JP2002252417A - Surface light-emitting type semiconductor laser device chip and optical communications system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light-emitting type semiconductor laser device chip that can reduce an operating voltage and an oscillation threshold current, be effectively used without reducing light-emitting efficiency, and prevent the opening portion of an insulating film layer from being deformed by heat produced at a light-emitting part. SOLUTION: A laser chip is a semiconductor distributed Bragg reflector that has an oscillation wavelength of 1.1 μm to 1.7 μm, contains elements selected from either a group composed of Ga, In, N and As or a group composed of Ga, In and As, has a resonator structure including a reflector provided on top and bottom parts of an active layer, wherein material layers constituting the reflector have refractive indexes changing periodically between a small value and a large value. The material layer having a small refractive index contains Alx Ga1-x As (0<;x<=1) and the material layer having a large refractive index contains Aly Ga1-y As (0<=y<;x<=1), a material layer having a refractive index that is between both the refractive indexes and contains Alz Ga1-z As (0<=y<;z<;x<<=1) is formed between both the material layers, an insulating film layer having an opening part is formed opposite to a light-emitting device part on the light-emitting surface side of the chip, and the opening part is larger than the light-emitting region of the light-emitting device part.

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 large-capacity communication.

[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 computer networks and the like. However, there is no long-wavelength band surface emitting semiconductor laser with a usable laser wavelength of 1.1 μm to 1.7 μm and a communication system using the same. , Its emergence is longing.

A surface-emitting type semiconductor laser device is generally incorporated into an optical communication system in a form in which a surface-emitting type semiconductor laser is integrated. Such an integrated module, that is, a module, has a chip having a surface-emitting type semiconductor laser device formed on a substrate surface, and a connector for inserting an optical fiber into a hole. The surface emitting semiconductor laser with an optical fiber for connecting the connector and the chip substrate with the center of the laser element correctly positioned is integrated. Recently, a laser array in which a plurality of surface emitting semiconductor laser elements are arranged in an array and a fiber array is integrated has been manufactured. In a surface-emitting type semiconductor laser module, it is important that the optical coupling between the laser array and the fiber array be coupled with high efficiency, and that the laser light emitted from the laser element be efficiently incident on the optical fiber. Is required to be positioned with high accuracy. Therefore, various positioning methods have been proposed in order to position the surface-emitting type semiconductor laser array and the fiber array with high accuracy. For example, a means for determining a position on a chip of a surface-emitting type semiconductor laser, for example, a method of forming a pin, and positioning a connector for inserting an optical fiber into a hole by forming a hole corresponding to the pin. There is.

In order to improve the reliability and environmental friendliness of the device, a method of forming an insulating film on a surface-emitting type semiconductor laser array chip as a protective layer has been devised.

[0011]

However, in the above-described conventional alignment method between the laser array and the fiber array, it is necessary to manufacture the connector, the pin, and the hole corresponding to the pin with high accuracy, and the manufacturing cost is high. There was a bulging problem. In addition, there is a problem that it is impossible to eliminate a manufacturing error and a mounting error of each component, and it is difficult to perform accurate positioning. Therefore, in the present invention, the diameter of the light emitting hole formed in the insulating film on the surface emitting semiconductor laser element gradually increases from the substrate direction toward the insulating film, and the diameter of the insulating film surface is optically connected. It is formed so as to be larger than the outer diameter of the optical fiber, the outer peripheral edge of the optical fiber contacts the side wall of the hole, and the optical fiber and the surface-emitting type semiconductor laser device are aligned and optically connected. Things.

Further, when an insulating film layer is provided on the light emitting surface side of the surface emitting type semiconductor laser element chip, even if an opening portion is opened corresponding to the light emitting element portion, even a small edge portion of the opening portion is formed in the light emitting element portion. Such (covering) causes a loss in the amount of light emission. For this reason, the present invention does not cover this. That is, the opening is formed so as to be larger than the light emitting region of the light emitting element portion, so that the loss of the light emission amount does not occur. Another point to consider is the problem of deformation of the opening of the insulating film layer due to heat generated by the light emitting element portion. According to the present invention, as a result of trial production with various sizes of the opening, if the opening is larger than the light emitting region of the light emitting element by 10% or more, the heat generated by the light emitting element causes the opening of the insulating film to be opened. It was found that defects such as deformation of the end were eliminated. That is, in the present invention, an insulating film layer having an opening is formed on the light emitting surface side of the surface emitting semiconductor laser element chip in correspondence with the light emitting region of the light emitting element portion. By being formed so as to be 10% or more larger than the light emitting region of the element portion, loss of light emission amount does not occur at all, and deformation of the opening of the insulating film layer due to heat generated in the light emitting element portion is prevented. It was made.

