JPH01318270A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To make it possible to perform a stable operation for a long period at high-output operation without non-luminescent layer being formed at the time of forming a dielectric multi-layer film by disposing a buffer layer between the end surface of a laser element and a dielectric multi-layer film. CONSTITUTION:In an InGaAlP semiconductor laser element 1, an n-InGaAlP clad layer 1b, an InGaP active layer 1c, an InGaAlP clad layer 1d, and a p- GaAs cap layer 1e are laminated in this order from top of a GaAs substrate 1a. On the end surface of the reflection side of the semiconductor laser element 1 is coated an a-Si:H buffer layer 5. ON the end surface of the incidence side of the InGaAlP semiconductor laser element 1 is adhered the a-Si:H buffer layer 5. As a result, at the time of forming an Al2O3 film 2 or an a-Si:H film 3, the formation of non-luminescent layers on the end surface is reduced, and laser beams of high output are stably output for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an InGaAl P semiconductor laser, and more particularly to a high reflection film formed on the end face of an InGaAl P semiconductor laser element.

[Conventional technology]

It is known that a highly reflective film is formed on the end face of a semiconductor laser element in order to improve the reflectance at the end face.
As a structure of a high reflection film, a dielectric multilayer film formed by laminating a dielectric film and an amorphous Si film in this order is known (Japanese Unexamined Patent Application Publication No. 1989-1999).
-235482).

FIG. 3 is a schematic diagram showing the structure of a semiconductor laser in which the high reflection film disclosed in Japanese Patent Application Laid-Open No. 60-235482 is applied to a GaAlAs semiconductor element. 31 in the figure is GaAl
The GaAlAs semiconductor laser device 31 is an As semiconductor laser device, and the GaAlAs semiconductor laser device 31 has n-GaAlA on the GaAs substrate 31.
s-clad layer 31b.

The lower surface of the GaAs substrate 31a and the p-
It has a structure in which electrodes 31f and 31g are formed on the upper surface of the GaAs camp layer 31e. GaAlAs semiconductor laser device 3
A1zO+ film 3 is coated on the reflective side end face of 1 as a high reflective film.
A dielectric multilayer film 34 is formed by alternately stacking two layers of 2+ a-Si films 3, and an A1 film is formed on the output side end surface.
A □03 film 32 is formed.

[Problem to be solved by the invention]

However, when a dielectric multilayer film as described above is formed as a high reflection film on the end face of an InGaAlP-based semiconductor laser device, a non-emissive layer is formed on the end face, making it difficult to increase the output power of short wavelength lasers and increase the length of the laser. There is a problem that the service life is hindered. Table 1 below shows the PL intensity (ratio of PL intensity before film formation to PL intensity after film formation) when dielectric films are formed using various materials on the end faces of InGaAl P-based semiconductor laser devices. It is understood from Table 1 that high output and long life cannot be obtained if the dielectric film is simply formed on the end face.

Table 1 [Means for solving the problems] The semiconductor laser according to the present invention is an InGaAlP semi-W semiconductor laser.
A semiconductor laser having a dielectric multilayer film (highly reflective) on an end facet of a body laser element is characterized in that a buffer layer is interposed between the end facet and the dielectric multilayer film.

[Function] In the semiconductor laser of the present invention, since the buffer layer is interposed between the end face of the semiconductor laser element and the dielectric multilayer film, the semiconductor laser element is No non-emissive layer is formed on the end face of the

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 is a schematic diagram showing the configuration of a semiconductor laser according to the present invention, and numeral 1 in the figure indicates an InGaAlP semiconductor laser element. The 1nGaAI P semiconductor laser device 1 is made of Ga
On As7J temporary la, n-1nGaAI P cladding layer 1b, InGaP active layer 1c, p-1nGaAI
An electrode 1f and an electrode 1 are formed on the upper surface of the GaAs substrate 1a and the lower surface of the p-GaAs cap layer 1e of a laminate formed by laminating the P cladding layer 1d and the p-GaAs cap layer 1e in this order.
It is constructed by forming a g.

On the reflection side end face of the InGaAlP semiconductor laser device 1, an a-3i: ) I buffer layer 5 (Ill:
535 people) were deposited, and this a-Si:tl
l buff 5, Aha, membrane 2 (film thickness: 985 people)
, a-5i: A dielectric multilayer film 4 is formed by alternately stacking two layers of II film formation (film thickness: 535 people). Further, an a-5i:H buffing layer 5 (thickness: 535 layers) is formed on the emission side end facet of the InGaAlP semiconductor laser device 1.
Buffing layer 5 has 1□0. Film 2 (thickness: 547 people) was formed. Then, the InGaAl of this example
The reflectances of the reflection side end face 1 and the emission side end face of the P semiconductor laser element 1 are 87.9% and 10%, respectively.

Table 2 below shows that Alz (h film and a
-3i: ) This is a table showing the relationship between the number of laminated layers and the reflectance (%). Note that the wavelength λ of the output laser light is 6
700 people and stack them ^120. Membrane, a-5i:
The film thickness of the If film was set to 1015 (λ/4n, refractive index n
: 1.65) 550 people (λ/4n, refractive index n:
3.05).

(Margin below) Table 2 In the example of the present invention, the a-5i:H buffing layer 5 is interposed between the end face of the InGa^IP semiconductor laser device 1 and the dielectric multilayer film 4, so it is different from the conventional example. Although the reflectance is slightly lower than that, there is no problem in practical use because the desired reflectance can be obtained by increasing the number of laminated layers of the multilayer film.

In the present invention, an a-
5i: ) Since the buffer layer 5 is interposed, A
1□03 film 2 or a-3i: When forming the H film 3, the formation of a non-emissive layer (damage layer) on the end face is reduced. As a result, high-power laser light is stably output over a long period of time.

〔Effect of the invention〕

Figure 2 shows the ridge type 1nG in the example of the present invention and the conventional example.
aAI P semiconductor laser (output laser light wavelength: 670
This is a graph showing the results of a lifespan test (50°C + 20 mw + APC operation) of 0 people.
r), and the vertical axis represents the drive current (mA). As can be understood from the graph, in the example of the present invention, the temperature rise at the end face is smaller than in the conventional example, and the life characteristics are significantly improved.

As detailed above, in the semiconductor laser of the present invention, since the buffer layer is interposed between the end face of the laser element and the dielectric multilayer film, a non-emissive layer is not formed when forming the dielectric multilayer film. . As a result, stable operation can be performed over a long period of time even in high output operation, and high output and long life can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of a semiconductor laser according to the present invention, Fig. 2 is a graph showing the results of a life test between an example of the present invention and a conventional example, and Fig. 3 is a schematic diagram showing the configuration of a conventional semiconductor laser. It is a diagram. 1-1nGaAI P semiconductor laser device 2'''Al
2O3 film 3... a-Si: H film 4... dielectric multilayer film 5... a-3i: H buffer layer

Claims (1)

[Claims] 1. In a semiconductor laser having a dielectric multilayer film as a high reflection film on the end face of an InGaAlP semiconductor laser element, a buffer layer is interposed between the end face and the dielectric multilayer film. A semiconductor laser featuring: