting the heat radiating member is required to have high thermal conductivity.

In view of this point, in the present invention, a heat radiating member was manufactured from various materials having different thermal conductivity, and the output characteristics of the laser due to heat generated during actual laser oscillation were examined.

The surface emitting laser used was the same as that used in the study of the mounting substrate. As the mounting substrate, a SiC substrate having the same size as the mounting substrate described above was used.

Table 6 shows the results. However, in Table 4,
The symbol “x” indicates that a stable output was obtained in a use environment of 0 to 70 ° C., and the symbol “x” indicates that a stable output was not obtained and was not practically used.

[0403]

[Table 6] The thermal conductivity of the laser diode of the present invention is 55 W / mK. Thus, it can be seen from the above results that good results can be obtained when the thermal conductivity of the heat radiating member is larger than the thermal conductivity of the laser diode of the present invention. That is, when the thermal conductivity of the heat radiating member is larger than the thermal conductivity of the laser diode of the present invention, the heat generated at the time of laser oscillation is transmitted to the mounting substrate, and then the heat radiating member does not return to the laser diode side. The heat can be efficiently dissipated. Therefore, the output characteristics of the laser do not fluctuate due to heat storage, and stable and practical characteristics can be obtained. Among them, AlN, Cu /
Materials such as W, W, Mo, and Cu are easily available, and are materials that can be particularly suitably used also from the viewpoint of easy production and processing as a heat radiation member.

Particularly, by controlling the composition ratio of Cu / W and setting the heat conduction in the above range, Cu / W can be used as a package substrate described later with reference to FIG.

An optical communication system according to the present embodiment using such members will be described below.

The communication system generally comprises a surface emitting laser diode and an optical transmitter having a driving circuit therefor, a surface light receiving element and an optical receiving section having a driving circuit therefor, and a light acting as a transmission path therebetween. It consists of a fiber or an optical waveguide.

The driving circuit for the laser diode and the surface-type light receiving element is mounted on the same mounting substrate as the respective elements, or the laser element is mounted on the laser diode element forming substrate by a wafer process. It is formed in the same way as the formation. In addition, by providing the optical transmitting unit and the optical receiving unit on both sides of the optical transmission path, an optical communication system that performs bidirectional communication can be realized.

[0408] Fig. 78 shows an example of an optical transmission section of such an optical communication system. However, in the figure, the same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 78, the light transmitting section includes a surface emitting laser diode chip 32, a driving circuit 32DR for driving the laser diode chip 32, and a mounting board 131 on which these are mounted. A heat dissipating member 132 for supporting the mounting substrate 131 and adjusting the position of the laser diode 32 and dissipating heat, and holding the heat dissipating member 132;
A metal package 133 used as a heat sink and a radiation fin, and an optical fiber 134 forming an optical transmission line
It is composed of The metal package 133, the heat radiation member 132, and the mounting board 131 are mechanically and thermally connected by solder or resin. The laser diode 32 and the drive circuit 32DR are electrically connected by wire bonding or the like.

The laser diode chip 32 includes, for example, a laser diode element having the structure shown in FIG. 1, and the laser diode element may oscillate at 1.2 μm, for example. On the other hand, as the mounting board 131,
A Si substrate having a linear expansion coefficient of 4 × 10 ⁻⁶ / K can be used. In this case, the laser diode 32 is die-bonded on the mounting substrate 131 with AuSn solder.
Electrical and mechanical connections are made with the electrodes.

The surface of the Si substrate 131 has a thickness of 200 nm.
SiO ₂ film having a thickness is formed of. This SiO ₂ film may be a thermal oxidation or an SiO ₂ film formed by a CVD method or an SOG method. The oxide film is used for insulation, but has a heat radiation property inferior to that of Si.
It is desirable that the insulating property is as thin as possible within a sufficient range. The laser laser
Drive circuit 32DR for driving this together with the chip 32.
Are also fixed on the same mounting board 131. As a heat dissipating member for fixing this mounting substrate, AlN (linear expansion coefficient 5 × 10 ⁻⁶⁾ having high thermal conductivity and excellent matching of linear expansion coefficient is used.
/ K, thermal conductivity 200 W / mK). As the metal package 133, a Cu / W powder molded product can be used. At this time, the metal package 1
The Cu / W molding constituting 33 had a composition of 89W-11Cu, a linear expansion integer of 6.5 × 10 ⁻⁶ / K, and a thermal conductivity of 180 W / mK. Such a powder molded product can obtain high dimensional accuracy at low cost, and can be easily formed such as a radiation fin shape, and can realize efficient heat radiation.

[0412] In the example of FIG.
A multi-mode optical fiber having a core diameter of 50 .mu.m is connected to a laser diode element 32A in the laser diode chip 32.
And optically connected. Examination of the stability of such an optical communication system in a use environment of 0 to 70 ° C. revealed that a good optical communication system with stable laser output, no change in characteristics, no deterioration in life, and the like was obtained. .

Note that GaAs is used instead of the Si substrate.
(Linear expansion coefficient 6 × 10 ⁻⁶ / K), AlN (linear expansion coefficient 5 × 10 ⁻⁶ / K), or SiC (linear expansion coefficient 4 ×
10 ^{- 6} / K) can also be used substrates as the mounting substrate 133. When an AlN substrate or a SiC substrate is used, the formation of an oxide film is unnecessary because these substrates are insulating substrates. Otherwise, the structure may be the same as above. In terms of handling and cost, Si and AlN are preferable as the mounting substrate.

As a heat radiation member, 8 instead of AlN was used.
9W-11Cu, 85W-15Cu, 80W-20Cu
Cu / W (the coefficient of linear expansion is 6 to 8 × 10 ⁻⁶⁾
/ K, thermal conductivity was 180-200 W / mK),
Alternatively, good results can be obtained by using W, Mo, and Cu.

In the example shown in FIG. 78, a single laser diode element is provided in the laser diode chip 32 of the transmission section. The member is the laser diode chip 32.
It is particularly suitable for constructing a large-capacity optical communication system by forming an array of a plurality of laser diode elements therein or by forming an array of laser diode chips 32 therein.

For example, in the case of a multi-laser array chip in which a plurality of laser elements 32A are formed on a single chip 32, a plurality of laser elements are formed close to each other.
Heat generation by laser oscillation and thermal stress by its heat storage,
Further, fluctuation of laser output characteristics due to thermal stress becomes a problem. Further, a laser element drive circuit 32DR may be formed on such a chip at the same time, and heat generated from the drive circuit 32DR is also superimposed, resulting in a more serious situation. In this embodiment, even in such a case, a stable laser output can be obtained without causing any problem by appropriately selecting the material of the mounting board 131 and the material of the heat radiating portion 132.

[0417] Conventionally, since a surface emitting laser diode device having an oscillation wavelength of 1.1 to 1.7 µm as in the present invention did not exist, a communication system using such a device or a long wavelength band such as this was used. The technical problem at the time of mounting the surface emitting laser diode chip has not been clarified. This time, the inventor of the present invention has recognized a specific technical problem for the first time by the present invention, and has provided means for solving the problem.

In the above description, the optical transmission line optically coupled with the laser diode chip 32 is a multi-mode optical fiber. However, this optical transmission line may be an optical waveguide, a single mode optical fiber, a plastic optical fiber, or the like. But it doesn't matter. The laser diode of the present invention does not need to use a high-cost heat radiating member such as a Peltier element module, but it is of course possible to use these heat radiating members.

Next, another embodiment of the present invention is shown in FIG. However, in FIG. 79, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 79, this embodiment also shows an optical transmission unit of an optical communication system as in the embodiment of FIG. However, in this embodiment, the heat radiation member 132 also serves as the metal package 133.

The optical transmitter shown in the figure is provided with a laser array chip 32 in which a plurality of laser diode elements are arrayed on one chip, a drive circuit 32DR for driving the laser diode elements, and these components are mounted. Mounting board 131
And a metal package 133 that fixes the mounting substrate 131 and is used as a heat sink and a radiation fin, an optical fiber 134 that forms an optical transmission path, and a ferrule 135 that fixes the optical fiber 134. The metal package 133 and the mounting board 131 are mechanically and thermally connected by solder or resin. Further, the laser diode chip 32 and a drive circuit (not shown) are electrically connected by wire bonding or the like.

In the illustrated example, a laser diode having an oscillation wavelength of 1.3 μm shown in FIG. 10 was used, and four elements were arranged at the same pitch of 250 μm as the arrangement pitch of the opposing optical fibers. As in the previous embodiment, a Si substrate was used as the mounting substrate, and the laser diode was AuSn.
Die bonding was performed on the mounting substrate with solder, and further, electrodes were electrically and mechanically connected.

The surface of the Si mounting substrate has a thickness of 200 n.
m SiO ₂ film is formed by thermal oxidation treatment,
Such an oxide film may be formed by a CVD method or an SOG method.
The oxide film is provided as an insulating film. However, since the heat dissipation characteristic is inferior to that of Si, it is desirable that the oxide film be as thin as possible within a sufficient range. Similarly, a drive circuit (not shown) for driving the laser diode is also provided on the mounting substrate.

Further, as a metal package holding the mounting substrate and also serving as a heat radiation member, a Cu / W powder molded product was used. The composition ratio of the metal package is 89W-
With 11 Cu, the coefficient of linear expansion is 6.5 × 10 ⁻⁶ / K, which is close to the coefficient of linear expansion of the laser diode and the mounting substrate. The thermal conductivity was 180 W / mK.
Such a powder molded product can obtain high dimensional accuracy at low cost, and can be easily formed into a heat radiation fin shape, and can form an efficient heat radiation structure.

As the optical transmission line, a multi-mode optical fiber having a core diameter of 50 μm arranged at a pitch of 250 μm was used, and was optically connected to a laser diode. Examination of such an optical communication system in a use environment of 0 to 70 ° C. has revealed that a favorable optical communication system has been obtained in which the laser output is stable, there is no characteristic change, and the life is not deteriorated. Since the metal package also functions as a heat radiating member, a system with a small number of components and high heat radiating efficiency could be constructed.

Note that a GaAs substrate or A
Similarly, good results can be obtained when an 1N substrate or a SiC substrate is used as a mounting substrate. AlN and SiC
In the case of a substrate, it is not necessary to form an oxide film because the substrate is an insulating substrate. Other than that is the same as above, and the description is omitted.

In this embodiment, four laser diodes and four laser diodes are used.
Although an optical fiber is used, the present invention is not limited to this particular configuration, and the laser diode may be one.
In the case of a single optical fiber, or a laser diode
The number of optical fibers is 8, 12, 16 and the number of optical fibers is 8
This is also effective in the case of 12, 16 or the like.

In particular, in the case of a multi-laser array chip in which a plurality of laser elements are formed on one chip by utilizing the features of the surface emitting laser diode of the present invention, a large number of laser elements can be easily formed. Optimum for large-capacity communication, but the problem of heat is important. Therefore, by properly selecting the mounting board material and heat radiation member as in the present invention, stable laser output can be achieved without any problem. It is possible to obtain

Although the optical transmission line for optically coupling with the laser diode is also a multimode fiber, it may be an optical waveguide, a single mode optical fiber, a plastic optical fiber, or the like. Fourteenth Embodiment Next, a communication system using a long-wavelength surface emitting laser diode according to still another embodiment of the present invention will be described with reference to FIG. However, FIG.
The same reference numerals are given to the parts described above, and the description is omitted.

Referring to FIG. 80, a communication system using a long-wavelength surface emitting laser diode includes a laser module 141 on which a laser diode chip 32 is mounted, a ferrule 142A for fixing an optical fiber 142, and a ferrule 142A. An adapter housing 143 that houses the optical fiber 142 together with the optical fiber 142, a bush 144 that fixes the optical fiber 142, a housing 145 that houses the bush 144, and the adapter housing 143, the laser module 141, and the housing 143 that are integrally held. And a base 146. At this time, in the configuration of FIG. 80, the length from the point A to the point B of the optical fiber 142 is set to the length of the housing 14 from the end surface of the adapter housing 143 on the side of the laser diode chip 32 in the figure.
5 is set longer than the distance L (fixed length) to the end face.

More specifically, referring to FIG.
Is 1, the length AB of the optical fiber 142 is 1.05. As described above, the optical fiber 142 is bent between the adapter housing 143 and the housing 145 and has elasticity by itself,
The optical fiber 142 is pressed so that a force acts in the axial direction (left direction in the figure) toward the light emitting portion 32A of the laser diode chip 32, and the mechanical connection between the two is stabilized.
As a result, good optical coupling is obtained in this embodiment.
Although a plastic optical fiber is used here as the optical fiber 142, a quartz glass fiber whose outer periphery is coated with plastic may be used.

FIG. 81 shows a case where the fixed length L in FIG. 80 is set to 1 and the optical fiber length AB is set to 2. Other configurations are the same as those in FIG. In the present embodiment, a larger elastic force is obtained as compared with that of FIG. 80, and the connection between the laser element and the optical fiber becomes more reliable.

FIG. 82 is a sectional view showing the structure of the adapter housing 143 used in the optical communication system having the structure shown in FIG. 80 or 64.

Referring to FIG. 82, the adapter housing 143 includes a split sleeve 1431 having a tapered shape.
A ferrule 142A for fixing the optical fiber 142, a coil spring 1432 made of a shape memory alloy for applying an axial pressing force to the ferrule 142 via the split sleeve 1431, a collar 1433 cooperating with the coil spring 1432, It includes a plug housing 1434 that houses the split sleeve 1431, the coil spring 1432, and the collar 1433, and a connector 1435 that connects the plug housing 1434 to the adapter housing 143.

The coil spring 1432 generates an elastic force due to the initial shape at a normal temperature or a heated state, and expands, for example, upon cooling, and presses the ferrule 142A in the axial direction of the ferrule. Depending on the design of the connector 1435, it is possible to store the shape so that the coil spring 1432 extends further on the high temperature side.

FIG. 83 shows a modification of the structure shown in FIG. However, in FIG. 83, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 83, in this embodiment, the shape memory alloy coil spring 1432 is replaced by a shape memory alloy leaf spring 1432A.
32A generates an elastic force due to the initial shape in a normal temperature or a heated state, for example, is extended with cooling, and generates a force for pressing the ferrule 142 in the axial direction of the optical fiber 142. Depending on the design of the connector 1435, it is possible to store the shape so that the leaf spring 1432A extends on the high temperature side.

Here, the spring 1432 or 143
Although an example in which a shape memory alloy is used as 2A has been described, in the present invention, the spring 1432 or 1432A does not necessarily need to be a shape memory alloy, and may be a shape memory plastic. In such a connection module, the temperature at which an optical communication system is assembled (generally higher than room temperature) and the temperature at which it is actually used (room temperature)
And there is a temperature difference. Therefore, such a shape memory member changes its shape due to the temperature difference, and generates an elastic force in a state where the shape memory member is incorporated in the structure as in the present invention. The difference in the temperature difference (the temperature when the system is assembled and the temperature when the system is actually used) may be reversed.

FIG. 84 shows another example of a communication system using a long-wavelength surface emitting laser diode according to this embodiment.
However, in FIG. 84, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 84, in the communication system of this embodiment, a laser module 141 having a laser diode chip 32 mounted thereon, a ferrule 142A for fixing an optical fiber 142, and the ferrule 142A are housed together with the optical fiber 142. An adapter housing 143,
It comprises a fixing device 147 for holding and fixing a part of the optical fiber 142, and a base 146 for integrally fixing the adapter housing 143, the fixing device 147 and the laser module 141. At this time, in the communication system shown in FIG. 84, the optical fiber 142 is bent between the adapter housing 143 and the optical fiber fixing device 147.

The optical fiber fixing device 147 is a device utilizing frictional gripping compression, and comprises a compression spring 1471 made of a shape memory alloy, a collar 1472 cooperating therewith, another collar 1473, and the collars 1472 and 1473.
And a sphere 1474 disposed between
And a housing 1475 having a conical surface that abuts an optical fiber 14 within the housing 1475.
Ferrule 142B and split sleeve 147 holding 2
6 is the collar 1472 and the split sleeve 147
6 is housed such that a shape memory alloy compression spring 1471 is interposed therebetween.

In the optical communication system having such a configuration, the force for the optical fiber 142 to expand due to thermal deformation acts on the left and right, but the compression spring 147 in the optical fiber fixing device 147.
1 pushes the ball 1474 to the right, and the optical fiber 142
In order to hold the optical fiber 142 firmly, the optical fiber 142 does not move to the right side, but exerts an elastic force on the opposite side of the adapter housing.

In the example shown in FIG. 80, the optical fiber 142
Is bent, and the optical fiber 142 presses the optical fiber 142 toward the laser diode chip 32 by the elastic force caused by the bending. The example shown in FIG. The elastic force of the spring 1471 made of a shape memory member is superimposed, and the optical fiber 142 can be pressed more effectively toward the laser diode chip 32.

FIG. 85 shows a tapered split sleeve 1431, a ferrule 142 A for holding the optical fiber 142, a coil spring 1432 for applying an axial pressing force to the ferrule 142 A, and a collar 1433, each shown in FIG. An optical connector comprising a split housing 1431, a plug housing 1434 for housing the coil spring 1432 and the collar 1433, and an adapter housing 143 for housing the ferrule 142 B and the plug housing 1475 is connected to the adapter housing and the plug housing. FIG. 10 is a cross-sectional view of a configuration in which two optical connectors each including a connector 1435 are fixed to each other by fixing screws 1436 to the adapter housing 143.

In the configuration shown in FIG. 82, the coil spring 1
432 generates an elastic force due to the initial shape at normal temperature. Then, the coil spring 1432 is extended by the temperature change, and presses the ferrule 142A in the axial direction of the optical fiber 142, so that the two fibers are effectively connected. Also in this example, instead of the shape memory member,
Shape memory alloy, shape memory plastic, etc. can be used. In the above description, an example is shown in which a shape memory member is used as a spring, but an elastic body such as phosphor bronze or urethane rubber, which is a usual spring material, may be used. By using such a general-purpose material, a low-cost module can be obtained. [Fifteenth Embodiment] Next, still another embodiment of the present invention will be described.

FIG. 86 shows an example of the configuration of an optical transmitter used in an optical communication system using a surface emitting laser diode according to the present invention. However, in FIG. 86, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 86, in this embodiment, a connector board 151 holding a plurality of optical fibers 142 on a mounting board 131 is provided with a plurality of optical fibers 142 each having a plurality of surfaces constituting an array. Light emitting laser diode 3
It is provided so as to face the corresponding one of the two. Further, on the connector board 151, a plurality of light receiving elements 142P for monitoring the optical power of the surface emitting laser diode 32 are provided corresponding to the plurality of optical fibers 142, respectively. The light receiving element 142
Each of P is provided so as to face the corresponding surface emitting laser diode 32, and detects an emitted light beam.

In FIG. 86, the surface emitting laser diode chip 32, the optical fiber 142, and the monitor light receiving element 1 are shown.
Although the state in which the 42Ps are arranged one-dimensionally in an array is illustrated, the same effect is exhibited even if they are arranged two-dimensionally on the mounting substrate. In this figure, each laser diode is shown as an independent chip 32 one by one, but these may be constituted by a plurality of laser diode elements 32A formed on a single chip 32.

In FIG. 86, since the drawing becomes complicated, a laser output control (stabilization) circuit for controlling the laser output using a signal obtained from the driving circuit of the surface emitting laser diode 32 or the monitoring light receiving element. Is not shown.

In the example of FIG. 86, the connector board 151 holds the optical fiber 142 and the connector guide 1.
It is mounted on the mounting substrate 131 using 51A.

Each optical fiber 142 is held in a through hole formed in the connector board surface 151 so that the end face of the optical fiber 142 faces the laser diode element 32A of the laser diode chip 32. And
Further, each laser diode element 32A and the optical fiber 142
Are positioned so that their optical axes are aligned with each other. Also, in the vicinity of the optical fiber insertion hole on the connector board 151 surface,
The monitor light receiving element 142P is disposed.

Here, the surface emitting laser diode element 32
Most of the laser light emitted from A is injected into the optically matched optical fiber 142 facing the laser light. In addition, part of the laser light that has not entered the optical fiber 142 enters the light receiving element 142P.

FIG. 87 is a block diagram of a control system for stabilizing the output of the surface emitting laser diode 32 using the monitoring light receiving element 142P shown in FIG.

Referring to FIG. 87, the surface emitting laser diode 32 is driven by a laser driving circuit 161 to which a data signal (electric signal) is supplied, and a laser beam is formed. A part of the formed laser light enters the monitor light receiving element 142P as leakage light,
The output electric signal of 2P is supplied to a feedback control circuit 162, and the feedback control circuit 162 performs feedback control of the laser drive circuit 161 so as to cancel the fluctuation of the output electric signal of the light receiving element 142P.

Note that the light intensity of the laser light incident on the monitoring light receiving element 142P does not need to be large, as long as the change in the laser output can be detected and feedback controlled. From the viewpoint of long-distance transmission, it is preferable that most of the laser light of the surface emitting laser diode is incident on an optical fiber for transmitting data as an optical signal. The laser light output control of the surface emitting laser diode using the leak light near the incident end, that is, a small amount of laser light not incident on the optical fiber 142, is sufficiently practical.

Next, another embodiment of the present invention is shown in FIG.

Referring to FIG. 88, also in this embodiment, the monitor light receiving element 142P is provided between the surface emitting laser diode chip 32 and the connector board 151 and opposed to the surface emitting laser diode chip 32. Optical fiber 142
Are formed in the vicinity of the incident end. It should be noted that FIG.
Similarly to FIG. 6, a state in which the surface emitting laser diode 32, the optical fiber 142, and the light receiving element 142P for monitoring are arranged in a one-dimensional array is shown. The present invention is not limited to the configuration, and the same effect can be obtained even if the two-dimensional arrangement is provided on the mounting substrate 131. Also, as in the above description, each laser diode is depicted as an independent chip 32 in this figure, but a plurality of laser diode light emitting portions 32A are monolithically formed on a single chip 32. Is also good. Note that the driving circuit of the surface emitting laser diode and the laser output control circuit are not shown because the drawing becomes complicated.

In the example of FIG. 88, unlike the case of FIG. 86,
The monitoring light receiving element 142P is arranged between the mounting board 131 and the connector board 151 via a support member 142Q.

Next, another embodiment of the present invention is shown in FIG.

Referring to FIG. 89, light receiving element 1 for monitoring
42P is disposed on the mounting board 131 together with the surface-emitting laser diode chip 32,
A part of the laser light reflected at 51 is received. The light receiving element 142P for monitoring may be arranged on the mounting substrate 131 together with the surface emitting laser diode chip 32 as in this example, but the surface emitting laser diode which can be suitably applied to the present invention. Utilizing the characteristics of a single laser diode
A plurality of laser diode light emitting portions 32
A is formed, and at this time, the monitoring light-receiving element 14 is placed on the chip 32 next to each laser diode light emitting portion 32A.
2P may be formed monolithically.

According to the latter configuration, since each laser diode light emitting portion 32A and the monitor light receiving element 142P are formed simultaneously on the laser diode chip, they can be formed compactly and with high precision, and the assembly cost can be reduced. Can be done. Also in FIG. 89, the surface emitting laser
The drive circuit and laser output control circuit of the diode 32
Illustration is omitted for simplicity.

In this embodiment, the surface emitting laser diode is used.
Most of the laser beam emitted from the laser diode 32 is injected into the optically matched optical fiber 142 facing the laser beam. At that time, a part of the laser beam not incident on the optical fiber 142 is reflected by the lower surface of the connector board 151,
The light enters a light receiving element 142P formed adjacent to the laser diode element 32. As described above, in this embodiment, similarly to the above-described embodiment, the surface-emitting laser diode is used by using the leak light near the incident end of the optical fiber 142, that is, by using the laser beam not incident on the optical fiber 142. 32 laser light output controls are possible.

Next, another embodiment of the present invention is shown in FIG.

Referring to FIG. 90, also in this embodiment, the arrangement of laser diode 32 and monitor light receiving element 142P is the same as that of FIG. 89, but the reflection efficiency of the laser beam reflected by connector board 151 is improved. Thus, the difference is that the reflector 151R is provided on the lower surface of the connector board 151.

The reflector 151R may be formed, for example, on the lower surface of the connector substrate 151, that is, on the side facing the laser diode element 32, by forming a metal thin film of Al, Ag, Au, or the like. In particular, in order to efficiently reflect a long-wavelength laser beam, it is preferable to provide a metal thin film made of Au.

In this embodiment, the laser light output of the surface emitting laser diode can be controlled by using the leak light near the optical fiber, that is, the laser light not incident on the optical fiber, as in the above-described embodiment. . In addition, since the reflector function is added, it is possible to accurately control even less leaked light. [Sixteenth Embodiment] Next, still another embodiment of the present invention will be described.

FIG. 91 shows an example of a communication system using a long-wavelength surface-emitting laser diode. Light extending from the surface-emitting laser diode chip 32 or a module package 71 accommodating the chip 32 is shown. Fiber 7
2 to the optical fiber 73 for communication.
1 is shown. In FIG. 91, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 91, the optical fiber 72 drawn out of the module package 71 is connected to the communication optical fiber 73 by the optical connector 171.

At this time, if an air layer is present at the joint in the optical connector 171, reflection occurs because the refractive index of the air layer is different from that of the optical fiber 72 or 73. In order to suppress such a change in the refractive index of the optical fiber connection portion, a method of injecting a gel-like refractive index matching agent or a PC (Phys) for completely bringing the optical fibers into close contact with each other.
ical contact) connection has been proposed,
In this embodiment, an optical fiber is connected by the PC connection.

As shown in FIG. 91, in the optical connector 171, the optical fibers 72 and 73 are bonded and fixed in ferrules 72F and 73F, respectively, to prevent breakage. Generally, the ferrule 72F or 73F is made of a cylindrical high-strength zirconia ceramic, and the optical fiber 72 or 73 is bonded and fixed to the hollow portion. Further, the ferrules 72F and 73
F is held in the optical connector 171 by a pair of split sleeves 172.

FIG. 92 shows the positional relationship among the optical fibers 73, 73, ferrules 72F, 73F, and split sleeve 172.

Referring to FIG. 92, the split sleeve 172
Has a shape obtained by dividing a cylindrical member in the axial direction, and is generally formed of phosphor bronze. As shown in FIG. 92, the ferrules 72F and 73F are held by a pair of split sleeves 172, and are pressed against each other by a predetermined pressure by both springs 173A and 173B, thereby realizing a desired PC connection.
Thus, the optical communication system 170 can be easily constructed. In the present embodiment, a strong and reliable optical fiber connection is realized by using the PC connection.

[0473] Generally, a laser device is provided with safety standards from the viewpoint of safety for the human body. The oscillation wavelength of the surface emitting laser diode element chip is 1.1 to 1.7.
μm, and the oscillation wavelength is in the visible region (wavelength: 0.4 to 0.
It is possible to comply with safety standards even when operated at a higher output than a device with a range of 7 μm). [Seventeenth Embodiment] Next, still another feature of the present invention, that is, the connection between a laser diode and an optical fiber or an optical waveguide will be described.

As shown in FIG. 93, the surface emitting laser of the present invention
In the diode, a laser beam emitted from the laser diode in a direction normal to the substrate exhibits an intensity distribution close to a Gaussian function in a plane perpendicular to the optical axis.

From such a light intensity distribution, the beam diameter is assumed to be the full width at half maximum (FWHM) of the profile, and from the obtained beam diameter and the distance between the laser diode and the detection surface, the light beam to be emitted is determined. The light emission angle θ can be measured.

In the surface emitting laser diode of this example, it was confirmed that the light emission angle θ was substantially axially symmetric and had a value of about 5 to 10 degrees.

On the other hand, the conventionally known 1.1 to 1.7 μm
It is known that the light emission angle θ is large and the aspect ratio is large in the m-band edge emitting laser diode. As typical values, the light emission angle _{θθ in the} direction perpendicular to the substrate of the laser diode is 〜35 degrees, and the light emission angle θ _{// in the} direction parallel to the substrate is _// 25 degrees. Therefore, in the conventional edge emitting laser diode, it is necessary to use a micro lens or the like in an optical fiber or an optical waveguide in order to obtain efficient optical coupling.

On the other hand, in the laser diode of this embodiment, since the light emission angle is small as described above, such a micro lens can be omitted, and the laser diode and the optical fiber or the laser diode can be omitted. -The distance between the diode and the optical waveguide can be reduced. Also, since the light emission angle θ is small,
Even when the distance between the laser diode and the optical fiber or between the laser diode and the optical waveguide is large, the spread of the light beam diameter is small, and within a predetermined range, the laser diode and the optical fiber Alternatively, it is possible to optically couple the laser diode and the optical waveguide without providing a lens between them.

FIG. 94 shows a surface emitting laser diode according to the present invention.
FIG. 95 is a schematic diagram showing the spread of the laser beam in the laser beam 32 and the positional relationship of the optical fiber or the optical waveguide with respect to the laser beam. FIG.

Referring to FIG. 94, laser diode 3
Numeral 2 has a light emitting portion 32A having an opening diameter d [μm], and forms a light beam at a radiation angle θ [degree]. An optical fiber 180 is located at a position away from the laser diode by an optical path length l [μm].
(Or an optical waveguide) end face is formed. The optical fiber 180 has a core 181 having a core diameter of X [μm] and a clad 182 surrounding the core.
The optical axis of the optical fiber is aligned with the optical axis of the optical fiber. Here, the opening diameter d is, when the opening is a circle,
In the case of a square, the diameter indicates the length of one side of the square. In the case where the opening has a rectangular shape or another shape, the diameter of a circle having an area corresponding to the area of an ellipse inscribed therein is defined as d.

The reason for using the laser diode and the optical path length at the end of the optical fiber or the end of the optical waveguide will be explained later with reference to FIG.
This is to include the case where light is deflected by a mirror as shown in FIG. When there is no such light deflection and the optical path is straight, the optical path length from the laser diode to the optical fiber end or the optical waveguide end is simply the laser path from the laser diode to the optical fiber end or the optical waveguide. Equal to the distance to the edge.
In the case of an optical waveguide, the cross section of the core is not circular, but is generally rectangular or square. Therefore, in the case of a square, one side is X [μm], and in the case of a rectangle, the short axis is X [μm].

In FIG. 94, the beam diameter of the light beam emitted perpendicularly from the laser diode expands with the light path length l at the light emission angle θ and reaches the end face of the optical fiber or the optical waveguide.

The laser beam diameter at the end face of the optical fiber or the waveguide is represented by d + 2ltan (θ / 2).

Therefore, if the beam diameter falls within the optical path length 1 which is equal to or smaller than the core diameter X of the optical fiber or the optical waveguide, it is considered that good optical coupling can be obtained.

FIG. 95 shows the relationship between the optical path length 1 and the beam diameter when the opening diameter of the laser diode is 5 μm and the light emission angle is 10 degrees as an example of this embodiment based on this equation. Is shown. FIG. 95 also shows, as a comparative example, the relationship between the optical path length 1 and the beam diameter in the case of the edge emission type in which the light emission angle is 35 degrees.

Referring to FIG. 95, in the case of this embodiment, a general multimode fiber having a smaller beam spread than the comparative example and having a core diameter of 50 μm (cladding diameter of 125 μm) as an optical fiber is used. , The optical path length l is 26
In the case of 0 μm, the core diameter X matches the beam diameter.

If the optical path length l is within the distance where the core diameter X and the beam diameter coincide with each other, the beam diameter is smaller than the core diameter of the fiber, and therefore a good laser beam loss is reduced. Optical coupling can be obtained. That is, when the surface emitting laser diode of the present invention is used,
It can be seen that the distance between the laser diode and the end of the optical fiber, that is, the alignment in the optical axis direction is much rougher than that of the comparative example. Also, if the core diameter is 100
In the case of a plastic optical fiber of .mu.m, the optical path length l at which the laser beam diameter matches the core diameter is as large as 550 .mu.m, so that a configuration in which the laser diode package and the optical fiber are separated can be adopted.

FIG. 96 shows an example of the structure of a coupling section between a laser diode for a communication system using the above-mentioned surface emitting laser diode and an optical fiber. However, in FIG. 96, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

The communication system includes a surface emitting laser diode and an optical transmitting section having a driving circuit thereof, a surface type photodetector and an optical receiving section having a driving circuit thereof, and an optical fiber acting as a transmission path therebetween. The laser diode and the photodetector drive circuit are constituted by optical waveguides and are mounted on the same mounting substrate as the respective elements. In addition, by providing an optical transmitting unit and an optical receiving unit on both sides of the optical transmission path, bidirectional communication may be performed.

Referring to FIG. 96, in this embodiment, a Si substrate having good heat conductivity is used as the mounting substrate 131, and the surface emitting laser diode element 32A having the structure shown in FIG. Are mounted in an array. In the illustrated example, the laser diode element 32A having an oscillation wavelength of 1.3 μm is used, and the opening diameter of each laser diode element 32A is set to 1.
It is 0 μm. Also, 12 on the mounting board 131
The laser diode elements 32A are integrated at a pitch of 200 μm.

Next, a hole array member made of aluminum nitride AlN in which a through hole having a diameter of 125 μm corresponding to the diameter of a multimode fiber was formed on the mounting substrate 131 at the same pitch of 200 μm as the laser diode element 32A. 191 to the marker 32 of the laser array chip 32
X and the guide 191X of the hole array member 191 are fixed so as to coincide with each other. The hole array member 19
1 has a very high thermal conductivity of about 300 Wm ^-1 K ^-1 and, when provided in contact with the laser array chip 32, also functions as an effective heat radiating portion. Therefore, heat generated by the oscillation of the laser diode can be radiated from the light emitting surface side, and a stable optical communication system is realized.

Each of the through holes in the hole array member 191 has a multimode optical fiber 19 whose end face is polished.
2 is inserted, and is fixed with an adhesive in a state where it is applied to the laser diode chip 32. With this configuration, accurate alignment can be obtained between the laser diode element 32A and the corresponding optical fiber 191 in the direction perpendicular to the optical axis.

On the other hand, in this embodiment, since the optical fiber 191 is merely abutted against the chip 32, only rough alignment can be obtained in the direction perpendicular to the optical axis.
A space of about 0 to 20 μm may be generated between the diode and the optical fiber. However, the light emission angle θ of the laser diode element 32A reaches 8 ° in the case of the present invention,
In addition, since the aperture diameter d is as large as 10 μm, even if the distance between the laser diode and the optical fiber is 50 μm, the beam diameter is only 17 μm.
The core diameter of 91 does not exceed 50 μm. That is, in this embodiment, the above expression is satisfied, and good optical coupling is obtained. The laser diode element and the optical fiber 19
There is no need to provide a lens between them.

Thus, according to the present embodiment, 1.3 μm
By using a surface emitting laser diode of m, an optical communication system with a small number of components, low cost, and moderate conditions for alignment in the optical axis direction can be constructed.

On the other hand, in this embodiment, the optical fiber 191
Was applied to the laser diode chip 32, and an experiment was conducted using a micrometer. When the distance between the laser diode and the optical fiber was 400 μm, the beam diameter could become 66 μm. confirmed. In this state, the light beam diameter is equal to the core diameter 5 of the multi-fiber 191.
It is larger than 0 μm and does not satisfy the above expression. Along with this,
Sufficient optical coupling cannot be obtained.

Table 7 shows the results of experiments performed by the present inventors.

[0497]

[Table 7] From the above results, the core diameter of the optical fiber is X, the opening diameter of the laser diode is d, the light emission angle of the laser diode is θ, and the optical path length from the laser diode to the optical fiber is l.
In this case, it can be seen that practical optical coupling cannot be obtained unless the core diameter X is equal to or more than d + 2 tan (θ / 2).

In the above description, the number of optical fibers is 12, but the number of optical fibers may be one, or may be 4, 8, 16, or any other necessary number depending on data to be transmitted.
Although the multimode fiber 191 is used as the optical fiber, a single mode fiber is suitable for transmitting large-capacity information over a long distance, and a plastic optical fiber (POF) is suitable for reducing the cost at a short distance. However, the above equation holds for any optical fiber. The end face of the optical fiber is preferably subjected to a treatment such as an anti-reflection coating.