The present invention relates to a long-wavelength surface-emitting type semiconductor laser device chip having a laser oscillation wavelength of 1.1 μm to 1.7 μm used for such optical communication and the like. , The oscillation threshold current can be reduced, and it can be used effectively without lowering the luminous efficiency.
It is still another object of the present invention to provide a surface-emitting type semiconductor laser device chip capable of eliminating deformation of an opening of an insulating film layer due to heat generated in a light-emitting device portion.

The second object is that the laser oscillation wavelength is 1.
The present invention relates to a long-wavelength surface-emitting type semiconductor laser device chip having a wavelength of 1 μm to 1.7 μm, which can reduce an operating voltage, an oscillation threshold current, and the like, can be used effectively without lowering luminous efficiency, and is generated in a light emitting element portion. It is an object of the present invention to provide a surface-emitting type semiconductor laser device chip capable of eliminating deformation of an opening of an insulating film layer due to heat generated.

A third object of the present invention is to use a surface emitting semiconductor laser device chip capable of lowering an operating voltage, an oscillation threshold current and the like as a light emitting light source to facilitate alignment of an optical fiber with the surface emitting semiconductor laser device. It is an object of the present invention to propose an optical communication system capable of performing the following.

A fourth object of the present invention is to use a long-wavelength surface emitting semiconductor laser device chip having a stable laser oscillation wavelength of 1.1 μm to 1.7 μm as a light source.
It is an object of the present invention to propose an optical communication system capable of facilitating alignment between an optical fiber and the surface-emitting type semiconductor laser device.

Still another object of the present invention is to provide a method for preventing the tip of an optical fiber from directly contacting the surface-emitting type semiconductor laser device to break the device in such an optical communication system. .

[0018]

According to the present invention, there is provided a surface emitting semiconductor laser device chip used 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 is a layer whose main element is made of Ga, In, N, or 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 for obtaining light, wherein said reflector has a refractive index of a material layer constituting said chip. Is a semiconductor distributed Bragg reflector that periodically changes between small and large and reflects incident light by light wave interference, and the material layer having a small refractive index is AlxGa1-xAs.
(0 <x ≦ 1), and the material layer having a large refractive index is Aly
A reflecting mirror having Ga1-yAs (0 ≦ y <x ≦ 1), and a material layer AlzGa1- between the material layers having the small and large refractive indexes, wherein the refractive index has a value between small and large. zAs (0
≦ y <z <x ≦ 1), and an insulating film layer having an opening corresponding to the light emitting element portion is formed on the light emitting surface side of the surface emitting semiconductor laser element chip. ,
A surface-emitting type semiconductor laser device chip characterized in that it is larger than the light-emitting area of the light-emitting device portion.

Second, the oscillation wavelength of the laser chip is 1.1 μm to 1.7 μm, and the active layer for generating light is used for a main element laser chip and an optical communication system connected to the laser chip. In the surface emitting type semiconductor laser device chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and forms an active layer that generates light by using a layer whose main element is Ga, In, N, or As, or A surface-emitting type semiconductor laser device chip having a resonator structure including a reflector made of a layer of Ga, In, and As and provided above and below the active layer for obtaining laser light, The mirror is a semiconductor distributed Bragg reflector that periodically changes its refractive index between small and large and reflects incident light by light wave interference.
The material having a small refractive index is AlxGa1-xAs (0 <x
≦ 1), and the material having a large refractive index is AlyGa1-y
A reflecting mirror having As (0 ≦ y <x ≦ 1), wherein GaInP or GaInPA is provided between the active layer and the reflecting mirror;
a non-radiative recombination prevention layer made of s
An insulating film layer having an opening corresponding to the light emitting element portion is formed on the light emitting surface side of the surface emitting semiconductor laser element chip, and the opening is larger than the light emitting region of the light emitting element portion. The surface-emitting type semiconductor laser device chip to be used is described.

Third, the laser chip and the laser chip
In an optical communication system connected to a
The oscillation wavelength is 1.1 μm to 1.7 μm.
The generated active layer is made of a material whose main elements are Ga, In, N, and As.
And a layer made of Ga, In, and As
In order to obtain a laser beam, the upper and lower portions of the active layer
Surface-emitting type having a resonator structure including a provided reflecting mirror
A semiconductor laser element chip, wherein the reflecting mirror
The refractive index of the constituent material layer changes periodically to small / large and enters
Semiconductor distributed Bragg reflection that reflects light by light wave interference
The material layer which is a mirror and has a low refractive index is Al_xG
a_1-xAs (0 <x ≦ 1), the material having a large refractive index
Layer is Al_yGa_1-yReflector with As (0 ≦ y <x ≦ 1)
And the refractive index is between the small and large material layers.
Material layer Al with a ratio between small and large _zGa_1-zAs (0
≦ y <z <x ≦ 1) surface emitting semiconductor laser
An element chip is used as a light emitting light source, and
The diameter of the light emitting hole formed in the insulating film on the
It gradually increases from the substrate direction toward the insulating film,
In addition, the diameter of the insulating film surface is outside the optical fiber to be optically connected.
It is formed to be larger than the diameter, and optical fiber
The outer peripheral edge of the fiber comes into contact with the optical fiber and the surface-emitting half.
So that the semiconductor laser element is aligned and optically connected
did.

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.
A surface-emitting type semiconductor laser device chip provided with a non-radiative recombination preventing layer made of InPAs is used as a light-emitting source, and a diameter of a light-emitting hole formed in an insulating film on the surface-emitting type semiconductor laser device is reduced. The diameter of the insulating film surface is gradually increased from the substrate direction toward the insulating film direction, and the diameter of the insulating film surface is formed so as to be larger than the outer diameter of the optical fiber to be optically connected, and the outer peripheral edge of the optical fiber contacts the side wall of the hole, The optical fiber and the surface-emitting type semiconductor laser device are positioned and optically connected.

Fifth, in the above third and fourth optical communication systems, the minimum diameter of the light emitting hole is larger than the core diameter of the optical fiber and smaller than the outer peripheral edge.

[0023]

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. (A) is a sectional view, and (b), (c), (c), (d), and (e) are top views.

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 by suggesting 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). And undoped lower G on it
an aAs spacer layer, a multiple quantum well active layer including 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 nm), and an undoped upper GaAs spacer layer. Are stacked to form a resonator having a thickness of one wavelength of the oscillation wavelength λ (thickness of λ) in the medium. Further thereon, C (carbon) doped _{p-Ga x In 1-x} P y As 1-y (x = 0.5, y = 1) layer and the Zn-doped _{p-Al x Ga 1-x} As ( x = 0) is alternately laminated in each medium at a thickness of 1/4 times the oscillation wavelength λ (one period), and a C-doped p-Al _x Ga _{1-x is formed} thereon. A periodic structure in which As (x = 0.9) and Zn-doped p-Al _x Ga _1-x As (x = 0) are alternately stacked with a thickness of １ ／ of the oscillation wavelength λ in each medium ( A semiconductor distributed Bragg reflecting mirror (Al _0.9 Ga _0.1 As / GaAs upper semiconductor distributed Bragg reflecting mirror) consisting of 25 periods) is formed. In this example, p-Ga _x In _1-x P _y
The As _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 reflectors are formed by alternately laminating a low refractive index layer (a layer having a low refractive index) / a high refractive index layer (a layer having a high 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 Al _z Ga _{1 -z} As having a refractive index 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). 1 shows a part of a semiconductor distributed Bragg reflector provided with (0 ≦ y <z <x ≦ 1) (FIG. 1)
Then, the 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 stage of study, 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. Such a material layer controls the gas flow rate during formation, etc.
The Al layer is formed so that the Al composition is changed continuously or stepwise so that the refractive index of the material layer is changed continuously or stepwise.

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.

Further lasing wavelength, such as such a refractive index takes a value between the small and large material layer _{Al z Ga 1-z As (} 0 ≦ y <z <x ≦ 1) the invention is 1 .1 μm to 1.7 μ
5 nm to 50 nm in the case of a long-wavelength surface emitting semiconductor laser
It is preferable that the thickness is less than 10 nm. If the thickness is smaller than this, there is a problem that the resistance becomes large and the current hardly flows, and the element generates heat and the driving energy becomes high. In addition, when the thickness is large, the resistance becomes small, which is advantageous in terms of heat generation of the element and driving energy, but there is a problem that the reflectance cannot be obtained this time,
As described above, it is necessary to select an optimum range (thickness of 5 nm to 50 nm).

As described above, it has been considered to provide such a material layer for 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 the semiconductor distributed Bragg reflector is particularly effective in the case of 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. I can say.

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 reflector, 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 entire surface emitting semiconductor laser was grown by MOCVD. In this case, no lattice relaxation was observed. Materials for forming each layer of the semiconductor laser include TMA (trimethylaluminum), TMG (trimethylgallium),
MI (trimethyl indium), 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) to form 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 reflector and is a part of the upper reflector, excluding the light emitting portion, and an n-side electrode is formed on the back surface of the substrate. Was formed. Further, a polyimide (insulating film) was formed on the entire surface and flattened, and a light emitting hole was formed on the light emitting portion such that the diameter of the hole gradually increased from the substrate direction toward the insulating film.
Here, the end of the light emitting hole on the surface of the insulating film is called the upper end of the light emitting hole, and the bottom of the insulating film, that is, the end in contact with the P-type electrode, is called the lower end of the light emitting hole.

FIG. 1B shows a case where the cross section of the optical fiber and the light emitting hole is circular. Here, the diameter is the diameter of the cross section of the outer peripheral edge of the optical fiber, and the diameter of the cross section when the hole is cut in parallel with the substrate for the light emitting hole. When the optical fiber is inserted into the light exit hole, the optical fiber stops when the diameter of the outer peripheral edge of the optical fiber matches the diameter of the light exit hole. Since the cross section of both the optical fiber and the connection hole is circular, the center of the light emitting portion of the surface emitting type semiconductor laser device and the center of the optical fiber can be easily aligned by making the light emitting hole the above structure. Can be.

FIG. 1C shows a case where the cross-sectional shape of the optical fiber and the light emitting hole is elliptical. Here, the diameter refers to the minor axis or major axis of the cross section of the outer peripheral edge of the optical fiber, and the minor axis or major axis of the section when the hole is cut in parallel with the substrate. When an optical fiber is inserted into the light exit hole, the optical fiber stops when the diameter of the outer peripheral edge of the optical fiber coincides with the diameter of the light exit hole. With the above structure of the optical fiber and the light emitting hole, the center of the light emitting portion of the surface emitting semiconductor laser device and the center of the optical fiber can be easily aligned. When one of the cross-sectional shapes of the optical fiber and the light exit hole is circular, the major axis of the optical fiber is equal to the diameter, and the major axis of the light exit hole is equal to the diameter. I can do it.

FIG. 1D shows a case where the cross-sectional shape of the optical fiber and the light emitting hole is a regular square. Here, the diameter is a side of a regular square for an optical fiber, and a side of a cross section when the hole is cut in parallel with a substrate for a light emitting hole. As in the case where the cross section is circular, the optical fiber stops when the sides of the optical fiber and the light exit hole coincide. In this example, the case where the diameter is described as the side is shown,
The same effect can be obtained even if the diagonal is defined as the diameter. FIG. 1E shows a case where the cross-sectional shapes of the optical fiber and the light exit hole are rectangular. Here, the diameter is the long side of the rectangle for the optical fiber, and the long side of the cross section when the hole is cut parallel to the substrate for the light emitting hole. As in the case where the cross section is a regular square, the optical fiber stops when the long sides of the optical fiber and the light exit hole coincide. Note that, in this example, the case where the diameter is described as the long side has been described, but a similar effect can be obtained even if the diagonal line is defined as the diameter.

