JP2002261400A - Laser, laser apparatus, and optical communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize the interaction of laser elements for providing a light source having high output, and to provide a laser for achieving long distance transmission at high speed, a laser apparatus, and an optical communication system. SOLUTION: A laser chip is set to a surface-emitting-type laser element chip. In the surface-emitting-type laser element chip, oscillation wavelength is set to 1.1 to 1.7 μm, and resonator structure is provided. The resonator structure includes a reflector provided at upper and lower sections of an active layer for emitting light. The reflector is set to a semiconductor distribution Bragg reflector. In the semiconductor distribution Bragg reflector, a refractive index in a composing material layer periodically changes from small to large, and incident light is reflected by light wave interference. In this case, in an emitting light source, the laser element is arranged to be at specific density, and an optical coupling means for propagating light emitted from at least one laser element to at least another element is provided. Also, at least one of the reflectors for sandwiching the active layer is provided as a common reflector to a plurality of light-emitting devices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser used for optical communication and the like and an optical communication system therefor, and more particularly to a so-called surface which emits light in a direction perpendicular to the surface of a semiconductor substrate used for manufacturing the semiconductor laser. The present invention relates to an optical communication system in which a plurality of laser elements are formed using a light emitting laser to enable high-speed and large-capacity communication, and a high-output light source such as a measurement laser light source device that requires a high output.

[0002]

2. Description of the Related Art A surface emitting semiconductor laser emits laser light in a vertical direction from the surface of a substrate, so that two-dimensional parallel integration is possible, and the spread angle of the output light is relatively narrow (about 10 degrees). Therefore, it is easy to couple with an optical fiber and easy to inspect the element.
Therefore, in particular, development as an element suitable for configuring an optical transmission module (optical interconnection device) of a parallel transmission type has been actively conducted. The immediate application of the optical interconnection device is parallel connection between housings of computers and the like and between boards, as well as short-distance optical fiber communication, but large-scale computer networks and long distances are expected applications in the future. There is a trunk system for distance and large-capacity communication.

Generally, a surface emitting semiconductor laser is made of GaAs.
Or, it is common to comprise an active layer made of GaInAs, and an optical resonator consisting of an upper semiconductor distributed Bragg reflector disposed above and below the active layer and a lower semiconductor distributed Bragg reflector on the substrate side. However, since the length of the optical resonator is significantly shorter than that of the edge emitting semiconductor laser, it is necessary to set the reflectivity of the reflecting mirror to an extremely high value (99% or more) so as to easily cause laser oscillation. There is. For this reason, 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 with a period of 1/4 wavelength is usually used.

By the way, as described above, a long wavelength band laser having a laser wavelength of 1.1 μm or more used for optical communication, for example, a long wavelength band having a laser wavelength of 1.3 μm or 1.55 μm. In the laser, InP is used for the production substrate and InGaAsP is used for the active layer. However, the lattice constant of InP of the substrate is large, and a large difference in the refractive index cannot be obtained with a reflecting mirror material that matches the substrate. Must be more than pairs. Another problem with the semiconductor laser formed on the InP substrate is that the characteristics greatly change with temperature. For this reason, it is necessary to add a device for keeping the temperature constant, and it is difficult to use the device for general purposes such as consumer use. Light emitting semiconductors have not yet been put to practical use.

As an invention made to solve such a problem, one disclosed in Japanese Patent Application Laid-Open No. 9-237942 is known. According to this, a GaAs substrate is used as a production substrate, and a semiconductor layer made of AlInP that can be lattice-matched with the substrate is used as a low refractive index layer of at least one of the semiconductor distributed Bragg reflectors in the lower part on the substrate side. A semiconductor layer made of GaInNAs is used as a high refractive index layer of at least one of the lower and upper semiconductor distributed Bragg reflecting mirrors so that a larger refractive index difference is obtained than in the prior art. It is to realize a mirror.

Further, GaInNAs is used as a material for the active layer. This is because the band gap (forbidden band width) is increased from 1.4 eV to 0 eV by increasing the N composition.
0.85 μm
This is because it can be used as a material that emits a longer wavelength. In addition, since lattice matching with the GaAs substrate is possible, the semiconductor layer made of GaInNAs is 1.3 μm.
Reference is also made to the fact that it is preferable as a material for long-wavelength surface emitting semiconductor lasers in the m-band and 1.55 μm band.

[0007] However, conventionally, this only suggests the possibility of realizing a surface emitting semiconductor laser in a wavelength band longer than 0.85 µm, and such a device is not actually realized. This is because the basic configuration is almost theoretically determined, but a more specific configuration for realizing 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. Or a device using a semiconductor layer made of AlInP, which is lattice-matched to the same substrate as the low refractive index layer of the semiconductor distributed Bragg reflector, as disclosed in JP-A-9-237942. The laser element does not emit light at all,
Alternatively, even if light is emitted, the light emission efficiency is low, which is far from a practical level. This is because the material containing Al is chemically very active, and crystal defects due to Al are likely to occur. In order to solve this problem, it is necessary to use a GaInNP containing no Al as disclosed in Japanese Patent Application Laid-Open Nos. 8-340146 and 7-307525.
There is a proposal for forming a semiconductor distributed Bragg reflector from GaAs and GaAs. However, the refractive index difference between GaInNP and GaAs is about half of the refractive index difference between AlAs and GaAs, and the number of stacked reflectors is very large, making it difficult to manufacture.

That is, at present, optical fiber communication is expected in a computer network or the like. However, a long wavelength band surface emitting semiconductor laser having a laser wavelength of 1.1 μm to 1.7 μm and a communication system using the same can be used. It does not exist and its appearance is longing for.

Further, in a conventional high-output laser in which stripe-type edge-emitting lasers are arranged one-dimensionally or two-dimensionally, heat cannot be integrated at a high density due to laser oscillation. They are discrete and have problems in use as a single light source.

[0011]

According to the present invention, a laser oscillation wavelength used for such optical communication or the like is 1.1 μm or more.
1. Field of the Invention The present invention relates to a long-wavelength surface emitting semiconductor laser having a wavelength of 1.7 μm and an optical communication system using the same. A long-wavelength surface-emitting type semiconductor laser device chip is used as a light-emitting light source, and a high-output light source is provided by utilizing the interaction of individual laser devices.
An object of the present invention is to propose a laser device capable of high-speed long-distance transmission.

A second object is to use a long-wavelength surface emitting semiconductor laser device chip having a laser oscillation wavelength of 1.1 μm to 1.7 μm, which can be used stably, as a light emitting light source and to interact with individual laser devices. An object of the present invention is to provide a laser device that provides a high-output light source by using the laser beam and enables high-speed long-distance transmission.

A third object is that the laser oscillation wavelength at which the operating voltage, oscillation threshold current and the like can be reduced is 1.1 μm to 1.
An optical communication system that uses a 7 μm long-wavelength surface emitting semiconductor laser device chip as a light source, provides a high-output light source by utilizing the interaction of individual laser devices, and enables high-speed long-distance transmission. It is to propose.

A fourth object is to use a long-wavelength surface emitting semiconductor laser device chip whose laser oscillation wavelength is 1.1 μm to 1.7 μm, which can be used stably, as a light emitting light source, and the interaction of individual laser devices. It is an object of the present invention to provide an optical communication system that provides a high-output light source by utilizing the technology and enables high-speed long-distance transmission.

A fifth object of the present invention is to propose a method of synchronizing the phase of laser light in such an optical communication system and optical device light source by utilizing the interaction of individual laser elements.

A sixth object is to propose a method of synchronizing the phase of laser light in such an optical communication system and light source for optical equipment by utilizing the interaction of individual laser elements. .

A seventh object of the present invention is to propose a laser light source which enables stable laser output by aligning the polarization directions of individual laser lights in such a light source for an optical communication system and optical equipment. It is in. An eighth object of the present invention is to provide a laser having a wide interval between elements and excellent stability by realizing individual laser elements in such an optical communication system and a light source for an optical device by coupling means using a diffraction grating. Is to do

A ninth object is a method of integrating additional functions such as a beam deflection function and a modulation function by controlling the phase of each laser beam in such an optical communication system and light source for an optical device. It is to propose.

[0019]

In order to achieve the above object, the present invention firstly provides a laser device comprising a laser chip and the laser chip, wherein the laser chip has an oscillation wavelength of 1.1 μm to 1 μm. 0.7 μm, and the light-generating active layer is a layer whose main element is Ga, In, N, As or a layer consisting of Ga, In, As. What is claimed is: 1. A surface-emitting type semiconductor laser device chip having a resonator structure including a reflecting mirror provided at a lower portion, wherein the reflecting mirror periodically changes the refractive index of a material layer constituting the reflecting mirror to be small / large and is incident. A semiconductor distributed Bragg reflector for reflecting light by light wave interference, and the material layer having a small refractive index is made of Al _x Ga _{1 -x} As.
(0 <x ≦ 1) and then, the material layer of the refractive index is large is Al _y
A reflecting mirror having Ga _1-y As (0 ≦ y <x ≦ 1),
And a material layer Al _z Ga _{1 -z} As (0 ≦ y <z) in which the refractive index takes a value between small and large between the material layers with small and large refractive indexes.
<X ≦ 1) is a laser device using a surface-emitting type semiconductor laser device chip provided as a light-emitting source, wherein the light-emitting light source has the laser elements arranged at a predetermined density, Optical coupling means capable of transmitting light emitted from the element to at least one or more other laser elements is provided.

Secondly, in a laser device having a laser chip and the laser chip arranged therein, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and the active layer for generating light includes a main element. Is a layer made of Ga, In, N, As or a layer made of Ga, In, As,
What is claimed is: 1. A surface-emitting type semiconductor laser device chip having a resonator structure including a reflector provided above and below said active layer to obtain a laser beam, wherein said reflector has a refractive index of a material constituting the same. Is a semiconductor distributed Bragg reflector that periodically changes to small / large and reflects incident light by light wave interference, and the material having a small refractive index is Al _x Ga _{1 -x} As.
(0 <x ≦ 1), and the material having a large refractive index is Al _y G
a _1-y As (0 ≦ y <x ≦ 1) reflecting mirror, wherein GaInP or GaI is provided between the active layer and the reflecting mirror;
A laser device using a surface emitting semiconductor laser element chip provided with a non-emitting recombination preventing layer made of nPAs as an emission light source, wherein the emission light source includes the laser elements arranged at a predetermined density, Optical coupling means capable of transmitting light emitted from one laser element to at least one or more other laser elements is provided.

Thirdly, in a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and the active layer for generating light includes a main element. Is Ga, In, N, A
s or a layer made of Ga, In, and As, and a surface-emitting type semiconductor laser device chip having a resonator structure including reflectors provided above and below the active layer to obtain a laser beam Wherein the reflector is a semiconductor distributed Bragg reflector in which the refractive index of a material layer constituting the reflector is periodically changed to small / large and reflects incident light by light wave interference, and the refractive index is small. The material layer is Al _x G
a _1-x As (0 <x ≦ 1), and the material layer having a large refractive index is a reflecting mirror made of Al _y Ga _1-y As (0 ≦ y <x ≦ 1), and the refractive index is Is a material layer Al _z Ga _{1 -z} As (0) in which the refractive index takes a value between the small and the large material layers.
≦ y <z <x ≦ 1), wherein the surface-emitting type semiconductor laser device chip provided with the light emitting source is an optical communication system,
The light emitting light source includes the laser elements arranged at a predetermined density, and has an optical coupling unit capable of transmitting light emitted from at least one laser element to at least one other laser element. I made it.

Fourthly, in a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and an active layer for generating light includes a main element. Is Ga, In, N, As
Or a layer made of Ga, In, As, and a surface emitting semiconductor laser device chip having a resonator structure including reflectors provided above and below the active layer in order to obtain a laser beam. The reflector is a semiconductor distributed Bragg reflector in which the refractive index of the material constituting the reflector changes periodically as small / large and reflects incident light by light wave interference. Al _x Ga _1-x
As (0 <x ≦ 1), the material having a large refractive index is Al
a reflecting mirror with _y Ga _1-y As (0 ≦ y <x ≦ 1),
GaInP or Ga between the active layer and the reflector.
An optical communication system in which a surface-emitting type semiconductor laser device chip provided with a non-light-emitting recombination prevention layer made of InPAs is used as a light-emitting source, wherein the light-emitting light source includes the laser devices arranged at a predetermined density, Optical coupling means capable of transmitting light emitted from at least one laser element to at least one other laser element is provided.

Fifth, in the laser device or the optical communication system according to any one of the first to fourth aspects, the light emitting light source may be configured such that at least one of the reflecting mirrors provided with an active layer interposed therebetween has a plurality of light emitting mirrors. It was provided as a common reflecting mirror for the element.

Sixth, in the laser device or the optical communication system according to any one of the first to fourth aspects, the light emitting light source is common to a plurality of light emitting elements, apart from a reflecting mirror provided with an active layer interposed therebetween. Is provided.

Further, seventhly, in the laser device or the optical communication system according to any one of the first to sixth aspects, the light emitting light source includes a polarization control means for oscillating light of each of the laser elements in a predetermined direction. It was provided.

Eighth, in the laser device or the optical communication system according to any one of the first to seventh aspects, the light-emitting light source performs coupling between the laser elements by means having a diffraction function.

Ninth, in the laser device or the optical communication system according to any one of the first to eighth aspects, a member whose refractive index can be controlled from outside is installed in a part of the optical path of the light emitting element. .

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a long-wavelength surface emitting semiconductor laser having a small laser oscillation wavelength of 1.1 to 1.7 .mu.m, which is a light emitting element applied to the optical communication system of the present invention, having a small transmission loss. This will be described with reference to FIG.

As described above, a long-wavelength surface emitting semiconductor laser with a laser oscillation wavelength of 1.1 μm to 1.7 μm to which the present invention is intended to be applied is realized only with the suggestion of the possibility. The materials for the use, as well as the more specific and detailed composition, were unknown. In the present invention, a material such as GaInNAs is used for the active layer, and a more specific configuration is clarified. The details are described below.

In the present invention, n-Ga having a plane orientation of (100) is used.
On the As substrate, n-Al _x Ga _{1 -x} A with a thickness (thickness of λ / 4) of 発 振 of the oscillation wavelength λ in each medium.
s (x = 1.0) (low refractive index layer to low refractive index layer) and n−
An n-semiconductor distributed Bragg reflector (AlAs / GaAs lower semiconductor distributed Bragg reflector) in which 35 cycles of Al _y Ga _1-y As (y = 0) (high refractive index layer to high refractive index layer) are alternately stacked. And n-Ga _x In _1-x P _{y having} a thickness of λ / 4 is formed thereon.
As _1-y (x = 0.5, y = 1) layers were laminated. In this example _{n-Ga x In 1-x} P y As 1-y (x = 0.5, y =
1) The layer is also a part of the lower reflecting mirror and is a low refractive index layer (a layer having a small refractive index).

An undoped lower GaAs spacer layer, an active layer (quantum well active layer), which is a three-layer Ga _x In _{1 -x} As quantum well layer, and a GaAs barrier layer (20 n
m) and an undoped upper G layer
The aAs spacer layer is laminated to form a resonator having a thickness of one oscillation wavelength λ (thickness of λ) in the medium.

Further, on top of this, C (carbon) doped p-
Ga _x In _{1-x Py} As _1-y (x = 0.5, y = 1) layer and Z
A periodic structure (one cycle) in which n-doped p-Al _x Ga _1-x As (x = 0) is alternately stacked with a thickness of １ ／ times the oscillation wavelength λ in each medium is stacked. C-doped p-Al _x Ga _{1 -x} As (x = 0.9) and Zn-doped p
A semiconductor distributed Bragg reflector (a periodic structure (25 periods) in which -Al _x Ga _{1 -x} As (x = 0) is alternately stacked with a thickness of １ ／ times the oscillation wavelength λ in each medium; Al _0.9 Ga _0.1 As / GaAs upper semiconductor distributed Bragg reflector)
Is formed. In this example _{p-Ga x In 1-x} P y As
_{The 1-y} (x = 0.5, y = 1) layer is also a part of the upper reflecting mirror and is a low refractive index layer (a layer having a small refractive index).

Here, both the upper and lower reflecting mirrors are formed by alternately laminating a low refractive index layer (a layer having a small refractive index) / a high refractive index layer (a layer having a large refractive index). Between these, the material layer Al _z G whose refractive index takes a value between small and large
a _1-z As (0 ≦ y <z <x ≦ 1) is provided. FIG.
Is a material layer AlzGa1-zAs (0 ≦ y) whose refractive index takes a value between small and large between a low refractive index layer (a layer with a small refractive index) and a high refractive index layer (a layer with a large refractive index). FIG. 1 shows a part of a semiconductor distributed Bragg reflector provided with <z <x ≦ 1) (in FIG. 1, illustration is omitted because the figure becomes complicated).

Conventionally, it has been studied to provide such a material layer for a semiconductor laser having a laser wavelength of 0.85 μm band, but it is still in the study stage, and the material and its thickness are not described in detail. Not considered. Further, the laser oscillation wavelength as in the present invention is 1.1 μm to 1.7 μm.
No consideration has been given to a long-wavelength surface emitting semiconductor laser having a wavelength of m. The reason for this is that this field (a long-wavelength surface emitting semiconductor laser having a laser oscillation wavelength of 1.1 μm to 1.7 μm) is a new field, and little research has yet been made.

The present inventor has quickly noticed the usefulness of this field (a long-wavelength surface emitting semiconductor laser having a laser oscillation wavelength of 1.1 μm to 1.7 μm and optical communication using the same).
In order to realize it, we studied diligently.

In such a material layer, the refractive index of the material layer is changed continuously or stepwise by controlling the gas flow rate at the time of formation and changing the Al composition continuously or stepwise. And formed.

More specifically, Al _z Ga _{1 -z} As (0 ≦
(y <z <x ≦ 1) The layer is formed so that the value of z of the layer changes from 0 to 1.0, that is, the ratio of Al to Ga gradually changes, such as GaAs to AlGaAs to AlAs. This is created by controlling the gas flow during layer formation as described above. Al and G
The ratio a may be formed so as to change continuously as described above, or the same effect can be obtained even if the ratio changes stepwise.

The reason for providing such a material layer is to solve the problem that the electrical resistance of the p-semiconductor distributed Bragg reflector, which is one of the problems of the distributed Bragg reflector, is high. This is due to the hetero barrier generated at the interface between the two types of semiconductor layers constituting the semiconductor distributed Bragg reflector. However, as in the present invention, the interface between the low refractive index layer and the high refractive index layer is changed from one composition to the other. It is possible to suppress the generation of the hetero barrier by changing the Al composition gradually to the composition and changing the refractive index.

The material layer AlzGa1-zAs having such a refractive index between a small value and a large value (0 ≦ y <z <x ≦
1) The laser oscillation wavelength as in the present invention is 1.1 μm or more.
In the case of a long-wavelength surface emitting semiconductor laser of 1.7 μm, 5n
The thickness is preferably from m to 50 nm. If the thickness is smaller than this, there is a problem that the resistance becomes large and current does not easily flow, and the element generates heat and the driving energy becomes high. If the thickness is large, the resistance becomes small, which is advantageous in terms of heat generation of the element and driving energy. However, there is a problem that the reflectance cannot be obtained, and the optimum range (thickness of 5 nm to 50 nm) as described above. You need to choose

As described above, it has been considered to provide such a material layer with respect to a conventional semiconductor laser having a laser wavelength of 0.85 μm band. In the case of a long-wavelength surface emitting semiconductor laser having a wavelength of 1.7 μm, it is more effective. This is because, for example, in order to obtain the same reflectance (for example, 99.5% or more), the band from 1.1 μm to 1.0 μm is more than 0.85 μm.
In the case of the 7 μm band, such a material layer can be approximately doubled, so that the resistance value of the semiconductor distributed Bragg reflector can be reduced, the operating voltage, the oscillation threshold current, and the like are reduced, and the laser device This is advantageous in terms of preventing heat generation, stable oscillation, and low energy driving.

In other words, providing such a material layer on a semiconductor distributed Bragg reflector is particularly effective for a long-wavelength surface emitting semiconductor laser having a laser oscillation wavelength of 1.1 μm to 1.7 μm as in the present invention. It can be said that it is a device.

As an example of a more detailed examination result for obtaining an effective reflectance, for example, in a 1.3 μm band surface emitting laser device, Al _x Ga _{1 -x} As (x = 1.0)
(Low refractive index layer to low refractive index layer) and Al _y Ga _1-y As (y
= 0) (in the case of a high refractive index layer-refractive index large layer) 20 period stacking, the reflectance 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 wavelength band in which the reflectance is 99.5% or more is 53 nm. When the reflectance is designed to be 99.5% or more, it is only necessary to control the film thickness by ± 2%. Therefore, when prototypes of 10 nm, 20 nm, and 30 nm which are equivalent to and thinner than this were prototyped, the reflectivity could be kept to a practically acceptable level, and the resistance value of the semiconductor distributed Bragg reflector could be reduced. A 1.3 μm band surface emitting laser device was realized, and laser oscillation was successful. Other configurations of the prototyped laser element 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 can be completely controlled). It is referred to as a high-reflectance band (including a region where the reflectivity is equal to or more than a required value for a target wavelength). This is the region where the reflectance at the design wavelength is the highest and decreases very little as the wavelength increases. It drops off sharply from some area. Originally, it is necessary to completely control the film thickness of the multilayer mirror at the atomic layer level so that the reflectance is higher than the required reflectance for the target wavelength. But actually ± 1
Since a film thickness error of about% occurs, the target wavelength deviates from the wavelength having the highest reflectance. For example, if the target wavelength is 1.3
In the case of μm, when 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 band of the high reflectance (here, the region where the reflectance is equal to or more than a required value with respect to a target wavelength) is wide. However, thickening the intermediate layer tends to narrow this band.

As described above, in the long-wavelength surface emitting semiconductor laser having a laser oscillation wavelength of 1.1 μm to 1.7 μm as in the present invention, the configuration of such a semiconductor distributed Bragg reflector is devised and optimized. Since the resistance value can be reduced while maintaining a high reflectance, the operating voltage, the oscillation threshold current, and the like can be reduced, so that heat generation of the laser element, stable oscillation, and low-energy driving can be achieved.

Returning again to FIG. 1, the uppermost p-Al _x G
The a _1-x As (x = 0) layer also has a role as a contact layer (p-contact layer) for making contact with the electrode.

Here, the In composition x of the quantum well active layer is 3
9% (Ga0.61In0.39As). The thickness of the quantum well active layer was 7 nm. The quantum well active layer is made of GaAs.
It had a compression strain of about 2.8% with respect to the substrate.

The whole surface-emitting type semiconductor laser was grown by MOCVD. In this case, no lattice relaxation was observed. The materials constituting each layer of the semiconductor laser include TMA (trimethylaluminum), TMG (trimethylgallium), TMI (trimethylindium),
AsH ₃ (arsine) and PH ₃ (phosphine) were used. H ₂ was used as a carrier gas. In the case where the strain is large as in the active layer (quantum well active layer) of the device shown in FIG. here,
The GaInAs layer (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 this example, a portion outside the current path was irradiated with protons (H ⁺ ) to form an insulating layer (high resistance portion), thereby forming a current narrowing portion.

In this example, a p-side electrode is formed on the p-contact layer, which is the uppermost layer of the upper reflecting mirror and is a part of the upper reflecting mirror, except for the light emitting portion, and is formed on the back surface of the substrate. An n-side electrode was formed.

In this embodiment, the active region (in this embodiment, a resonator composed of the upper and lower spacer layers and the multiple quantum well active layer) sandwiched between the upper and lower reflectors and into which carriers are injected and recombined is used. In the material containing Al (II
The ratio of the low refractive index layer of the lower and upper reflecting mirrors closest to the active layer is G.
It is set to _{a x In 1-x P y} As 1-y (0 <x <1,0 <y ≦ 1) non-radiative recombination preventing layer. Since the carriers are confined between the low-refractive index layers of the upper and lower reflecting mirrors which are closest to the active layer and have a wide gap, only the active region is constituted by a layer containing no Al (the percentage of group III is 1% or less). However, if the low-refractive index layer (wide gap layer) of the reflector in contact with the active region has a structure including Al, when carriers are injected and recombined, non-radiative recombination occurs at this interface, and the luminous efficiency is reduced. Will drop. Therefore, it is desirable that the active region be formed of a layer containing no Al.

The Ga _x In _{1-x Py} As _1-y (0 <x
The non-radiative recombination preventing layer composed of <1, 0 <y ≦ 1)
Its lattice constant is smaller than that of a GaAs substrate and has tensile strain.

In the epitaxial growth, since the growth is performed by reflecting the information of the base, if there is a defect on the surface of the substrate, it goes up to the growth layer. However, it is known that the presence of a strained layer is effective in preventing such defects from climbing.

When the defect reaches the active layer, the luminous efficiency is reduced. In the case of an active layer having a strain, there arises a problem that the critical thickness is reduced and a layer having a required thickness cannot be grown. In particular, when the amount of compressive strain of the active layer is large, for example, 2% or more, or when the thickness of the strained layer is larger than the critical thickness, even if non-equilibrium growth such as low-temperature growth is performed, growth cannot be performed due to the presence of defects. This is particularly problematic. If a strained layer is present, such a defect can be prevented 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 reduced to a critical film. It becomes possible to grow thicker than thick.

This Ga _x In _{1-x Py} As _1-y (0 <x <
1,0 <y ≦ 1) layer also has the role of carrier confinement in which the active region in contact with the active region but, Ga _x an In
_{The 1-x Py} As _1-y (0 <x <1, 0 <y ≦ 1) layer can have a larger band gap energy as the lattice constant decreases. For example, in the case of Ga _x In _1-x P (when y = 1), as x increases and approaches x GaP, the lattice constant increases and the band gap increases. Band gap E
g is a direct transition, Eg (Γ) = 1.351 + 0.643x + 0.786
x ² , and Eg (X) = 2.24 + 0.02x in the indirect transition. Therefore, the active region and Ga _x In _{1-x Py} As _1-y (0
<X <1, 0 <y ≦ 1) The hetero barrier in the layer is large, so that the carrier confinement is good, the threshold current is reduced,
This has the effect of improving temperature characteristics.

Further, the Ga _x In _{1-x Py} As _1-y (0 <
x <1, 0 <y ≦ 1) The non-radiative recombination preventing layer has a larger lattice constant than the GaAs substrate, has a compressive strain, and has a lattice constant of the active layer of Ga _x.
It has a larger compressive strain than the In _{1-x Py} As _1-y (0 <x <1, 0 <y ≦ 1) layer.

The Ga _x In _{1-x Py} As _1-y (0 <x
<1, 0 <y ≦ 1) Since the direction of strain of the layer is the same as that of the active layer, it acts in the direction of reducing the substantial amount of compressive strain felt by the active layer. The larger the strain is, the more easily affected by external factors. Therefore, it is particularly effective when the amount of compressive strain of the active layer is as large as 2% or more, or when it exceeds the critical film thickness.

For example, a surface emitting laser having an oscillation wavelength of 1.3 μm band is preferably formed on a GaAs substrate, and a semiconductor multilayer mirror is often used as a resonator, and the total thickness is 5 to 8 μm. It is necessary to grow 50 to 80 semiconductor layers before growing the active layer. (On the other hand, in the case of an edge-emitting laser, the total thickness before growing the active layer is about 2 μm, and it is only necessary to grow about three semiconductor layers.) In this case, even if a high-quality GaAs substrate is used, various methods are used. Due to the cause (defects once generated basically creep up in the crystal growth direction and defects are generated at the hetero interface).
The defect density on the surface immediately before the active layer growth is inevitably higher than the defect density on the s substrate surface. If the insertion of a strained layer or the substantial amount of compressive strain felt by the active layer is reduced before the growth of the active layer, the influence of defects on the surface immediately before the growth of the active layer can be reduced.

In this example, since Al is not contained in the active region and at the interface between the reflector and the active region, non-radiative recombination caused by crystal defects caused by Al during carrier injection is eliminated. And non-radiative recombination was reduced.

As described above, it is preferable to apply a structure that does not contain Al at the interface between the reflector and the active region, that is, to provide a non-radiative recombination prevention layer for both the upper and lower reflectors. It is effective even when applied to a reflector. In this example, both the upper and lower reflecting mirrors are semiconductor distributed Bragg reflecting mirrors, but one reflecting mirror may be a semiconductor distributed Bragg reflecting mirror and the other reflecting mirror may be a dielectric reflecting mirror. In the above-described example, only the layer closest to the active layer in the low-refractive index layer of the reflector is Ga _x In _{1-x Py} As _1-y (0 <x <1,
Although a non-radiative recombination prevention layer of 0 <y ≦ 1) is used, a plurality of layers of Ga _x In _{1-x Py} As _1-y (0 <x <1, 0 <y ≦
1) may be a non-radiative recombination preventing layer.

Further, in this example, this idea is applied to the lower reflector between the GaAs substrate and the active layer, and the crystal defect caused by Al, which is a problem during the growth of the active layer, rises into the active layer. The adverse effect is suppressed, and the active layer can be crystal-grown with high quality. As a result, a surface-emitting type semiconductor laser having high luminous efficiency and sufficient reliability for practical use was obtained. In addition, not all of the low refractive index layers of the semiconductor distributed Bragg reflector but at least a portion closest to the active region is Ga _x In _{1 -x Py} As _{1 -y} (0 <x <
Since only 1, 0 <y ≦ 1) layers, the above-described effect can be obtained without particularly increasing the number of stacked reflectors.

The oscillation wavelength of the surface emitting semiconductor laser manufactured as described above was about 1.2 μm. GaInAs on a GaAs substrate has a longer wavelength due to an increase in the In composition, but with an increase in the amount of strain. Conventionally, up to 1.1 μm has been considered to be the limit of a longer wavelength (see the document “IEEE Photo”).
onics. Technol. Lett. Vol. 9
(1997) p. 1319-1321 ").

However, as produced by the present inventors, a high strain GaInAs quantum well active layer can be grown coherently thicker than before by a growth method with a high degree of non-equilibrium, such as growth at a low temperature of 600 ° C. or less. Reached 1.2 μm. This wavelength is transparent to the Si semiconductor substrate. Therefore, light transmission through the Si substrate becomes possible in a circuit chip in which an electronic element and an optical element are integrated on the Si substrate.

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

As described above, such a surface emitting semiconductor laser can be grown by MOCVD, but other growth methods such as MBE can also be used.
In addition, a triple quantum well structure (TQ
Although the example of W) is shown, a structure (SQW, MQW) using a quantum well of another number of wells or the like can be used.

The structure of the laser may be another structure. Although the length of the resonator 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, as the active layer, a layer whose main element is Ga, In, and As, that is, Ga _x In _{1 -x}
Although an example of As (GaInAs active layer) has been described, in order to perform laser oscillation of a longer wavelength, a layer (GaInNAs active layer) in which N is added and the main element is Ga, In, N, and As is used. Good.

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 studying the composition, a longer wavelength, for example, 1.7
A surface emitting laser in the μm band is also possible.

Further, when GaAsSb is used for the active layer,
A 1.3 μm band surface emitting laser can be realized on an aAs substrate. As described above, a semiconductor laser having a wavelength of 1.1 μm to 1.7 μm has not conventionally been available with a suitable material.
By using aInAs, GaInNAs, and GaAsSb, and providing a non-radiative recombination preventing layer, a high-performance surface emitting laser in a long wavelength region of the 1.1 μm to 1.7 μm band where stable oscillation has been difficult in the past. Can be realized.

Next, another configuration of a long wavelength band surface emitting semiconductor laser which is a light emitting element applied to the optical transmitting / receiving system of the present invention will be described with reference to FIG.

In this case as well, as in the case of FIG.
00) is used. N-Al _x Ga _{1 -x} As (x = 0.9) and n-A at a thickness of 1/4 (λ / 4 thickness) of the oscillation wavelength λ in each medium.
n in which l _x Ga _1-x As (x = 0) are alternately stacked for 35 periods
Forming a semiconductor distributed Bragg reflector (Al _0.9 Ga _0.1 As / GaAs lower reflector) on which a λ / 4 thick n-Ga _{x
In 1-x P y As 1} -y (x = 0.5, y = 1) was laminated layer. In this example _{n-Ga x In 1-x} P y As 1-y (x = 0.
5, y = 1) layer is also a part of the lower reflecting mirror and is a low refractive index layer.

On top of that, undoped lower GaAs
A multi-quantum well active layer (a quantum well active layer) composed of a spacer layer, an active layer (quantum well active layer) which is a three-layer Ga _x In _1-x N _y As _1-y quantum well layer, and a GaAs barrier layer (15 nm). In the example, triple quantum well (TQW)) and undoped upper Ga
An As spacer layer is laminated to form a resonator having a thickness (λ thickness) of one oscillation wavelength in the medium.

Further, a p-semiconductor distributed Bragg
A reflecting mirror (upper reflecting mirror) is formed. Top reflector
Is a method in which an AlAs layer to be a selectively oxidized layer is formed as a GaInP layer.
Low refractive index layer having a thickness of 3λ / 4 sandwiched between AlGaAs layers
(C-doped p-Ga having a thickness of (λ / 4-15 nm)_xI
n_1-xP_yAs_1-y(X = 0.5, y = 1) layer, C-doped
p-Al _zGa_1-zAs (z = 1) selective oxidation layer (thickness 3
0 nm) and a C-doped p having a thickness of (2λ / 4-15 nm)
-Al_xGa_1-xAs layer (x = 0.9)) and the thickness is λ /
4 GaAs layer (one period) and C-doped p-Al_xG
a_1-xAs layer (x = 0.9) and p-Al_xGa_1-xAs
The (x = 0) layer has an oscillation wavelength of 1 in each medium.
With a periodic structure (22 periods) alternately stacked with a thickness of / 4 times
Consisting of a semiconductor distributed Bragg reflector (Al_0.9G
a_0.1As / GaAs upper reflector).

Also in this example, although not shown in FIG. 3 because it becomes complicated in FIG. 3, the structure of the semiconductor distributed Bragg reflector has a low refractive index layer (low refractive index layer) as shown in FIG. Layer) and a high refractive index layer (high refractive index layer), a material layer Al _z Ga _1-z having a refractive index between low and high
As (0 ≦ y <z <x ≦ 1) is provided.

The uppermost p-Al _x Ga _{1 -x} As
The (x = 0) layer also serves as a contact layer (p-contact layer) for making contact with the electrode.

Here, the In composition x of the quantum well active layer is 37
%, And the N (nitrogen) composition was 0.5%. The thickness of the quantum well active layer was 7 nm.

The surface-emitting type semiconductor laser was grown by MOCVD. The materials constituting each layer of the semiconductor laser include TMA (trimethylaluminum), TM
G (trimethyl gallium), TMI (trimethyl indium), AsH ₃ (arsine), PH ₃ (phosphine), and DMHy (dimethylhydrazine) were used as raw materials for nitrogen. DMHy decomposes at low temperature, so 600
It is suitable for low-temperature growth at a temperature of less than or equal to ° C., 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.

In this example, the GaInNAs layer (quantum well active layer) was grown at 540 ° C. The MOCVD method has a high degree of supersaturation and is suitable for crystal growth of a material containing N and another V group simultaneously. 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.

