JPH10223973A - Surface emission type semiconductor laser device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a plane of polarization by intermittently arranging a plurality of semiconductor reflecting films in a multilayered semiconductor reflecting film which forms an area having reflectance which is different from that of the surrounding area to the light emitted from an active layer so that the reflecting films may be separated from each other by two or more layers. SOLUTION: In a p-type Al0.9 Ga0.1 As/Al0.3 Ga0.7 As upper multilayered reflecting film 8, light confining layers 6 having current constricting functions are intermittently formed by desultorily inserting AlAs layers 7 into the film 8 at the positions to be occupied by the Al0.9 Ga0.1 As layers of the layer 8 and selectively oxidizing the layers 7 from the periphery of a semiconductor pillar so that the central parts of the layers 7 may be left unoxidized. Since a reflectance changing area is continuously provided from the light emitting port of a semiconductor device from the vicinity of an active area in order to control a plane of polarization, a highly efficient current constricting effect can be obtained and, at the same time, the plane of polarization can be controlled by controlling the size of the reflectance changing area formed for controlling the plane of polarization with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical cavity surface emitting laser capable of controlling a transverse mode and a polarization plane.

[0002]

2. Description of the Related Art A high-density semiconductor laser array is required as a light source for optical communications, optical computers, and the like. In the semiconductor laser array, a plurality of semiconductor lasers are arranged at an appropriate pitch, each of which is independently driven and controlled to emit light. Edge-emitting lasers, which have been widely used in the past, have the advantage of high luminous efficiency.However, since only one-dimensional parallelization is possible on the same substrate, a semiconductor laser array in which many semiconductor lasers are integrated is used. It was difficult to form. On the other hand, a surface emitting laser emits light in a direction perpendicular to the substrate, so that it can be two-dimensionally parallelized on the same substrate, and a high-precision and high-density matrix array can be obtained. It has advantages and looks promising.

A vertical cavity surface emitting laser, which is one of the surface emitting lasers, has an intermediate layer composed of an active layer and a spacer layer, and two sets of upper and lower distributed feedback reflecting films (Distributed) sandwiching the intermediate layer. Brug Reflactor) and the DBR
Is a semiconductor laser that forms a resonator and emits light in a direction perpendicular to the substrate. In an edge emitting laser, a TE (transverse electri) in which the electric field vector is in the xy plane is used.
c mode) TM where the magnetic field vector is in the xy plane
(Transverse magnetic mode) Although there are polarization determining factors such as a difference in waveguide loss and reflectivity between modes, the direction of the surface emitting laser is uncertain. When the shape of the light emitting surface of a surface emitting laser is point symmetric, it is almost impossible to control the polarization of the surface emitting laser because it is almost always the case that individual elements are used in a specified random direction. Is important.

There have been several reports on attempts to control the polarization of a vertical cavity surface emitting laser. For example, there is an example of a gain waveguide type surface emitting laser which gives anisotropic gain by an electrode having an anisotropic shape. It has a laser A and a laser B oscillated by two or more divided electrodes, and the two polarization directions can be arbitrarily controlled by turning on and off the laser B (Japanese Unexamined Patent Publication No. 4-104). 2
42989). In addition, as disclosed in Japanese Patent Application Laid-Open No. 1-265584, there is an attempt to provide a rectangular high-refractive-index waveguide section in a light emitting section, and to pass polarized waves parallel to the long side thereof. In addition, Applied Physics Letters, No. 66
Vol. 8, No. 8, pp. 908 to 910 (1995) (Ap.
pl., Phys., Lett., Vol. 66, No. 8, p. 908-910, 1995) and JP-A-8-181391, the post shape is such that an arbitrary set of post side surfaces is parallel. The polarization control is performed by creating a post shape so that the side is the longest. As shown in FIG. 4, a laser is used to convert a triple quantum well active layer made of indium gallium arsenide (InGaAs) to a gallium arsenide / aluminum arsenide DB.
A typical VCSEL structure sandwiched by R.
After forming a rectangular photoresist mask arranged so that the short axis is in the <110> direction, a part of the upper semiconductor multilayer reflective film is removed by reactive ion beam etching using chlorine gas, so-called “residual ion beam etching”. Form a post shape. Further, after the active layer except the portion immediately below the post portion is deactivated (increased resistance) by proton implantation due to current constriction, an anode and a cathode are formed at predetermined positions to complete the process. The direction of light emission is on the back side of this substrate.

Although it is not intended to control the plane of polarization, a natural oxide film is introduced into the distributed feedback type reflection film to lower the threshold of the surface emitting laser, and the current is confined. Examples are Applied Physics Letters, Volume 65,
No. 1, pages 97 to 99 (1994) (Appl., Phy
s., Lett., Vol. 65, No. 1, p. 97-99, 1994). This laser is also made of InGaAs as shown in FIG.
Is a typical VCSEL structure in which a triple quantum well active layer of GaAs / AlAs is sandwiched by a DBR of GaAs / AlAs. However, the p-type DBR is one of GaAs / AlAs.
In the pair, GaAs is located on the upper layer. The process first processes the p-type GaAs layer into a 30 or 60 μm-shaped circle using photolithography and etching techniques. Subsequently, the exposed p-type AlAs layer is heat-treated for about 3 minutes in a furnace heated to 475 ° C. At this time, steam maintained at 95 ° C. was introduced into the furnace using nitrogen as a carrier gas. The exposed AlAs layer is gradually oxidized from the lateral direction, and finally, the remaining 2 to 8 μm is left without being oxidized.
An m-square region is formed. The oxidized region becomes an aluminum oxide compound, and almost no current flows, so that current confinement is possible. Further, in order to further lower the threshold of a surface emitting laser, an example in which a plurality of natural oxide films are introduced into a DBR to perform current confinement is disclosed in IEE Photonics, Technology Letters, Vol.
No., pages 1234 to 1235 (1995) (IEEE, Ph.
oton.Technol. Lett., Vol. 7, No. 11, p. 1234-1236, 1995)
Is shown in As shown in FIG. 6, this laser has upper and lower DBRs formed of a laminated film of GaAs / AlAs, and after etching the DBRs to form posts,
All exposed AlAs layers are heat treated in a furnace heated to 400 ° C. At this time, steam maintained at 80 ° C. was introduced into the furnace using nitrogen as a carrier gas. The exposed AlAs layer is gradually oxidized from the lateral direction, and finally a 15 to 20 μm square region remains without being oxidized. The oxidized region becomes a compound of aluminum oxide and hardly conducts electric current, so that current confinement becomes possible. The surface reconnection current is further suppressed, and a low threshold value of 70 μA is realized.

[0006]

However, in the gain-guided laser disclosed in Japanese Patent Application Laid-Open No. 4-242989, light is weakly confined and light diverges. Sex is very small. Therefore, it is considered that the polarization control effect is small. In addition, those having the electrodes of laser A and laser B arranged in an L-shape or T-shape have the drawback that the laser beam is deflected by polarization control. It is necessary to pass a current equal to or more than a substantially equal threshold value to the two lasers, so that there is a problem that the driving power is increased, and that there is a problem that the laser beams are apt to be symmetrical and that it is difficult to keep the laser beam in the single transverse mode. . In the structure disclosed in Japanese Patent Application Laid-Open No. 2-265584, it is questionable whether light is efficiently confined by the high refractive index waveguide, and therefore, it is considered that the waveguide control effect is small. In the structure shown in Applied Physics Letters, the polarization plane is controlled by using the diffraction loss of the DBR. However, the structure including the recombination of electrons and holes that did not contribute to the light emission is considered. Since the loss is generated as heat, this element with a relatively small post part does not have sufficient heat dissipation,
Light output characteristics are limited. In fact, the authors of this paper say that even if the shape in the minor axis direction is further reduced, the current threshold value does not decrease but rather increases. Furthermore, in this structure, it is difficult to make the aperture diameter of the current constriction part smaller than the diameter of the post part due to the restrictions at the time of proton injection, and it is necessary to ignore non-radiative recombination at the interface between the active region and the proton injection region. Can not. Therefore, the efficiency of carrier injection into the active region is not high,
There is a limit to lowering the threshold.