FIG. 1 shows the case where the cross section is a regular polygon.
As shown in (f) (in this case, a regular pentagon), assuming that the center of the regular polygon is the diameter, the optical fiber and the light exit hole stop at the same diameter as in the case of the regular square.

In this embodiment, the optical fiber and the light exit hole are mainly similar in shape, but the present invention is not limited to this. For example, when a circular cross section optical fiber is used for a light exit hole having a regular polygonal cross section or vice versa ((g) and (h) in FIG. 1), a light exit hole having a regular square cross section has a cross section. In the case where a circular optical fiber is used or vice versa ((i) and (j) in FIG. 1), the center of the light emitting portion of the surface emitting semiconductor laser device is easily aligned with the center of the optical fiber. Any shape can be used.

In this example, an active region (in this embodiment, a resonator composed of upper and lower spacer layers and a multiple quantum well active layer) sandwiched between upper and lower reflectors and into which carriers are injected and recombined, is used as an active region. In the material containing Al (II
The ratio of the low refractive index layer of the lower and upper reflectors 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 reflectors, 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, the growth is performed by reflecting the information of the base, and 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 defects reach 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. Furthermore, this Ga _x In
_The non-radiative recombination preventing layer composed of _{1-x Py} As _1-y (0 <x <1, 0 <y ≦ 1) layers has a lattice constant larger than that of a GaAs substrate and has a compressive strain. And the lattice constant of the active layer is Ga _x In _{1-x Py} As _1-y (0 <x <1, 0
<Y ≦ 1) It has a larger compressive strain than the 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, Al is not included in the active region and at the interface between the reflector and the active region. Therefore, non-radiative recombination due to crystal defects caused by Al during carrier injection is eliminated, and Recombination was reduced.

As described above, it is preferable to apply a structure in which Al is not contained at the interface between the reflector and the active region, that is, to provide a non-radiative recombination preventing 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 a 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 in this manner 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 manufactured by the inventor of the present invention, a high strain GaInAs quantum well active layer can be grown coherently thicker than before by a high non-equilibrium growth method such as low temperature growth at 600 ° C. or lower. 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 apparent 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. Although the triple quantum well structure (TQW) has been described as an example of the stacked structure of the active layer, a structure (SQW, MQW) using a quantum well of another number of wells may 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, the main elements of the active layer are Ga, In, and A.
s, that is, Ga _x In _{1 -x} As (GaInA
Although the example of the (s active layer) was shown, in order to perform laser oscillation of a longer wavelength, N was added, and the main elements were Ga, In, and
What is necessary is just to make it the layer (GaInNAs active layer) which consists of N and As.

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. In addition, G
Even when aAsSb is used, a 1.3 μm band surface emitting laser can be realized on a GaAs substrate. Thus, the wavelength of 1.1 μm
Conventionally, there is no suitable material for a 1.7 μm semiconductor laser, but a high strain GaInAs, GaInNAs, G
By using aAsSb and providing a non-radiative recombination preventing layer, a wavelength of 1.1 μm, which has conventionally been difficult to achieve stable oscillation,
In the long wavelength region of the m to 1.7 μm band, a high-performance surface emitting laser 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. (A) is a sectional view, and (b) is a top view. In this case, as in the case of FIG. 1, an n-GaAs substrate having a plane orientation of (100) is used. In each medium, n-Al _x Ga _{1 -x} As (x = thickness) that is 倍 of the oscillation wavelength λ (thickness of λ / 4) in each medium.
0.9) and n-Al _x Ga _{1 -x} As (x = 0) alternately 3
N-semiconductor distributed Bragg reflector (Al _0.9 G
a _0.1 As / GaAs lower reflector) is formed, thereon n-Ga thickness of _{λ / 4 x In 1-x} P y As 1-y (x = 0.5, y =
1) Layers were laminated. In this example _{n-Ga x In 1-x} P y A
The s _1-y (x = 0.5, y = 1) layer is also a part of the lower reflector 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. Furthermore, a p-semiconductor distributed Bragg reflector (upper reflector) is formed thereon.

