JPS63194234A - Semiconductor optical deflecting device - Google Patents

Abstract

PURPOSE:To largely deflect the deflection angle of an emitting light beam with a sufficient resolution by controlling a voltage applied to a voltage applying part of a deflecting device by an outer voltage controller. CONSTITUTION:A light beam 20 propagated through the inside of an optical waveguide 10 containing a quantum well layer 13 is emitted to the outside by a diffraction grating 15 and becomes an emitted light 21. When a reverse bias is applied to the laminated body optical waveguide 10 from a voltage controller 19 through electrodes 16, 17, an electric field can be applied effectively to the multiple quantum well layer 13, and the refractive index of that part can be varied. That is, the direction of the emitted light beam can be controlled freely such as the emitted light beam is brought to a scanning motion by varying periodically an applied voltage, or the irradiating position of the emitted light beam is switched in accordance with an output signal from other device connected to a voltage controller 16. In such a way, the deflection angle of the emitting light beam can be enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical deflection device for deflecting laser light used in an optical information processing system.

[Description of prior art]

Conventionally, as this type of optical deflection device, there is a structure shown in FIG. 1, for example (Japanese Patent Application Sho TT-SO64!R3).

The semiconductor optical deflection device shown in the figure has a substrate made of GaAS or the like.
An optical waveguide made of a semiconductor having an electro-optic effect such as GaAJAs is provided on the top, a diffraction grating 3 is formed roughly on the optical waveguide, and electrodes 4 (A, 4B) are provided for applying an electric field onto the optical waveguide λ. are provided, and a voltage control device j is connected to these electrodes.

In the optical deflection device described above, the guided light 6 propagated within the optical waveguide λ is emitted from the substrate surface at a certain angle by the diffraction grating 3. The optical axis angle θ of the light beam 7 emitted from the diffraction grating 3 depends on the refractive index of the optical waveguide 2.

On the other hand, the voltage control device! By applying an electric field to the optical waveguide λ through the electrodes i and 4'B, the refractive index of the optical waveguide λ having an electro-optic effect can be changed. Therefore, the voltage applied to electrode #A, i is controlled by the voltage control device! By controlling this, the output angle of the output light beam 7 can be controlled.

[Problem that the invention seeks to solve]

In the conventional semiconductor optical deflection device described above, since the electro-optic effect is used as a means to change the refractive index of the optical waveguide, the proportion of the refractive index that can be changed is small;
As a result, there is a drawback that the deflection angle of the emitted light beam cannot be made very large.

Specifically, the angle θ of the light beam emitted from the optical waveguide by the diffraction grating is expressed by the following equation.

sinθ−n−mλ/I) (
1) In equation (1), n is the effective refractive index of the waveguide, m is the order of diffraction, λ is the wavelength of light in free space, and p is the period of the diffraction grating. From this, the following equation is obtained.

Δθ/Δn−//CO8θ (2) On the other hand, the ratio Δn/n of the refractive index that can be changed by the electro-optic effect is 0. /%, and θ-approximately 90°
, n-JJ, and the deflection angle Δθ is calculated from the above equation using the value of Δn/n as Δθ-0.2°. Since the beam divergence angle in the optical axis direction of the laser beam emitted by such a diffraction grating is about 0.10, sufficient resolution cannot be obtained with such a small deflection angle as described above.

[Means for solving problems]

In order to solve the above conventional problems, the present invention provides a quantum well structure in a semiconductor optical waveguide, and further provides a voltage application section for applying a vertical Km field to the quantum well structure.

The quantum well structure that can be used in the present invention may be a single quantum well structure consisting of a single potential well layer, or a multiple quantum well structure in which multiple potential well layers are alternately sandwiched between multiple potential barrier layers. do not have.

Two or more semiconductors having different band gaps may be used as the materials constituting the quantum well structure. For example, the potential well layer is formed of GaAs, and the potential barrier layer is formed of AlGaAs.

In the present invention, GaAJA is used as the material constituting the optical waveguide.
In addition to s-based semiconductor crystals, InGaASP-based and AlGa
Semiconductor crystals such as InP-based crystals can also be used.

However, in order to effectively utilize the well-shaped refractive index change caused by the electric field, the energy of the light propagating within the waveguide,
It is desirable that the energy level of the electron in the quantized conduction band formed in the quantum well and the energy of the difference in the energy level of the hole in the valence band are approximately the same.

In the present invention, the quantum well structure may be incorporated into either the core portion or the cladding portion of the optical waveguide, or may be incorporated into the partition portion.

Furthermore, the entire core and/or cladding of the optical waveguide may be completely composed of a quantum well structure.

However, in order to effectively utilize the change in the refractive index of the quantum well layer due to the electric field, it is desirable that the core portion of the optical waveguide be constituted by the multiple quantum well. Further, in the present invention, as a method of applying an electric field perpendicularly to the quantum well structure, for example, a pn junction or a Schottky junction can be used.

[For production]

According to the present invention, since the change in the refractive index of the quantum well structure due to the electric field is larger than the change in the refractive index of a normal bulk, a large deflection angle can be obtained.

For example, in the case of a multiple quantum well structure, /X105■/c
The refractive index changes by about 7% by applying an electric field of m, and this value is expressed as (
2) Substituting into the equation, the deflection angle becomes co0.