In the examples shown in Applied Physics Letters, IEE Photonics, and Technology Letters, the oxidation rate of the AlAs layer should be uniquely determined if the composition and the doping concentration are determined.
There is variation in the oxidation rate. The AlAs layer is oxidized to A
It is self-evident that there is a volume change when changing to l _x O _y , and this effect affects the activation energy of the oxidation,
There is a variation in the oxidation rate presumably due to this, and the diameter of the region through which the current passes tends to be uneven.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surface-emitting type semiconductor laser capable of controlling a polarization plane without particularly affecting the optical output characteristics. I do.

[0009]

The features of the present invention are as follows.
In a surface emitting laser in which an optical resonator is formed in a direction perpendicular to the substrate surface, a reflection having a region having a reflectance different from that of a surrounding region with respect to emission light in at least one semiconductor multilayer reflection film of the active layer. The present invention is characterized in that a plurality of film layers are arranged apart from each other from the vicinity of the active layer toward the emission port. That is, according to the present invention, in a surface emitting laser in which an active layer is sandwiched between upper and lower semiconductor multilayer reflective films and an optical resonator is formed in a direction perpendicular to the substrate surface,
At least the upper semiconductor multilayer reflective film intermittently forms a plurality of reflective film layers in which a region having a reflectance different from that of a surrounding region with respect to light emitted from the active layer is separated by two or more layers. It is characterized by being arranged.

[0010] Preferably, the regions having different reflectivities are characterized in that the cross-sectional shape as viewed from a direction perpendicular to the semiconductor substrate forms a rectangle having a short side and a long side.

Preferably, the first light confinement has a light confinement region in which at least the upper semiconductor multilayer reflection film forms an aperture formed of a region having a lower reflectance than the surrounding region with respect to the outgoing light. A second optical confinement layer having a light confinement region having an aperture diameter larger than that of the first light confinement layer, and a third light confinement layer having a light confinement region having a larger aperture diameter than the first light confinement layer. It is characterized in that it is formed so as to be separated from each other as it separates.

According to a second aspect of the present invention, a lower semiconductor multilayer reflective film, a lower spacer layer, an active layer, and an upper spacer layer are sequentially formed on a semiconductor substrate so that x gradually decreases at least in the direction of the light exit port. A step of sequentially laminating an upper semiconductor multilayer reflective film formed so as to include an Al _x Ga _1-x As layer intermittently, and etching until at least reaching the lower spacer layer to form a semiconductor pillar of a desired shape And the intermittently formed Al _x Ga _{1 -x} A
a selective oxidation step of oxidizing the s layer from the outer wall of the semiconductor pillar to a desired depth, wherein at least the upper semiconductor multilayer reflective film surrounds the emitted light from the active layer in the direction toward the light emission port with respect to the surrounding area. And a reflective film layer having an opening region having a reflectance different from that of the first region is intermittently formed.

According to the present invention, a reflective film layer having a high-efficiency current confinement effect and having a portion for changing the reflectance to form an optical waveguide is provided from the vicinity of the photoactive region to the emission port. Since it is provided intermittently, it is possible to form an effective waveguide with uniformity, good controllability, and high reproducibility.

Further, if the regions having different reflectivities are formed so that the cross-sectional shape viewed from the direction perpendicular to the semiconductor substrate forms a rectangle having short sides and long sides, the transverse mode can be stabilized. However, the polarization plane can be controlled efficiently.

Further, since the waveguide maintains the light propagation space of the same size as the light emitting portion and guides the light to the emission port, the stability of the polarization plane of the light from the active layer is improved at a low threshold value. . In addition, since the generated heat can be radiated to the mesa structure having a relatively large volume, heat generation can be suppressed, and the polarization plane can be stabilized without deteriorating the optical output characteristics over a wide output range.

Further, since the aperture diameter of the light confinement layer is made larger as the distance from the active region increases, the current confinement effect of light efficiency can be obtained, and the plane of propagation of light from the light emitting portion can be reduced. A waveguide whose shape gradually opens upward without a sudden increase in its size is formed in the DBR with good uniformity, and the stability of the polarization plane of light from the active layer at a low threshold is improved. Becomes possible.

These light confinement layers are made of AlAs
Alternatively, it is easily formed by selective oxidation of the AlGaAs layer. However, when a layer having a large thickness due to a large volume change due to oxidation is formed, there is a possibility that distortion is generated or dimensional accuracy of the aperture diameter is reduced. However, since it is sufficient to dispose the thin layers in multiple layers and oxidize them, there is no problem of distortion due to volume change due to oxidation. In addition, since the multilayer optical confinement layers are formed apart from each other, the effect is close to a state in which the layers are continuously formed.

Furthermore, since the waveguides formed by these light confinement layers are arranged so as to be anisotropic, the zero-order TE mode determined by the long side of the waveguide cross section in the waveguides first At this time, a polarized wave parallel to the short side of the waveguide section can be efficiently obtained. That is, the polarization can be controlled in the direction of the shortest distance in the current injection region.

In addition, the stronger the light confinement state, the greater the divergence angle of the output beam. Therefore, if the current distribution is controlled only by a plurality of insulating light confinement layers (consisting of aluminum oxide layers) whose aperture diameters are widened. In addition, a waveguide that is open upward so that the planar size of the light propagation space from the light emitting portion does not suddenly spread is DB.
Since it is formed with good controllability in R,
The transverse mode and the plane of polarization of light from the active layer can be further stabilized.

As described above, according to the present invention, the polarization plane can be stabilized. In addition, the method is simple, has high reproducibility, and has no possibility of deteriorating laser characteristics.

In the method of the present invention, in the selective oxidation using ordinary water vapor, the oxidation rate of the Al _x Ga _{1 -x} As layer increases as the aluminum content, that is, x, increases, and the diameter of the aperture remaining without being oxidized is increased. Gradually increases toward the light exit port. Therefore, the above configuration can be formed very easily.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a top view and a sectional view of a surface emitting semiconductor laser device according to a first embodiment of the present invention.

[0024] The surface-emitting type semiconductor laser device, AlAs a p-type _{Al 0.9 Ga 0.1 As / Al 0.3} Ga 0 .7 Al 0.9 Ga 0.1 area should As layer enters the upper multilayer reflection film 8 of As layer 7 Are inserted at a discrete interval, and this AlA
The s layer 7 is selectively oxidized from the periphery of the semiconductor pillar except for the central portion to form a light confinement layer 6 having a current confinement function, and an intermittent light confinement layer is provided in the upper multilayer reflection film 8. It is characterized by. That is, this laser device
n formed on an n-type gallium arsenide (GaAs) substrate 1
-Type Al _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As lower semiconductor multilayer reflective film 2, lower spacer layer 3 made of undoped Al _0.6 Ga _0.4 As, and undoped Al _0.11 Ga
_A quantum well active layer 4 composed of a _0.89 quantum well layer and an undoped Al _0.3 Ga _0.7 As barrier layer;
_An upper spacer layer 5 made of _0.6 Ga _0.4 As and a p-type Al
_{A 0.9} Ga _0.1 As / Al _0.3 Ga _0.7 As upper semiconductor multilayer reflective film 8 and a p-type GaAs contact layer 9 are sequentially laminated, and are etched to a depth reaching the active layer 4 to form the post 13. . And Cr on the surface
The p-side electrode 10 made of / Au is formed to form a circular frame, and the n-side electrode 11 made of Au-Ge / Au is formed on the back surface of the substrate.

Here, the n-type lower semiconductor multilayer reflective film 2
-Type Al _0.9 Ga _0.1 As layer and n-type Al _0.7 Ga _0.3 AsGa
An As layer is formed by laminating about 40.5 cycles each with a thickness of λ / (4n _r ) (λ: oscillation wavelength, n _r : refractive index of medium), and the silicon concentration is 2 × 1
0 ¹⁸ cm ^-3 . The lower spacer layer is made of undoped A
It consists l _{0 .6} Ga _0.4 As layer, the quantum well active layer, Al _{0. 11} Ga _0.89 quantum well layer of undoped (thickness 8 nm × 3) and undoped Al _0.3 Ga _0.7 As barrier layer (film The upper spacer layer is composed of undoped Al _0.6 Ga _0.4 As, and the total film thickness is an integral multiple of λ / n _r . The lowermost layer of the upper semiconductor multilayer reflective film 8 is a p-type AlAs layer 7, and the AlAs layer 7 is inserted at intervals in a region where the Al _0.9 Ga _0.1 As layer is to enter, and the film thickness λ / (4n _r )
And the carbon concentration is 3 × 10 ¹⁸ cm ⁻³ . Also,
The upper semiconductor multilayer reflective film 8 is made of p-type Al _0.9 Ga _0.1 As
A layer and a p-type Al _0.7 Ga _0.3 AsGaAs layer are alternately laminated with a film thickness of λ / (4n _r ) (λ: oscillation wavelength, n _r : refractive index) for 30 periods.
The carbon concentration is 3 × 10 ¹⁸ cm ⁻³ . Finally, the p-type contact layer 9 has a thickness of 5 nm and a carbon concentration of 1 × 10
^{It is 20} cm ^-3 .

Next, the manufacturing process of this surface emitting semiconductor laser will be described.

First, n-type Al _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As is deposited on a silicon-doped n-type GaAs (100) substrate 1 by metal organic chemical vapor deposition (MOCVD).
A lower semiconductor multilayer reflective film 2 and undoped Al _0.6 Ga
A lower spacer layer 3 of _0.4 As and an undoped A
l _0.11 Ga _0.89 quantum well layer and undoped Al _0.3 Ga _0
.7 a quantum well active layer 4 composed of an As barrier layer, an upper spacer layer 5 composed of undoped Al _0.6 Ga _0.4 As,
The p-type Al _0.9 Ga _0.1 As / is a p-type Al _0.9 Ga _0.1 As / layer in which the AlAs layer 7 is inserted at intervals in the region where the Al _0.9 Ga _0.1 As layer should enter.
Al _0.3 Ga _0.7 As upper semiconductor multilayer reflective film 8 and p-type G
An aAs contact layer 9 is laminated.

Then, a resist mask is formed on the crystal growth layer by photolithography, and the surface of the active layer 4 is etched by reactive ion etching using boron trichloride and chlorine gas as an etching gas. A post (semiconductor pillar) 13 is formed.

Thereafter, a heat treatment is performed at 420 ° C. for 10 minutes under steam, and the intermittently formed AlAs layer 7 is oxidized into an Al ₂ O ₃ layer 6. At this time, it can be considered that the oxidation rate of the other layers of the semiconductor multilayer reflective film is significantly lower than that of AlAs and hardly oxidizes.

Next, if necessary, a polyimide film or the like is applied, the periphery of the semiconductor pillar is filled, the surface is flattened, and an electrode is formed.

Here, the reason why the number of periods of the upper semiconductor multilayer reflective film 8 is made smaller than the number of periods of the lower semiconductor multilayer reflective film 2 is to take out outgoing light from the upper surface of the substrate with a difference in reflectance. is there. The kind of the dopant is not limited to those used here, and selenium,
If it is a p-type, it is also possible to use zinc or magnesium. The period is determined depending on whether the light extraction direction is taken on the front surface side or the rear surface side, and the reflectance increases as the period increases. Upper DBR 8 and p-side electrode 9
An interlayer insulating film such as SiOx, SiNx, SiON, polyimide or the like may be inserted between them to insulate the p-side electrode 9 from the upper semiconductor multilayer reflective film 8. The current path 12 is formed by increasing the resistance of the AlAs layer 7 by selective oxidation, has a circular shape in plan view, and has a three-dimensional columnar shape. Similarly, an optical confinement layer is formed in the n-type DBR. May be. Here, it was designed to extract a laser beam having an oscillation wavelength λ: 780 nm.