The upper reflecting mirror is made of AlA to be a selectively oxidized layer.
s layer is sandwiched between a GaInP layer and an AlGaAs layer by 3λ /
4 low refractive index layer (thickness of (λ / 4-15 nm)
C-doped p-Ga_xIn_1-xP_yAs_1-y(X = 0.5, y
= 1) layer, C-doped p-Al _zGa_1-zAs (z = 1)
Selective oxidation layer (thickness 30 nm), thickness (2λ / 4-15)
nm) C-doped p-Al_xGa_1-xAs layer (x = 0.
9)), a GaAs layer having a thickness of λ / 4 (one period), and C
Doped p-Al_xGa_1-xAs layer (x = 0.9) and p-
Al_xGa_1-xAs (x = 0) layer in each medium
Periodic structure laminated alternately with a thickness of 1/4 times the oscillation wavelength
Structure (22 cycles)
Reflector (Al_0.9Ga_0.1As / GaAs upper reflector).

Also in this example, although the illustration is omitted because it is complicated in FIG. 3, the structure of the semiconductor distributed Bragg reflecting mirror 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. And the uppermost p-Al _x Ga _{1 -x} As (x = 0) layer is
It 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 is 0.1%.
5%. The thickness of the quantum well active layer was 7 nm. The method of growing this surface emitting semiconductor laser is MOC.
Performed by the VD method. The materials constituting each layer of the semiconductor laser include TMA (trimethylaluminum), TMG (trimethylgallium), TMI (trimethylindium),
AsH ₃ (arsine), PH ₃ (phosphine), and DMHy (dimethylhydrazine) were used as raw materials for nitrogen. 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. In this example, GaIn
The NAs layer (quantum well active layer) was grown at 540 ° C. M
The OCVD 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. Further, in this example, a mesa portion having a predetermined size is formed by p-Ga _x In _1-x P
_y As _1-y (x = 0.5, y = 1), p-
Al _z Ga _{1 -z} As (z = 1) is formed by exposing the side surface of the selectively oxidized layer, and the Al _z Ga _{1 -z} As (z =
1) The layer is oxidized from the side with water vapor to form an Al _x O _y current narrowing layer. Further, a portion removed by mesa etching with a 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 a light emitting portion. An n-side electrode was formed on the back surface of. In addition, polyimide (insulating film)
Was formed over the entire surface and flattened, and a light emitting hole was formed on the light emitting portion such that the diameter of the hole gradually increased from the substrate direction toward the insulating film.

When an optical fiber is inserted into the light exit hole, the optical fiber stops when the diameter of the outer peripheral edge of the optical fiber coincides with the diameter of the light exit hole. Since the cross section of both the optical fiber and the connection hole is circular, the center of the light emitting portion of the surface emitting type semiconductor laser device and the center of the optical fiber can be easily aligned by making the light emitting hole the above structure. Can be. In this embodiment, the optical fiber and the light exit hole have a circular cross section. However, the present invention is not limited to this. For example, as in the embodiment shown in FIG. A shape that can easily align the center of the light-emitting portion of the surface-emitting type semiconductor laser device with the center of the optical fiber, such as when an optical fiber having a circular cross section is used for the emission hole or vice versa. I don't care.

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. Also, the surface-emitting type half of this example
When one-dimensional or two-dimensional integration of conductor lasers (elements)
In this case, good controllability during device fabrication
The uniformity and reproducibility of the device characteristics of each device in the array.
There is an effect that it becomes better.

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, the active region No material containing Al is used, 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, in this example, the same idea as that of the example of FIG. 1 is applied to the lower reflector between the GaAs substrate and the active layer. Therefore, the active layer of the crystal defect caused by Al which causes a problem during the growth of the active layer. As a result, the active layer can be grown with high quality.