In this embodiment, AlN is used as the hole array member 191 which also serves as a heat radiating portion. However, any material having a high thermal conductivity such as ceramics such as Si, C, and alumina is effective as a heat radiating portion. . [Eighteenth Embodiment] Next, another embodiment of the present invention will be described.
As described above, the connection between the laser diode and the optical fiber will be described.

The structure of this embodiment is almost the same as that shown in FIG. 96, except that the laser diode chip 32 and the optical fiber 1
The distance between the laser diode chip 32 and the optical fiber 191 or the optical waveguide is substantially zero. The term "contact" as used herein means that the distance between the laser diode and the optical fiber or the waveguide is almost zero, but taking into account the accuracy of the assembly, Actually, even the range of 0 to 10 μm is included in the “contact”.

[0501] As the mounting substrate 131, Si having good heat conductivity is used.
A laser array chip 32 in which surface emitting laser diode elements 32A having the structure shown in FIG. 1 are arranged in an array is mounted on the mounting substrate 131 using a substrate. Note that also in this case, one having an oscillation wavelength of 1.3 μm is used.

In this embodiment, the opening diameter of the laser diode is 10 μm, and the number of the laser diodes is 12.
At this time, the pitch of the laser diode is set to 200 μm.

Next, a laser is placed on the substrate 131 of the embodiment.
The multi-mode optical fiber 192 is inserted into a hole array member 191 made of AlN having the same 200 μm pitch as that of the diode and formed with a large number of 125 μm through holes corresponding to the multi-mode fiber diameter. The tip of the optical fiber 192 is made to protrude slightly from the surface in close contact with the laser array chip 32.

Next, the tip of the optical fiber is polished,
The end of the optical fiber is made to coincide with the surface of the hole array member 191 that is in close contact with the laser array chip 32.
After such a configuration, the marker 32X
And the guides 191X, the respective surface emitting laser diode elements 32A and the optical axes of the corresponding optical fibers 192 are aligned. By fixing the laser array chip 32 and the hole array member 191 in this state, the laser diode chip 32 and the optical fiber 19 are fixed.
1 can be contacted.

In this embodiment, higher optical coupling efficiency than in the previous embodiment can be obtained. That is, in this embodiment, the laser beam does not spread, and the diameter of the laser beam approximately matches the aperture diameter. That is, the beam diameter of the laser beam is sufficiently smaller than the core diameter of the optical fiber 191, and the alignment margin orthogonal to the optical axis is further increased. Therefore, it is possible to construct an optical communication system using a 1.3 μm band surface emitting laser at low cost. [Nineteenth Embodiment] FIGS. 97A and 97B show a structure of a coupling portion between a laser diode and an optical waveguide according to another embodiment of the present invention. Note that FIG. 97A is a perspective view of the structure of this embodiment, and FIG. 97B is a cross-sectional view. In the present embodiment, a configuration is shown in which the laser beam emitted from the laser diode element 32A is deflected by the mirror 301. In FIGS. 97 (A) and 97 (B), the same reference numerals are given to the parts described above, and the description will be omitted.

Referring to FIGS. 97 (A) and 97 (B), in this embodiment, a Si substrate having good thermal conductivity is used as the mounting substrate 131, and the surface light emission having the structure shown in FIG. A laser array chip 32 in which laser diode elements 32A are arranged in an array is mounted. In this embodiment, the laser diode element 32A has an opening diameter of 15 μm,
Four laser diode elements 32A form an array.

On the other hand, in this embodiment, another mounting board 131A
Mount the mirror 301 on it or form it monolithically,
Further, the optical waveguide 302 is formed on the mounting substrate 131A. Here, the mirror 301 anisotropically etches the Si substrate constituting the mounting substrate 131A with KOH,
It is formed by depositing Ag on the formed crystal plane.

In the present embodiment, the mounting substrate 131A
An optical waveguide 302 is formed thereon. After forming the lower clad layer 302A, the optical waveguide 302 deposits a polymethyl methacrylate (PMMA) layer as a core layer, and then patterns this to form a core pattern 302B, and further forms an upper clad layer 302C thereon. To form Typically, the cross-sectional shape of the core pattern 302B is 50 × 50 μm. As the optical waveguide 302, in particular, the core layer, a polymer waveguide such as polyimide, epoxy resin, polyurethane or polyethylene, or an inorganic film such as a silicon oxide film can be used in addition to PMMA. Further, these organic films can be formed by combining an application method such as spin coating or dip coating with patterning, or by resin molding or die processing.

In this embodiment, the mounting substrate 131 having the laser array element and the mounting substrate 1 having the optical waveguide 302
31A is fixed so that the optical axis of the laser diode element 32A and the optical axis of the optical waveguide 302 coincide with each other via the mirror 301.

In experiments conducted by the inventor of the present invention, a surface emitting laser diode having a light emission angle of about 10 degrees and an aperture diameter of 15 μm was used as the laser diode element 32A. By changing the position of the end face of the optical waveguide 302, the optical path length l between the
Three values of 0, 100, and 250 μm were set. As a result, the optical path length satisfying the above equation is 50 μm and 1
Good optical coupling was obtained for the case of 00 μm,
When the optical path length that does not satisfy the above equation is 250 μm,
Good optical coupling was not obtained.

In any case, lenses and the like are not required in this embodiment, and the alignment in the optical axis direction may be roughly.
Therefore, by using a 1.2 μm surface emitting laser diode, it was possible to construct an optical communication system in which alignment in the optical axis direction was gradual.

In this embodiment, the mirror 301 is formed separately from the waveguide 302. However, the end face of the waveguide is processed into a 45-degree slope by a dicing blade or the like, and a metal such as Ag is formed on the slope. The waveguide 302
And an integral mirror may be formed. In this embodiment, the diameter of the optical waveguide is set to 50 in accordance with the multimode optical fiber.
However, when a single mode optical fiber is used, it is necessary to reduce the diameter to about 10 μm. In this case as well, basically the same expression holds. In the present embodiment, the cross section of the core pattern 302B in the optical waveguide 302 is a square, but it may be formed in a rectangular shape. Further, a plurality of optical signals may be transmitted by a single waveguide like an optical sheet. [Twentieth Embodiment] FIG. 98 shows a structure of a coupling portion between a laser diode chip 32 and an optical waveguide 302 in another embodiment of the present invention.

Referring to FIG. 98, in this embodiment, a Si substrate having good heat conductivity is used as the mounting substrate 310, and the surface emitting laser diode having the structure shown in FIG. The laser diode chip 32 carried as the element part 32A is mounted. In this embodiment, the laser diode chip 32 having an oscillation wavelength of 1.3 μm is used. The laser diode used in this embodiment has an aperture diameter of 7 μm and a light emission angle θ of 8 degrees, and is used alone, not in an array form.

The mounting substrate 310 on which the laser diode chip 32 is mounted is positioned and fixed on the package body 311. Further, the optical axis of the laser diode 32 is adjusted by the guide 311A on the package body 311 and the optical fiber guide 312 aligned with the guide pin 312A, thereby the single mode optical fiber 313 held by the optical fiber guide 312. To the optical axis of

The single mode optical fiber 313 is
A core 313A having a diameter of 10 μm and a cladding having a diameter of 125 μm surrounding the core 313A;
The diameter of the optical fiber guide 312 matches the outer diameter of the cladding.

In the structure of this embodiment, good optical coupling was realized by bringing the single mode optical fiber 313 into contact with the laser diode 32. Further, in the present embodiment, since the single mode optical fiber 313 is used, it is possible to transmit an optical signal over a long distance and in a wide band. As described above, according to the present embodiment, it is possible to construct an optical communication system having good optical coupling by using a 1.3 μm surface emitting laser diode. [Twenty-first Embodiment] Next, still another embodiment of the present invention will be described.

FIG. 99 shows an example of an optical communication system using a long wavelength surface emitting laser diode.

[0518] Referring to Fig. 99, the optical communication system comprises:
It is composed of a surface emitting laser diode 32 having a light emitting section 32A and an optical fiber 352. In the example of FIG. 99, the surface emitting laser diode 32 and the optical fiber 352 are directly coupled in the light emitting section 32A. Of course, optical coupling may be realized using a lens or a lens system.

[0519] When the diameter of the light emitting portion 32A of the surface emitting laser 32 is d and the core diameter of the optical fiber 312 is F,
The laser beam from the surface emitting laser diode diverges as shown by a dotted line 351B in FIG. However, in FIG. 99, d represents the diameter of a circle inscribed when the light emitting portion 32A is polygonal. In this case, the divergence angle of the laser beam is smaller than the divergence angle of the laser beam in the edge-emitting laser diode. When the surface emitting laser and the optical fiber are brought close to each other as shown in FIG. 99, if the optical axis is perpendicular to the optical fiber end face, coincides with the center of the end face, and is substantially the same as the core diameter at the optical fiber end face position, light The coupling efficiency can be maximized.

The surface emitting laser diode used in this embodiment operates in the wavelength band of 1.1 to 1.7 μm as described above.
In particular, when a laser diode having a band of 1.3 to 1.55 μm is used, long-distance transmission is realized because the internal loss when the laser beam propagates in the quartz fiber is small.

The light emitting section 32 of the surface emitting laser diode 32
When the diameter of A is d (the diameter of an inscribed circle is d when the light emitting unit 32A is polygonal) and the core diameter of the optical fiber 352 is F, the ratio of F and d is F / d. ≦ 2 (Equation 1) The optical coupling efficiency can be increased. In the embodiment of FIG. 99, the laser diode light emitting section 32A
And the optical fiber 352 are directly coupled, and no coupling lens or the like is provided between them.

In a conventional optical communication system using an edge emitting laser diode in the 1.3 μm band or the like, the optical coupling efficiency between an optical fiber and a laser diode is low, and it is difficult to directly optically couple the laser. Further, there has been a problem that the laser oscillation state fluctuates due to the influence of the return light from the optical fiber. However, in the present invention, since the surface emitting laser operating in the long wavelength band is used, the shape of the laser beam is circular, and the divergence angle does not have anisotropy. Therefore, the optical coupling efficiency is much higher than in the case of the end face type laser diode. Further, since the surface emitting laser diode has an anti-structure with a very high reflectance, it is hardly affected by return light. For this reason, the laser diode and the optical fiber can be directly coupled, and the optical isolator used in the conventional optical communication system can be omitted.

If the diameter of the light emitting portion of the surface emitting laser is d (the diameter of the inscribed circle is d if the light emitting portion is a polygon) and the core diameter of the optical fiber is F, the above F and F d
Is set within the range given by 0.5 ≦ F / d ≦ 2 (Equation 2), the optical coupling efficiency can be increased. Hereinafter, the reason will be described in detail.

[0524] Table 8 shows the results of an investigation by the present inventors on the optical coupling loss between the surface emitting laser diode and the single mode optical fiber diode. However, Table 6 shows the case where direct optical coupling was performed.

Referring to Table 8, when the light emitting portion of the surface emitting laser diode is larger than the core diameter, the optical coupling efficiency decreases, but d ≦ 2F (ie, 0.5 ≦ F / d).
Then, it can be seen that the optical coupling loss can be suppressed within 3 to 5 dB. When the size of the light emitting portion is smaller than the core diameter, the divergence angle of the laser beam determined by the diameter and the wavelength of the circle inscribed in the light emitting portion is determined by the NA that can be optically coupled to the single mode optical fiber in a single mode. (Aperture ratio)
Highly efficient coupling can be achieved. For example, if the core diameter is 10 μm,
The refractive index of the core is 1.4469 and the refractive index of the cladding is 1.
If it is 4435 and the laser wavelength is 1.3 μm, the NA that can be coupled in a single mode is 0.0995. This N
The diameter of the light emitting portion 32A corresponding to A is about 6.5 μm.

However, even if the diameter of the light emitting section 32A is 6.5 μm or less, if the diameter is, for example, about 5 μm, the optical coupling loss is 3 to 5 μm.
dB. From this, it is concluded that d ≧ 0.5F (ie, F / d ≦ 2) is sufficient.

As described above, when the surface emitting laser is directly coupled to the optical fiber, the coupling is established by setting F and d so that 0.5 ≦ F / d ≦ 2 (Equation 2) The loss can be made relatively small, and efficient optical coupling can be realized. Although a single mode optical fiber is used in the present embodiment, the condition of Expression 2 is also satisfied when optically coupling to a single mode optical fiber via a multimode optical fiber or a tapered light guide path. A similar effect can be obtained by designing the connecting portion in the following manner.

[0528]

[Table 8] Next, as another example, FIG. 100 shows an example of an optical communication system in which a surface emitting laser diode is coupled to an optical fiber via a coupling lens.

Referring to FIG. 100, in this embodiment, a coupling lens 353 is provided between the surface emitting laser diode 32 and the single mode optical fiber 352. The lens 353 may be a single lens or a lens system combining a plurality of lenses. When a single lens is used, the lens 353 is preferably disposed near the light emitting portion 32A of the surface emitting laser diode 32.

In the configuration shown in FIG. 100, by appropriately selecting the lens power (or focal length) of the coupling lens 353, the diameter d of the light emitting section 32A (the diameter of the inscribed circle when the light emitting section is a polygon) is selected. Is d) and the optical fiber 3
Even if the core diameter is 53 or more, the optical coupling loss can be kept small.

For example, when the core diameter is set to 10 μm,
When the diameter of A is 20 μm, the beam diameter is reduced to に よ っ て by the lens 353. Assuming that the focal length of the lens 353 is f, the laser wavelength is λ (= 1.3 μm), the radius of the light emitting unit 32A is ω ₀ (= 10 μm), and the refractive index n (= 1),

[0532]

(Equation 1) It is sufficient to find f that satisfies. At this time, the focal length f is about 1
It becomes 40 μm.

When a coupling lens is used, the diameter of the light emitting portion is d (the diameter of the inscribed circle is d when the light emitting portion is polygonal), and the core diameter of the optical fiber is F. If ≧ F, that is, F / d ≦ 1 (Equation 3), efficient optical coupling to the optical fiber becomes possible. See Table 9 below.

[0534]

[Table 9] In the embodiment of FIG. 100, the coupling lens 353 is constituted by a single lens, but this may be constituted by a lens system including a plurality of lenses. For example, as shown in FIG.
The lens 353 may be composed of two lenses 353A and 353B.

Referring to FIG. 101, first lens 35
3A, the light emitting section 32 of the surface emitting laser diode 32
The divergent light from A is converged toward the second lens 353B, and becomes a beam waist on the surface of the second lens 353B. The second lens 353B has the same function as the lens 353 of FIG. According to the present embodiment, when a single lens can not be placed near the light emitting portion of the laser diode,
When the divergence angle of the laser light is large and the coupling efficiency to the optical fiber is low, high coupling efficiency can be maintained by configuring the lens 353 with a plurality of lenses.

In the above embodiment, a single mode optical fiber is used as the optical fiber 352. However, in the present embodiment, even when a multimode optical fiber is used or a tapered light guide path is used, the equation 3 is used. As long as the relationship is satisfied, the same effect can be obtained.

[0537] In a conventional configuration using an edge-emitting laser diode, the laser oscillation state may fluctuate due to the return light from the coupling lens, and it is necessary to provide an optical isolator to avoid this. But,
Since the surface emitting laser diode uses a mirror structure having a high light reflectance, it is hardly affected by return light. Therefore, the optical isolator can be omitted.

Next, an embodiment comprising a surface emitting laser diode array and an optical fiber array will be described with reference to FIG.

Referring to FIG. 102, in this embodiment, the surface emitting laser diode 32 has a plurality of light emitting portions 32A arranged in an array. Of course, in the present embodiment, the surface emitting laser diodes 32 themselves may be arranged in an array. Further, a plurality of laser diode chips may be arranged in an array.

In FIG. 102, since the light emitting section 32A and the corresponding optical fiber 352 are directly connected, as described above with reference to FIG. 99, the diameter d of the circle inscribed in the light emitting section 32A and the optical fiber 352 By setting the core diameter F so as to satisfy the relationship of Equation 2, the optical coupling loss can be minimized and the optical coupling efficiency can be maximized.

In this embodiment, since the light emitting sections 32A are arranged in an array, an optical communication system having a large amount of information can be constructed.

FIG. 103 shows an embodiment in which a coupling lens array is further inserted into the configuration of FIG.

In the configuration of FIG. 103, the relationship between the light emitting section 32A, the lens array, and the optical fiber 352 is the same as that described with reference to FIG. That is, if the relationship between the diameter d of the light emitting portion (when the light emitting portion is polygonal, the diameter of the inscribed circle is d) and the core diameter F of the optical fiber is expressed by Equation 3, coupling can be efficiently performed. . Since these are arranged in an array, an optical communication system having a large amount of information can be constructed. In this embodiment, in the lens array 355, each lens element is configured by a single lens, but may be configured by combining a plurality of lenses. [Twenty-second Embodiment] Next, still another embodiment of the present invention will be described.

FIGS. 104A and 104B show an example of a communication system using a long-wavelength surface-emitting laser diode according to the present invention. FIG. FIGS. 4A and 4B are a side view and a plan view, respectively, showing a state in which a laser driving IC 32D including a CMOS circuit is connected to a laser diode chip 32 on which elements are formed.

Referring to FIGS. 104 (A) and (B), the laser driving IC 32D composed of the laser diode chip 32 and the CMOS has a conductive sub-mount 40, respectively.
1 is mounted by a conductive adhesive. A high-frequency transmission line 402 (microstrip line in this embodiment) is formed between the laser diode chip 32 and the laser driving IC 32D, and each chip 32 is connected to the microstrip line 402 by a bonding wire 403. Have been.

In a surface emitting laser diode for optical communication,
Since very high-speed modulation of several hundred MHz to several GHz is required, the laser diode chip 32 and the laser driving I
It is preferable to make the distance between C32D and C32D as short as possible.
Such a preferable configuration may not be possible due to the layout of the optical system. However, in such a case, if the laser diode chip 32 and the laser driving IC 32D are connected with normal wiring, unnecessary electromagnetic radiation will be generated from this wiring portion. In this embodiment, the high-frequency transmission line 402 connects between the laser diode chip 32 and the laser driving IC 32D so that such electromagnetic radiation does not occur.