According to this configuration, a region for changing the reflectance for controlling the polarization plane is intermittently provided from the vicinity of the active region to the emission port, thereby providing a high-efficiency current confinement effect and providing a polarization plane. The size of the reflectance change region formed to control the wavelength can be controlled with high accuracy, and an effective waveguide can be efficiently formed. Further, since the waveguide guides the light to the emission port while maintaining the light propagation space of the same size as the light emitting unit, the lateral mode of the light from the active layer and the stability of the polarization plane at a low threshold value are reduced. Enhanced. Further, since the generated heat can be radiated to the DBR 8 forming the semiconductor pillar having a relatively large volume, the heat generation is suppressed, and the transverse mode and the polarization plane of light are stabilized without deteriorating the optical output characteristics over a wide output range. It becomes possible.

Each semiconductor layer is formed by metal organic chemical vapor deposition,
It may be formed by a molecular beam epitaxy (MBE) method or the like.

The operation of the surface-emitting type semiconductor laser device thus manufactured is as follows. Here, the path of the carrier injected from the p-side electrode 10 is an intermittently formed aluminum oxide layer (reflectance change region).
The carrier injected into the quantum well layer emits light by electron-hole recombination, and this light is reflected by the upper and lower semiconductor multilayer reflective films, and when the gain exceeds the loss, the laser is emitted. Oscillation occurs. At this time, it is led to the area surrounded by the intermittently formed reflectance change area,
The oscillation laser light is emitted from the window of the p-side electrode 10 provided on the substrate surface.

The shape of the post, the shape of the aperture, and the shape and size of each electrode are not limited to these, and can be changed as appropriate.

For example, as shown in FIG. 2 as a second embodiment of the present invention, the post is constituted by a square pole, and the aperture is
The ratio of the short axis to the long axis may be a rectangle of 5: 6 to 1: 6. Thereby, it is possible to perform better polarization control. FIG. 2 is a top view, a sectional view in the X-axis direction and a sectional view in the Y-axis direction of a surface emitting semiconductor laser device according to a second embodiment of the present invention.

Next, a surface emitting semiconductor laser device according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a top view, a cross-sectional view in the X-axis direction, and a cross-sectional view in the Y-axis direction of a surface emitting semiconductor laser device according to a third embodiment of the present invention.

In the first and second embodiments, the aperture diameter of the intermittently formed aluminum oxide layer (reflectance change region) is fixed, but in this example, as shown in FIG. It is characterized in that it is formed so as to gradually spread in the emission direction. The other configuration is formed in exactly the same manner as in the first and second embodiments.

[0039] The surface-emitting type semiconductor laser device, p-type _{Al 0.9 Ga 0.1 As / Al 0.3} Ga 0 .7 upper multilayer reflection film 28 consisting of As Al _0.9 Ga _0.1 the area to As layer enters Al _x Ga _{The 1-x} As (x = 0.96 to 1) layers 27 are inserted at discrete intervals, and the Al _x Ga _1-x As layers 27 are selectively oxidized from the periphery of the semiconductor pillar except for the center,
A light confinement layer 26 having a current confinement function is formed, and an intermittent light confinement layer is provided in the upper multilayer reflection film 8. Here, Al _x Ga _{1 -x} As (x = 0.96
-1) In the layer 27, x gradually decreases toward the light exit port, and the aperture diameter gradually increases toward the light exit port.

