JP3546628B2 - Surface-emitting type semiconductor laser device - Google Patents

Description

[0001]
TECHNICAL 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]
[Prior art]
A high-density semiconductor laser array is required as a light source for optical communication, optical computers, and the like. The semiconductor laser array is configured to arrange a plurality of semiconductor lasers at an appropriate pitch, control the driving of each semiconductor laser independently, and 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, surface-emitting lasers emit light in a direction perpendicular to the substrate, so that they can be two-dimensionally parallelized on the same substrate, and a high-precision, high-density matrix array can be obtained. It has advantages and looks promising.
[0003]
A vertical cavity surface emitting laser, which is one of the surface emitting lasers, includes an intermediate layer including an active layer and a spacer layer, and two pairs of upper and lower distributed feedback reflectors sandwiching the intermediate layer. And a semiconductor laser that forms a resonator with the DBR and emits light in a direction perpendicular to the substrate. In an edge-emitting laser, the difference between the waveguide loss and the reflectance between the TE (transverse electric mode) mode in which the electric field vector is in the xy plane and the TM (transverse magnetic mode) mode in which the magnetic field vector is in the xy plane. Although there are various factors that determine the polarization, 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 by defining a random direction. Is important.
[0004]
There have been several reports of 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 in which anisotropic gain is provided by an electrode having an anisotropic shape. It has a laser A and a laser B oscillated by two or more divided electrodes, and two polarization directions can be arbitrarily controlled by turning on and off the laser B (Japanese Patent Application Laid-Open No. 4-104). 24289). 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 pass polarized waves parallel to the long side thereof. Further, Applied Physics Letters, Vol. 66, No. 8, pp. 908 to 910 (1995) (Appl., Phys., Lett., Vol. 66, No. 8, p. 908-910, 1995). In Japanese Patent Application Laid-Open No. HEI 8-181391, polarization control is performed by creating a post shape such that an arbitrary set of post side surfaces is parallel and the sides thereof are the longest. is there. As shown in FIG. 4, the laser has a typical VCSEL structure in which a triple quantum well active layer made of indium gallium arsenide (InGaAs) is sandwiched by a gallium arsenide / aluminum arsenide DBR. After forming a rectangular photoresist mask having a short axis in the <110> direction, a part of the upper semiconductor multilayer reflective film is removed by reactive ion beam etching using chlorine gas. Form a post shape. Further, after the active layer except the portion immediately below the post portion is inactivated (increased in resistance) by proton implantation due to current constriction, an anode and a cathode are formed at predetermined positions to complete the active layer. The direction of light emission is on the back side of this substrate.
[0005]
Although it is not intended to control the polarization plane, an example in which a natural oxide film is introduced into a distributed feedback type reflective film to lower the threshold of a surface emitting laser and current confinement is performed is known. Physics Letters, Vol. 65, No. 1, pp. 97-99 (1994) (Appl., Phys., Lett., Vol. 65, No. 1, p. 97-99, 1994). ing. This laser also has a typical VCSEL structure in which a triple quantum well active layer made of InGaAs is sandwiched by a DBR made of GaAs / AlAs, as shown in FIG. However, the p-type DBR is a pair of GaAs / AlAs, and GaAs is located in the upper layer. The process first processes the p-type GaAs layer into a 30 or 60 μm-shaped circle using photolithography and etching. . 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, a region of 2 to 8 μm square remaining without being oxidized is formed. The oxidized region becomes an aluminum oxide compound and hardly allows current to flow, so that current constriction becomes possible. Also, 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 and current constriction is performed is disclosed in IEE Photonics, Technology Letters, Vol. 7, No. 11 , Pages 1234 to 1235 (1995) (IEEE, Photon. Technol. Lett., Vol. 7, No. 11, p. 1234-1236, 1995). As shown in FIG. 6, this laser has upper and lower DBRs formed of a laminated film of GaAs / AlAs. After the DBRs are etched to form posts, all exposed AlAs layers are heated to 400 ° C. Heat treatment in 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 region of 15 to 20 μm square remains without being oxidized. The oxidized region becomes a compound of aluminum oxide and hardly conducts current, so that current confinement is possible. The surface reconnection current is further suppressed, and a low threshold value of 70 μA is realized.
[0006]
[Problems to be solved by the invention]
However, in the gain-guided laser disclosed in Japanese Patent Application Laid-Open No. 4-242989, light is weakly confined and light diverges, and the gain anisotropy given by the change in electrode shape is very small. Therefore, it is considered that the polarization control effect is small. Also, the lasers A and B in which the electrodes are arranged in an L-shape or T-shape have the drawback that the laser beam is deflected by the polarization control. It is necessary to supply 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 large, and that there is a problem that the laser is apt to be symmetrical and 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 doubtful 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 the above-mentioned Applied Physics Letters, the polarization plane is controlled by using the diffraction loss of the DBR. However, the structure includes the recombination of electrons and holes that did not contribute to the light emission. Since the loss is generated as heat, the element having a relatively small post portion does not have sufficient heat dissipation, and the light output characteristics are limited. In fact, the authors of this paper say that even if the shape in the short 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 confinement part smaller than the diameter of the post part due to the restrictions at the time of proton injection. In addition, non-radiative recombination at the interface between the active region and the proton injection region is neglected. Can not. Therefore, the efficiency of carrier injection into the active region is not high, and there is a limit to lowering the threshold voltage.
[0007]
In addition, 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, but the oxidation rate varies. The AlAs layer is oxidized to Al_xO_yIt is self-evident that there is a volume change at the time of change, and this influence affects the activation energy of oxidation. Tended to be.
[0008]
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 optical output characteristics.
[0009]
[Means for Solving the Problems]
Therefore, a feature of the present invention is that, in a surface emitting laser in which an optical resonator is formed in a direction perpendicular to the substrate surface, at least in a semiconductor multilayer reflective film on one side of the active layer, a region surrounding the emitted light is reflected by an area surrounding the active layer. A plurality of reflective film layers having regions with different rates are arranged away from each other from the vicinity of the active layer toward the emission port. That is, in the present invention, in the surface emitting laser in which the active layer is sandwiched between the upper and lower semiconductor multilayer reflective films and the optical resonator is formed in a direction perpendicular to the substrate surface, at least the upper semiconductor multilayer reflective film has the active layer. It is 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 layer, are intermittently arranged so as to be separated by two or more layers.
[0010]
Preferably, the regions having different reflectivities are configured such that a cross-sectional shape viewed from a direction perpendicular to the semiconductor substrate forms a rectangle having a short side and a long side.
[0011]
Also preferably, at least the first semiconductor confinement layer has a light confinement region formed by forming an aperture composed of a region having a lower reflectance than the surrounding region with respect to the outgoing 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 moving away from the active layer, It is characterized by being formed apart from each other.
[0013]
According to the present invention, the reflective film layer having a high-efficiency current confinement effect and having a portion for changing the reflectance to form an optical waveguide is intermittently provided from the vicinity of the photoactive region to the emission port. Since it is provided, it is possible to form an effective waveguide with uniformity, good controllability, and high reproducibility.
[0014]
Further, when the regions having different reflectivities are configured so that the cross-sectional shape viewed from the direction perpendicular to the semiconductor substrate forms a rectangle having a short side and a long side, the polarization mode is stabilized while the transverse mode is stabilized. Can be controlled efficiently.
[0015]
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 increased at a low threshold. Further, since the generated heat can be dissipated to the mesa structure having a relatively large volume, it is possible to suppress heat generation and stabilize the polarization plane without deteriorating the optical output characteristics over a wide output range.
[0016]
Furthermore, since the aperture diameter of the light confinement layer is increased with distance from the active region, the current confinement effect of light efficiency can be obtained, and the planar size of the light propagation space from the light emitting portion can be obtained. Is not spread rapidly, a waveguide that is gradually open upward is formed in the DBR with good uniformity, and it is possible to increase the stability of the polarization plane of light from the active layer at a low threshold. Become.
[0017]
These optical confinement layers are easily formed by selective oxidation of an AlAs or AlGaAs layer. However, when a layer having a large volume change due to oxidation and a thick film is formed, distortion occurs or an aperture diameter is reduced. Although the dimensional accuracy may be reduced, thin layers may be separated and arranged in multiple layers and oxidized, so that there is no problem of distortion due to volume change due to oxidation. Further, since the multiple optical confinement layers are formed apart from each other, the effect is close to a state where the layers are continuously formed.
[0018]
Furthermore, since the waveguides formed by these light confinement layers are arranged to be anisotropic, the 0th-order TE mode determined by the long side of the waveguide cross section in the waveguide is dominant 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.
[0019]
Also, since the divergence angle of the emitted beam increases as the light confinement state increases, not only the current distribution is controlled by a plurality of insulating light confinement layers (consisting of an aluminum oxide layer) whose aperture diameters increase, but also the light emission. Since the waveguide that is open upward is formed in the DBR with good controllability so that the planar size of the propagation space of light from the part does not suddenly spread, the active layer has a low threshold value. The horizontal mode and the polarization plane of the light from the light source can be further stabilized.
[0020]
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.
[0022]
【Example】
Hereinafter, the present invention will be described with reference to the drawings.
[0023]
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]
This surface-emitting type semiconductor laser device has a p-type Al_0.9Ga_0.1As / Al_0.3Ga_{0 . 7}Al of the upper multilayer reflective film 8 made of As_0.9Ga_0.1An AlAs layer 7 is inserted into the region where the As layer is to be inserted at a discrete interval. And an intermittent light confinement layer is provided in the upper multilayer reflection film 8. That is, this laser device is an n-type Al-arsenide (GaAs) substrate formed on an n-type gallium arsenide (GaAs) substrate 1._0.9Ga_0.1As / Al_0.3Ga_0.7As lower semiconductor multilayer reflective film 2 and undoped Al_0.6Ga_0.4Lower spacer layer 3 made of As and undoped Al_0.11Ga_0.89Quantum well layer and undoped Al_0.3Ga_0.7A quantum well active layer 4 comprising an As barrier layer;_0.6Ga_0.4An upper spacer layer 5 made of As and a p-type Al_0.9Ga_0.1As / Al_0.3Ga_0.7The As upper semiconductor multilayer reflective film 8 and the p-type GaAs contact layer 9 are sequentially laminated and etched to a depth reaching the active layer 4 to form the post 13. A p-side electrode 10 made of Cr / Au is formed on the front surface so as to form a circular frame, and an n-side electrode 11 made of Au-Ge / Au is formed on the back surface of the substrate.
[0025]
Here, the n-type lower semiconductor multilayer reflective film 2 is made of n-type Al_0.9Ga_0.1As layer and n-type Al_0.7Ga_0.3The thickness of the AsGaAs layer is λ / (4n_r) (Λ: oscillation wavelength, n_r: Refraction index of the medium) and a silicon concentration of 2 × 10¹⁸cm^-3It is. The lower spacer layer is made of undoped Al._0.6Ga_0.4The quantum well active layer is composed of an undoped Al layer._0.11Ga_0.89Quantum well layer (8 nm thick x 3) and undoped Al_0.3Ga_0.7Combination with As barrier layer (5 nm thick x 4), upper spacer layer is undoped Al_0.6Ga_0.4As, and the total thickness is λ / n_rBe an integral multiple of. The lowermost layer of the upper semiconductor multilayer reflective film 8 is a p-type AlAs layer 7,_0.9Ga_0.1The AlAs layer 7 is inserted at an intermittent period into the region where the As layer is to be inserted, and the thickness λ / (4n_r) And the carbon concentration is 3 × 10¹⁸cm^-3It is. The upper semiconductor multilayer reflective film 8 is made of p-type Al_0.9Ga_0.1As layer and p-type Al_0.7Ga_0.3The thickness of the AsGaAs layer is λ / (4n_r) (Λ: oscillation wavelength, n_r: Refractive index) and alternately laminated for 30 periods, and the carbon concentration is 3 × 10¹⁸cm^-3It is. Finally, the p-type contact layer 9 has a thickness of 5 nm and a carbon concentration of 1 × 10²⁰cm^-3It is.
[0026]
Next, a manufacturing process of the surface emitting semiconductor laser will be described.
[0027]
First, on a silicon-doped n-type GaAs (100) substrate 1, n-type Al is deposited by metal organic chemical vapor deposition (MOCVD)._0.9Ga_0.1As / Al_0.3Ga_0.7As lower semiconductor multilayer reflective film 2 and undoped Al_0.6Ga_0.4Lower spacer layer 3 made of As and undoped Al_0.11Ga_0.89Quantum well layer and undoped Al_0.3Ga_0.7A quantum well active layer 4 comprising an As barrier layer;_0.6Ga_0.4An upper spacer layer 5 made of As;_0.9Ga_0.1P-type Al in which AlAs layers 7 are inserted at intervals in the area where the As layers should enter_0.9Ga_0.1As / Al_0.3Ga_0.7An As upper semiconductor multilayer reflective film 8 and a p-type GaAs contact layer 9 are laminated.
