JPH03136287A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To easily protect a semiconductor laser of this design against optical damage and to make it high in output power by a method wherein the first parts of a heat sink in contact with a resonator adjacent to its end faces are made larger than the second part of the heat sink in contact with the part of the resonator other than the end faces in thermal conductivity or area conducive to thermal conduction. CONSTITUTION:A heat sink 2 is composed of first diamond heat sinks 21 in contact the resonator of a laser chip near its end faces and a second cBN (cubic boron nitride) heat sink 22 which is in contact with the part of the resonator other than the end faces and sandwiched between the heat sinks 21. The first part 21 is made larger than the second part 22 in thermal conductivity or relative area conducive to thermal conduction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor laser used for optical information processing, laser printers, laser processing, etc., and particularly to a semiconductor laser capable of increasing output.

[Conventional technology]

As the range of applications of semiconductor lasers expands, higher output power is required. In a semiconductor laser, laser light exists at a high density at the laser beam emitting end facet, so the maximum optical output of the semiconductor laser is determined by the optical destruction (ca) of the end facet.
tastrophic optical damage
:C0D) and thermal saturation of optical output due to increase in junction temperature.

LOG (
Lasers with a large optical cavity structure, window structure lasers, and the like are well known. A LOG structure laser is a semiconductor laser in which a light guide layer is provided adjacent to or in the vicinity of an active layer to reduce the optical density at the end facet. A window structure laser is a semiconductor laser that eliminates light absorption at the end face by using a material whose band gap is larger than the energy of the laser light emitted near the end face.

[Problem to be solved by the invention]

However, in the LOG structure laser, the optical density at the end face decreases and the confinement of light in the active layer also deteriorates.
The disadvantage is that thermal saturation of the optical output is likely to occur.

In addition, the window structure laser has a complicated structure and requires epitaxial crystal growth multiple times during its manufacture, resulting in a complicated manufacturing process.

The present invention has been made in view of the above circumstances, and solves the above-mentioned difficulties by making the structure of the heat sink different between the region in contact with the vicinity of the resonator end face and the region in contact with a region other than the vicinity of the resonator end face. COO easily
An object of the present invention is to provide a semiconductor laser that can prevent the above problems and achieve high output.

[Means to solve the problem]

In the semiconductor laser according to the present invention, in the semiconductor laser in which a heat sink is attached to the laser chip by a junction down, the heat sink has a first portion that contacts near an end face of a resonator of the laser chip, and a first portion that is in contact with the vicinity of an end face of a resonator of the laser chip. and a second portion that is in contact with a portion other than the vicinity of the end face, and the first portion is characterized in that it has a higher thermal conductivity or a larger area involved in heat conduction than the second portion.

[Effect]

In the semiconductor laser of the present invention, the first portion of the heat sink that is in contact with the vicinity of the resonator end face (hereinafter referred to as the first region) is the first portion of the heat sink that is in contact with the vicinity of the resonator end face (hereinafter referred to as the second region). Compared to the two parts, either the thermal conductivity is high or the area involved in heat conduction is relatively large. Therefore, the first region has better heat dissipation than the second region. The bandgap narrows as the temperature rises, and most of the laser light is generated from the second region, so
The bandgap in the first region is larger than the energy of the laser beam corresponding to the hand gap in the second region, so that light absorption at the end face portion is less likely to occur and COD is prevented from occurring.

〔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 structure of an embodiment of a semiconductor laser according to the present invention, and numeral 1 in the figure is a stem made of copper. A heat sink 2 is placed on the stem 1, and the heat sink 2
A broad area type laser chip 3 having a D)I structure is mounted above with a junction down. The resonance direction of the laser chip 3 is the left-right direction in the figure, the resonator length is 500 μm, the slice width is 80 μm, and the oscillation wavelength is 830 nm.

The heat sink 2 is mainly composed of three parts.
The area other than the diamond heat sink 21 (thermal conductivity: 20W/cm ``C) which is the first part in contact with the area) and the vicinity of both end faces of the resonator of the laser chip 3 (first Si area)
These diamond heat sinks 2L 2
cBN (cubicbor), which is the second part sandwiched between
on n1tride) heat sink 22 (thermal conductivity: 6W/cI11℃), a 5iOz sandwiched between a diamond heat sink 21 and a cBN heat sink 22.
Membrane 23 (thermal conductivity: 0,02 W/cm″C)
The heat sink 2 is constructed from the above. The height of heat sink 2 (11 in the figure) is 300 μm,
The width (length in the direction perpendicular to the drawing) is 750 μm, and the total length of the heat sink 2 is about 500 μm, the length of each diamond heat sink 21 (Ll in the figure) is 50 μm, and the length of the cBN heat sink 22 (Lz in the figure)
) is 400 μm, Sin□ film 23 film length 3 (L3 in the figure)
is several μm.

