JP2008311556A - Semiconductor laser device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device capable of providing an enhanced output. <P>SOLUTION: The semiconductor laser device comprises a semiconductor laser array 10 having a plurality of ridges 13 arranged in parallel with one another on a substrate 10, a heat sink 20, a solder layer 30 disposed between the semiconductor laser array 10 and the heat sink 20, and a stress relaxation layer 31. The heat sink 20 has a thermal coefficient of expansion that is larger than that of the ridge 13. The stress relaxation layer 31 has a thermal coefficient of expansion that is smaller than that of ridge 13, and is arranged at a part of the region facing the semiconductor laser array 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device including a semiconductor laser array in which a plurality of strip-shaped waveguides are arranged in parallel, and a display device incorporating the semiconductor laser device.

    The so-called broad-area type semiconductor laser with an expanded width of the strip-shaped waveguide, that is, the stripe width, is a small, highly reliable, low-cost, high-power laser light source. