JP2741292B2 - Surface emitting semiconductor laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a surface emitting semiconductor laser.

[0002]

2. Description of the Related Art In general, a surface emitting semiconductor laser having a resonator perpendicular to a substrate, that is, emitting light in a direction perpendicular to the substrate, has difficulty in controlling the polarization direction. For example, in the 38th Spring Meeting of 1991 Applied Physics Related Lectures, p. As shown in 1011, 31a-D-3, it has been shown that three types of polarization characteristics can be obtained with respect to the crystal orientation of the substrate, and the main cause is that the asymmetry of the buried shape is increased. However, it is difficult to control the embedded shape to the extent that the polarization direction can be controlled.

[0003]

As described above, the conventional surface emitting semiconductor laser having a vertical resonator has a problem that it is difficult to control the polarization direction. An object of the present invention is to provide a surface emitting semiconductor laser having a vertical resonator capable of controlling the polarization direction.

[0004]

According to the present invention, in a surface emitting semiconductor laser having a resonator perpendicular to a substrate, the substrate is a semiconductor substrate having a surface in a (110) direction. A semiconductor multi-layer reflecting mirror is formed on a substrate, comprising a multiple quantum well in the (110) direction of a semiconductor having a zinc blende type crystal structure and having a different refractive index with respect to the direction of linearly polarized light in the plane of the substrate. Is obtained. Further, according to the present invention, a first conductivity type clad layer, an active layer, and a second conductivity type clad layer are sequentially formed on a substrate, and a current constriction layer is formed in a removed portion of the second conductivity type clad layer. In a surface emitting semiconductor laser having a current constriction structure having a resonator perpendicular to the substrate, the substrate is a semiconductor substrate having a plane in a (110) direction, and a zinc-blende crystal is provided on the semiconductor substrate. A surface emitting semiconductor laser characterized by forming a semiconductor multilayer reflecting mirror comprising a multiple quantum well in the (110) direction by a semiconductor having a structure and having a different refractive index with respect to the direction of linearly polarized light in the plane of the substrate. Can be Further, according to the present invention, [1be
A surface-emitting semiconductor laser characterized in that it oscillates with respect to light linearly polarized in the [r 10] direction. Furthermore, according to the present invention, a surface emitting semiconductor laser characterized in that laser light is emitted for light linearly polarized in the [001] direction.

[0005]

In the quantum well layer in a predetermined direction except for the (001) direction and the (111) direction, the oscillator intensity of the optical transition with respect to the linearly polarized light traveling in the vertical direction becomes anisotropic. That is, in the active layer in which the quantum well is formed, the gain is large for light linearly polarized in a specific direction, and only the light linearly polarized in this direction oscillates. Moreover, in a semiconductor multilayer film reflecting mirror in which a quantum well is formed, the refractive index varies depending on the direction of linearly polarized light (in-plane direction of the substrate), and the resonance condition is satisfied only for light linearly polarized in a specific direction. Only laser light linearly polarized in this direction oscillates.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. First, the following layers were grown on an n-type GaAs (110) substrate 11 by metal organic vapor phase epitaxy. The grown layers are Al _0.2 Ga _0.8 As / AlAs (25 pairs) in order from the bottom.
n-type semiconductor multilayer film 12, Al _0.35 Ga _0.65 As n-type cladding layer 13 (0.5 μm), GaAs / Al _0.35 G
a _0.65 As multiple quantum well p-type active layer 14 (1.0 μm
m), Al _0.35 Ga _0.65 As p-type cladding layer 15
(0.5 μm), and Al _0.2 Ga _0.8 Asp type cap layer 16 (0.5 μm). Here, the active layer 14
Is an AlGaAs layer having a thickness of 5 nm and an Al composition of 35%;
This is a multiple quantum well in the (110) direction composed of a GaAs layer having a thickness of 5 nm. Next, an SiO ₂ mask having a diameter of 7 μm was formed at the center of the surface of the cap layer 16, and the p-type cladding layer 15 was etched by reactive ion etching so that the active layer 14 was not exposed. Then, after the etching, the n-type GaAs layer 1 was used as a current constricting layer.
7 was grown selectively at 0.7 μm, and the p-type GaAs layer was grown at 0.3 μm. As described above, the surface emitting semiconductor laser of this embodiment has a multiple quantum well in the (110) direction.
In this multiple quantum well in the (110) direction, [1ber 1
The oscillator strength of the optical transition for the light linearly polarized in the [0] direction is about 1.2 times as large as the oscillator strength of the optical transition for the light linearly polarized in the [001] direction. Therefore,
In this surface emitting semiconductor laser, only light linearly polarized in the [1ber 10] direction oscillated. Note that [1ber 1
0] is as shown in the following chemical formula 1.

[0007]

[1ber 10] = [10]

Next, a second embodiment of the present invention will be described. This embodiment has the same configuration as that of the first embodiment.
l _0.2 Ga _0.8 As / AlAs (25 pairs) Instead of the Al _0.2 Ga _0.8 As film of the n-type semiconductor multilayer film 12, Al
_{A 0.1} Ga _0.9 As / Al _0.35 Ga _0.65 As multiple quantum well was grown. That is, (110)
Directional quantum wells were formed. Also, GaAs / Al _0.35
Ga _0.65 As Multiple Quantum Well Instead of the p-type active layer 14,
A p-type Al _0.1 Ga _0.9 As was grown. As described above, in the second embodiment, (11)
A quantum well in the 0) direction is formed.
In the quantum well in the direction, the refractive index differs with respect to the direction of linearly polarized light in the plane of the substrate. As a result, the resonance condition is satisfied for light linearly polarized in a specific direction (in-plane direction of the substrate), and only light linearly polarized in that direction oscillates.
The specific direction is determined by the film thickness of the semiconductor multilayer film. In this embodiment, the film thickness is such that the laser beam oscillates with respect to the light linearly polarized in the [1ber 10] direction. As described above, the polarization direction can be controlled in both the first embodiment and the second embodiment. In the above embodiment, an AlGaAs surface emitting semiconductor laser has been described. However, if a part of the active layer or the semiconductor multilayer film reflecting mirror is a semiconductor having a zinc blende type crystal structure, an AlGaInP type and a GaIn
The present invention can be applied to surface emitting semiconductor lasers of the III-V group and the II-IV group such as AsP. Further, in the above embodiment, the surface emitting semiconductor laser that emits light from the growth surface side has been described, but the present invention can be similarly applied to a surface emitting semiconductor that emits light from the substrate side. Further, in the above embodiment, the semiconductor multilayer film reflecting mirror is provided on the substrate side, but may be provided on the surface side. Furthermore, in the above-described embodiment, the surface-emitting semiconductor laser having the current constriction structure has been described. However, any surface-emitting semiconductor laser having a resonator perpendicular to the substrate may be used, even if the surface-emitting semiconductor laser has an embedded structure. Good. Further, in the second embodiment, the example in which the laser light linearly polarized in the [1ber 10] direction is oscillated has been described. However, by changing the thickness and composition of the semiconductor multilayer film, the laser light is linearly polarized in the [001] direction. You can do so.

[0009]

According to the present invention, a surface emitting semiconductor laser that emits laser light whose polarization direction is controlled can be obtained by forming a quantum well in an active layer or a multilayer reflector.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a first embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 11 n-type GaAs (110) substrate 12 Al _0.2 Ga _0.8 As / AlAs n-type semiconductor multilayer film 13 Al _0.35 Ga _0.65 As n-type clad layer 14 GaAs / Al _0.35 Ga _0.65 As multiple quantum well p-type active layer 15 Al _0.35 Ga _0.65 As p-type cladding layer 16 Al _0.2 Ga _0.8 As p-type cap layer 17 n-type GaAs layer 18 p-type GaAs layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-55704 (JP, A) Kenichi Iga, Fumio Koyama “Surface emitting laser” Ohmsha (1990) 3 volumes 11p-ZM-5 Spring 1991 Proceedings of the Japan Society of Applied Physics 3rd Volume 31a-D-3 Proceedings of the Annual Meeting of the Physical Society of Japan 46-2! (1991) P.A. 143 28p-C-14

Claims (4)

(57) [Claims] 1. A surface emitting semiconductor laser having a resonator perpendicular to a substrate, wherein the substrate is a semiconductor substrate having a surface in a (110) direction, and a zinc blende type crystal structure is formed on the semiconductor substrate. A surface emitting semiconductor laser comprising a semiconductor multilayer reflector formed of a semiconductor having multiple quantum wells in the (110) direction and having a different refractive index with respect to the direction of linearly polarized light in the plane of the substrate. A first conductive type clad layer, an active layer, and a second conductive type clad layer are sequentially formed on the substrate, and a current constriction layer is formed in a portion where the second conductive type clad layer is removed. In a surface-emitting semiconductor laser having a current constriction structure having a resonator perpendicular to a semiconductor substrate, the substrate is a semiconductor substrate having a surface in a (110) direction, and a semiconductor having a zinc blende type crystal structure is formed on the semiconductor substrate. A multi-quantum well in the (110) direction according to (1) and a semiconductor multilayer reflector having a different refractive index with respect to the direction of linearly polarized light in the plane of the substrate. 3. A laser oscillation for light linearly polarized in the [1ber 10] direction.
The surface emitting semiconductor laser as described in the above. 4. The surface emitting semiconductor laser according to claim 1, wherein laser oscillation is performed for light linearly polarized in the [001] direction.