That is, this laser device is an n-type Al-arsenide (GaAs) substrate formed on an n-type gallium arsenide (GaAs) substrate 21.
_0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As Lower semiconductor multilayer reflective film 22, lower spacer layer 23 made of undoped Al _0.6 Ga _0.4 As, undoped Al _0.11 Ga _0.89
A quantum well active layer 24 comprising a quantum well layer and the undoped Al _0.3 Ga _0.7 As barrier layer, an undoped Al _0.6
An upper spacer layer 25 made of Ga _0.4 As;
_{A 0.9} Ga _0.1 As / Al _0.3 Ga _0.7 As upper semiconductor multilayer reflective film 28 and a p-type GaAs contact layer 29 are sequentially laminated and etched to a depth reaching the active layer 24 to form the post 33. . A p-side electrode 30 made of Cr / Au is formed on the front surface so as to form a rectangular frame, and Au-Ge /
An n-side electrode 31 made of Au is formed.

Here, Al _x Ga _{1 -x} As (x = 0.96 to
1) The layer 27 is formed such that x gradually becomes smaller as it goes toward the light emission port, and is selectively oxidized to form an aluminum oxide layer leaving an aperture. In this method, the oxidation rate increases as the aluminum content, that is, x, increases by ordinary selective oxidation using water vapor, and the diameter of the aperture remaining without being oxidized gradually increases toward the light emission port. Actually, it is a rectangle having a ratio of the short axis to the long axis of 5: 6 to 1: 6. Then, it becomes a mold that is open upward in three dimensions.

Here, the n-type lower semiconductor multilayer reflection film 22, lower spacer layer 23, quantum well active layer 24, upper spacer layer 25, and upper semiconductor multilayer reflection film 28 are the same as those in the first and second embodiments. Has a composition.

Here, the design was also made so as to extract a laser beam having an oscillation wavelength λ: 780 nm. According to this configuration, a region for changing the reflectance for controlling the polarization plane is provided intermittently from the vicinity of the active region to the emission port, thereby providing a highly efficient current confinement effect and controlling the polarization plane. Therefore, the size of the reflectivity change region formed can be controlled with high accuracy, and an effective waveguide is formed efficiently. Further, the waveguide is provided with a DBR 8 without gradually increasing the planar size of the light propagation space from the light emitting portion.
The waveguide opening upward inside the DBR is formed with good uniformity in the DBR, and the stability of the transverse mode of light from the active layer and the polarization plane can be enhanced at a low threshold. In addition, the generated heat is used to form a DBR that forms a relatively large volume semiconductor pillar.
8, heat generation is suppressed, and the lateral mode of light without deteriorating light output characteristics over a wide output range.
It is possible to stabilize the plane of polarization.

When it is desired to obtain a polarized wave along the BB axis direction, the p-side electrode may be formed to have a rectangular shape elongated in the AA axis direction.

In this example, since the current distribution in the BB axis direction is narrowed, light polarized in the BB axis direction can be obtained.

In the above embodiment, a GaAs / AlGaAs-based semiconductor was used as a material constituting the quantum well active layer. However, the present invention is not limited to this. For example, a GaAs / InGaAs-based or InP /
It is also possible to use an InGaAsP-based semiconductor. Needless to say, the present invention can be realized by another method within a range satisfying the constituent requirements of the present invention.

[0047]

As described above, according to the present invention, a reflective film layer having a high-efficiency current confinement effect and having a portion for changing the reflectivity to form an optical waveguide is provided. Since it is provided intermittently from the vicinity of the photoactive region to the emission port, it is possible to form an effective waveguide with uniformity, controllability, and high reproducibility.

Further, when the regions having different reflectivities are formed so that the cross-sectional shape as viewed from the direction perpendicular to the semiconductor substrate forms a rectangle having a short side and a long side, the transverse mode can be stabilized. However, the polarization plane can be controlled efficiently.

Further, since the waveguide maintains the light propagation space of the same size as the light emitting portion and guides the light to the emission port, the stability of the polarization plane of the light from the active layer can be enhanced at a low threshold. . In addition, since the generated heat can be radiated to the mesa structure having a relatively large volume, heat generation can be suppressed, and the polarization plane can be stabilized without deteriorating the optical output characteristics over a wide output range.

