JPH037152B2 - - Google Patents

Abstract

PURPOSE:To extend operating life of semiconductor laser element by mounting a semiconductor laser element to the area near the center of a submount and by giving an inclination to the one side surface of the submount so that the edge of submount is not irradiated with the laser beam. CONSTITUTION:A submount 7 is composed of molybdenum or silicon and is brazed to a step 6 consisting of copper or iron through a brazing material 8. A semiconductor laser element 9 is brazed to the area near the center of mount 7 with a brazing material 10 and the one side end of submount 7 is the inclined surface 7a being cut at the angle of at least 30 degrees for the bottom surface and is coupled at the contact position with the reflecting surface 9a. Moreover, since the lower end of inclined surface 7a is coupled to the edge of stem 6. Therefore, if a semiconductor laser element 9 is placed on the area near the center of submount 7, when it emits the laser beam, the stable laser beam can be obtained without irregular reflection of laser beam. Since a semiconductor laser element 9 is coupled to the area near the center of submount 7, difference of line expansion coefficient to the semiconductor laser element 9 is reduced, suppressing the generation of strain.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor laser device, and particularly to a bonding structure of a semiconductor laser element.

In order to continuously oscillate a semiconductor laser at room temperature and improve its operating life, it is necessary to promptly dissipate the heat generated by the semiconductor laser element to the outside, and to use a submount that does not generate a cup for the semiconductor laser element. There is a need.

For this reason, the conventional bonding structure of a semiconductor laser device is as shown in FIG.
The most common structure was to connect the parts through a . In the above joint structure, the stem 1 is made of copper or iron, the submount 2 is made of copper, silver, molybdenum, or silicon, and the brazing material is made of a semiconductor material such as indium, tin, gold-silicon, or solder. .

Submount 2 needs to be made of highly thermally conductive material such as copper or silver from the viewpoint of heat dissipation.
These materials have a large difference in coefficient of linear expansion with the semiconductor laser element, so when they are bonded to the submount 2 via the brazing material 3 and cooled from high temperature to room temperature, the semiconductor laser element 4 is strained, significantly shortening its operating life. There are drawbacks. Further, when molybdenum or silicon is used for the submount 2, compared to the above-mentioned copper or silver, the difference in linear expansion coefficient between the material and the semiconductor laser element 4, which reduces thermal conductivity, is small, so less strain occurs. For example, when silicon is used for the submount 2, the strain generated in the center of the semiconductor laser element is approximately 40% of that when copper is used, but this is not a sufficiently low strain value to improve the lifespan. I can not say.

Furthermore, as shown in FIG. 2, the radiation pattern of the semiconductor laser element 4 has the characteristic that it is oscillated in a spot on the reflecting surface 4a and expands in a conical shape along the direction of light propagation, resulting in diffuse reflection of light. In order to prevent this and obtain stable light, it is necessary to prevent the submount from being located in the direction in which the light travels, that is, to mount the semiconductor laser element such that the end face of the semiconductor laser element is aligned with the end face of the submount.

In view of the above points, it is an object of the present invention to provide a semiconductor laser device having a bonding structure that minimizes strain applied to a semiconductor laser element and improves its operating life.

The present invention is characterized in that in a semiconductor laser device comprising a submount mounted on a stem and a semiconductor laser element mounted on the submount, the stem is made of iron, the submount is made of silicon, and the semiconductor A laser element is mounted near the center of the submount with solder material, and one end face of the submount is attached to the bottom face to the extent that when laser light is output from this semiconductor laser element, the laser light does not irradiate the end face of the submount. The surface is inclined at an angle of at least 30° to the surface.

An embodiment of the semiconductor laser device of the present invention will be described below, but before that, the principle will be explained.

When a submount made of silicon, for example, is bonded to a stem made of copper via a solder filler metal, the difference in linear expansion coefficient between the stem and the submount when cooled from high temperature to room temperature causes the difference in the coefficient of linear expansion between the stem and the submount, as shown in Figure 3. Such distortion occurs. In FIG. 3, the horizontal axis represents the distance from the center of the submount to the end, and the vertical axis represents the amount of strain. This strain value becomes larger toward the center of the submount, and has the effect of increasing the apparent coefficient of linear expansion of the submount. As a result, when a semiconductor laser element with a larger linear expansion coefficient is bonded to the submount, the difference in linear expansion coefficient between the semiconductor laser element and the semiconductor laser element is reduced by locating it in the center rather than at the edges, which is the conventional bonding position. Therefore, the strain generated in the semiconductor laser device is reduced.

FIG. 4 shows an embodiment of the present invention. In the figure, 6 is a stem made of iron, and 7 is a submount made of silicon, which are joined onto the stem 6 via a brazing material 8.

9 is the brazing material 1 near the center on the submount 7.
One end face of the submount 7 is an inclined surface 7a cut at an angle A° of at least 30° with respect to the bottom surface, and the semiconductor laser element It is joined at a position where it touches the end face including the laser output section of No. 9, that is, the reflective surface 9a. Furthermore, the lower end of the inclined surface 7a of this submount 7 and the end of the stem 6 are joined together. Therefore, the semiconductor laser element 9
When the semiconductor laser element 9 outputs laser light even if it is bonded near the center of the submount 7,
Since the submount is cut along the light traveling direction, stable light can be obtained without causing diffuse reflection of light.

Furthermore, by bonding the semiconductor laser element 9 near the center of the submount 7, the apparent coefficient of linear expansion of the submount 7 can be increased, thereby reducing the difference in the coefficient of linear expansion with the semiconductor laser element 9. This makes it possible to reduce strain caused by bonding with the submount 7.

Furthermore, by giving an angle to the end face of the submount, there is an effect of preventing contamination of the reflective surface 9a with the brazing material 8 when the semiconductor laser element 9 and the submount 7 are bonded with the brazing material.

According to the present invention, strain applied to a semiconductor laser element can be minimized, and a semiconductor laser device with a long operating life can be provided.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional semiconductor laser device, Figure 2 is a diagram showing the light emission pattern of the semiconductor laser element, Figure 3 is a diagram showing changes in the amount of strain generated on the submount, and Figure 4 is 1 is a perspective view of an embodiment of a semiconductor laser device of the present invention. 6...Stem, 7...Submount, 9...Semiconductor laser element.

Claims (1)

[Claims] 1. In a semiconductor laser device consisting of a submount mounted on a stem and a semiconductor laser element mounted on the submount, the stem is made of iron, the submount is made of silicon, and the semiconductor laser element is mounted in the center of the submount. One end face of the submount is angled at least 30° with respect to the bottom face so that the end face of the submount is not irradiated with laser light when the semiconductor laser element is mounted nearby with solder material and outputs laser light from this semiconductor laser element. A semiconductor laser device characterized by having an inclined surface.