With this configuration, even if the laser diode is modulated at a frequency of several GHz, unnecessary electromagnetic wave radiation does not occur from the wiring portion, and accordingly, a special measure for suppressing the radiation of unnecessary electromagnetic waves is provided. This is unnecessary, and the cost of the system can be further reduced.

In this embodiment, a microstrip line is used as the high-frequency transmission line 402, but any unbalanced transmission line such as a coplanar line or a triplate line may be used. Also, the connection between the laser diode chip 32 or the laser driving IC 32D and the transmission line 402 is not limited to the wire bonding of the present embodiment, but may employ techniques such as flip chip connection, TAB connection, and micro bump connection. It can be used as needed. Twenty-third Embodiment Referring first to FIG. 52, as an example of the communication system of the present invention, a laser oscillation wavelength is 1.1 to 1.7.
A system using a long wavelength surface emitting laser diode in the μm band has been described.

Conventionally, an optical communication system has been studied for a wavelength in the 0.85 μm band, but the transmission loss of the optical fiber is large and is not practical. Although a stable laser element could not be obtained in a practical long wavelength band where transmission loss is small, the present invention improves the semiconductor Bragg reflectors 12 and 18 or the non-radiative recombination preventing layer 13 as described above. , 17 enable a surface emitting laser diode having a laser oscillation wavelength of 1.1 to 1.7 μm to be driven stably with low power, and a practical long wavelength band optical communication system can be realized. It has become possible.

In the example shown in FIG. 52, the optical communication system
Long-wavelength surface emitting laser diode chip 32 as described above
A first optical fiber FG1 into which a laser beam emitted from a laser emitting section 32A in the chip 32 is injected and which functions as an optical transmission path; and a first optical fiber FG1
A second optical fiber FG2, which is injected with a laser beam propagated through the inside and functions as an optical transmission line, and a third light, which is injected with a laser beam emitted from the second optical fiber FG2 and functions as an optical transmission line It comprises a fiber FG3 and a photodiode chip 34 having an optical detector 34A for receiving the laser beam emitted from the third optical fiber FG3.

An optical connection module MG1 is provided between the laser diode chip 32 and the first optical fiber FG1. Similarly, between the optical fiber and the optical fiber, and between the optical fiber and the photodiode chip. Also, an optical connection module MG2, an optical connection module MG3, or an optical connection module MG4 is provided.

In the example shown in FIG. 52, the first optical fiber FG1 used in such a system is directly optically coupled to the laser diode light emitting section 32A without any intervening optical system.

In FIG. 94, the relationship required between the laser diode of the present invention and the optical fiber has been described.

The long-wavelength surface-emitting laser diode of the present invention having a 1.1 to 1.7 μm band has a light divergence angle θ of about 10 °, for example, a core diameter of 50 μm (cladding diameter of 125 μm).
Used in combination with optical fiber. In such a combination of a laser diode and an optical fiber, to obtain a good coupling between the laser diode and the optical fiber,
The size of the light emitting unit 32A is, for example, 0.005 mm × 0.
005 mm to 0.02 mm × 0.02 mm, when viewed in area S, 0.000025 mm ^{2 to} 0.0001 mm
^Two are used. In this case, by opposing the laser diode and the optical fiber at a distance of 0 to 0.33 mm, good optical coupling can be realized without inserting a special optical system therebetween. A similar situation holds when an optical waveguide is used instead of an optical fiber.

In the present invention, the one having the light emitting portion 32 of the above size is used. This is an optical communication system using a long-wavelength surface emitting laser diode element in the 1.1 to 1.7 μm band. It is also closely related to the operating voltage.

In this embodiment, attention has been paid to this point, and an operation voltage suitable for causing the surface emitting laser diode 32 to perform stable continuous oscillation instead of simple pulse oscillation has been studied.

Table 10 shows the experimental results of this example.

In the experiment of this embodiment, a laser diode having a configuration shown in FIG. 10 and having a laser oscillation wavelength of 1.3 μm was used. In the experiment, the size and operating voltage of the light emitting section 32A (in this case, a square) were changed, and conditions for stable continuous oscillation were searched. The shape of the light emitting portion 32A is not necessarily a square, and may be, for example, a circular shape. In such a case, the same concept as the present invention can be applied by performing area conversion.

[0559]

[Table 10] From the above results, assuming that the area of the light emitting portion of the surface emitting laser diode element chip is S (mm ² ) and the operating voltage of the laser element is V (V), V / S is 15,000 to 30,000.
It can be seen that the laser beam can be stably and continuously oscillated without damaging the laser element in the range described above. Therefore, under such conditions, a long-wavelength surface emitting laser diode in the 1.1 to 1.7 μm band is used. By operating an optical communication system using the elements, a practical and stable system can be realized. [24th Embodiment] Next, still another embodiment of the present invention will be described.

FIG. 105 shows an example of an optical communication system using a long-wavelength surface emitting laser diode according to this embodiment. However, in FIG. 105, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 105, in the optical communication system according to the present embodiment, the laser provided on the mounting
The light output of the diode 32A is connected to another mounting substrate 301A.
The mirror 301 formed above splits the light beam for optical communication and the light beam for monitoring, and the split monitoring light beam is detected by the monitoring light receiving element 142P provided on the mounting substrate 301A. Is done. The monitoring light receiving element 142P corresponds to the monitoring light receiving element 142P described above with reference to FIG. Note that FIG. 105 and FIGS. 107 and 108 to be described later are the same, but a plurality of the laser diode light emitting portions 32A are arranged in a direction perpendicular to the paper surface to form an array. Are provided.

The communication system according to the present embodiment comprises: a light emitting unit having the surface emitting laser diode 32 and its driving circuit; a light receiving unit having a surface light receiving element and its driving circuit; It is composed of an optical fiber or an optical waveguide that acts as a transmission path between the transmission section and the optical reception section and between them. Although the laser diode 32 and the drive circuit for the surface light receiving element are not shown here, they can be mounted on the same mounting board as the respective elements. Alternatively, it may be integrated with the formation of the laser element on the laser diode element formation substrate by a wafer process. In addition, by providing an optical transmitting unit and an optical receiving unit on both sides of the optical transmission path, an optical communication system that performs bidirectional communication can be realized.

As shown in FIG. 105, a laser beam emitted from one surface of a long-wavelength surface emitting laser device is split by a mirror 301 and an optical waveguide 30 whose optical axis is aligned.
It is led to 2. This optical waveguide 302 may be an optical fiber.

[0564] The other laser beam split by the mirror 301 is guided to the monitor light receiving element 34 formed on the mounting substrate 301A. The mirror 301 splits the light beam supplied to the monitoring light receiving element 142P. The laser beam supplied to such a monitoring light receiving element is laid using the output of the monitoring light receiving element.
It is preferable that the output of the diode is small in a range where the output can be correctly controlled, that is, within the sensitivity of the light receiving element. In consideration of the power consumption of the optical communication system, it is preferable that as much optical energy as possible is transmitted as an optical signal through the optical waveguide 302 or the optical fiber. For this reason,
In the embodiment of the present invention, Au or A used as the mirror 301 is used.
g, Al, etc. by controlling the film thickness of the metal thin film.
The transmittance is controlled in the wavelength range of 7 μm. Alternatively, a thick metal film may be used as the mirror 301, and under the condition of total reflection, openings of various shapes such as grooves, circles, and squares may be provided on the reflection surface to control the transmittance.
In the latter case, in order to avoid interference by light, it is preferable to randomly set the pitch of the groove and the size of the opening, and to randomize the position of the opening. Further, the transmittance of the mirror 301 can be controlled by using a dielectric multilayer film or a semiconductor multilayer film.

As compared with the conventional edge emitting laser diode,
The oscillation wavelength used in the optical communication system of the present invention is 1.1.
A surface emitting laser diode having a band of about 1.7 .mu.m is a very stable laser which has a small variation in light output due to temperature and has little change over time. On the other hand, to form a more reliable optical communication system, it is preferable to monitor the laser diode output and control the output. In a conventional edge emitting laser diode, the laser diode output is controlled by monitoring a laser beam emitted from a rear cleavage plane.

On the other hand, the surface emitting laser as in this embodiment is used.
In a system using the diode, the laser output is
It can be obtained only on one side of the diode, so that the arrangement of the monitor light receiving element as in the case of the conventional edge emitting laser diode cannot be adopted. In the surface emitting laser diode having an oscillation wavelength of 1.1 to 1.7 μm used in the system of the present invention, the divergence angle of the emitted laser beam is only about 10 °, and therefore the laser beam is emitted. Although the diode can be optically coupled without using a lens by bringing the diode close to an optical fiber or an optical waveguide, there is no room for inserting a monitor light receiving element.

On the other hand, in this embodiment, by using the mirror 301 as described above, the laser diode can be used without increasing the optical path length between the laser diode 32 and the optical waveguide 302 or the optical fiber. Monitor the optical output of the
Therefore, the light output of the laser diode can be reliably controlled. In this embodiment, since the optical axis is deflected by using the mirror 301, the surface of the laser diode 32 and the optical axis of the optical waveguide 302 or the optical fiber become parallel, and the optical waveguide 302 or the optical fiber is Can be fixed parallel to the plane of the module. For this reason, in the present embodiment, the optical waveguide 302
Alternatively, the optical fiber can be easily fixed, and a strong configuration can be obtained. In addition, although the size of the module of the optical communication system becomes large, the laser diode 3 is used.
It is also possible to provide a coupling lens before and after the mirror along the second optical axis.

Although not shown, a plurality of laser diode elements and an optical waveguide (optical fiber in this example) corresponding to the laser diode elements can be used in the present invention. The mirror 301 is a common mirror (FIG. 105). , A single mirror extending in a direction perpendicular to the plane of the paper) can be used. As a result, it is possible to reduce the size and the manufacturing cost of the optical transmission unit including the laser diode array, the monitoring light receiving element array, and the light branching unit.

FIG. 106 is a block diagram showing a feedback control circuit for controlling the output of the laser diode 32 using the laser beam split in this way.

Referring to FIG. 106, the laser diode 32 is driven by the drive circuit 161 corresponding to the drive circuit 161 described above with reference to FIG. 87, and a part of the formed laser beam is reflected by the mirror 301. The light is branched and guided to the monitor light receiving element 142P. The monitor light receiving element 142P detects the light intensity of the supplied laser beam,
The laser output control unit is controlled by the correspondingly formed electric output signal so that the output becomes constant. As the driving circuit, a laser diode used in the system of the present invention preferably uses a CMOS in terms of low power consumption because the oscillation voltage has a low threshold, but a bipolar may be used. Further, since the wavelength range of the present invention is 1.1 to 1.7 μm, the monitoring light-receiving element has an InGa
A photodiode made of As material can be used. Since the fluctuation of laser light due to aging or temperature change is a gradual change with time, a photodiode with a low response speed but high sensitivity may be used. Returning to FIG. 105 again, the description of this embodiment will be continued.

In this embodiment, a laser diode array in which four long-wavelength surface emitting laser diode elements shown in FIG. 1 are arranged, a drive circuit and a laser output control unit (not shown) It is mounted on a good Si mounting substrate 301.
The four laser diode elements are formed on a single chip at an arrangement pitch of 200 μm and have an oscillation wavelength of 1.3 μm.

Next, the mirror 301 is formed of a Si substrate having good thermal conductivity and transparent to light in the 1.3 μm band. By using a single crystal Si substrate as the mounting substrate 301A, by performing anisotropic etching,
The mirror 301 can be formed. At this time, a cut plane with respect to the crystal axis of the wafer is determined in consideration of a crystal plane formed by anisotropic etching on the single crystal Si substrate. Note that KOH can be used as an etchant. Thus, the 45-degree mirror surface 3
01 is formed monolithically on the mounting substrate 301A, and after an Au film is deposited, an optical waveguide 302 is formed.

By setting the Au film thickness in this step, the transmittance of a laser beam having a wavelength of 1.3 μm can be controlled.

When forming the optical waveguide 302, after forming the clad 302A, a polymethyl methacrylate (PMMA) film is formed as a core layer, and the core layer thus formed is patterned to form a core pattern 302B. I do. Further, an upper clad layer 302C is formed so as to cover the core layer 302B.

In this embodiment, the core pattern 302B is
Patterning was performed to form a cross section of 50 × 50 μm. After the module is formed, the optical waveguide 302 thus formed is optically coupled to an optical fiber (not shown) to form a long-distance communication system.

As the optical waveguide 302, besides PMMA, a polymer waveguide such as polyimide, epoxy resin, polyurethane or polyethylene, or an inorganic film such as a silicon oxide film can be used. The formation of the optical waveguide 302 can also be performed by combining an application method such as spin coating or dip coating with patterning, or by resin molding or die processing.

Further, the optical axis of the laser diode is made to coincide with the optical axis of the optical waveguide, and each of the mounting substrates 301 and 301
A is fixed, and a surface-incidence type photodiode is placed on the mounting substrate 301A on which the mirror surface 301 is formed so as to coincide with the optical axis of the split laser beam.
It is fixed as 42P. As the photodiode, for example, a photodiode in which a buffer layer is provided on an InP substrate and an InGaAs layer is provided as a light absorbing layer can be used.

[0578] Further, the output of the light receiving element 142P thus formed is electrically connected to the laser output control section 162 by wire bonding. This allows
A feedback control circuit for controlling the output of the laser diode described with reference to FIG. 106 is formed.

[0579] Table 11 shows the results of evaluating the operation of the optical transmission unit by changing the external temperature. However, Table 9 shows only the results when the temperature was set to 20 ° C. Actually, the inventor of the present invention evaluated by changing the external temperature radiation from 0 ° C. to 70 ° C. in steps of 10 ° C., and the result was almost the same as the case of 20 ° C.

[0580]

[Table 11] Referring to Table 11, when the transmittance is smaller than 1%, the light power of mW level used in communication is 10%.
The light power of μW level is applied to the monitor light receiving element 142.
However, since the fluctuation range of the optical power is smaller than P, sufficient light for detecting and controlling the fluctuation of the laser output is not guided to the light receiving element side, and the output of the laser diode is reduced. It can be seen that there are fluctuations. On the other hand, the mirror 30
In the region where the transmittance of 1 exceeds 50%, the energy consumption for controlling the output of the laser diode is large as compared with the optical signal transmission, and the efficiency of the optical communication system is reduced.

When used as an actual system, the transmittance is preferably 2% or more and 30% or less in terms of system design. Therefore, by adopting such a configuration, it is compact and is not easily affected by an external temperature change.
An optical transmitter capable of stably controlling the laser output is obtained, and a highly reliable optical communication system can be constructed. At that time, it has been found that it is practical to set the light transmittance of the mirror for branching the light output from the laser diode to 1% or more and 50% or less.

In this embodiment, the number of laser diode elements is four. However, the number of laser diode elements may be one, 8, 12, or 1.
Any number, such as six, depending on the data to be transmitted may be used. In this embodiment, the laser beam emitted from the laser diode is optically coupled to the optical waveguide, but an optical fiber may be used instead. A single mode fiber is suitable for transferring a large amount of information over a long distance, while a plastic optical fiber (POF) is suitable for transmitting a short distance at low cost. Further, a multi-mode fiber is suitable for a region where both are balanced, and in the present embodiment, these optical fibers can be appropriately used. Next, as another embodiment of the present invention, FIG. 107 shows an example in which an electrode of a light receiving element and a mirror are formed integrally.

In this embodiment, the long-wavelength surface-emitting laser diode 32 shown in FIG. 1 is mounted on a Si mounting substrate 301 together with a drive circuit and a laser output control unit (not shown). In this embodiment, a laser diode having an oscillation wavelength of 1.2 μm is used.

Further, as in the previous embodiment, a photodiode using a GaAsP material is used as the monitoring light receiving element 142P. In this embodiment, the p-type electrode on the light detection surface also serves as the mirror 301. You.

More specifically, an Au film having a thickness of 300 nm which does not transmit light having a wavelength of 1.2 μm is deposited on the photodiode as an electrode, and a random circular shape having a diameter of 0.7 to 5 μm is formed thereon. An opening was formed. In this case, the transmittance of the obtained mirror 301 is 5%.

[0583] The photodiode 142P thus formed is connected to the laser diode 32 by 45 degrees.
Fixed at an angle of degrees and the photodiode 142P
106 is electrically connected to the laser output control section 162 to form a laser diode feedback control system shown in FIG.

Further, the diameter of the core 302f is set to 50 in accordance with the optical axis of the laser beam reflected by the mirror 301.
An optical communication system is constructed by providing a multimode fiber 302F having a diameter of 125 μm and a diameter of a cladding 302c of 125 μm. With such a configuration, a compact optical transmission module with a small number of components can be formed.
In such an optical transmission module, since the laser output can be controlled stably, a highly reliable optical communication system can be constructed by using this.

In the present embodiment, the monitoring light receiving element 14
Although the 2P electrode is formed integrally with the mirror 301, it may be formed separately from the electrode on the surface of the monitor light receiving element 142P.

Next, as another embodiment of the present invention, FIG. 108 shows an example in which a mirror is formed on the end face of an optical waveguide.

Referring to FIG. 108, in this embodiment, a long-wavelength surface emitting laser diode array 32 is mounted on a Si mounting substrate 301 together with a drive circuit and a laser output control unit (not shown). In this embodiment, the array 3
The four laser diode elements 32A in 2
They are arranged at a pitch of m. The laser oscillation wavelength of each laser diode element is 1.3 μm.

In this embodiment, the optical waveguide 302 is formed on the mounting substrate 301. In this embodiment, the end face of the waveguide 302 is processed to 45 ° using a diamond blade, and the formed slope is further formed. Then, an Au film is deposited to form a mirror 301. At this time, a transmittance of 3% was given to the mirror 301 by setting the thickness of the Au film. The optical waveguide 302 and the laser diode 32 are optically coupled so that their optical axes are aligned with each other, and the monitor light receiving element 142P is fixed on the optical path of the light beam split by the mirror 301. Accordingly, it is possible to control the output of the laser diode 32 via the laser output control unit 162 using the output of the monitoring light receiving element 142. By adopting such a configuration, a compact optical module having a small number of components can be formed, and a highly reliable optical communication system capable of stably controlling the laser output can be constructed. [Twenty-fifth Embodiment] Next, still another embodiment of the present invention will be described.

