JPH02177583A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To prevent an element of this design from rising in temperature and deteriorating in characteristics even if it operates at a high output power by a method wherein a heat sink is provided to one surface of a semiconductor laser element to whose other surface another heat sink has been provided. CONSTITUTION:A semiconductor laser element A is provided with a heat sink 10 fitted to its surface and another heat sink 21 attached to its other surface. Heat released from the active layer and its vicinity of the semiconductor laser element A is absorbed by both the heat sink 10 attached to a growth layer side and the heat sink 21 fitted to a substrate side. Furthermore, heat generated due to a substrate resistance is absorbed by the heat sink 21. By this setup, the semiconductor laser element A is reduced in temperature rise and improved in output characteristic, and can be made to operate at a high output power.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor laser device, and particularly to a semiconductor laser device capable of high output operation.

(Prior art) In order to operate a semiconductor laser device at a high output of 100 mW or more, research is actively being conducted on laser arrays in which multiple laser firing stripes are lined up and broad area lasers in which the stripe distribution of the laser oscillation region is widened. is being carried out. Such a high-output semiconductor laser device 1 is used as a pumping light source for a solid-state laser such as a YAG laser, or as a light source for generating second harmonics from a nonlinear optical material. As an example of a high-power semiconductor laser device, as shown in FIG.
anneled 5ubstrate Inner 5
(J, Appl, Phys, 58).
(7), October 1985).

This high-power semiconductor laser device is manufactured as follows. First, n-A 1 @, I is deposited on the p-GaAs substrate 1.
Gal, gA S current confinement layer 2 is grown by liquid phase epitaxial method. A plurality of rows of grooves 3 extending from the surface of the current confinement layer 2 to the substrate 1 are formed by photolithography and chemical etching. A p-Al1,33G as, atA S cladding layer 4 is grown by the liquid crystal epitaxial method, the rows of grooves 3 are filled flat, and p-Al
A196@G a @, g2A s active layer 5, n
-AI 9,33G am, stAS cladding layer 6
and grow an n-GaAs cap layer 7.

An n-side electrode 8 is provided on the surface of the p-GaAs substrate 1.
An n-side electrode 9 is provided on the surface of the s-cap layer 7. A pair of mutually parallel reflecting surfaces are formed by cracking, and a semiconductor laser device A (cavity length 250 μm) is obtained.

The operation of the semiconductor laser device A formed in this way will be explained. When a voltage is applied between the n-side electrode 8 and the n-side electrode 9, a current is injected into the active layer 5 from the row of grooves 3, causing laser oscillation. In this way, current is injected into the active layer 5 through the plurality of rows of grooves 3, so that the guided light propagating through the active layer 5 is spread out and distributed in correspondence with the rows of the grooves 3, and the light in the active layer 5 is Density is reduced. Furthermore, since the guided lights corresponding to the valley grooves 3 oscillate synchronously with each other in a constant phase relationship, stable laser oscillation can be obtained up to high output.

In this type of semiconductor laser device A, the injection current is considerably higher than that of a normal single stripe laser, so a large amount of heat is generated when it is operated continuously. operation becomes impossible. Therefore, in a high-power laser such as the illustrated device, it is an important issue to efficiently dissipate the heat generated by the injection current.

For this reason, conventionally, as shown in FIG. 3, the semiconductor laser element A is thermally fused onto a Cu heat sink 10 on which an electrode 11 is formed on the surface using an In solder material 12. ing. The semiconductor laser device shown in FIG. 3 employs a junction down mount method in which the crystal growth surface of the laser element A near the active layer 5 is fused to the heat sink 10. In this configuration, laser element A
Of the heat due to non-radiative recombination generated in the active layer 5 and its vicinity, the heat flowing toward the heat sink 10 is efficiently absorbed by the heat sink 10, and heat radiation is performed satisfactorily. However, regarding the heat flowing to the substrate 1 side, since the thermal conductivity of the substrate 1 is lower than that of the heat sink 10, the efficiency of heat radiation is poor.The arrows in the figure indicate the flow of heat.

Furthermore, when the injection current is large, Joule heat caused by the resistance of the laser element becomes a problem. In the above laser element A, the width of 4 μm is ? Optical output, reactive power, and injected power (sum of optical output and reactive power) with respect to injection current when 113 is formed with a period of 5 μm (that is, when 10 oscillation stripes are formed). The state of change is shown in FIG. 4. Also shown in FIG. 4 is the change in Joule heat due to the element resistance of the reactive power with respect to the injection current. As is clear from Figure 4, Joule heat increases rapidly at the rate of the square of the increase in current.
If A, the optical output is 0. 36W, reactive power is 1.1
6W, whereas the Joule heat due to element resistance is 0.
．． It also becomes 4W. Further, the maximum optical output of laser element A in such a configuration is 0.7W.

(Problem to be solved by the invention) Regarding element resistance, it is necessary to consider not only the resistance on the growth layer side but also the resistance of the substrate.Since the substrate is thick compared to the thickness of the growth layer, the resistance of the substrate is It will be relatively large. The heat generated on the substrate side due to the resistance of the substrate is difficult to dissipate into the air. Therefore, the heat increases the temperature of the active layer of the laser element and its vicinity, deteriorating the characteristics of the laser element. .

The present invention is a semiconductor laser device that can efficiently dissipate heat generated in a semiconductor laser element, so that even when the laser element is operated at high output, the temperature rise of the element is small and deterioration of characteristics can be prevented. The purpose is to provide

(Means for Solving the Problems) A semiconductor laser device of the present invention includes a heat sink, a semiconductor laser element whose one surface is attached to the heat sink, and another heat sink attached to the other surface of the semiconductor laser element. The above objective is thereby achieved.

Further, the semiconductor laser device of the present invention may be configured such that a recess is formed on the other surface of the semiconductor laser element, and the other heat sink has a convex portion that fits the recess. can.

(Function) In the semiconductor laser device of the present invention, heat generated in the active layer of the semiconductor laser element and its vicinity is transferred to one heat sink attached to the growth layer side and the other heat sink attached to the substrate side. absorbed by both.

Furthermore, heat generated due to substrate resistance is absorbed by the other heat sink. Therefore, the temperature rise of the semiconductor laser element is reduced, the output characteristics are improved, and high output operation is possible.

(Example) The invention will now be described with reference to examples.

FIG. 1 shows an embodiment of the present invention. This embodiment is a semiconductor laser device A having a structure similar to that of the conventional example shown in FIG.
The manufacturing procedure of this example using the following will be described. First of all,
Semiconductor laser device A was manufactured using the same process as described above. However, the thickness of the substrate 1 is 70 μm due to chemical etching.
And so. In addition, Wei 3 has a period of 5 μm and 10
The book was formed. Rectangular parallelepiped Cu heat sink 21 (Fuku 50
An electrode 22 was formed on the bottom surface of the 0B m x JJ row 500 μm x height 200 μm), and this electrode 22 and the electrode 8 on the substrate side of the element A were heat-fused and attached via an In solder material 23 . Thereafter, the electrode 9 on the crystal growth layer side of the element A and the tall of the Cu heat sink 10 were thermally fused via the In solder material 12 to obtain the device of this example.

In this example, when a current was injected into the laser element A and the maximum optical output was measured, it was 1.0 W, which was significantly improved compared to 0.7 W in the conventional example. Furthermore, a reliability test was conducted on the conventional example and the present example in a high temperature atmosphere (50° C.) with an optical output of 200 mW. While the device in the conventional example stopped oscillating after about 300 hours, the device in this example oscillated stably for about 1000 hours or more.

Note that the thinner the substrate 1 is, the greater the heat dissipation effect is, and the more the Joule heat generated in the substrate is reduced, so it is preferable that the thickness of the substrate 1 be as thin as possible, as described above.

FIG. 2 shows another embodiment of the present invention. In this embodiment, the substrate 1 of the laser element B has a groove-like recess 13 with an inverted trapezoidal cross section extending between both emission end faces in the laser oscillation direction. (width 100μ
m×depth 40 μm) was formed by chemical etching. A heat sink 24 that is thermally fused to the electrode 8 on the substrate side of the element B is provided with a protrusion 25 having a shape corresponding to the recess 13, that is, a protrusion 25 that fits into the recess 13. Therefore, the voltage [8] of the laser element B is connected to the electrode 22 of the heat sink 24.
The entire surface was thermally fused via n solder material 23.

In this embodiment, since the distance from the laser stripe of laser element B to the heat sink 24 is as short as 30 μm, the heat generated in the active region of the semiconductor laser element is more efficiently absorbed by the heat sink 24.

Furthermore, since the thickness of the substrate 1 in the vicinity of the active region is reduced, the substrate resistance is reduced and heat generation is accordingly reduced. Therefore, in this embodiment, which can operate at a higher output than the embodiment shown in FIG. 1, the maximum optical output of laser element B is 1.2
W, and in a reliability test at 50° C. and 200 mW, it oscillated stably for about 2000 hours or more.

The recess 13 can also be provided only near the emission end face of the laser element. Alternatively, the recess 13 may be formed only in the central region of the surface of the substrate 1. In these cases, the shape of the convex portion 25 of the heat sink 24 may be adapted to the shape of the recess. It is natural that it will be done. Further, although the recess 13 is formed in the substrate 1, the recess may be formed on the growth layer side of the device. In this case, the laser device is formed with the vertical relationship of the laser device shown in FIG. 2 reversed. It is arranged as follows.

In the apparatuses of the embodiments described above, a laser array with a VSIS structure is used as the semiconductor laser element, but a laser array with another waveguide structure can also be used. Alternatively, a laser element having a single oscillation drive may be used.

(Effects of the Invention) As described above, the semiconductor laser device of the present invention can efficiently radiate the heat generated by the semiconductor laser element. Therefore, the temperature rise of the semiconductor laser element is small, the deterioration of the characteristics of the laser element can be prevented, and the laser element can be operated at high output.

,・t;8 FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the invention, FIG. 3 is a sectional view of a conventional example, and FIG. 4 is a graph showing the output characteristics of the conventional example.

A, B... Semiconductor laser element, 10.21.24...
- Heat sink, 13... recess, 25... protrusion.

that's all

Claims (1)

[Claims] 1. A semiconductor laser device comprising a heat sink, a semiconductor laser element having one surface attached to the heat sink, and another heat sink attached to the other surface of the semiconductor laser element. 2. The semiconductor laser device according to claim 1, wherein a recess is formed on the other surface of the semiconductor laser element, and the other heat sink has a convex portion that fits the recess.