JPH0439985A - Light beam deflector - Google Patents

Abstract

PURPOSE:To obtain a high-performance deflector which maintains the variability of beam deflection, and simultaneously compensates coupling loss and carrier loss by enabling the change in a refractive index and the amplification degree of light beam to be controlled independently. CONSTITUTION:On a single conductor type semiconductor substrate 11, there are laminated a conductor type optical guide layer 13, an opposite conductor type spacer layer 14, a single conductor type optical amplifier layer 15 where a band gap is either smaller or equivalent to the optical guide layer, a one conductivity type clad layer 16 by way of a secondary or higher-order diffraction grating 12. Then, electric current is independently injected into the layer 13 and the layer 15 with power sources V1 and V1 where input light is arranged to enter from the end face of the laminated layer while output light is plane-discharged from the surface of the clad layer. The band filing effect of the layer 13 by the injection current of the power source V1 with its plasma effect reduces the refractive index and changes an angle theta of discharge beam from its vertical direction. Furthermore, the gain of the optical amplification layer can be controlled with the injection current based on the power supply V2. It is, therefore, possible to obtain a high-performance light beam deflector which compensates coupling loss and carrier loss by controlling the power sources V1 and V2.

Description

[Detailed description of the invention] 〔overview〕 Concerning surface pair type optical beam deflector.

coupling loss while maintaining beam deflection variability.

The purpose is to provide a high-performance optical beam deflector that compensates for propagation loss.

■) - Conductive light guide layer (1
39 Opposite conductivity type spacer layer α4. having one conductivity type optical amplification layer α and one conductivity type rad layer αG having a bandgap smaller or equal to that of the optical guide layer, and injecting current into the optical guide layer and the optical amplification layer independently; The input light is input from the end face of the laminated structure, and the output light is output from the surface of the cladding layer.

2) at least one of the light guide layer and the light amplification layer;
One is configured to have a multiple quantum well structure.

[Industrial application field]

The present invention relates to a surface pair type optical beam deflector.

With the recent development of optical communication networks, it is desired to realize a deflector that spatially deflects a light beam.

A light beam deflector with a variable deflection angle is an essential element for IXN's space division type optical switch and NXN's cross-sectional switch, and there is a demand for a variable deflector with low loss.

The present invention can be used as a deflector that fulfills this desire.

[Conventional technology]

A method of mechanically moving a mirror is known as a conventional deflector, but in this case, the optical system is large and there are mechanically movable parts, so there are problems with reliability.

For this purpose, a deflector using a semiconductor and having the structure shown in FIG. 3 has been proposed.

FIGS. 3(a) and 3(b) are a sectional view and an equivalent circuit diagram of a conventional semiconductor deflector.

In the figure, 21 is a p-type (p-) GaAs substrate.

22 is a p-AlGaAs cladding layer, 23 is a non-doped GaAs layer, 24 is an n-type (n-) AlGaAs optical guide layer, 25 is a diffraction grating, and 26 is an n-AlGaAs cladding layer.

This structure inputs light from the end face and is made of n-AlGaAs
Light output is emitted into space in a vertical direction from the surface of the cladding layer 26, and the refractive index is changed by current injection in order to change the emission angle.

[Problem to be solved by the invention]

Basically, the conventional structure described above was not practical because the gain also changes greatly when the refractive index is changed by current injection.

The present invention maintains the variability of beam deflection.

The purpose of this invention is to provide a high-performance optical beam deflector that compensates for coupling loss and propagation loss.

[Means to solve the problem]

What is the solution to the above problem?

(2) - Light guide layer 19 of one conductivity type and spacer layer α4 of opposite conductivity type sequentially laminated on a conductivity type semiconductor substrate (11) via a second-order or higher order diffraction grating (12). One conductivity type optical amplification layer α9 whose bandgap is smaller than or equal to that of the optical guide layer. - having a conductive cladding layer αG, in which current is independently injected into the optical guide layer and the optical amplification layer, input light is input from the end face of the laminated structure, and output light is emitted from the surface of the cladding layer; 2) a light beam deflector for extracting light beams in pairs;
This is achieved by the optical beam deflector described in ).

[Effect]

FIGS. 1(a) and 1(b) are diagrams explaining the principle of the present invention and an equivalent circuit diagram.

In the figure, 11 is a p-1nP substrate.

12 is a high-order diffraction grating of second order or higher.

13 is a p-1nGaAsP (band gap El) optical guide layer.

14 is an n-InP spacer layer.

15 is a p-InGaAsP (band gap E2) optical amplification layer.

(Ez≦E1).

16 is a p-1nP cladding layer.

Here, the above condition E2≦E1 was adopted for the following reason.

This is because the optical amplification layer amplifies incident light.

The band gap E2 is set to correspond to the wavelength λ2 of the incident light.

On the other hand, the light guide layer must have as little loss (light absorption) as possible for the incident light.Therefore, the bandgap E1 of the light guide layer must be made sufficiently thicker than E2. For example, since there is little change in the refractive index due to current injection, some light absorption remains, but at a slightly shorter wavelength than the wavelength λ2 of the incident light.

That is, the bandgap E corresponding to the wavelength λ2 of the incident light
Set E+ slightly larger than 2 to make the refractive index change thicker (
do.