[0028]
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. Column 13 is formed.
[0029]
Thereafter, heat treatment is performed at 420 ° C. for 10 minutes under steam, and the intermittently formed AlAs layer 7 is oxidized to Al₂O₃Turns into 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 slower than that of AlAs and hardly oxidizes.
[0030]
Next, if necessary, a polyimide film or the like is applied, the periphery of the semiconductor pillar is filled, the surface is flattened, and then an electrode is formed.
[0031]
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 make outgoing light from the upper surface of the substrate with a difference in reflectance. The kind of the dopant is not limited to those used here, and selenium may be used for n-type, and zinc or magnesium may be used for p-type. The period is determined depending on whether the light extraction direction is taken on the front surface side or the back surface side, and the reflectance increases as the period increases. An interlayer insulating film made of SiOx, SiNx, SiON, polyimide, or the like may be inserted between the upper DBR 8 and the p-side electrode 9 so that the p-side electrode 9 and the upper semiconductor multilayer reflective film 8 are insulated. The current path 12 is formed by increasing the resistance of the AlAs layer 7 by selective oxidation. The current path 12 has a circular shape in plan view and is a three-dimensional column. Similarly, a light confinement layer is formed in the n-type DBR. May be. Here, it was designed to take out a laser beam having an oscillation wavelength λ: 780 nm.
[0032]
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 precision, and an effective waveguide is formed efficiently. 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 portion, the transverse 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.
[0033]
Note that each semiconductor layer may be formed by a metal organic chemical vapor deposition method, a molecular beam epitaxy (MBE) method, or the like.
[0034]
The operation of the surface emitting semiconductor laser device manufactured as described above is as follows.
Here, the path of the carrier injected from the p-side electrode 10 is defined by an intermittently formed aluminum oxide layer (reflectance change region), and the carrier injected into the quantum well layer is formed by electron-hole recombination. Light is emitted by the coupling, and the light is reflected by the upper and lower semiconductor multilayer reflective films, and laser oscillation occurs when the gain exceeds the loss. At this time, the laser light is guided to a region surrounded by the intermittently formed reflectance change region, and the oscillation laser light is emitted from the window of the p-side electrode 10 provided on the substrate surface.
[0035]
The shape of the post, the shape of the aperture, and the shape and size of each electrode are not limited thereto, and can be appropriately changed.
[0036]
For example, as shown in FIG. 2 as a second embodiment of the present invention, the post is formed of a square pole, and the aperture is formed as a rectangle having a ratio of the short axis to the long axis of 5: 6 to 1: 6. May be. Thereby, it is possible to perform better polarization control. FIG. 2 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 second embodiment of the present invention.
[0037]
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 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 third embodiment of the present invention.
[0038]
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 by being formed so as to gradually spread toward it. Other configurations are formed in exactly the same manner as in the first and second embodiments.
[0039]
This surface-emitting type semiconductor laser device has a p-type Al_0.9Ga_0.1As / Al_0.3Ga_0.7Al of the upper multilayer reflective film 28 made of As_0.9Ga_0.1In the area where the As layer should enter, Al_xGa_1-xAs (x = 0.96 to 1) layers 27 are inserted at discrete intervals, and this Al_xGa_1-xThe As layer 27 is selectively oxidized from the periphery of the semiconductor pillar except for the central portion to form a light confinement layer 26 having a current confinement function, and an intermittent light confinement layer is provided in the upper multilayer reflective film 8. It is characterized. Where Al_xGa_1-xIn the As (x = 0.96 to 1) layer 27, x gradually decreases toward the light exit port, and the aperture diameter gradually increases toward the light exit port.
[0040]
That is, this laser device is an n-type Al-arsenide (GaAs) substrate formed on an n-type gallium arsenide (GaAs) substrate 21._0.9Ga_0.1As / Al_0.3Ga_0.7As lower semiconductor multilayer reflective film 22 and undoped Al_0.6Ga_0.4Lower spacer layer 23 made of As, undoped Al_0.11Ga_0.89Quantum well layer and undoped Al_0.3Ga_0.7A quantum well active layer 24 comprising an As barrier layer;_0.6Ga_0.4An upper spacer layer 25 made of As and a p-type Al_0.9Ga_0.1As / Al_0.3Ga_0.7The As upper semiconductor multilayer reflective film 28 and the 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 an n-side electrode 31 made of Au-Ge / Au is formed on the back surface of the substrate.
[0041]
Where Al_xGa_1-xThe As (x = 0.96 to 1) layer 27 is formed so that x gradually decreases as it goes toward the light exit port, and is selectively oxidized to form an aluminum oxide layer leaving an aperture. You. In this method, the oxidation rate increases as the aluminum content, that is, x, increases by ordinary selective oxidation using water vapor, and the aperture diameter 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 opened upward in three dimensions.
[0042]
Here, the n-type lower semiconductor multilayer reflection film 22, the lower spacer layer 23, the quantum well active layer 24, the upper spacer layer 25, and the upper semiconductor multilayer reflection film 28 have the same composition as in the first and second embodiments. are doing.
[0043]
Also in this case, it was designed 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 precision, and an effective waveguide is formed efficiently. Further, in the waveguide, a waveguide that is gradually upwardly opened in the DBR 8 without abruptly increasing the planar size of the propagation space of the light from the light emitting unit is formed with high uniformity in the DBR. With a low threshold value, the stability of the transverse mode of light from the active layer and the polarization plane can be improved. 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.
[0044]
When it is desired to obtain polarized waves along the BB axis direction, the p-side electrode may be formed to have a rectangular shape elongated in the AA axis direction.
[0045]
In this example, since the current distribution in the BB axis direction is configured to be narrow, light polarized in the BB axis direction can be obtained.
[0046]
In the above embodiment, a GaAs / AlGaAs-based semiconductor was used as a material for forming the quantum well active layer. However, the present invention is not limited to this. Semiconductors can also be used.
Needless to say, the present invention can be realized by another method as long as the constituent features of the present invention are satisfied.
[0047]
【The invention's effect】
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 near the photoactive region. Since it is provided intermittently from to the emission port, it is possible to form an effective waveguide with uniformity, good controllability, and high reproducibility.
[0048]
Further, when the regions having different reflectivities are configured so that the cross-sectional shape viewed from the direction perpendicular to the semiconductor substrate forms a rectangle having a short side and a long side, the polarization mode is stabilized while the transverse mode is stabilized. Can be controlled efficiently.
[0049]
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 increased at a low threshold. Further, since the generated heat can be dissipated to the mesa structure having a relatively large volume, it is possible to suppress heat generation and stabilize the polarization plane without deteriorating the optical output characteristics over a wide output range.
[0050]
Furthermore, since the aperture diameter of the light confinement layer is increased as the distance from the active region is increased, a high-efficiency current confinement effect with low resistance can be obtained, and the planar shape of the light propagation space from the light emitting portion can be obtained. A waveguide whose shape gradually expands upward without increasing its size rapidly is formed in the DBR with good uniformity, and the stability of the polarization plane of light from the active layer at low threshold is improved. Becomes possible.
[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 type 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]
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 posts
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_xGa_1-xAs 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 (3)

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,
A plurality of intermittent reflecting film layers are formed so that at least the upper semiconductor multilayer reflecting film forms a region having a different reflectance from the surrounding region with respect to the light emitted from the active layer. A surface-emitting type semiconductor laser device, characterized in that it is arranged in a uniform manner. 2. The surface-emitting type according to claim 1, wherein the regions having different reflectivities have a cross section viewed from a direction perpendicular to the semiconductor substrate and having a rectangular shape having a short side and a long side. Semiconductor laser device. A first light confinement layer having a light confinement region in which the semiconductor multilayer reflective film forms an aperture formed of a region having a lower reflectance than the surrounding region with respect to the outgoing light, and the first light confinement layer A second light confinement layer having a light confinement region having a larger aperture diameter and a third light confinement layer having a light confinement region having a larger aperture diameter are formed apart from each other as the distance from the active layer increases. 2. The surface-emitting type semiconductor laser device according to claim 1, wherein:

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