The above deflection angle is ten times larger than when using conventional bulk electro-optic effects.

In this way, by controlling the voltage applied to the voltage application section of the deflection device using the external voltage control bag &, the deflection angle of the emitted light beam can be largely deflected with sufficient resolution.

〔Example〕

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a perspective view showing a semiconductor optical deflection device of the present invention, in which 1n Al0 is placed on a substrate made of n+ -GaAs.
0? Gao, 3AS (n −j X/ 0-17cm
-3) Layer 12, undoped multiple quantum well layer 13, P-A
IQ, 5 Ga□, 5as (P-jX1017cm-3
) An optical waveguide 10 is provided in which layers lq are sequentially stacked. The multi-quantum well layer/3 is made of GaASJll/J with a thickness of 100, as shown in the enlarged cross section in FIG.
It is formed by alternately laminating a large number of Alo, 5Ga□, and 5As layers/jB with a thickness of JOOA and a thickness of JOOA. These layers 1.3k, /JB, . . . can be grown by molecular beam epitaxy, organometallic CVD, liquid phase epitaxy, or the like.

A diffraction grating /j is integrally formed in a part of the uppermost AJGaAS layer /l.

The diffraction grating /j can be formed, for example, by photolithography using interference exposure. Furthermore, A
Electrodes /4 and 17 are formed on the front surface of the ltGaAs layer 11 and the back surface of the substrate //, respectively, to form ohmic contact. Electrode #, /7 is conductor wire /r
It is connected to the voltage control device 19 via.

In the above-mentioned optical deflection device, the light beam O that has propagated within the optical waveguide 10 including the quantum well layer 13 is outputted to the outside by the diffraction grating /j and becomes the output beam beam I. Electrode/6. /
7 from the voltage control device 19, the laminated optical waveguide 10
By applying a reverse bias to the multi-quantum well layer 1
An electric field can be effectively applied to the portion 3, and the refractive index of the portion can be changed.

In this way, by controlling the applied voltage by the voltage control device 19, the deflection angle of the emitted light can be controlled.

For example, the output light beam may be scanned by periodically changing the applied voltage, or the irradiation position of the output light beam may be switched according to an output signal from another device connected to the voltage control device lB. The direction of can be freely controlled.

The semiconductor optical deflection device described above allows semiconductor lasers to be easily integrated.

The table shown in FIG. 1 is an example in which a semiconductor optical deflection device and a semiconductor laser according to the present invention are integrated, and the semiconductor laser section 22 provided on the optical waveguide IO is a distributed feedback laser. The multi-quantum well layer 13 can be used as the semiconductor active layer of the laser section λ2, and the diffraction grating for distributed feedback can be formed by the same process as the diffraction grating lj of the optical waveguide IO. It is possible to integrate both.

〔Effect of the invention〕

According to the present invention, the deflection angle of the emitted light beam in the semiconductor optical deflection device can be made larger than that of the conventional device.

Furthermore, integration with other semiconductor elements is also easy.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
FIG. 3 is a perspective view showing an example in which the optical deflection device of the present invention and a semiconductor laser are integrated, and FIG. 4 is a perspective view showing a conventional semiconductor optical deflection device. 10... Optical waveguide lj... Substrate/
2...-n -AIo, 7 Ga□, s As layer 1
3...Multi-quantum well layer 1...P-Am! 0.5 Ga(,,5As
Layer lj... Diffraction grating /l, /7...
Electrode 19... Voltage control device 20...
・Propagating light -7...Outgoing light -Co...Semiconductor laser section Fig. 1 (Example) I-S Fig. 2 (Example) Fig. 3 (Example) 19 Fig. 4 Diagram (Conventional example) Procedural amendment document Japanese Patent Application No. 62-27767 2 Name of the invention Semiconductor optical deflection device 3 Relationship with the person making the amendment Patent applicant address 2-7-4 Nishi-Shinbashi, Minato-ku, Tokyo Name Photonics Research and Development Co., Ltd. Representative Uenohara Pass 4, Agent voluntary 6 Subject of amendment Z Contents of amendment (1) Specification letter page 7! In the line, "n-jXlo-17cm-3J (!: Arunohor
n-jX#717cm-3J Correction. (2) Correct the third figure in the drawing as shown in the attached sheet (reference number 1)
(add 0). that's all

Claims (4)

[Claims] (1) A diffraction grating is provided in the semiconductor optical waveguide, and the light propagating within the waveguide is radiated to the outside of the waveguide through the diffraction grating, and
In an optical deflection device that controls the radiation direction by changing the refractive index of the optical waveguide, a quantum well structure is provided in the optical waveguide, and a voltage is applied to apply an electric field perpendicular to the quantum well structure. What is claimed is: 1. A semiconductor optical deflection device, comprising: a semiconductor light deflecting device, wherein the refractive index of the quantum well structure portion is changed by changing the voltage applied to the voltage applying portion, and the emitted light is deflected. (2) The semiconductor optical deflection device according to claim 1, wherein the material constituting the optical waveguide is a GaAlAs-based semiconductor crystal. (3) The semiconductor optical deflection device according to claim 1, wherein the material constituting the optical waveguide is an InGaAsP-based semiconductor crystal. (4) The semiconductor optical deflection device according to claim 1, wherein the material constituting the optical waveguide is an AlGaInP-based semiconductor crystal.