JPS61253882A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To provide a semiconductor laser with high output and high reliability, oscillating in a basic transverse mode, by making a structure in which the stripe width becomes smaller as nearer the end face in the vicinity of the end face, not so as to inject current into the vicinity of the end face. CONSTITUTION:On an N<+> GaAs substrate 1, an N-GaAlAs clad layer 2 active layer 3 containing a quantum well structure, P-GaAlAs clad layer 4 and N-GaAs light absorbing layer 5 are sequentially grown by metal organic chamical vapor deposition. Thereafter, to make the stripe width as shown in the figure with phosphoric acid based chemical etchant, the light absorbing layer is etched. Using again the MOCVD method, a P-GaAlAs buried layer 8 and P-GaAs cap layer 7 are grown, and Zn diffusion forms a Zn diffusion layer 8. Last, an N- type electrode 9 and P-type electrode 10 are formed evaporating, and the P-type electrode is etched away only by 50mum near the end face. In this way, high output and high reliability can be attained at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a high-output and highly reliable transverse mode controlled semiconductor laser.

[Background of the invention]

Conventional semiconductor lasers that achieve high output by thinning the active layer and increasing the optical spot size (GP Agraval, GA Applied Physics Vol. 56, 1)
984, pp. 3100-3108 (G, P.

Agrawal, J., Appl-Phys, 5
6 p., 3100-3108゜1984))
has a high threshold current density due to a small optical confinement coefficient;
The drawback was that it had a short lifespan. Furthermore, the method of enlarging the light spot size by increasing the stripe width also has the disadvantage that the transverse mode tends to become unstable.

[Purpose of the invention]

An object of the present invention is to provide a semiconductor laser that oscillates in the fundamental transverse mode and has high output and high reliability.

[Summary of the invention]

In order to increase the output of a semiconductor laser, it is necessary to enlarge the optical spot size. However, if the active layer is made thinner to increase the light spot size, the threshold current density increases and the lifetime becomes shorter. Therefore, it is possible to increase the stripe width, but increasing the stripe width tends to make the transverse mode unstable.

Therefore, by making the stripe width smaller near the end face, the transverse mode can be stabilized and the light spot size can be increased. In addition, when using such a striped shape, the light spot size becomes smaller near the end face, so
Carrier distribution tends to change near the end face. Therefore, in the present invention, a structure is adopted in which no current is injected near the end face.

Furthermore, the region where current is not injected becomes an absorption region in a normal double hetero type laser, but in the structure of the present invention, almost no light is absorbed because it has an active layer containing a quantum well structure. As a result of the above, it is possible to obtain a semiconductor laser that oscillates in the fundamental transverse mode and has high output and high reliability.

- [Embodiments of the invention] A first embodiment of the present invention will be described below with reference to FIG.

First, a method for manufacturing the semiconductor laser device shown in FIG. 1 will be described. n”-n on the GaAs substrate 1
-GaAμAs cladding layer 2, active layer 3 with built-in quantum well structure, P -GaA Q As cladding layer 4, n-
The Gap light absorption layer 5 is sequentially formed by metal organic pyrolysis vapor phase epitaxy (
Grown by MOCVD method). Thereafter, the light absorption layer is etched using a phosphoric acid-based chemical etching solution so as to have a stripe width as shown in FIG. M again
Using OCVD method, P-GaA QAs buried layer 6
, a P-GaAs cap layer 7 is grown, and Zn is diffused to form a Zn diffusion layer 8.

Finally, the n-type electrode 9. Each p-type electrode 10 is formed by a vapor deposition method. Then, by etching away the P-type electrode by 50 μm near the end face, a semiconductor laser device as shown in the figure is manufactured.

A second embodiment of the invention is shown in FIG. The manufacturing method is the same as the first example up to the formation of stripes. In buried growth, p -GaA Q As buried layer 6゜n G
An aAs cap layer 7' is formed. Zn diffusion is caused by p -GaA m As in a region other than 50 μm near the end face.
The process is continued until the cladding layer 6 is reached, and a Zn diffusion layer 8 is formed. Finally, by forming the n-type electrode 9 and the p-type electrode 10 by vapor deposition, the semiconductor laser device as shown in the figure is manufactured.

1st. In both the second example, a high-output, highly reliable laser was realized in which the fundamental transverse mode was maintained up to an optical output of 100 mW, and which was capable of continuous oscillation at 70° C. and 100 mW for more than 2000 hours.

The present invention can be similarly applied to general semiconductor lasers using compound semiconductors other than GaA Q As-based laser materials, such as InGaAs-based and InGaP-based laser materials.

(Effects of the Invention) According to the present invention, since the stripe width is wide at the center of the resonator, the optical spot size is expanded and high output can be achieved.Furthermore, since the stripe width near the end faces becomes narrower as it approaches the end faces, the transverse mode is stabilized.The deformation of the transverse mode is caused by the deformation of the carrier distribution in areas where the optical density is high.

In the structure of the present invention, since the light confinement effect is large near the end face, no transverse mode deformation occurs due to the deformation of High output can be achieved without raising the power. As a result of device fabrication, devices with an average lifespan of 2000 hours or more at 70° C. and 100 mW were obtained with a good yield of 6 or more, indicating that the present invention is quite effective in achieving both high output and high reliability. Ta.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a device according to an embodiment of the present invention, and FIG. 2 shows the stripe width W and the seat ′ in the resonator direction! FIG. 3, which shows the relationship with sz, is a schematic diagram of an element according to an embodiment of the present invention. 1-n''-GaAs substrate, 2-n-GaAQ
As cladding layer, 3... active layer with built-in quantum well structure, 4... P-GaA 42 As cladding layer,
5- n-GaAs light absorption layer, 6- P-GaA Q
As buried layer, 7- P-GaAs cap layer, 7'
...n-GaAs cap layer, 8...Zn diffusion layer,
Tomi 3 Figure/j

Claims (1)

[Claims] A quantum well self-aligned semiconductor laser device that has a structure in which the stripe width becomes gradually narrower near the end surface, and current does not flow near the end surface.