[0078] Further in this example, the predetermined size mesa portion of the _{p-Ga x In 1-x} P y As 1-y (x = 0.5, y =
Until reaching 1) _{layer, p-Al z Ga 1-} z As (z = 1)
The selective oxidation layer is formed by exposing the side surface, and the Al _x Ga _{1 -z} As (z = 1) layer on the side surface is oxidized from the side surface with water vapor to form an Al _x O _y current narrowing layer. .

Finally, the portion removed by mesa etching with polyimide (insulating film) is buried and flattened, the polyimide on the upper reflector is removed, and a p-side electrode is formed on the p-contact layer except for the light emitting portion. And n on the back surface of the GaAs substrate.
Side electrodes were formed.

In this example, the lower part of the selectively oxidized layer
Ga as part of the top reflector_xIn_{1 -x}P_yAs_1-y(0 <
x <1, 0 <y ≦ 1) layers are inserted. For example
In the case of etching, a sulfuric acid-based etchant is used.
For example, the GaInPAs system is an etch to the AlGaAs system.
Ga can be used as a stopping layer._xIn
_1-xP_yAs_1-y(0 <x <1, 0 <y ≦ 1) layer inserted
The high mesa etching for selective oxidation.
Can be strictly controlled. Therefore, uniformity and reproducibility are improved.
Cost can be reduced.

When the surface-emitting type semiconductor laser (element) of this example is integrated one-dimensionally or two-dimensionally, the controllability at the time of manufacturing the element is improved, and the uniformity of the element characteristics of each element in the array is improved. In addition, there is an effect that reproducibility becomes extremely good.

In this example, Ga _x In _{1-x Py} As _1-y (0 <x <1, 0 <y ≦
1) Although the layer is provided on the upper reflecting mirror side, it may be provided on the lower reflecting mirror side.

Also in this example, in the active region (in this embodiment, a resonator composed of the upper and lower spacer layers and the multiple quantum well active layer) sandwiched between the upper and lower reflectors and into which carriers are injected and recombined, No material containing Al is used in the active region, and the lower refractive index layers of the lower and upper mirrors, which are closest to the active layer, are formed of Ga _x In _{1-x Py} As _1-y (0
<X <1, 0 <y ≦ 1). That is, in this example, Al is not included in the active region and at the interface between the reflecting mirror and the active region, so that non-radiative recombination caused by crystal defects caused by Al during carrier injection is reduced. Can be done.

It is preferable to apply a configuration in which Al is not contained at the interface between the reflecting mirror and the active region to the upper and lower reflecting mirrors as in this example, but it is effective to apply it to only one of the reflecting mirrors. . In this example, both the upper and lower reflecting mirrors are semiconductor distributed Bragg reflecting mirrors, but one reflecting mirror may be a semiconductor distributed Bragg reflecting mirror and the other reflecting mirror may be a dielectric reflecting mirror.

Further, also in this example, the same idea as in the example of FIG. 1 was applied to the lower reflector between the GaAs substrate and the active layer, so that crystal defects caused by Al which became a problem during the growth of the active layer. Of the active layer is suppressed, and crystal growth of the active layer with high quality can be achieved.

Incidentally, such a non-radiative recombination preventing layer is
1 and 3, a part of the semiconductor distributed Bragg reflector is formed, and its thickness is 、 of the oscillation wavelength λ in the medium (thickness of λ / 4). ). Alternatively, a plurality of layers may be provided.

As is clear from the above description, a surface-emitting type semiconductor laser having high luminous efficiency and sufficient reliability for practical use was obtained with such a configuration. Also, not all of the low refractive index layers of the semiconductor distributed Bragg reflector, but at least the portion closest to the active region is Ga _x In containing no Al.
_{1-x Py} As _1-y (0 <x <1, 0 <y ≦ 1) is used only as a non-radiative recombination prevention layer, so that the above-described effect can be obtained without particularly increasing the number of stacked reflectors. I was able to.

In addition, even in such a configuration, since the polyimide can be easily embedded, the wiring (p-side electrode in this example) is hardly disconnected, and a device having high reliability can be obtained.

The oscillation wavelength of the surface emitting semiconductor laser manufactured as described above was about 1.3 μm.

In this example, the main elements are Ga, In,
A layer composed of N and As was used as an active layer (GaInNAs
As a result, a long-wavelength surface emitting semiconductor laser could be formed on the GaAs substrate. Further, the current was narrowed by selective oxidation of the selectively oxidized layer containing Al and As as main components, so that the threshold current was low.

According to the current narrowing structure using the current narrowing layer made of the Al oxide film obtained by selectively oxidizing the selectively oxidized layer,
By forming the current narrowing layer close to the active layer, the spread of current can be suppressed, and carriers can be efficiently confined in a minute region that is not exposed to the atmosphere. Further oxidized to Al
By forming an oxide film, the refractive index is reduced, and light can be efficiently confined in a minute region in which carriers are confined by the effect of the convex lens, and the efficiency is extremely improved, and the threshold current can be reduced. In addition, since the current narrowing structure can be easily formed, the manufacturing cost can be reduced.

As is clear from the above description, a 1.3 μm band surface emitting semiconductor laser can be realized in the configuration as shown in FIG. 3, as in FIG. Is obtained.

The surface emitting semiconductor laser shown in FIG.
The growth can be performed by the MOCVD method as in the case of the above, but another growth method such as the MBE method can also be used.
Although DMHy is used as a nitrogen source, activated nitrogen and other nitrogen compounds such as NH ₃ can be used.

Further, an example of a triple quantum well structure (TQW) has been shown as the laminated structure of the active layer, but a structure using other quantum wells (SQW, DQW, MQW) or the like can also be used. The structure of the laser may be another structure.

In the surface-emitting type semiconductor laser shown in FIG. 3, by changing the composition of the GaInNAs active layer, 1.
A surface emitting semiconductor laser in the 55 μm band, and even in the longer wavelength 1.7 μm band, is also possible. The GaInNAs active layer may contain other III-V elements such as Tl, Sb, and P. Also, even if GaAsSb is used for the active layer, a 1.3 μm band surface emitting semiconductor laser can be realized on a GaAs substrate.

When GaInAs is used for the active layer,
Conventionally, up to 1.1 μm has been considered to be the limit of increasing the wavelength.
The quantum well active layer can be grown thicker than before, and the wavelength can reach up to 1.2 μm. in this way,
Conventionally, there is no suitable material for the semiconductor laser having a wavelength of 1.1 μm to 1.7 μm, but GaInAs, G
By using aInNAs and GaAsSb and providing a non-radiative recombination prevention layer, a high-performance surface-emitting laser can be realized in the long wavelength region of the 1.1 μm to 1.7 μm wavelength band where stable oscillation has conventionally been difficult. As a result, application to optical communication systems has become possible.

FIG. 4 shows an example in which such a long wavelength band surface emitting semiconductor laser device is formed as a large number of chips on an n-GaAs wafer having a (100) plane orientation, and a laser device chip. In the laser element chip shown here, 1 to n laser elements are formed, and the number n and the arrangement method are determined according to the application.

FIG. 5 shows an example of a high-output light source using a long-wavelength band surface emitting semiconductor laser. In the drawing, a mark ▲ indicates a laser light emitting direction. Here, one laser element is configured such that a part of the emitted light is optically coupled to another laser element, so that the phase of each emitted laser light is synchronized,
By a not-shown optical system at the subsequent stage, it is possible to convert into various beams like a single laser beam. For example, in the case of light having the same phase, the light can be focused on a minute spot and can be coupled with an optical fiber. FIG. 6 shows a specific structure. In the present embodiment, one of the semiconductor multilayer film reflecting mirrors provided with the active layer interposed therebetween (the substrate side in the present embodiment)
Are formed on the surface of the element substrate at a predetermined distance from the active layer, and are commonly formed for each element, and a common electrode is further provided thereon. Assuming that current is injected into each element to cause laser oscillation, the light that makes multiple reflections in each resonator and reciprocates in each active layer forms a small spot in the active layer due to its diffraction effect, and the reflecting mirror It has a beam shape that spreads out in the vicinity. A part of the light reflected by the reflecting mirror provided on the substrate between the elements placed in a predetermined vicinity enters another adjacent laser element due to a diffraction effect. At this time, if the common reflecting mirror and the active layer are provided at a desired distance so that the incident light satisfies a phase condition in which the laser element can oscillate, the laser element is injection-locked and the laser element is Laser oscillation synchronized with the above. As a result, a plurality of laser beams having the same phase or a predetermined phase shift can be obtained.

FIG. 7 shows another embodiment. In this embodiment, a common reflecting mirror for optically coupling the plurality of lasers is provided separately from the pair of reflecting mirrors forming the resonator. At this time, in order to strengthen the optical coupling of each other,
The reflectivity of the substrate-side multilayer mirror is set to be smaller than the reflectivity when oscillating in a normal single body. This allows
In addition to stabilizing individual laser oscillations, injection locking is enabled.

FIG. 8 shows another embodiment. In this embodiment, in order to align the polarization directions of the oscillating light of each laser element,
For example, in FIG. 8, the shape of the laser element is formed such that the cross-sectional shape parallel to each crystal layer becomes elliptical. This allows
Oscillation with polarized light having a polarization component parallel to the long axis direction of the ellipse is facilitated, and the elements are formed so that the long axes of each element are parallel, so that the polarization direction is aligned and stable and stable injection locking Has been realized.

As shown in FIG. 9, by integrating a deflecting element such as a diffraction grating on the coupling reflecting surface, it is possible to increase the distance between the laser elements. As a result, it becomes possible to largely deflect the propagating light beyond the reflection angle due to the regular reflection shown in the above-described embodiment, it is possible to increase the element spacing, and to reduce the thermal influence of each element. This improves the stability and reliability of the device.

FIGS. 10 and 11 show another embodiment. In this embodiment, as shown in FIG. 10, a spatial modulation element is provided at the laser emission end, and the phase of each emitted laser beam is phase-modulated by the spatial modulation element to generate a beam group having a desired phase relationship. For example, as shown in FIG. 11, a liquid crystal element in which predetermined regions (hereinafter, referred to as dots) can be independently driven is used for the spatial light modulator. Each dot is set so as to be on the optical path of the emission beam of the corresponding laser element. When a voltage is applied to each dot, the filled liquid crystal molecules are aligned along the electric field. At this time, the alignment angle of the liquid crystal molecules changes according to the applied voltage, and the equivalent refractive index for the laser beam that passes equivalently changes. As a result, each beam undergoes phase modulation by the applied voltage. If the voltage applied to each dot of the spatial light modulator is controlled so that each phase changes little by little, the combined output light will be deflected in a predetermined direction, and the output light deflection function will be added to the present laser light source. It becomes possible.

[0103]

(Effect corresponding to Claim 1) The laser oscillation wavelength at which optical fiber communication is expected, such as a computer network or a trunk system for long-distance large-capacity communication, is 1.1.
In the field of the μm band to the 1.7 μm band, there has been no surface emitting semiconductor laser capable of lowering the operating voltage, the oscillation threshold current and the like, generating less heat from the laser element and performing stable oscillation, and a communication system using the same. However, by devising a semiconductor distributed Bragg reflector as in the present invention, the operating voltage, oscillation threshold current, and the like can be reduced, the laser element generates less heat, and stable oscillation can be achieved. A laser device that can be used for the system was realized.

Furthermore, a laser device that can be used to enable high-speed long-distance transmission by realizing a high-output light source by utilizing the interaction of individual laser elements and providing an unprecedented high-output plateau. Was realized.

(Effects Corresponding to Claim 2) The laser oscillation wavelength at which optical fiber communication is expected to be 1.1 μm, such as a computer network or a trunk system for long-distance large-capacity communication, is 1.1 μm.
In the field of m band to 1.7 μm band, there is no long wavelength band surface emitting semiconductor laser that can be used stably and a communication system using the same. By using the provided surface emitting semiconductor laser element chip, stable oscillation can be achieved, and a laser device which can be used in a practical optical communication system using this as a light source can be realized.

Further, a high-power light source is realized by utilizing the interaction of individual laser elements, and an unprecedented high-power plateau is provided, so that it can be used in an optical communication system capable of high-speed long-distance transmission. Laser device that can be realized.

(Effect Corresponding to Claim 3) The laser oscillation wavelength at which optical fiber communication is expected to be 1.1 μm such as a computer network, a trunk system for long-distance large-capacity communication, etc.
In the field of the m band to 1.7 μm band, there has been no surface emitting semiconductor laser capable of lowering the operating voltage, the oscillation threshold current and the like, generating less heat of the laser element and performing stable oscillation, and a communication system using the same. However, by devising a semiconductor distributed Bragg reflector as in the present invention, the operating voltage, oscillation threshold current, and the like can be reduced, the laser element generates less heat, and stable oscillation can be achieved. The system has been realized.

Further, an optical communication system capable of high-speed and long-distance transmission is realized by realizing a high-output light source by utilizing the interaction between individual laser elements and providing an unprecedented high-output plateau. did it.

(Effect Corresponding to Claim 4) The laser oscillation wavelength at which optical fiber communication is expected to be 1.1 μm, such as a computer network or a trunk system for long-distance large-capacity communication, is 1.1 μm.
In the field of m band to 1.7 μm band, there is no long wavelength band surface emitting semiconductor laser that can be used stably and a communication system using the same. By using the surface emitting semiconductor laser device chip thus provided, stable oscillation became possible, and a practical optical communication system using this as a light emitting light source was realized.

Furthermore, an optical communication system capable of high-speed and long-distance transmission is realized by providing a high-output light source utilizing the interaction of individual laser elements and providing an unprecedented high-output plateau. did it.

(Effect Corresponding to Claim 5) A method for synchronizing the phase of laser light by utilizing the interaction of individual laser elements was realized, and a high-power laser device and an optical communication system were realized.

(Effect Corresponding to Claim 6) A method of synchronizing the phase of laser light by utilizing the interaction of individual laser elements was realized, and a high-power laser device and an optical communication system were realized.

(Effect Corresponding to Claim 7) By aligning the polarization directions of the individual laser beams, a laser device and an optical communication system capable of achieving stable laser output can be realized.

(Effects Corresponding to Claim 8) By realizing coupling of individual laser elements by a diffraction grating, a laser device and an optical communication system having excellent stability by widening the element intervals can be realized.

(Effect Corresponding to Claim 9) A laser device and an optical communication system can be realized by integrating additional functions such as beam deflection by controlling the phase of each laser beam.

[Brief description of the drawings]

FIG. 1 is a sectional view of an element part of a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 2 is a diagram showing a partial cross section of a configuration of a semiconductor distributed Bragg reflector of a long wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of an element portion according to another configuration of the long wavelength band surface emitting semiconductor laser according to one embodiment of the present invention.

FIG. 4 is a plan view showing a wafer substrate and a laser element chip on which a long wavelength band surface emitting semiconductor laser element according to one embodiment of the present invention is formed.

FIG. 5 is a perspective view of a laser light source using a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 6 is an element cross-sectional view of a laser light source using a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 7 is an element cross-sectional view of a laser light source using a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 8 is a perspective view of a laser light source using a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 9 is a cross-sectional view of an element of a laser light source using a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 10 is a perspective view of a laser light source using a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 11 is a sectional view of an element of a laser light source using a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Kanai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kazuya Miyagaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Atsuyuki Watada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Shuichi Hikichi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Shunichi Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Yukie Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Invention Satoru Sugawara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Takuro Sekiya 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company In Ricoh (72) Inventor Shinji Sato 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Company (reference) 5F073 AA09 AA11 AA51 AA65 AA74 AB03 AB17 BA02 BA09 CA07 CA17 CB02 DA05 EA24

Claims (9)

[Claims] 1. A laser device comprising a laser chip and a laser chip having the laser chip arranged therein, wherein the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and has an active layer for generating light, wherein the main element is Ga, A layer composed of In, N, and As;
Alternatively, a surface emitting semiconductor laser device chip having a resonator structure including a reflecting mirror provided on an upper portion and a lower portion of the active layer in order to obtain a laser beam as a layer made of Ga, In, and As, The reflecting mirror is a semiconductor distributed Bragg reflecting mirror in which the refractive index of a material layer constituting the reflecting mirror periodically changes between small and large and reflects incident light by light wave interference, and the material layer having a small refractive index is Al _x Ga _1-x As (0 <
x ≦ 1), and the material layer having a large refractive index is Al _y Ga _1-y
A reflecting mirror having As (0 ≦ y <x ≦ 1), and a material layer Al _z Ga _{1 in which the} refractive index takes a value between small and large between the material layers having small and large refractive indexes. _-z As (0 ≦ y <z <x ≦
1) A laser device using a surface-emitting type semiconductor laser element chip provided with 1) as a light-emitting light source, wherein the light-emitting light source has a configuration in which the laser elements are arranged at a predetermined density. A laser device comprising: an optical coupling unit capable of transmitting outgoing light to at least one or more other laser elements. 2. A laser device comprising a laser chip and the laser chip, wherein the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and has an active layer for generating light, wherein the main element is Ga, A layer composed of In, N, and As;
Alternatively, a surface emitting semiconductor laser device chip having a resonator structure including a reflecting mirror provided on an upper portion and a lower portion of the active layer in order to obtain a laser beam as a layer made of Ga, In, and As, The reflecting mirror is a semiconductor distributed Bragg reflecting mirror in which the refractive index of a material constituting the reflecting mirror periodically changes between small and large and reflects incident light by light wave interference, and the material having a small refractive index is Al _x Ga _{1. -x} As (0 <x
≦ 1), and the material having a large refractive index is Al _y Ga _1-y As.
(0 ≦ y <x ≦ 1), and emits light from a surface-emitting type semiconductor laser device chip having a non-radiative recombination prevention layer made of GaInP or GaInPAs between the active layer and the reflector. A laser device as a light source, wherein the light emitting light source includes the laser elements arranged at a predetermined density, and light emitted from at least one laser element is transmitted to at least one or more other laser elements. A laser device comprising optical coupling means capable of propagating. 3. In a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and has an active layer for generating light, wherein the main element is Ga, A surface emitting type having a layer structure of In, N, and As or a layer of Ga, In, and As and having a resonator structure including reflectors provided above and below the active layer to obtain a laser beam. A semiconductor laser element chip, wherein the reflecting mirror is a semiconductor distributed Bragg reflecting mirror that periodically changes a refractive index of a material layer constituting the reflecting mirror to small / large and reflects incident light by light wave interference; The material layer having a small ratio is Al _x Ga _{1 -x} As.
(0 <x ≦ 1) and then, the material layer of the refractive index is large is Al _y
A reflecting mirror having Ga _1-y As (0 ≦ y <x ≦ 1),
And a material layer Al _z Ga _{1 -z} As (0 ≦ y <z) in which the refractive index takes a value between small and large between the material layers with small and large refractive indexes.
<X ≦ 1) is an optical communication system using a surface-emitting type semiconductor laser device chip provided with a light-emitting light source, wherein the light-emitting light source includes the laser elements arranged at a predetermined density;
An optical communication system comprising an optical coupling unit capable of transmitting light emitted from at least one laser element to at least one other laser element. 4. In a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and has an active layer for generating light, wherein the main element is Ga, A surface emitting type having a layer structure of In, N, and As or a layer of Ga, In, and As and having a resonator structure including reflectors provided above and below the active layer to obtain a laser beam. A semiconductor laser device chip, wherein the reflecting mirror is a semiconductor distributed Bragg reflecting mirror that periodically changes the refractive index of a material forming the reflecting mirror to small / large and reflects incident light by light wave interference; Is smaller than Al _x Ga _{1 -x} As (0 <
x ≦ 1), and the material having a large refractive index is Al _y Ga _1-y A
s (0 ≦ y <x ≦ 1), wherein GaInP or GaInPAs is provided between the active layer and the reflector.
An optical communication system using a surface-emitting type semiconductor laser device chip provided with a non-light-emitting recombination prevention layer comprising a light-emitting light source, wherein the light-emitting light source includes the laser elements arranged at a predetermined density, at least. An optical communication system, comprising: an optical coupling unit capable of transmitting light emitted from one laser element to at least one other laser element. 5. The light source according to claim 1, wherein at least one of the reflecting mirrors provided with an active layer interposed therebetween is provided as a common reflecting mirror for a plurality of light emitting elements. Item 5. The laser, the laser device, or the optical communication system according to any one of Items 1 to 4. 6. The light emitting source according to claim 1, wherein a common reflecting mirror is provided for a plurality of light emitting elements, separately from a reflecting mirror provided with an active layer interposed therebetween. The laser, laser device, or optical communication system according to claim 1. 7. The light-emitting light source according to claim 1, wherein the light-emitting light source is provided with polarization control means for causing the polarization of oscillation light of each of the laser elements to be in a predetermined direction. A laser, a laser device, or an optical communication system according to item 1. 8. The laser, laser device, or optical communication device according to claim 1, wherein the light emitting light source performs coupling between the laser elements by means having a diffraction function. system. 9. The laser or laser device according to claim 1, wherein the light emitting light source is provided with a member whose refractive index can be controlled from the outside in a part of an optical path of the light emitting element. Or an optical communication system.