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 with such a configuration, since the polyimide can be easily embedded, the wiring (the 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 in this manner was about 1.3 μm. In this example, a layer composed mainly of Ga, In, N, and As was used as the active layer (GaInNAs active layer), so that a long-wavelength surface emitting semiconductor laser could be formed on a GaAs substrate. A
Since the current was narrowed by selective oxidation of the layer to be selectively oxidized containing l and As as main components, the threshold current was low. According to the current narrowing structure using the current narrowing layer made of the Al oxide film in which the selective oxidation layer is selectively oxidized, the current spreading can be suppressed by forming the current narrowing layer close to the active layer, so that the current narrowing can be prevented from being exposed to the atmosphere. Carriers can be efficiently confined in the region. Further, by oxidizing to form an Al oxide film, the refractive index is reduced, light can be efficiently confined in a minute region in which carriers are confined by the effect of a convex lens, the efficiency is extremely improved, and the threshold current can be reduced. . In addition, because the current narrowing structure can be easily formed,
Manufacturing costs 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 the case of FIG. Is obtained. The surface emitting semiconductor laser of FIG. 3 can be grown by MOCVD as in the case of FIG. 1, but other growth methods such as MBE can be used. Although DMHy is used as a nitrogen source, activated nitrogen and other nitrogen compounds such as NH ₃ can be used. Furthermore, although an example of a triple quantum well structure (TQW) has been shown as the stacked structure of the active layer, a structure (SQW, DQW, MQW) using a quantum well of another number of wells may be used. The structure of the laser may be another structure. In the surface emitting semiconductor laser of FIG.
By changing the composition of the aInNAs active layer, 1.55 μm
A surface emitting semiconductor laser in the m band, and even in the longer wavelength 1.7 μm band, is also possible. T in the GaInNAs active layer
Other III-V group elements such as l, Sb, and P may be included. Even if GaAsSb is used for the active layer,
A surface emitting semiconductor laser in the 1.3 μm band can be realized on an aAs 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. 1 to n laser elements are formed in the laser element chip shown here, and the number n and the arrangement method are determined according to the application.

[0067]

(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 that can lower the operating voltage, the oscillation threshold current, and the like, generate less heat from the laser element, and perform stable oscillation. By devising a semiconductor distributed Bragg reflector, the operating voltage, oscillation threshold current, etc. can be reduced, the laser element generates less heat, stable oscillation can be achieved, and a low-cost, practical surface-emitting semiconductor laser can be realized. . Further, the opening of the insulating film layer having an opening corresponding to the light emitting element portion on the light emitting surface side of the surface emitting semiconductor laser element chip, which has not been studied conventionally, is devised as in the present invention, so that light emission is achieved. A surface-emitting type semiconductor laser device chip which can be used effectively without lowering the efficiency and can eliminate the deformation of the opening of the insulating film layer due to heat generated in the light-emitting device portion has been realized.

(Effect According 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 has been no long-wavelength band surface emitting semiconductor laser that can be used stably, but a surface emitting semiconductor having a non-radiative recombination prevention layer as in the present invention. By using a laser element chip, stable oscillation became possible, and a surface-emitting type semiconductor laser was realized. Further, the opening of the insulating film layer having an opening corresponding to the light emitting element portion on the light emitting surface side of the surface emitting semiconductor laser element chip, which has not been studied conventionally, is devised as in the present invention, so that light emission is achieved. A surface-emitting type semiconductor laser device chip which can be used effectively without lowering the efficiency and can eliminate the deformation of the opening of the insulating film layer due to heat generated in the light-emitting device portion has been 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. Furthermore, by devising the diameter of the light emitting hole formed in the insulating film on the surface-emitting type semiconductor laser device, which has not been conventionally studied, as in the present invention,
An optical communication system capable of easily aligning the center of the light emitting section of the surface emitting semiconductor laser device with the center of the optical fiber has been realized.

(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, 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. Further, by devising the diameter of the light emitting hole formed in the insulating film on the surface-emitting type semiconductor laser device, which has not been studied conventionally, as in the present invention, the center of the light-emitting portion of the surface-emitting type semiconductor laser device is improved. Thus, an optical communication system capable of easily aligning the axis with the center of the optical fiber has been realized.

(Effect Corresponding to Claim 5) In such an optical communication system, the diameter of the light emitting hole formed in the insulating film on the surface-emitting type semiconductor laser device is devised as in the present invention. An optical communication system capable of easily aligning the center of the light emitting section of the surface emitting semiconductor laser device with the center of the optical fiber has been realized.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of an element portion of a long-wavelength band surface emitting semiconductor laser and an optical fiber according to an embodiment of the present invention.