Conventionally, an edge emitting laser diode has been widely used in an optical communication system. However, when such an edge emitting laser diode is used in a communication system using a plurality of optical fibers, an individual light emitting diode is required. It is necessary to optimize the optical coupling between the light emitting unit and the optical fiber one by one. In addition, since the edge emitting laser diode has a large divergence angle of the light beam emitted from the light emitting portion and an aspect ratio greatly deviated from 1, it is necessary to provide a coupling lens between the light emitting portion and the fiber.

For these reasons, in an optical communication system using an edge emitting laser diode, laser diodes could not be formed at high density in an array. On the other hand, in the present invention, a long wavelength surface emitting laser diode in which a plurality of laser diodes are monolithically formed on a single chip is used, and an optical fiber fiber group arranged at a high density is used in this. By coupling, a large capacity optical communication system can be realized.

FIG. 109 shows that the laser oscillation wavelength is 1.1 to 1.0.
1 shows an example of an optical communication system in which a long-wavelength surface emitting laser diode array of 7 μm band and a plurality of optical fibers are combined.

FIG. 11 shows a surface emitting laser diode of the present invention.
As shown in FIG.
It is characterized in that it is smaller than the edge emission type shown in (B), and its beam cross section is almost circular. From this, it is understood that when the long-wavelength surface emitting laser diode of the present invention is used, the optical connection with the optical fiber can be favorably performed without installing a coupling lens. Therefore, the surface emitting laser diode and the optical fiber can be installed close to each other, and a large-capacity optical communication system in which a laser element and a plurality of optical fiber groups are arranged at high density can be constructed.

In such a high-density optical communication system, it is difficult to provide a coloring layer and an identification ring for identifying individual optical fibers, such as those used on the outer periphery of a fiber in a normal optical fiber cable. It is.

In the case of a surface-emitting laser diode array, the individual light-emitting portions 32A constituting the array can be collectively formed on the same substrate with high precision by using lithography or etching. On the other hand, when handling a plurality of optical fibers, handling and alignment as a whole are easier when handled as a bundle than when the individual optical fibers 101 are handled individually. Making the arrangement of the core 101a in the optical fiber bundle bundled in advance and the arrangement of each surface emitting laser diode element 32A the same,
As described above, this is easy in the case of the surface emitting laser diode array 32.

However, when the optical fibers 101 are bundled, it is not easy to identify the center of the optical fiber bundle or any optical fiber in the bundle, and some method is required.

For example, as shown in FIGS. 111A to 111C, when the clad 101b of the optical fiber 101X located at the center of the optical fiber bundle is colored, the optical fiber is easily identified. Therefore, the surface emitting laser
Surface emitting laser diode 32 at the center of the diode
AX is made to emit light, and this is
By associating with 1X, the correspondence between the optical fiber bundle and the surface emitting laser diode can be easily performed.

In the example of FIG. 111, an example is shown in which the cladding 101b of the optical fiber 101X at the center of the bundle is colored, but as shown in FIG. 112, for example, every four out of several tens of optical fiber bundles If a colored optical fiber is arranged, a specific optical fiber can be easily recognized based on the optical fiber. Here, as shown in the cross section of the optical fiber in FIG.
a and the cladding 101b, but the light actually propagates in the core 101a, and the cladding 101b has a role of confining the light. Therefore, clad 10
Even if 1b is colored in the visible region, it does not contribute to the propagation of light, and thus does not affect optical communication at all.

FIG. 111 (B) and FIG. 111 (C) show FIG.
FIG. 111A shows a modification example, in which the optical fibers 101 are arranged in a close-packed structure in the example of FIG. 111A, whereas the optical fibers 101 are arranged in a square in FIG. 111B. ing. Further, in FIG. 111 (C), the optical fiber 1
01 are arranged in a square shape in the holding ferrule 101F.

In particular, as shown in the cross section of the optical fiber of FIG. 114, when the optical fiber has a single mode optical fiber core, the diameter of the core 101a is larger than that of the optical fiber having a multimode optical fiber core shown in FIG. Is 9.5
μm, which is much smaller than the diameter of the cladding 101b of 125 μm. In such a case, the optical fiber in which the cladding 101b is colored becomes easier to identify. [Twenty-sixth Embodiment] Next, still another embodiment of the present invention will be described.

In a conventional laser diode, the threshold current changes due to a change in temperature. Therefore, when used in a communication system, it is difficult to control with a constant current. For this reason, in the case of an end-face type laser, a light receiving element (photodiode) is provided on the side opposite to the light emitting surface by utilizing light leaking to the side opposite to the light emitting surface, and the laser is used by using the detected light amount. So that the output of the diode is constant
The drive of the laser diode was feedback-controlled. On the other hand, since the light receiving element cannot be arranged on the opposite side in the surface emitting laser, the light receiving element is provided until the emitted laser beam reaches the optical fiber or after the optical fiber so that the light amount becomes constant. Used a complex mechanism that controlled in real time.

On the other hand, FIG. 115 shows an example of an IL (current-light output) characteristic of a long-wavelength surface emitting laser diode according to the present invention.

Referring to FIG. 115, in the laser diode of the present invention, unlike the conventional laser diode, the fluctuation of the threshold current due to the temperature change is very small, and
The slope of the curve is only affected by the temperature change.
Therefore, when the laser diode is driven with a constant drive current, the fluctuation range of the optical output does not become large even if the temperature changes are included. For example, in FIG. 115, when the driving current is set to 6 mA and the laser diode is driven, 1
The fluctuation range of the light output in the temperature range from 0 ° to 70 ° is 0.1
mW, and even in a temperature range of 10 ° to 100 °, the fluctuation range of the optical output is only 0.25 mW. When expressed in terms of S / N (signal-to-noise ratio), they are 26 dB and 18 dB, respectively, from 20 ° which is a general environment to 70 °.
In communication in the above temperature range, sufficient signal quality can be obtained.

Generally, the current fluctuation of the constant current power supply is within ± 2 to 3% even if a circuit having a simple structure is used.
It is easy to control the constant current. Therefore, as shown in FIG. 116, an upper limit and a lower limit of the light output are set, an upper limit temperature and a lower limit temperature are set, and a drive current a corresponding to the light output upper limit at the lower limit temperature and a light output lower limit at the upper limit temperature are set. By controlling the drive current of the laser diode to a constant value x within the range of the corresponding drive current b, an optical output within a predetermined range shown in FIG. 116 can be obtained. As described above, in the laser diode of the present invention, a practical communication system can be constructed by setting a current with respect to a target optical output and driving the laser with a constant current. [Twenty-seventh embodiment] The threshold current of a laser diode gradually increases with aging and reaches its life. Therefore, means for preventing signal quality from deteriorating due to aging is desired.

For example, as shown in FIG. 117, a half mirror 411 is provided in the communication path 410 coupled to the laser diode 32, and the intensity of the light beam split by the half mirror 411 is detected by the light receiving element 412. You can also. In this case, the value of the laser beam intensity detected by the light receiving element 412, that is, the monitor light amount is fed back to the light emission control unit 415 and the constant current power supply 416.

[0608] In the illustrated example, the output signal of the light receiving element 412 is supplied to the communication control section 414 via the light receiving processing section 413.
A correction value of the drive current is obtained based on the monitor light amount detected by 12 using a conversion table 414A showing a relationship between the monitor light amount and a correction value of the drive current for driving the laser diode 32. According to such a configuration, by correcting the set current value periodically or at any time with the correction value, it is possible to remove fluctuations in optical output due to aging, and to construct a practical communication system. .

In order to monitor the secular change or abnormality of the laser diode, it is only necessary to know the output of the light receiving element on the receiving side. Therefore, the output of the light receiving element on the light receiving side is transmitted as data to the transmitting side. It is also possible. For example, separately from the optical communication data, the data of the light receiving element is transmitted to the optical transmission unit periodically or as needed, and the data is supplied from the communication control unit to the emission control unit, and the drive current of the laser diode is monitored by the monitor. The correction current corresponding to the light amount may be corrected. With this configuration, fluctuations in optical output due to aging can be removed, and a practical communication system can be constructed. [28th Embodiment] Next, still another embodiment of the present invention will be described.

FIG. 118 shows an example of a communication system using the long-wavelength surface emitting laser diode 32 according to the present invention. The laser diode module 422 to which an optical fiber 421 is connected and the laser diode module 42
2 and an electronic circuit board 42 arranged to sandwich the optical circuit board 423A and forming an air flow path.
3B and 423C are housed. A side of the case 420 is provided with a blower 424A, and a side facing the blower 424A is provided with a discharge port 42A.
4B is provided. The electronic circuit boards 423B, 4
An electronic component 423a is mounted on 23C.

[0611] The blower 424A is a forced blower such as a sirocco fan, and supplies a cooling medium such as air to the inside of the housing 420.
3B and 423C, the optical circuit board 4
Heat is exchanged on the surface of the laser diode module 422 on 23A. The air that has exchanged heat on the surface of the laser module is discharged to the outside of the housing from the outlet 424B.

In the illustrated embodiment, the substrate 423B which generates the least heat is disposed on the lower side, and the large substrate 423C is disposed on the upper side.

[0613] Of the optical circuit board 423A, the surface facing the electronic circuit board 423C reduces unevenness and reduces turbulence in the air flow. The electronic circuit board 423
A similar effect can be obtained when a flat plate on which no electronic component is mounted is used instead of B and 423C. In this embodiment, only one blower 424A is used. However, since the heat generated by laser oscillation increases as the number of laser elements increases, the number of blowers 424A is set to two or more in accordance with the number of laser elements. Is also good. Alternatively, the blowing amount may be increased. In accordance with this, the area of the outlet 424B is also increased. In this embodiment, the blower 424A is set on the air introduction side, and air is introduced from the outside into the housing. May be discharged. Furthermore, air introduction and discharge may be performed using a set of forced air blowers. [Twenty-ninth embodiment] FIG. 119 shows an example of a laser diode module using a long-wavelength surface emitting laser diode 32 of the present invention.

Referring to FIG. 119, here, two laser diode elements 32A are monolithically formed on a GaAs substrate 32 constituting a laser diode chip, and the GaAs substrate 32 has a large thermal conductivity.
It is carried on a mounting board 131. Further, the Si mounting substrate 131 is mounted on a ceramic substrate 136 having higher thermal conductivity. The ceramic substrate 136 may be an optical circuit substrate 434A as shown in FIG.
Mounted on top and cooled. The electrical connection to the laser diode element 32A is
6 and the laser diode element 32A
It is made by a bonding wire connecting the upper electrode.

With such a configuration, the heat generated in the laser diode element 32A is transferred to the Ga
The heat transported to the As substrate is transported to the Si mounting substrate 131 at a lower temperature. Further, the heat is transferred to the lower temperature ceramic substrate 136, so that the laser diode element 32A is efficiently cooled.
The surface area of the ceramic substrate 136 is the largest among the components, and therefore, the ceramic substrate 136 is most efficiently cooled by heat radiation by heat radiation and cooling by air.

The GaAs constituting the laser diode chip applied to the present invention has a thermal conductivity of 0.54 W / cm · K, but the thermal conductivity of Si is 1.48 W / cm · K.
Is larger than the value of GaAs. As a material having a higher thermal conductivity than Si, for example, a thermal conductivity of 2.72 W / c is used.
It is also possible to use m · K BeO or 9.0 W / cm · K C (diamond). However, these values are at a temperature of 300K.

By the way, the contact surface between the two substrates is reduced in surface roughness and the degree of adhesion is further improved.
Heat can be transmitted efficiently. However, even if the surface accuracy is extremely increased, the cost is increased but the merit is small. Specifically, an attempt to increase the surface accuracy beyond 10 nm increases the cost and is not practical. Therefore, in order to achieve a practically industrial level, the lower limit of the surface roughness is set to 10 n.
m.

As for the upper limit, if the surface roughness is too rough, the substrates cannot be brought into close contact with each other. In view of this point, the present inventor has conducted intensive studies and experiments and found that if the surface roughness value is 1000 nm or less, the mutual substrates can be considered to be in close contact with each other when viewed from the heat transfer surface. When the substrates 32, 131, and 136 were actually laminated and laser oscillation was performed within this range, the laser diode element 32
The heat generated by A moves from the laser chip 32 to the first substrate 131 and then to the second substrate 136, and it has been confirmed that heat can be efficiently radiated without accumulating heat in any part. In addition, the fluctuation of the threshold current density of the laser diode due to heat generation was reduced. As described above, according to the present embodiment, stable laser emission can be performed.

FIG. 120 shows a long-wavelength surface emitting laser diode.
Laser diode element 32
A and a GaAs substrate 32 forming the element 32A
Are fixed to a Si mounting substrate 131 via a heat conductive layer 137, and the Si mounting substrate 131 is further fixed to a ceramic substrate 136 via another heat conductive layer 138.

In this embodiment, the respective substrates 32, 13
The contact surfaces of 1 and 136 were made to have a surface roughness Ra of 10 to 1000 nm by mechanical polishing using alumina abrasive grains,
This gap is filled with the heat conductive layer 137 or 138.

The heat conduction layer 137 or 13 used here
8 is a material obtained by dispersing metal fine particles such as aluminum, gold, silver, and copper in an organic polymer material such as an epoxy resin, a silicone resin, and an acrylic resin.
The thickness was applied. The size of the metal fine particles is from several nm to 1
At 00 nm, the dispersion compounding ratio was 0.1 to 1 for the fine metal particles per 1 resin.

FIG. 121 shows an example of a long-wavelength surface emitting laser diode module of this embodiment, which comprises a laser module package 431 having a laser diode module 422 and an optical fiber 421 of FIG. 118 mounted thereon. Eight cooling fins 431 having a base length of 1 mm, a height of 3 mm, and a triangular cross section are provided on one outer surface of 431, and air is supplied in parallel to the cooling fins.

The outer surface of the laser module package 431 of this embodiment plays a role of heat radiation equivalent to that of the ceramic substrate 136, and also has a laser module packaging function. The surface on which the cooling fins 431 are provided may be another surface parallel to the air blowing direction, and the shape and number thereof are not limited to the illustrated configuration.

In this embodiment, the cooling fin 431A is provided outside the laser module package 431. However, the main point of this embodiment is that the first substrate including the heat source and the second substrate not including the heat source are provided. In the heat dissipation structure where
The present invention is characterized in that the surface area of a portion of the second substrate that is not in close contact with the first substrate is larger than the surface area of the portion that is in close contact with the first substrate, thereby improving heat radiation efficiency. Therefore, any shape other than the fin shape described above can be used as long as the surface area of a portion of the second substrate not in contact with the first substrate increases.

As described above, the surface emitting laser diode having a laser oscillation wavelength of 1.1 to 1.7 μm used in the present invention.
Can easily form multiple laser diode elements on a single chip, and is particularly suitable for a large-capacity communication system using a laser diode array. The more the heat, the more important the heat problem becomes. Therefore, the configuration of the present embodiment exerts its effect as the number of laser elements increases. [Thirtieth Embodiment] Next, still another embodiment of the present invention will be described.

FIGS. 122 and 123 show an example of a laser chip of a communication system using a long-wavelength surface emitting laser diode according to the present embodiment. FIG. 122 shows a one-dimensional laser diode element on the chip. FIG. 123 shows an example in which laser diode elements are two-dimensionally arranged on a chip.

[0627] In the figure, the laser diode elements with diagonal lines are provided with corresponding light-receiving elements, so that the optical output can be monitored. On the other hand, a laser element without hatching is not provided with a corresponding light receiving element, and can output light output to the outside.

FIG. 124 shows the configuration of FIG. 122 viewed from another angle.

Referring to FIG. 124, among the laser diode elements 32A, some of the hatched portions in FIG. 122 are provided with light receiving elements 142P, and therefore, the laser beam of these laser diode elements 32A is provided. Is shut off, but light output can be taken out from the laser diode element 32A in which the light receiving element 142P is not provided, and the laser beam is injected into the optical fiber 352 by the condenser lens 353.

The light output of the laser diode element 32A without the light receiving element 142P is the output of the light receiving element 142P closest to the laser diode element 32A or the output of a plurality of light receiving elements 142P provided near the laser diode element 32A. It can be calculated based on the value. That is, in the present embodiment, the output of each laser diode element 32A is controlled based on the output value of the laser diode element 32A obtained in this manner.
The variation in the output of each laser diode element 32A is:
If this is measured in advance and the correction coefficient is determined, it can be easily corrected.

FIGS. 125, 126 and 130 correspond to FIG.
4 shows an example of output control of the laser diode element 32A using the configuration of FIG.

Referring to FIG. 125, the laser diode chip 32 has the same laser diode element 3 as that of FIG.
Although a two-dimensional array of 2A is included, in this embodiment, the laser diode elements 32A are numbered (1) to (6) for convenience of explanation. <Example 1> In Example 1, as shown in FIG. 126, in the chip of FIG.
The output value of the light receiving element 142P for monitoring the output of 2A, I
When i is the drive current of the i-th laser element, FIG.
Using the drive circuit 106, and controls the _{I 1} based on the value of _a 1 _{O 1,} and controls the _{I 2} based on the value of _a 2 _{O 1,} and _{I 3 a 3}
O ₄ is controlled based on the value of I ₄ , I ₄ is controlled based on the value of a ₄ O ₄ , I ₅ is controlled based on the value of a ₅ O ₄ , and I ₆ is controlled based on the value of a ₆ O _7.
, And an operation of controlling I ₇ based on the value of a ₇ O ₇ is performed.

Here, a _i is a correction coefficient, and the output of each laser element is measured in advance under various conditions and set so that the error from the actual output value of each laser element is minimized. <Example 2> In Example 2, as shown in FIG. 127, in the chip 32 of FIG. 125, Oi is the output of the photodetector 142P for monitoring the output of the i-th laser diode element, and Ii is the drive of the i-th laser element. As a current, the driving circuit 106
, I ₁ is controlled based on the value of a ₁ O ₁ , and I ₂ is controlled by a ₂
Control is performed based on the value of O ₁ + b ₂ O ₄ , and I _{3 is changed} to a ₃ O ₁ + b
₃ The value of O ₄ controls based on, and controls the _{I 4} based on the value of _a 4 _{O 4,} and controls the _{I 5} based on the value of _{a 5 O 4 + b 5 O} 7, I
₆ is controlled based on the value of a ₆ O ₄ + b ₆ O ₇ , and I ₇ is controlled by a ₇
The value of O ₇ operates to control based on.

Here, a _i and b _i are correction coefficients, and the output of each laser element is measured in advance under various conditions and set so that the error from the actual output value of each laser element is minimized. deep. <Example 3> In Example 3, the laser diode element 32A forms a two-dimensional array in the laser diode chip 32 as shown in FIG. In this example, Oij is ij
Th output of the photodetector to monitor the output of the laser diode element 32A, when the drive current of the ij-th laser element Iij, by the driving circuit 161, the I ₀₀ a
₀₀ O ₀₀ is controlled based on the value of I ₀₁ , I ₀₁ is controlled based on the value of a ₀₁ O ₀₀ , I ₁₀ is controlled based on the value of a ₁₀ O ₀₀ , and I ₁₁ is the value of a ₁₁ O ₀₀ . , I ₀₂ is controlled based on the value of a ₀₂ O ₀₃ , and I ₀₃ is controlled based on a ₀₃ O _03.
, I ₀₄ is controlled based on the value of a ₁₄ O ₀₃ , I ₁₂ is controlled based on the value of a ₁₂ O ₀₃ , and I ₁₃ is controlled based on the value of a ₁₂ O _03.
Is controlled based on the value of a ₁₃ O ₀₃ , and I ₁₄ is controlled by a ₁₄ O
₀₃ , the output of the photodetector closest to the laser diode element 32A is set to 1
And control. a _ij is a correction coefficient, and the output of each laser element is measured in advance under various conditions, and is set so that the error from the actual output of each laser element is minimized. <Example 4> In the example of FIG. 129, Oij is the output of the photodetector that monitors the output of the ij-th laser diode element 32A, and Iij is the drive current of the ij-th laser element.
I ₀₀ is controlled based on the value of a ₀₀ O ₀₀ , and I _{01 is set} to a
₀₁ O ₀₀ + b ₀₁ O ₀₄ + c ₀₁ O ₂₂ is controlled based on the value, I ₁₁ is controlled based on the value of a ₁₁ O ₀₀ + b ₁₁ O ₂₂ , and I ₂₁ is controlled based on the value of a ₂₁ O ₀₀ + b ₂₁ O ₂₂ + c. ₂₁
The value of O ₄₀ controls based on, the control of ..., controls the individual laser diode element 32A by a plurality utilizing the output of the nearest optical detector. Where a _ij and b _ij
And c _ij are correction coefficients which are measured in advance under various conditions and set so that the error from the actual output value of each laser diode element 32A is minimized. [Thirty-First Embodiment] Next, still another embodiment of the present invention will be described.

Next, the manufacturing control of a laser array module including a laser diode array provided in a communication system using a long-wavelength surface emitting laser diode according to the present invention will be described. Note that a laser array module means that a plurality of surface emitting laser diodes are modularized, and that a plurality of surface emitting laser diode elements are formed on a single chip, or a plurality of such chips are provided. And further arranged ones. Also,
A single chip in which a plurality of laser diode elements are formed on a single chip is also included.

Normally, in manufacturing such a laser array module, a laser chip module including a laser diode array is manufactured through a predetermined manufacturing process.

In the above-described manufacturing process, a predetermined number of laser diode elements or laser diode chips are prepared for array manufacture, and a laser array module is formed by arranging them.

Subsequently, a quality inspection is performed on the laser chip modules arrayed in the quality inspection step. At this time, all the laser diode elements mounted in the module and all the laser diode chips are inspected. On the other hand, a quality inspection is performed. If it is confirmed that the desired quality has been secured for all the elements and chips, the laser array module is ready to be delivered as a product.

On the other hand, when at least one laser diode element chip less than a predetermined product characteristic value is detected among n laser diode element chips mounted in the laser array module, This laser chip module is usually treated as a defective product.

On the other hand, in the manufacture of a functional module having an array structure consisting of n elements, the number c of laser diode elements or chips is reduced by the laser diode mounted in the laser chip module. Even if the number of elements or chips is equal to or less than the specified number n, when (nc) non-defective products are mounted in the laser chip module,
If this laser chip module can be handled as a legitimate product, its productivity will be very high.

The inventor of the present invention quickly realized the importance of obtaining a higher yield by finding a product / manufacturing process and a method of producing such a high productivity. As a result of intensive studies on a manufacturing process for forming an array using a plurality of elements of the same function and a single function, and a method of manufacturing the array, the manufacturing process and quality control steps shown in FIGS. 130 and 131 are proposed.

The present embodiment will be described below with reference to FIGS.
1 will be described in detail.

FIG. 130 shows a process for manufacturing and commercializing a laser diode module in which laser diode elements or chips of the present invention are arrayed.

Referring to FIG. 130, the production of a laser diode element or a chip is performed in wafer process steps S1,
The process is performed by a predetermined manufacturing process including a laser diode array forming process S2 and a laser diode module manufacturing process S3. The array or module formed in the processes S2 and S3 is subjected to a quality inspection in a process S4, and is out of stock. Is checked.

In this embodiment, even if there is a laser diode element or chip determined to be no as a result of the quality inspection, the number c of missing parts is determined by the laser diode mounted in the laser chip module. The total number of elements or chips is n
If the value of nc is equal to or less than a predetermined value, (nc)
It is delivered as a regular product with individual quality. In the process of FIG. 130, this determination is made in step S6. Of course, if the total number n of the laser diode element chips is missing, the LD module is determined to be defective.

In the quality inspection step S4 of FIG.
As shown in FIG. 1, the quality and characteristic values of the inspection laser diode array and the laser diode module, which are the quality inspection targets, are determined for each channel (ch) by an inspection process S41 using an analyzer such as a high-frequency probe. Extract.

[0647] The quality / characteristic values for each channel obtained in this way are then checked in a quality check step S42. In the quality check step S42, it is inspected / determined whether or not a predetermined quality is secured for all of the laser diode elements or chips mounted on the module. This determination is made, for example, by I-
Items such as L characteristics, IV characteristics, fiber coupling loss, pulse modulation characteristics, and temperature dependence are performed. further,
Based on the result of the determination, the product is delivered as a laser diode module corresponding to the number of normally operating laser diode element chips.

[0648] As is clear from the above description, in the present embodiment, 1.1 to 1.1 used in such an optical communication system are used.
In a system using a 1.7 μm band surface emitting laser diode as a light source, a laser chip module having a plurality of laser diode elements used therein is effectively used as a product according to the situation of the module. can do.

In other words, even if all of the n laser diode elements do not completely operate, that is, even if only (nc) pieces of the laser diode elements operate, such a module will have (nc) ) As a module for individual
It can be used for applications suitable for this. This makes it possible to effectively use the manufactured laser diode element or module.

Conventionally, there has been no surface emitting type laser diode element which is easy to form an array and has excellent mass productivity in a long wavelength band having an oscillation wavelength of 1.1 to 1.7 μm.
The device of the present invention as described above can realize such a device for the first time in the world, thereby opening the way to a large-capacity and efficient optical fiber communication system for the first time.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the specific embodiment, and various modifications and changes can be made within the scope of the claims. is there.

[0652]

According to the first to third aspects of the present invention, the laser oscillates at a wavelength of 1.1 to 1.7 .mu.m suitable for optical fiber communication, such as a computer network or a trunk system for long-distance large-capacity communication. Although a surface emitting laser diode which has low operating voltage, low oscillation threshold current and the like, generates little heat, and can perform stable oscillation has not existed conventionally, according to the present invention, according to the present invention, a distributed Bragg reflection semiconductor is used. By devising a mirror, laser oscillation can be performed in the above wavelength range, the operating voltage and the oscillation threshold current can be reduced, the heat generation of the laser element can be reduced, and a surface emitting laser diode that performs stable oscillation is realized. By using a surface emitting laser diode, a practical point-to-point optical transmission / reception system can be realized at low cost.

In constructing such a point-to-point optical transmission / reception system, in this embodiment, the direction of the transmission line is changed by bending the optical fiber so that a local angle is not formed. An optical transmission / reception system that connects two points easily and at low cost can be realized without damaging the fiber.

According to the present invention, the laser oscillation wavelength at which optical fiber communication such as a computer network and a trunk system for long-distance large-capacity communication is expected is from 1.1 μm to 1.7 μm. In the field, there has been no surface emitting laser diode and an optical transmitting / receiving system using the same, which can lower the operating voltage, the oscillation threshold current, etc., generate less heat from the laser element, and perform stable oscillation.
By devising a semiconductor distributed Bragg reflector as in the present invention, the operating voltage, the oscillation threshold current, etc. can be reduced, the laser element generates less heat, and stable oscillation can be achieved. ) An optical transmission and reception system was realized.

[0655] Furthermore, in constructing such an optical premise transmission / reception system, a reflection member for changing the direction of the transmission line is provided, so that the transmission line can be arranged efficiently according to the shape of the building. The unnecessary transmission line is not exposed to the eyes, and the transmission line does not occupy more area than necessary in the ceiling, under the floor, or inside the wall, so that the building design can be effectively performed. At the same time, the degree of freedom in aesthetic design has increased.

According to the present invention, since the optical transmission / reception system for spatially transmitting the optical signal of the laser light source is provided inside the apparatus, the internal signal transmission / reception can be performed by this optical transmission / reception system. As a result, it became possible to omit the conductor cable used for signal transmission and reception inside the device. Conventionally, the conductor cables used for signal transmission and reception inside the device were complicated and complicated, and the layout process was complicated. Not only is it possible, but the degree of freedom in the layout of each part / unit inside the device has been increased. Further, since the light emitting element section and the light receiving element section of the laser light emitting light source and the light receiving unit of this optical transmitting and receiving system are provided with cover members for covering these elements, the light emitting element section and the light receiving element section float inside the apparatus. The optical transmission / reception system can be stably operated by being prevented from being damaged by a foreign substance or the like.

The laser emission light source of the optical transmission / reception system inside such an apparatus has a laser oscillation wavelength of 1.1.
Since a surface emitting laser diode of μm band to 1.7 μm band is used and a semiconductor distributed Bragg reflector of this surface emitting laser diode is devised, the operating voltage, oscillation threshold current and the like can be reduced, and the laser can be reduced. Stable oscillation can be performed with little heat generation of the element, and a low-cost and practical optical transmitting and receiving system can be obtained.

According to the tenth aspect of the present invention, by providing such an optical transmission / reception system in a recording apparatus using the electrophotographic principle, it is possible to omit a conductor cable used for signal transmission and reception inside the apparatus. It has become possible. Also,
In such a recording apparatus, toner and paper dust are constantly flying inside the apparatus, which adversely affects the light emitting element section and the light receiving element section of the optical transmitting and receiving system. In the present invention, a cover member covering those elements is used. With the provision, the adverse effect can be prevented, and the optical transmission / reception system can operate stably.

According to the present invention as set forth in claims 11 to 13,
In the field of laser oscillation wavelength of 1.1 μm to 1.7 μm where optical fiber communication is expected, such as computer networks and trunk lines for long-distance large-capacity communication, the operating voltage and oscillation threshold current can be reduced. Although there was no surface emitting laser diode capable of generating stable oscillation with little heat generation of the element and a communication system using the same, the operating voltage and the operating voltage were improved by devising a semiconductor distributed Bragg reflector as in the present invention. The oscillation threshold current and the like can be reduced, stable oscillation can be performed with little heat generation of the laser element, and a practical optical communication system can be realized at low cost.

That is, the laser oscillation wavelength which can be conventionally used for such an application is in the range of 1.1 μm band to 1.7 μm band.
There was no long wavelength surface emitting laser diode,
A surface emitting laser diode element chip in which a semiconductor distributed Bragg reflector is devised as in the present invention can reduce the operating voltage, oscillation threshold current, and the like, realize less energy generation, generate less energy, and realize a stable optical transmission and reception system at low cost. did it.

According to the present invention as set forth in claims 14 to 16,
In the field of laser oscillation wavelengths of 1.1 μm to 1.7 μm where optical fiber communication is expected, such as computer networks and trunk lines for long-distance large-capacity communication, the operating voltage and oscillation threshold current can be reduced. Although there was no surface emitting laser diode capable of generating stable oscillation with little heat generation of the element and a communication system using the same, the operating voltage and the operating voltage were improved by devising a semiconductor distributed Bragg reflector as in the present invention. The oscillation threshold current and the like can be reduced, stable oscillation can be performed with little heat generation of the laser element, and a practical optical communication system can be realized at low cost.

Further, since there has been no practical optical communication system in the field where the laser oscillation wavelength is in the 1.1 μm band to 1.7 μm band, a surface emitting laser diode used for this has been known. There has been no study on how to make the fiber cable length of the optical fiber cable drawn out of the element chip or the module package accommodating the chip, but as in the present invention, this length is set to 1 mm or more. By doing so, it became possible to significantly improve the productivity of assembly manufacturing of the package. Further, when an optical communication system is constructed by connecting a transmission fiber cable to an optical fiber drawn from a module package accommodating the chip, by setting the length of the optical fiber to 1 mm or more as described above. These connections can be made easily and reliably, and a highly reliable optical communication system can be easily constructed. According to the present invention described in claims 17 to 19, in the field of laser oscillation wavelengths in which optical fiber communication is expected, such as a computer network and a trunk system of long-distance large-capacity communication, in the 1.1 to 1.7 μm band, There has been no surface emitting laser diode and communication system using the same, which can lower the operating voltage, the oscillation threshold current, etc., generate less heat from the laser element, and provide stable oscillation. By devising a Bragg reflector, the operating voltage, the oscillation threshold current, and the like can be reduced, the laser element generates less heat, stable oscillation can be achieved, and a practical optical communication system can be realized at low cost.

Further, by defining the length of the optical fiber with respect to the core diameter of the optical fiber, efficient terminal processing of the optical fiber becomes easy, and highly reliable and low-cost optical communication can be realized.

According to the present invention as set forth in claims 20 to 22,
In the field of laser oscillation wavelength of 1.1 to 1.7 μm band where optical fiber communication is expected, such as a computer network, a trunk system of long-distance large-capacity communication, an operating voltage, an oscillation threshold current, and the like can be reduced. Although there was no surface emitting laser diode and a communication system using the same capable of generating stable oscillation with little heat generation, by devising a semiconductor distributed Bragg reflector as in the present invention,
The operating voltage, oscillation threshold current, etc. can be reduced, with low power consumption.
Stable oscillation was achieved with little heat generation of the laser element, and a practical optical communication system at low cost was realized.

The difference between the coefficient of linear expansion of the laser chip and the material of the substrate on which the laser chip is mounted is 2 × 10 ⁻⁶ /
K, the high strain GaIn
Since the difference between the linear expansion coefficient of the long-wavelength surface emitting laser having an NAs active layer and the linear expansion coefficient of the mounting substrate can be reduced, the generation of thermal stress is suppressed, and as a result, the laser diode generated by the thermal stress is reduced. An optical communication system with high reliability was able to be realized while reducing the characteristic fluctuation and preventing the life from being shortened.

According to the present invention as set forth in claims 23 to 25,
In the field of laser oscillation wavelength of 1.1 to 1.7 μm band where optical fiber communication is expected, such as a computer network, a trunk system of long-distance large-capacity communication, an operating voltage, an oscillation threshold current, and the like can be reduced. Although there was no surface emitting laser diode and a communication system using the same capable of generating stable oscillation with little heat generation, by devising a semiconductor distributed Bragg reflector as in the present invention,
The operating voltage, the oscillation threshold current, and the like can be reduced, the laser element generates less heat, stable oscillation can be achieved, and a practical optical communication system can be realized at low cost.

Further, since the optical fiber optically coupled to the light emitting portion of the laser chip of the present invention is mechanically connected with the direction of the fiber axis being pressed in the direction of the light emitting portion, the optical fiber is connected to the laser emitting portion. Good optical coupling of the optical fiber was obtained, and a highly reliable optical communication system was obtained.

According to the present invention described in claims 26 to 28,
In the field of laser oscillation wavelengths of 1.1 μm to 1.7 μm where optical fiber communication is expected, such as computer networks and trunk lines for long-distance large-capacity communication, the operating voltage and oscillation threshold current can be reduced. Although there was no surface emitting laser diode capable of generating stable oscillation with little heat generation of the element and a communication system using the same, the operating voltage and the operating voltage were improved by devising a semiconductor distributed Bragg reflector as in the present invention. The oscillation threshold current and the like can be reduced, stable oscillation can be performed with little heat generation of the laser element, and a practical optical communication system can be realized at low cost.

Furthermore, by using a surface emitting laser diode capable of lowering the operating voltage, oscillation threshold current and the like as in the present invention as compared with the case of using the conventional edge emitting laser, low power consumption optical communication is achieved. In the case of a conventional edge emitting laser diode, it is necessary to insert a lens optical system between the laser diode and an optical fiber or an optical waveguide. By making the laser diode and the optical fiber or the optical waveguide have such a positional relationship,
Since there is no need to use a lens, the number of parts is small, alignment is gradual in the optical axis direction, and good optical coupling efficiency with an optical fiber or an optical waveguide can be realized.

According to the present invention as set forth in claims 29 to 31,
In fields where the laser oscillation wavelength is expected to be in the 1.1 to 1.7 μm band, such as computer networks and trunk lines for long-distance large-capacity communications, optical fiber communications are expected.
A surface emitting laser diode and an optical communication system using the same which can lower the oscillation threshold current and the like and generate stable laser with less heat generation from the laser element did not exist. By devising the mirror, the operating voltage, the oscillation threshold current, and the like can be reduced, the laser element generates less heat, stable oscillation can be achieved, and a practical optical communication system can be realized at low cost.

Furthermore, in order to increase the efficiency of coupling between the edge emitting laser of the 1.1-1.7 μm band and the single-mode optical fiber with high efficiency, the shape of the light emitting portion of the laser and the coupling lens system must be changed. Although it had to be devised, the use of the surface emitting laser of the present invention has realized an optical communication system capable of coupling to a single mode optical fiber with high efficiency in the same band.

According to the present invention as set forth in claims 32 to 34,
In the field of laser oscillation wavelengths of 1.1 μm to 1.7 μm where optical fiber communication is expected, such as computer networks and trunk lines for long-distance large-capacity communication, the operating voltage and oscillation threshold current can be reduced. Although there was no surface emitting laser diode capable of generating stable oscillation with little heat generation of the element and a communication system using the same, the operating voltage and the operating voltage were improved by devising a semiconductor distributed Bragg reflector as in the present invention. The oscillation threshold current and the like can be reduced, stable oscillation can be performed with little heat generation of the laser element, and a practical optical communication system can be realized at low cost.

Furthermore, since the relationship between the area of the light emitting portion of the surface emitting laser diode element chip and the operating voltage of the laser element has been optimized, it is possible to realize an optical communication system that can be used favorably without damaging the laser element. Was.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an element structure of a long-wavelength surface emitting laser diode according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a reflection spectrum of a distributed Bragg reflector used in the laser diode of FIG. 1;

FIG. 3 is a cross-sectional view showing a configuration of a semiconductor distributed Bragg reflector of a long-wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 4 is a diagram showing an example in which the composition gradient of the hetero-spike buffer layer of the semiconductor distributed Bragg reflector applied to the present invention is larger near the GaAs layer than the AlAs layer.

FIG. 5 is a diagram showing an example in which the Al composition of the heterospike buffer layer is changed linearly.

6 is a diagram showing a result of estimating a differential sheet resistance of the distributed Bragg reflector of FIG. 3;

FIG. 7 shows the distributed Bragg reflector of FIG.
FIG. 4 is a diagram showing a band structure in a thermal equilibrium state near a hetero interface when formed by stacking s.

8 is a diagram showing a band structure of the hetero-spike buffer layer of FIG. 4 in a thermal equilibrium state.

FIG. 9 is a diagram showing an example of a band structure of a hetero spike buffer layer.

FIG. 10 is a diagram showing an example of a band structure of a hetero-spike buffer layer.

FIG. 11 is a diagram showing an example of a band structure of a hetero spike buffer layer.

FIG. 12 is a diagram illustrating an example of a band structure of a hetero-spike buffer layer.

FIG. 13 is a diagram showing the relationship between the differential sheet resistance of the distributed Bragg reflector and the Al composition profile in the heterospike buffer layer.

14 is another diagram showing the relationship between the differential sheet resistance of the distributed Bragg reflector of FIG. 3 and the Al composition profile in the heterospike buffer layer.

FIG. 15 is a diagram showing another band structure of the hetero spike buffer layer.

FIG. 16 is a diagram showing the relationship between the reflectance of a distributed Bragg reflector and the thickness of a hetero-spike buffer layer.

FIG. 17 is a diagram showing the relationship between the resistivity of a distributed Bragg reflector and the thickness of a hetero-spike buffer layer.

FIG. 18 is another diagram showing the relationship between the resistivity of the distributed Bragg reflector and the thickness of the hetero-spike buffer layer.

FIG. 19 is yet another diagram showing the relationship between the resistivity of the distributed Bragg reflector and the thickness of the hetero-spike buffer layer.

FIG. 20 is a diagram showing still another example of the band structure of the hetero-spike buffer layer.

FIG. 21 is a diagram showing the relationship between the resistivity determined for the distributed Bragg reflector having the hetero-spike buffer layer of FIG. 20 and the thickness of the hetero-spike buffer layer.

FIG. 22 is another diagram showing the relationship between the resistivity obtained for the distributed Bragg reflector having the hetero-spike buffer layer of FIG. 20 and the thickness of the hetero-spike buffer layer.

FIG. 23 is a diagram showing the relationship between the resistivity obtained for various distributed Bragg reflectors and the thickness of the hetero-spike buffer layer.

FIG. 24 is another diagram showing the relationship between the resistivity obtained for various distributed Bragg reflectors and the thickness of the hetero-spike buffer layer.

FIG. 25 is a diagram showing the relationship between the reflectance obtained for various distributed Bragg reflectors and the thickness of the hetero-spike buffer layer.

FIG. 26 is another diagram showing the relationship between the reflectance obtained for various distributed Bragg reflectors and the thickness of the hetero-spike buffer layer.

FIG. 27 is a cross-sectional view showing another configuration of a long-wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 28 shows a GaInNAs / G according to one embodiment of the present invention.
It is a figure which shows the room temperature photoluminescence spectrum of the active layer which consists of aAs double quantum well structure.

FIG. 29 is a diagram showing a sample structure.

FIG. 30 is a diagram showing the distribution of nitrogen and oxygen concentrations in the depth direction.

FIG. 31 is a diagram showing the distribution of Al concentration in the depth direction.

FIG. 32 is a view showing a structure in the case where growth is interrupted by carrier gas purge.

FIG. 33 is a diagram showing the distribution of the Al concentration in the depth direction when a growth interruption step is provided and purged with hydrogen.

FIG. 34 is a diagram showing a depth direction distribution of nitrogen and oxygen concentrations when a growth interruption step is provided and purged with hydrogen.

FIG. 35 is a plan view showing a wafer substrate and a laser device chip on which a long-wavelength surface emitting laser diode device according to one embodiment of the present invention is formed.

FIG. 36 is a diagram showing an example of an optical transmitting and receiving system in which a light emitting light source and a light receiving unit are linearly connected by a transmission line.

FIG. 37 is a diagram showing an outline of the optical transmission / reception system.

FIG. 38 is a diagram showing an example in which a transmission line connecting a light emitting light source and a light receiving unit is bent at a right angle in order to avoid an obstacle.

FIG. 39 is an example of an optical transmission / reception system of the present invention, showing an example in which a light emitting light source and a light receiving unit are connected while bending a transmission path while avoiding an obstacle.

FIG. 40 is an example of another optical transmission / reception system of the present invention,
FIG. 4 is a diagram illustrating an example in which a light emitting light source and a light receiving unit are connected while bending a transmission path while avoiding an obstacle.

FIG. 41 is a diagram showing an example of an optical transmitting and receiving system using a long-wavelength surface emitting laser diode element of the present invention as a light source.

FIG. 42 is a plan view showing an example of a room where the optical transmission / reception system of the present invention is arranged in a premises.

FIG. 43 is a plan view showing an example of a room in which a conventional optical transmission / reception system is arranged in a premises.

FIG. 44 is a plan view showing another example of a room where a conventional optical transmission / reception system is arranged in a premises.

FIG. 45 is a conceptual diagram showing an example of the optical transmission / reception system of the present invention.

FIG. 46 is a conceptual diagram showing another example of the optical transmission / reception system of the present invention.

FIG. 47 is a diagram showing an example of an electrophotographic copying machine to which the present invention is applied.

FIG. 48 is a diagram showing an example of an electrophotographic copying machine incorporating the optical transmission / reception system of the present invention.

FIG. 49 is a diagram illustrating an example of an inkjet recording apparatus to which the present invention is applied.

FIG. 50 is a diagram showing an example of an ink jet recording apparatus incorporating the optical transmission / reception system of the present invention.

FIG. 51 is a conceptual diagram showing still another example of the optical transmission / reception system of the present invention.

FIG. 52 is a diagram showing an example of a long wavelength surface emitting laser diode and an optical communication system to be connected according to an embodiment of the present invention.

FIG. 53 is a diagram showing a bidirectional system formed using a long-wavelength surface emitting laser diode and an optical communication system to be connected according to an embodiment of the present invention.

FIG. 54 is a diagram showing an example of a large-capacity optical communication system using a plurality of fiber groups in a long wavelength surface emitting laser diode and an optical communication system to be connected according to an embodiment of the present invention.

FIG. 55 is a diagram showing a long wavelength surface emitting laser diode and an optical communication system to be connected according to an embodiment of the present invention.

FIG. 56 is a view showing a configuration of an optical connection module used in an optical communication system using a long wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 57 is another diagram showing a configuration of an optical connection module used in an optical communication system using a long-wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 58 is a diagram showing another configuration of an optical communication system using a long-wavelength surface emitting laser diode according to an embodiment of the present invention.

FIG. 59 is another diagram showing another configuration of the optical communication system using the long-wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 60 is a diagram illustrating a configuration of an optical connection module of an optical communication system using a long-wavelength surface emitting laser diode according to an embodiment of the present invention.

FIG. 61 is a diagram showing a configuration of an optical communication system using a long-wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 62 is a view showing the setting of the length of a guide optical fiber in an optical communication system using a long-wavelength surface emitting laser diode according to an embodiment of the present invention.

FIG. 63 is a diagram showing a configuration of an optical communication system using a long wavelength surface emitting laser diode device and a plurality of optical fibers according to an embodiment of the present invention.

FIG. 64 is a view showing an emission angle of a light beam in a long wavelength surface emitting laser diode device according to one embodiment of the present invention.

FIGS. 65A to 65C are diagrams illustrating a process of fixing a plurality of fibers with a resin according to an embodiment of the present invention.

FIGS. 66 (A) to (C) are diagrams showing a connection form between a long wavelength surface emitting laser diode element and a plurality of optical fibers according to one embodiment of the present invention.

FIG. 67 is a diagram showing positions where optical fibers can be arranged in close packing according to an embodiment of the present invention.

FIG. 68 is a diagram showing an example in which a plurality of fibers are arranged by close packing according to an embodiment of the present invention.

FIG. 69 is a cross-sectional view showing a configuration of an optical fiber connected to a long wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 70 is a plan view showing a configuration of an optical communication system using a long-wavelength surface emitting laser diode and an optical fiber to be connected according to an embodiment of the present invention.

FIG. 71 is a plan view showing a configuration of a bidirectional optical communication system using a long wavelength surface emitting laser diode and an optical fiber to be connected according to an embodiment of the present invention.

FIG. 72 is a plan view showing a configuration of an intra-building LAN in which functions of a long-wavelength surface emitting laser diode and an optical fiber to be connected according to an embodiment of the present invention are separated.

73 (A) and 73 (B) are a plan view and a cross-sectional view of an optical waveguide showing a long-wavelength surface emitting laser diode and an integrated optical communication device according to one embodiment of the present invention.

FIGS. 74A and 74B are views showing a configuration of a long-wavelength surface emitting laser diode chip according to one embodiment of the present invention.

75 is a diagram illustrating the operation of the semiconductor laser diode chip shown in FIG. 74.

76 (A) and (B) are diagrams showing a configuration of a long-wavelength surface emitting laser diode chip according to one embodiment of the present invention.

FIG. 77 is a view illustrating the operation of the laser diode chip shown in FIG. 76.

FIG. 78 is a diagram showing an optical transmission unit of a communication system using a long-wavelength surface emitting laser diode device according to one embodiment of the present invention.

FIG. 79 is a diagram showing an optical transmitter of a communication system using a long-wavelength surface emitting laser diode device according to an embodiment of the present invention.

FIG. 80 is a sectional view showing an optical coupling device used in a long wavelength surface emitting laser diode device according to an embodiment of the present invention.

FIG. 81 is a sectional view showing the optical coupling device of FIG. 80;

FIG. 82 is a sectional view showing an optical coupling device for optically coupling with a long wavelength surface emitting laser diode device according to an embodiment of the present invention.

FIG. 83 is a cross-sectional view showing an optical coupling device for optically coupling with a long-wavelength surface emitting laser diode device according to an embodiment of the present invention.

FIG. 84 is a sectional view showing an optical fiber fixing device used in a long wavelength surface emitting laser diode device according to an embodiment of the present invention.

FIG. 85 is a diagram showing a cross-sectional structure of the optical coupling device.

FIG. 86 is a diagram showing a positional relationship between a surface emitting laser diode and a monitoring light receiving element in an optical communication system using a long wavelength surface emitting laser diode element according to an embodiment of the present invention.

FIG. 87 is a block diagram showing a configuration of a control circuit for controlling the output of a surface emitting laser diode according to one embodiment of the present invention.

FIG. 88 is a diagram showing a configuration of an optical communication system using a long-wavelength surface emitting laser diode device according to an embodiment of the present invention.

FIG. 89 is a schematic diagram showing a configuration of an optical communication system using a long-wavelength surface emitting laser diode device according to an embodiment of the present invention.

FIG. 90 is a diagram showing a surface-emitting laser diode, a monitoring light-receiving element, and a reflection surface of an optical communication system using a long-wavelength surface-emitting laser diode element according to an embodiment of the present invention.

FIG. 91 is a diagram showing a configuration of an optical communication system including a long-wavelength surface emitting laser diode, an optical fiber, and an optical connector according to an embodiment of the present invention.

FIG. 92 is a diagram showing a positional relationship among an optical fiber, a ferrule, and a split sleeve according to an embodiment of the present invention.

FIG. 93 is a diagram showing the relationship between the light emission angle and the beam diameter of a long wavelength surface emitting laser diode according to one embodiment of the present invention.

FIG. 94 is a diagram showing the relationship between the beam spread of a long wavelength surface emitting laser diode, the core diameter of an optical fiber, and the optical path length according to one embodiment of the present invention.

FIG. 95 is a diagram showing a calculation example showing the relationship between the beam diameter and the optical path length of a long-wavelength surface emitting laser diode element according to one embodiment of the present invention.

FIG. 96 is a diagram showing a configuration of a laser diode / optical fiber coupling portion of an optical communication system using a long wavelength surface emitting laser diode element according to an embodiment of the present invention.

FIGS. 97A and 97B are diagrams showing a configuration of a coupling portion between a laser diode and an optical waveguide in an optical communication system using a long-wavelength surface emitting laser diode device according to one embodiment of the present invention; FIG.

FIG. 98 is a diagram showing a configuration of a coupling portion between a laser diode and an optical waveguide in an optical communication system using a long-wavelength surface emitting laser diode device according to one embodiment of the present invention.

FIG. 99 is a diagram showing a configuration of an optical communication system in which a long wavelength surface emitting laser diode device and an optical fiber are directly coupled according to an embodiment of the present invention.

FIG. 100 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an optical communication system using the diode element.

FIG. 101 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
It is a block diagram of the optical communication system using the diode element.

FIG. 102 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an optical communication system using the diode element.

FIG. 103 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an optical communication system using the diode element.

FIGS. 104A and 104B are diagrams showing an example in which a long-wavelength surface emitting laser diode element according to an embodiment of the present invention is mounted.

FIG. 105 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an optical communication system using the diode element.

FIG. 106 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a control device used in an optical communication system using the diode element.

FIG. 107 is a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of an optical communication system using the diode element.

FIG. 108 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an optical communication system using the diode element.

FIG. 109 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an optical communication system using the diode element.

FIGS. 110A and 110B are diagrams showing emission angles of a laser diode element according to one embodiment of the present invention.

FIGS. 111A to 111C are diagrams showing an optical fiber bundle according to an embodiment of the present invention.

FIG. 112 is a diagram showing an optical fiber bundle according to one embodiment of the present invention.

FIGS. 113A and 113B are diagrams showing cross sections of a multimode transmission optical fiber according to an embodiment of the present invention.

FIG. 114 is a diagram showing a cross section of an optical fiber for single mode transmission according to one embodiment of the present invention.

FIG. 115 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
It is a figure which shows the current-light output characteristic for every temperature of the diode element.

FIG. 116 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 4 is a diagram for explaining current control of the diode element.

FIG. 117 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 3 is a diagram showing a configuration used for current control of the diode element.

FIG. 118 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
It is a figure which shows the inside of the optical communication apparatus in which the diode element was mounted.

FIG. 119 is a long wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a diode module.

FIG. 120 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a diode element.

FIG. 121 shows a long-wavelength surface emitting laser according to an embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a diode module.

FIG. 122 is a diagram showing an example of a laser chip used in the present invention.

FIG. 123 is a diagram showing another example of the laser chip used in the present invention.

FIG. 124 is a diagram showing an example of the system of the present invention.

FIG. 125 is a diagram showing a configuration of a laser chip for explaining the system of the present invention.

FIG. 126 is a diagram illustrating an example of a control system of the system of the present invention.

FIG. 127 is a diagram showing another example of the control system of the system of the present invention.

FIG. 128 is a diagram for explaining the system of the present invention.

Fig. 129 is another diagram for explaining the system of the present invention.

FIG. 130 shows a long-wavelength surface emitting laser according to one embodiment of the present invention.
It is a figure showing the manufacturing process of the laser array module using the diode element.

FIG. 131 is a diagram detailing a product quality step in the manufacturing process shown in FIG. 130.