As shown in the figure, two power supplies V, , V control the injection currents of the lower partial section and the upper amplifier section.

Now, let θ be the angle of the emitted beam from the vertical direction.

kosinθ=β−K.

However, ko=2π/λ.

β = n * t + k o, K = 2 M / A.

Here λ: wavelength of incident light A: Diffraction grating pitch : Absolute value of lattice vector β: propagation constant na, t: equal polarized refractive index It is.

With the current injected by the power supply vl, the refractive index n*ff decreases due to the band filling effect of the optical guide layer and the plasma effect, and θ
can be changed.

Since the gain of the optical amplification layer can be controlled by the current injected by the power source v2, a high-performance optical beam deflector that compensates for coupling loss and propagation loss can be obtained by appropriately controlling the power source VllV2.

〔Example〕

FIG. 2 is a perspective view illustrating a light beam deflector according to an embodiment of the present invention.

Here, an optical beam deflector and amplifier in which the optical input and optical output wavelengths are 1.55 μm will be described.

The structure will be explained below along with an overview of the manufacturing process.

In fig.

First, a second-order diffraction grating of A to 5000 is formed on a p-InP substrate II.

in addition.

p-1nGaAsP light guide layer (λPL-1, 3μm, thickness 0.2.czm) 1
3゜n-InP spacer layer (thickness 0.5 μm) 14゜p-1nGaAsP optical amplification layer (λPL~1.55μm, thickness 0.2μm) 15゜p
-1nP cladding layer (thickness 0.5 μm) 16 is grown.

Here, the composition of the quaternary compound 1nGaAsP is expressed by the photoluminescence wavelength λ and L.

Next, using the SiO□ film as an etching mask, 3 widths of 1.
Mesa etching is performed until it reaches the p-InP substrate 11 in a stripe shape of 5 to 10 μm.

After that, the n-InP layer 17. p-1nP layer 18゜p
”-InGaAsP contact layer 19 is buried in this order.

Thereafter, the p''-1nGaAsP contact layer 19 and p-InP layer 18 on one side of the stripe were removed by etching.

An n electrode (AuGe/
Au) is formed.

A p electrode (AuZn/Au or T
i/Pt/Au).

A p-electrode is also formed on the back surface of the p-InP substrate 11 as the electrode 1 .

Note that the end face is covered with an AR film (SiN film).

A current is injected into the light guide layer using electrodes 1 and 2, and the refractive index n1.
, to control. On the other hand, it is possible to control the gain by injecting current into the optical amplification layer using the electrodes 3 and 2.

In the above example, p-InGaAsP (λpt
, ~1.3 μm) light guide layer 13. p-InGaA
Although a single layer is used for the sP (λPL-1, 55 μm) optical amplification layer 15, at least one of them may have a multi-quantum well structure, for example, as shown below.

Light guide layer: thickness 70 μm)-InGaAsP (λPL ~ 1.4
μm) layer with 10 layers.

9 layers of IOO thick InP layer Each layer is laminated alternately.

Light amplification layer: 10 p-1nGaAs layers with a thickness of 70 mm.

100 nm thick p-1nGaAsP (λPL-1,1,
czm) layers are laminated alternately.

Here, the number of nine layers is desirably about 3 to 20.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to independently control the change in the refractive index (change in the emission angle of the light beam) and the amplification degree of the light beam, and when the beam is deflected as in the past, the output This makes it possible to prevent changes in the

As a result, the beam deflection remains variable.

A high-performance optical beam deflector that compensates for coupling loss and propagation loss can be obtained.

15 is a p-1nGaAsP (band gap E2) optical amplification layer.

(E2≦E1).

16 is p-InP cladding layer

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are diagrams explaining the principle of the present invention and other circuit diagrams. FIG. 2 is a perspective view illustrating a light beam deflector according to an embodiment of the present invention. FIGS. 3(a) and 3(b) are a sectional view and other circuit diagrams of a conventional semiconductor deflector. In fig. 11 is a p-InP substrate. 12 is a high-order diffraction grating of second order or higher. 13 is a p-InGaAsP (bandgap B+) optical guide layer. 14 is an n-1nP spacer layer. (CA) (b) Diagram for explaining the present invention and other circuit diagrams Figure 1 Practical Rinto inkstone diagram of the 4th bow Figure 2 Cross-sectional view of the damaged row A and answers A surface circuit Nissin 3 Flash

Claims (1)

[Claims] 1) A light guide layer (13) of one conductivity type laminated in order on a semiconductor substrate (11) of one conductivity type via a diffraction grating (12) of a second or higher order, and a light guide layer (13) of an opposite conductivity type. a spacer layer (14), an optical amplification layer (15) of one conductivity type whose bandgap is smaller or equal to that of the optical guide layer, and a cladding layer (15) of one conductivity type.
6), injecting current into the optical guide layer and the optical amplifying layer independently;
A light beam deflector, characterized in that input light enters from the end face of the laminated structure, and output light is emitted from the surface of the cladding layer to be taken out. 2) at least one of the light guide layer and the light amplification layer;
Claim 1, characterized in that one has a multiple quantum well structure.
The optical beam deflector described.