FIG. 3 is a sectional view of an element portion of a long wavelength band surface emitting semiconductor laser and an optical fiber according to an embodiment of the present invention.

FIG. 4 is a partial cross-sectional view 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. 5 is a sectional view of an element portion of another configuration of a long wavelength band surface emitting semiconductor laser and an optical fiber according to an embodiment of the present invention.

FIG. 6 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.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayoshi Kato 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Teruyuki Furuta 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kazuya Miyagaki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Ken Takeshi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Watada Atsuyuki 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) Invention Person Yukie Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Satoru Sugahara 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company In Ricoh (72) Inventor Shuichi Hikichi 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 5F073 AA51 AA61 AA65 AA74 AB17 AB28 BA02 CA12 DA05 DA14 DA21 DA27 DA35 EA23 FA07

Claims (5)

[Claims] 1. A surface emitting semiconductor laser device chip used in a laser chip and an optical communication system connected to the laser chip, wherein the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm and emits light. The active layer to be generated is a layer whose main element is made of Ga, In, N, As, or a layer made of Ga, In, As, and reflectors provided above and below the active layer to obtain a laser beam. Wherein the reflective mirror periodically changes the refractive index of a material layer constituting the reflector to small / large, and reflects incident light by light wave interference. In addition to the semiconductor distributed Bragg reflector, the material layer having a small refractive index is made of AlxGa1-xAs.
(0 <x ≦ 1), and the material layer having a large refractive index is Aly
A reflecting mirror having Ga1-yAs (0 ≦ y <x ≦ 1), and a material layer AlzGa1- between the material layers having the small and large refractive indexes, wherein the refractive index has a value between small and large. zAs (0
≦ y <z <x ≦ 1), and an insulating film layer having an opening corresponding to the light emitting element portion is formed on the light emitting surface side of the surface emitting semiconductor laser element chip. ,
A surface-emitting type semiconductor laser device chip characterized in that the light-emitting region is larger than a light-emitting region of the light-emitting device portion. 2. A surface emitting semiconductor laser device chip used in a laser chip and an optical communication system connected to the laser chip, wherein the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm and emits light. The active layer to be generated is a layer whose main element is made of Ga, In, N, As, or a layer made of Ga, In, As, and reflectors provided above and below the active layer to obtain a laser beam. A semiconductor laser device chip having a resonator structure including: a semiconductor device in which the reflecting mirror periodically changes the refractive index of a material constituting the reflecting mirror to small / large and reflects incident light by light wave interference. A distributed Bragg reflector,
The material having a small refractive index is AlxGa1-xAs (0 <x
≦ 1), and the material having a large refractive index is AlyGa1-y
A reflecting mirror having As (0 ≦ y <x ≦ 1), wherein GaInP or GaInPA is provided between the active layer and the reflecting mirror;
a non-radiative recombination prevention layer made of s
An insulating film layer having an opening corresponding to the light emitting element portion is formed on the light emitting surface side of the surface emitting semiconductor laser element chip, and the opening is larger than the light emitting region of the light emitting element portion. Surface emitting semiconductor laser chip. 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 used as a light emitting light source, and the diameter of a light emitting hole formed in an insulating film on the surface emitting semiconductor laser element is insulated from the substrate direction. The diameter of the insulating film surface is gradually increased toward the film direction, and the diameter of the insulating film surface is formed so as to be larger than the outer diameter of the optical fiber to be optically connected. An optical communication system wherein the surface-emitting type semiconductor laser device is positioned and optically connected. 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.
A surface-emitting type semiconductor laser element chip provided with a non-light-emitting recombination prevention layer comprising a light-emitting source, and a light-emitting hole formed in an insulating film on the surface-emitting type semiconductor laser element has a diameter of the substrate. From the direction toward the insulating film direction, the diameter of the insulating film surface is formed so as to be larger than the outer diameter of the optical fiber to be optically connected, and the outer peripheral edge of the optical fiber contacts the side wall of the hole, An optical communication system wherein an optical fiber and the surface-emitting type semiconductor laser device are aligned and optically connected. 5. The optical communication system according to claim 3, wherein a minimum diameter of the light exit hole is larger than a core diameter of the optical fiber and smaller than an outer peripheral edge.