[Explanation of symbols]

11, 201 Substrate 12 Lower semiconductor distributed Bragg reflector 13, 17 Non-radiative recombination preventing layer 14, 16 Spacer layer 15 Active layer 15F High resistance region 15R Active region 15a Quantum well active layer 15b Barrier layer 18 Upper semiconductor distributed Bragg reflector 18a low refractive index layer 18b high refractive index layer 18c hetero spike buffer layer 18 ₁ AlAs layer 18 ₂ Al _x O _y current blocking layer 18 ₃ polyimide region 19 contact layer 20 upper electrode 20A light exit aperture 21 lower electrode 31 GaAs substrate 32 Laser diode chip 32A Laser diode element (light emitting unit) 32D Laser diode drive circuit 32B, 34B Cover 32X Marker 33 Optical fiber 34 Photo diode chip (light receiving element) 34A Photo detector 35A, 35B, 35C, 35D, 35E Object 41 Wall 41A Inside wall 42 Room 51 Ceramic substrate 52, 53 Optical waveguide 54, 55 Optical fiber 56, 57 Optical connection module 58 Silicon substrate 61 Laser diode chip holder 61A, 62B Flange surface 62 Optical fiber holder 64, 65 Optical fiber group Holder 71 Module package 71A Connector 71a, 71b Connector joint 72, 73, 95 Optical fiber 72F, 73F Ferrule 81 Communication controller 82 Laser diode drive circuit 91 Jig 96 Resin coating 101, 101A, 101B, 101-A, 101- B
Optical fiber 101C Repeater 101F Optical fiber holding ferrule 101X Colored optical fiber 101a Core 101b Cladding 102A, 101B Optical transceiver 102C Terminal equipment 110 Station-side device 111, 112, 117a, 117b, 117c Optical fiber 111R Optical repeater 115 Network terminator 116 Optical communication system 120 Laser diode chip 121, 122 Upper electrode 123 Lower electrode 125 Optical fiber 125A Core 125B Cladding 131 Mounting substrate 132 Heat dissipation member 133 Metal package 134 Optical fiber 135 Ferrule 136 Ceramic substrate 136A Electrode 137, 138 Thermal conductive layer 141 Laser diode Module 142 Optical fiber 142A Ferrule 142P Light receiving element 142Q Supporting part 43,1436 Adapter housing 1431,1476 Split sleeve 1432,1432A, 1471 Spring 1433,1472 Collar 1435 Connector 144 Bush 145,1475 Housing 146 Base 147 Optical fiber fixing device 1474 Sphere 1475 151 Connector board 151A Connector guide 151R Mirror 161 Laser diode Drive circuit 162 Control circuit 170 Optical communication system 171 Optical connector 172 Split sleeve 180 Optical fiber 181 Core 182 Cladding 191 Hole array 191X Guide 192 Optical fiber 202, 205 Cladding layer 203A, 203B Intermediate layer 204 Active layer 301 Mirror 302 Optical waveguide 302A, 302C clad 302B core 310 mounting substrate 311 package 3 1A guide 312 optical fiber guide 312A guide pin 313 optical fiber 351B laser beam 352 optical fiber 353, 353A, 353B lens 401 submount 402 high frequency transmission line 403 bonding wire 410 optical fiber 411 half mirror 412 light receiving element 413 light receiving processing section 414 communication control Unit 414A Correction table 415 Emission control unit 416 Constant current power supply 420 Optical communication device housing 421 Optical fiber 422 Laser diode module 423A Optical circuit board 423a Electronic components 423B, 423C Electronic circuit board 424 Blower 431 Laser diode module package 431A Cooling fin 541 Electrophotographic copier 542 Paper feed tray 543 Collection tray 546 Photosensitive drum 547 Housing 547a Housing cover 548 Sheet feeding mechanism 554a 550 Electronic circuit 551 Inkjet recording device 554 Housing 554a Upper housing 554b Lower housing 555 Paper feed mechanism 556 Inkjet recording head 556A Carriage 557 Recording unit 558 Platen F1, F2, F12, FG1, FG2, FG3, FR
1, FR2, FR3, fg1 Optical fiber FGA, FGB Transmission system MFG1, MFG2, MFG3 Optical fiber group MG1, MG2, MG3, MG4, MR1, MR2, M
R3, MR4 Optical connection module R Reflector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01S 5/343 610 H04B 9/00 W H04B 10/02 B41J 3/00 D 10/28 (72) Inventor Takeshi Kanai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Akira Sakurai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Inventor Shunichi Sato Tokyo 1-3-6 Nakamagome, Ota-ku, Ricoh Co., Ltd. (72) Inventor Shinji Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor, Naoto Shakuya Naka, Ota-ku, Tokyo 1-3-6, Magome, Ricoh Co., Ltd. (72) Inventor Satoru Satoru Satoru 1-3-6, Nakamagome, Ota-ku, Tokyo Co., Ltd. Ricoh Co., Ltd. 1-3-6 Nakamagome, Ota-ku Ricoh Co., Ltd. (72) Inventor Takashi Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Shuichi Hikichi Nakamagome, Ota-ku, Tokyo 1-3-6, Ricoh Co., Ltd. (72) Inventor Teruyuki Furuta 1-3-6, Nakamagome, Ota-ku, Tokyo Tokyo (72) Inventor Kazuya Miyagaki 1-3-3, Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Co., Ltd. (72) Inventor Atsuyuki Watada 1-3-6 Nakamagome, Ota-ku, Tokyo F-term inside Ricoh Co., Ltd. 2C362 AA03 AA10 AA45 CB77 2H037 AA01 BA02 BA03 BA04 BA05 BA12 BA13 BA14 BA24 CA38 2H038 AA21 CA32 CA62 5F073 AA07 AA22 AA65 AB06 AB17 AB27 AB28 BA02 BA07 CA07 CB02 EA24 FA06 FA22 FA29 GA03 GA12 5K002 BA01 BA13 BA21 FA01

Claims (34)

[Claims] 1. A surface emitting laser diode device chip comprising an active layer and a resonator structure comprising a reflector provided above and below the active layer, wherein the reflector has a reflection wavelength. Comprises a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of 1.1 μm or more and a small refractive index and a second material layer having a large refractive index are periodically repeated, and the first material layer and the second Between the first material layer and the second material layer, a hetero-spike buffer layer having a refractive index between 5 nm or more and a design reflection wavelength of the distributed Bragg reflector at 5 nm or more. λ [μm], (50λ−15) [n
m], a surface emitting laser diode element constituting a light emitting light source, an optical fiber transmission line having one end optically coupled to the light emitting light source, and the light A light receiving unit optically coupled to the other end of the fiber transmission line; and a direction change of the optical fiber transmission line between a place A where the light emitting light source is installed and a place B where the light receiving unit is installed. By bending the optical fiber transmission line itself so that a local angle is not formed. 2. The active layer according to claim 1, wherein the main element is Ga, I
2. The optical transmitting / receiving system according to claim 1, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. 3. The first material layer is made of Al _x Ga _1-x A.
has a composition represented by s (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of _Alz
The optical transceiver system according to claim 1, wherein the optical transceiver system has a composition represented by Ga _1-z As (0 ≦ y <z <x ≦ 1). 4. A surface emitting laser diode element chip comprising an active layer and a resonator structure comprising a reflector provided above and below the active layer, wherein the reflector has a reflection wavelength. Is composed of a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of at least 1.1 μm and a small refractive index and a second material layer having a large refractive index are periodically repeated. Between the first material layer and the second material layer, a hetero-spike buffer layer having a refractive index between 5 nm or more and a design reflection wavelength of the distributed Bragg reflector at 5 nm or more. λ [μm], (50λ−15) [n
m], a surface emitting laser diode element constituting a light emitting light source, an optical fiber transmission line having one end optically coupled to the light emitting light source, and the light A light receiving unit optically coupled to the other end of the fiber transmission line; and a reflecting member between a point A in the building where the light emitting light source is provided and a point B in the building where the light receiving unit is provided. An optical transmission / reception system, wherein the direction of the optical fiber transmission line is changed by the reflection member. 5. The active layer according to claim 1, wherein the main element is Ga, I
The optical transmission / reception system according to claim 4, comprising a layer made of n, N, As or a layer made of Ga, In, As, and emitting light of 1.1 to 1.7 m. Wherein said first material layer is _Al x _{Ga 1-x} A
has a composition represented by s (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of _Alz
The optical transceiver system according to claim 4, wherein the optical transceiver system has a composition represented by Ga _1-z As (0 ≦ y <z <x ≦ 1). 7. An optical transmission / reception system for performing communication inside a device, comprising: a device; a laser light source provided in the device for forming an optical signal; and a laser light source provided in the device for receiving the optical signal. A light receiving unit, and a cover member that covers the light emitting element portion and the light receiving element portion of the laser light source and the light receiving unit, respectively. The laser light source is provided on an active layer and on upper and lower portions of the active layer. A surface emitting laser diode element chip having a resonator structure comprising a reflecting mirror, wherein the reflecting mirror has a reflection wavelength of 1.1 μm or more and a small refractive index.
And a second material layer having a large refractive index and a semiconductor distributed Bragg reflector periodically repeated.
Between the first material layer and the second material layer, a hetero-spike buffer layer having a refractive index between the first material layer and the second material layer having a refractive index of 5 nm or more. Assuming that the design reflection wavelength of the reflecting mirror is λ [μm], (50λ−1
5) An optical transmission / reception system having a configuration provided with a thickness of [nm] or less and comprising a surface-emitting laser diode element constituting a light-emitting light source. 8. The active layer has a main element of Ga, I
The optical transmission / reception system according to claim 7, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 m. Wherein said first material layer is _Al x _{Ga 1-x} A
has a composition represented by s (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of _Alz
The optical transceiver system according to claim 7, wherein the optical transceiver system has a composition represented by Ga _1-z As (0 ≦ y <z <x ≦ 1). 10. The optical transmission / reception system according to claim 7, wherein the device is a recording device using an electrophotographic principle. 11. A laser element, a first optical fiber coupled to the laser element and receiving a laser beam formed by the laser element, and a first optical fiber coupled to the first optical fiber A second optical fiber for transmitting an optical signal in the fiber, a third optical fiber coupled to the second optical fiber, for receiving light in the second optical fiber, and a third optical fiber And an optical communication system comprising: a light receiving element for receiving light in the third optical fiber; wherein the laser element comprises: an active layer; and reflecting mirrors provided above and below the active layer. A surface emitting laser diode element chip having a resonator structure, wherein the reflecting mirror has a first material layer having a reflection wavelength of 1.1 μm or more and a small refractive index and a second material layer having a large refractive index. Layers are repeated periodically Semiconductor distributed consists Bragg reflector, wherein between the first material layer and the second material layer, wherein a refractive index first
The hetero-spike buffer layer having a value between the first material layer and the second material layer has a design reflection wavelength of λ [μm] of 5 nm or more and the distributed Bragg reflector (50λ−15).
An optical transmission / reception system having a configuration provided with a thickness of [nm] or less and comprising a surface emitting laser diode element constituting a light emitting light source. 12. The active layer, wherein the main element is Ga, I
12. The optical transmitting and receiving system according to claim 11, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. Wherein said first material layer is _Al x _{Ga 1-x}
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
13. The optical transceiver system according to claim 11, wherein the optical transceiver system has a composition represented by _z Ga _1-z As (0 ≦ y <z <x ≦ 1). 14. A laser element, a first optical fiber coupled to the laser element, for receiving a laser beam formed by the laser element, and a first optical fiber coupled to the first optical fiber. A second optical fiber for transmitting an optical signal in the fiber, a third optical fiber coupled to the second optical fiber, for receiving light in the second optical fiber, and a third optical fiber And an optical communication system comprising: a light receiving element for receiving light in the third optical fiber; wherein the laser element comprises: an active layer; and reflecting mirrors provided above and below the active layer. A surface emitting laser diode element chip having a resonator structure, wherein the reflecting mirror has a first material layer having a reflection wavelength of 1.1 μm or more and a small refractive index and a second material layer having a large refractive index. Layers are repeated periodically Semiconductor distributed consists Bragg reflector, wherein between the first material layer and the second material layer, wherein a refractive index first
The hetero-spike buffer layer having a value between the first material layer and the second material layer has a design reflection wavelength of λ [μm] of 5 nm or more and the distributed Bragg reflector (50λ−15).
An optical communication system, having a configuration provided with a thickness of [nm] or less, wherein the first optical fiber has a length of 1 mm or more. 15. The active layer, wherein the main element is Ga, I
The optical communication system according to claim 14, comprising a layer made of n, N, and As or a layer made of Ga, In, and As, and generating light of 1.1 to 1.7 m. 16. The first material layer is _Al x _{Ga 1-x}
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
The optical communication system according to claim 14, wherein the optical communication system has a composition represented by _z Ga _1−z As (0 ≦ y <z <x ≦ 1). 17. An optical communication system comprising: a laser device; and an optical transmission line coupled to the laser device.
In the system, the laser element includes: an active layer; and reflection layers provided on upper and lower portions of the active layer.
Surface-emitting laser diode having a resonator structure consisting of a mirror
A reflection element having a reflection wavelength of 1.1.
The first material layer having a small refractive index at μm or more and a large refractive index
Semiconductor distribution brachter which periodically repeats a second material layer
The first material layer and the second material
Between the first material layer and the second material layer.
A hetero-spike buffer layer having a value between
above λ, the design reflection wavelength of the distributed Bragg reflector is λ
[Μm] and a thickness of (50λ−15) [nm] or less
Wherein the optical transmission line comprises an optical fiber comprising a core and a clad.
When the diameter of the core is D and the length of the optical fiber is L,
Relationship 10⁵≦ L / D ≦ 10⁹  An optical communication system characterized by the following. 18. The active layer, wherein the main element is Ga, I
18. The optical communication system according to claim 17, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. 19. The first material layer is _Al x _{Ga 1-x}
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
_19. The optical communication system according to claim 17, wherein the optical communication system has a composition represented by _z Ga _1-z As (0 ≦ y <z <x ≦ 1). 20. An optical communication system comprising: a laser element; a mounting board on which the laser element is mounted; and an optical waveguide coupled to the laser element, wherein the laser element has an active layer, an active layer, A surface emitting laser diode having a resonator structure comprising upper and lower reflecting mirrors;
A reflection element having a reflection wavelength of 1.1.
a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of at least μm and having a small refractive index and a second material layer having a large refractive index are periodically repeated, wherein the first material layer and the second material layer are formed. Between the first material layer and the second material layer.
A hetero-spike buffer layer having a value between
above λ, the design reflection wavelength of the distributed Bragg reflector is λ
[Μm], a thickness of not more than (50λ−15) [nm], comprising a surface-emitting laser diode element constituting an emission light source, wherein the laser element and the substrate material Wherein the difference in the coefficient of linear expansion between the two is within 2 × 10 ⁻⁶ / K. 21. The active layer, wherein the main element is Ga, I
21. The optical communication system according to claim 20, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. 22. The first material layer is made of Al _x Ga _1-x
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
_z Ga _1-z As optical communication system according to claim 20 or 21, wherein it has a composition represented by (0 ≦ y <z <x ≦ 1). 23. An optical communication system comprising a laser element and an optical fiber coupled to the laser element, wherein the laser element comprises: an active layer; and reflectors provided above and below the active layer. Surface emitting laser diode having resonator structure
A reflection element having a reflection wavelength of 1.1.
a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of at least μm and having a small refractive index and a second material layer having a large refractive index are periodically repeated, wherein the first material layer and the second material layer are formed. Between the first material layer and the second material layer.
A hetero-spike buffer layer having a value between
above λ, the design reflection wavelength of the distributed Bragg reflector is λ
[Μm] and a thickness of (50λ−15) [nm] or less, comprising a surface-emitting laser diode element constituting a light-emitting light source, wherein the optical fiber is the laser element. An optical communication system characterized in that the fiber axis direction is pressed in the direction of the light-emitting section and mechanically connected. 24. The active layer, wherein the main element is Ga, I
24. The optical communication system according to claim 23, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. 25. The first material layer is _Al x _{Ga 1-x}
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
The optical communication system according to claim 23, wherein the optical communication system has a composition represented by _z Ga _1-z As (0 ≦ y <z <x ≦ 1). 26. An optical communication system comprising: a laser device; and an optical fiber or an optical waveguide optically coupled to the laser device, wherein the laser device includes: an active layer; and an upper portion and a lower portion of the active layer. Surface emitting laser diode having a resonator structure comprising a provided reflecting mirror
A reflection element having a reflection wavelength of 1.1.
a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of at least μm and having a small refractive index and a second material layer having a large refractive index are periodically repeated, wherein the first material layer and the second material layer are formed. Between the first material layer and the second material layer.
A hetero-spike buffer layer having a value between
above λ, the design reflection wavelength of the distributed Bragg reflector is λ
[Μm], a thickness of (50λ−15) [nm] or less, comprising a surface-emitting laser diode element constituting a light-emitting light source, and a core of the optical fiber or the optical waveguide. Assuming that the diameter is X, the opening diameter of the laser diode is d, and the light emission angle of the laser diode is θ, the optical path length l from the laser diode to the optical fiber or the end of the optical waveguide has a relation d + 2ltan. An optical communication system, wherein (θ / 2) ≦ X is satisfied. 27. The active layer, wherein the main element is Ga, I
27. The optical communication system according to claim 26, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. 28. The first material layer is made of Al _x Ga _1-x
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
_z Ga _1-z As optical communication system of claim 26 or 27, wherein the having the composition represented by (0 ≦ y <z <x ≦ 1). 29. An optical communication system comprising a laser element and an optical waveguide coupled to the laser element, wherein the laser element comprises an active layer, and reflectors provided above and below the active layer. Surface emitting laser diode having resonator structure
A reflection element having a reflection wavelength of 1.1.
a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of at least μm and having a small refractive index and a second material layer having a large refractive index are periodically repeated, wherein the first material layer and the second material layer are formed. Between the first material layer and the second material layer.
A hetero-spike buffer layer having a value between
above λ, the design reflection wavelength of the distributed Bragg reflector is λ
[Μm], a surface light-emitting laser diode having a thickness of not more than (50λ-15) [nm], and comprising a surface-emitting laser diode element constituting a light-emitting light source; An optical communication system characterized by the relationship 0.5 ≦ F / d ≦ 2, where d is the diameter of a circle inscribed in the light emitting portion of the element and F is the core diameter of the optical fiber. 30. The active layer, wherein the main element is Ga, I
30. The optical communication system according to claim 29, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. 31. The first material layer is made of Al _x Ga _1-x
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
_z Ga _1-z As optical communication system of claim 29 or 30, wherein the having the composition represented by (0 ≦ y <z <x ≦ 1). 32. An optical communication system comprising a laser element and an optical waveguide coupled to the laser chip, wherein the laser element comprises: an active layer; and reflectors provided above and below the active layer. Surface emitting laser diode having resonator structure
A reflection element having a reflection wavelength of 1.1.
a semiconductor distributed Bragg reflector in which a first material layer having a refractive index of at least μm and having a small refractive index and a second material layer having a large refractive index are periodically repeated, wherein the first material layer and the second material layer are formed. Between the first material layer and the second material layer.
A hetero-spike buffer layer having a value between
above λ, the design reflection wavelength of the distributed Bragg reflector is λ
[Μm], a surface emitting laser diode element having a thickness of (50λ−15) [nm] or less, comprising a surface emitting laser diode element constituting a light emitting light source; An optical communication system, wherein V / S is in a range of 15,000 to 30,000, where S (mm ² ) is an area of a light emitting portion of an element chip, and V (V) is a laser element operating voltage. 33. The active layer, wherein the main element is Ga, I
33. The optical communication system according to claim 32, comprising a layer made of n, N, As or a layer made of Ga, In, As, and generating light of 1.1 to 1.7 [mu] m. 34. The first material layer is made of Al _x Ga _1-x
Has a composition represented by As (0 <x ≦ 1) , the second material layer has a composition represented by _{Al y Ga 1-y As (} 0 ≦ y <x ≦ 1), wherein The heterospike buffer layer is made of Al
The optical communication system according to claim 32, wherein the optical communication system has a composition represented by _z Ga _1−z As (0 ≦ y <z <x ≦ 1).