Further, since the aperture diameter of the light confinement layer is increased as the distance from the active region increases, it is possible to obtain a low-resistance, high-efficiency current confinement effect, and a space for transmitting light from the light emitting portion. A waveguide having a shape gradually opening upward is formed with good uniformity in the DBR without a sudden increase in the planar size of the laser, and the stability of the polarization plane of light from the active layer at a low threshold value Can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface emitting semiconductor laser device according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a surface emitting semiconductor laser device according to a second embodiment of the present invention;

FIG. 3 is a diagram showing a surface emitting semiconductor laser device according to a third embodiment of the present invention;

FIG. 4 is a diagram showing a conventional surface emitting semiconductor laser device;

FIG. 5 is a diagram showing a surface-emitting type semiconductor laser device according to a conventional example.

FIG. 6 is a diagram showing a surface-emitting type semiconductor laser device according to a conventional example.

[Explanation of symbols]

Reference Signs List 1 n-type gallium arsenide (GaAs) substrate 2 n-type lower semiconductor multilayer reflective film 3 lower spacer layer 4 active layer 5 upper spacer layer 6 AlAs layer 8 upper semiconductor multilayer reflective film 9 p-type GaAs contact layer 10 p-side electrode 11 n side Electrode 12 Current path 13 Post 21 n-type gallium arsenide (GaAs) substrate 22 n-type lower semiconductor multilayer reflective film 23 lower spacer layer 24 active layer 25 upper spacer layer 26 Al _x Ga _1-x As layer 28 upper semiconductor multilayer reflective film 29 p-type GaAs contact layer 30 p-side electrode 31 n-side electrode 32 current path 33 post

Claims (4)

[Claims] 1. A surface emitting laser in which an active layer is sandwiched between upper and lower semiconductor multilayer reflective films and an optical resonator is formed in a direction perpendicular to a substrate surface, wherein at least the upper semiconductor multilayer reflective film has an active layer. Characterized in that a plurality of reflective film layers, each of which forms a region having a different reflectance from the surrounding region with respect to the light emitted from the light source, are intermittently arranged so as to be separated from each other by at least two layers. Semiconductor laser device. 2. The semiconductor device according to claim 1, wherein the regions having different reflectivities have a rectangular cross section having a short side and a long side when viewed from a direction perpendicular to the semiconductor substrate. The surface-emitting type semiconductor laser device according to the above. 3. A first light confinement layer having a light confinement region in which the semiconductor multilayer reflective film has an aperture formed of a region having a lower reflectance than the surrounding region with respect to emitted light. A second light confinement layer having a light confinement region having an aperture diameter larger than that of the first light confinement layer, and a third light confinement layer having a light confinement region having a larger aperture diameter move away from the active layer. 2. The surface emitting semiconductor laser device according to claim 1, wherein the surface emitting semiconductor laser device is formed to be spaced apart. 4. A lower semiconductor multilayer reflective film on a semiconductor substrate,
A lower spacer layer, an active layer, and an upper spacer layer, and at least an upper semiconductor formed so as to include an Al _x Ga _{1 -x} As layer intermittently so that x gradually becomes smaller toward the light emitting port direction. Sequentially stacking a multilayer reflective film, and exposing the Al _x Ga _1-x As layer to a cross section,
Forming a semiconductor pillar having a desired shape; and forming the Al _x exposed from a cross section or a periphery of the semiconductor pillar.
The gas containing water vapor is brought into contact with the Ga _1-x As layer,
an oxidizing step of oxidizing the l _x Ga _1-x As layer, wherein at least the upper semiconductor multilayer reflective film has a reflectance and a peripheral region with respect to the light emitted from the active layer toward the light exit opening. A method of manufacturing a surface-emitting type semiconductor laser device, wherein a reflection film layer having different opening regions is intermittently formed.