JPH0644659B2 - Optical integrated circuit device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical integrated circuit device that can be used as a light source for optical communication and a light source for compact discs.

2. Description of the Related Art Conventionally, when a semiconductor laser is used, in order to obtain a constant light output, light emitted from the rear of the laser is detected by a light receiving element, and the signal is fed back to a laser drive circuit, so-called APC (Automatic Power). Control) operation. Therefore, the light receiving element has to be bonded behind the laser chip. Further, when the reflected light from the light receiving element returns to the laser cavity, the longitudinal mode of the oscillated light becomes unstable. Therefore, care must be taken to prevent the reflected light from returning to the laser cavity. Aside from this, a method of stabilizing the longitudinal mode by utilizing the returning light is also being studied. In order to stabilize these longitudinal modes, a method of providing a reflecting mirror on the outside has been performed.

Problems to be Solved by the Invention As described above, the method of providing the light receiving element in the rear for the APC operation of the laser and the method of providing the external reflecting mirror for stabilizing the longitudinal mode are not reproducible at the time of mounting. Poor and lacking stability.

In view of the above drawbacks, the present invention provides an optical integrated circuit device capable of stabilizing the longitudinal mode with good stability.

Means for Solving the Problems In order to solve the above problems, the optical integrated circuit device of the present invention has a semiconductor laser and a cavity between the semiconductor laser and an insulating film so as to be adjacent to the active layer of the laser. It is configured by forming a Pn junction which becomes a light receiving element.

With this configuration, a part of the light distributed in the active layer of the laser can be detected by the light receiving element, and the signal can be used to detect the APC.
Can perform actions. In addition, internal reflection of light occurs at the interface between the light-receiving element part formed locally adjacent to the laser cavity and the cavity part other than that, forming a composite cavity and stabilizing the longitudinal mode. it can.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are a perspective view and a sectional view of an optical integrated circuit according to an embodiment of the present invention.

1 is a p-type GaAs substrate, 2 is an n-type GaAs layer, 3 is a p-type Ga _1-x Al _x
As clad layer, 4 is a non _- doped Ga _1-y Al _y As active layer, 5 is an n-type Ga _1-x ′ Al _x ′ As clad layer, 6 is an n-type GaAs layer, 7 is a p-side ohmic electrode, and 8 is n. Side ohmic electrode, 9 is a SiO ₂ film that electrically separates the laser and the light receiving element, and 10 is an n-type
GaAs layer, 11 is p-type GaAs layer, 12 is ohmic electrode, 1
3 to 15 are electrode terminals.

The n-type GaAs layer 2 is 1 μm, and the p-type Ga _1-x Al _x As clad layer 3 is
0.3 μm, active layer 4 is 0.1 μm, n-type Ga _1-x ′ Al _x ′ As layer 5
Is 2 μm and the n-type GaAs layer 6 is 2 μm. The SiO ₂ film 9 is located 5 μm from the groove edge of the cladding layer 3 and has a thickness of 3000 Å. The junction between the n-type GaAs layer 10 and the p-type GaAs layer 11 coincides with the active layer 4.

The operation of the optical integrated circuit configured as described above will be described.

First, when the terminal 13 is positive and the terminal 14 is negative and the laser portion is biased, single transverse mode oscillation is performed in the active layer 4 immediately above the groove portion of the cladding layer 3. Here, 15 is also made negative with respect to the terminal 13, and a reverse bias is applied to the junction of the n, p-GaAs layers 10 and 11.

The near-field distribution of light in the direction parallel to the active layer bonding surface in the cavity spreads beyond the groove width of the cladding layer 3 and part of the light distribution passes through the SiO ₂ film 9 to bond the n, p-GaAs layers 10, 11 together. The light is absorbed by a part, and by using the signal, it is possible to perform the APC operation in which the light output of the laser is made constant.

The laser of this embodiment has three cavities l ₁ , l ₂ , l
_It is a compound cavity laser having ₃ and wavelengths that cause interference in 3 cavities in the gain distribution are selected, and single longitudinal mode oscillation is performed.

Further, it is not necessary to emit light in the laser direction, and a high reflection coating film 16 is formed on the rear end surface of the cavity to form a high reflection surface having a reflectance close to 100%, thereby increasing the laser output. Easy to do. Although the internal stripe type laser is shown as the laser in the embodiments, the present invention is not limited to this, and any stripe type laser can be used. Although the pn junction is shown as the light receiving portion, the light receiving portion is not limited to this, and any light receiving element (pin, avalanche photodiode, photoconductor, etc.) may be used. Also, although shown as GaAs-CaAlAs-based materials, InGaAs p-based and other III-V, II-I
The use of Group V semiconductors is also possible.

It goes without saying that an insulating material other than SiO ₂ can be used. In this embodiment, the light receiving portion is located at the center of the laser cavity, and the structure of three cavities is shown. However, the light receiving portion may be formed at the end of the cavity to form two cavities. In addition, the number of light-receiving units is 3
Two or more composite cavity lasers can also be constructed. It can also be provided on both sides of the oscillator.

As described above, according to the present invention, by providing the light receiving element adjacent to the stripe-shaped cavity of the laser, the laser of the light receiving element can be used for the APC operation, and moreover, the composite cavity is provided. Can take a structure,
Stable single longitudinal mode oscillation can be performed, and its practical effect is great.

Further, by making the rear end face have a high reflectance, an effect of high power operation of the laser can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical integrated circuit device according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. 1 ... p-type GaAs substrate, 2 ... n-type GaAs layer, 3 ... p-type Ga
_1-x Al _x As layer, 4 ... Non _- doped Ga _1-y Al _y As active layer, 5 ...
... n-type _{Ga 1-x 'Al x'} As layer, 6 ...... n-type GaAs layer, 7 ...... p
Side ohmic electrode, 8 ... n side ohmic electrode, 9 ...
SiO ₂ film, 10 ... n-type GaAs layer, 11 ... p-type GaAs layer, 1
2 ... Ohmic electrode, 13-15 ... Electrode terminal, 16
...... Highly reflective coating film.

Claims (2)

[Claims] 1. A semiconductor laser having a double heterojunction including an active layer on a semiconductor substrate and a current limiting layer having a stripe-shaped window, wherein at least a part of the double heterojunction adjacent to the laser cavity is formed. In the removed portion, a light receiving element is formed through an insulating film so as to be located at the same position as the junction and the active layer, and internal reflection of light is generated at the interface between the light receiving element and the laser cavity portion, and An optical integrated circuit device comprising a cavity. 2. A high-reflectivity film is formed on the rear end face of the laser cavity.
An optical integrated circuit device according to the item.