Note that in order to easily generate a temperature difference between the first region and the second F+i region, a 5iOz film 23 having a low thermal conductivity is used.
Therefore, the 5iot film 23 does not necessarily need to be provided. Note that the surface of the heat sink 2 is metallized so that current can flow through the stem 1.

FIG. 2 shows the junction temperature distribution when the heat generation amount is 5.4 W in the semiconductor laser of the present invention having the above-described configuration, and FIG. 3 shows the band gap distribution in this case. It shows. Since the first region has better heat dissipation than the 281st region, the bonding temperature on the first region side is about 20° C. lower than the bonding temperature on the second region side (see FIG. 2). - The band gap of semiconductors used for boat fishing narrows as the temperature rises, and the hand gap on the second region side is approximately 1.3 x 10-”eV larger than the band gap on the first region side.
(about 5 nm when converted into wavelength) (see Figure 3).

Since most of the laser light is generated from the second region, which has a large area, the bandgap in the first region is larger than the energy of the laser light. As a result, light absorption is less likely to occur at the end face portion of the resonator, and COD can be prevented.

FIG. 4 is a perspective view of a heat sink 2 in another embodiment of the invention. In the embodiment described above, the object of the present invention was achieved by using materials with different thermal conductivities in the first part and the second part, but in this other embodiment, the materials with different thermal conductivities were used in the first part and the second part. The configuration is such that the dimensions involved in heat conduction, that is, the relative areas, are different.

The heat sink 2 of this embodiment includes a first portion 24 made of copper (thermal conductivity: 4 W/cm'c) that is in contact with the first region, and a second portion 24 made of copper (thermal conductivity: 4 W/cm'c).
A second portion 25, also made of copper, is in contact with the region and sandwiched between the first portions 24 and 24, and an outer layer 3 of the SiO□ film 23 is sandwiched between the first portion 24 and the second portion 25.

The width of the first portion 24 is 900 μm and the width of the second portion 25 is 300 μm, and the dimension involved in heat conduction in the first portion 24 is made longer than that of the second portion 25. That is, the relative area of the first portion 24 involved in heat conduction is made larger than that of the second portion 25. Note that the widths of the two first portions 24 do not need to be the same, and the width of the first portion 24 corresponding to the rear end surface side of the resonator may be made longer than in the embodiment.

Therefore, in this embodiment as well, the first portion 24 has better heat dissipation than the second portion 25, and as in the previous embodiment, the laser light is absorbed near the resonator end face. COO can be prevented. The same laser chip as in the previous example was used, and the amount of heat generated was the same.
When the junction temperature is measured at 5.4 W, the junction temperature in the first region is approximately 5° C. lower than that in the second region.

Note that the present invention is not limited to the above-described embodiments, and a semiconductor laser having a configuration that combines the two embodiments described above is also possible. Further, the laser chip is not limited to a broad area laser, and can be applied to various semiconductor lasers.

〔Effect of the invention〕

As detailed above, in the present invention, since the material of the heat sink or the area involved in heat radiation is changed between the region near the resonator and the region outside the resonator, COO can be easily prevented and the semiconductor laser can be It is possible to output it.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the semiconductor laser according to the present invention, FIG. 2 is a graph showing the distribution of junction temperature, FIG. 3 is a graph showing the distribution of the hand gear, and FIG. FIG. 3 is a perspective view of a heat sink in another embodiment of the semiconductor laser according to the present invention.

Claims (1)

[Claims] 1. In a semiconductor laser in which a heat sink is attached to a laser chip with a junction down, the heat sink has a first portion that is in contact with the vicinity of an end face of a resonator of the laser chip, and a first portion that is in contact with the vicinity of an end face of a resonator of the laser chip. and a second portion touching other than the vicinity of the end face of the
A semiconductor laser characterized in that the first portion has a higher thermal conductivity or a larger area involved in heat conduction than the second portion.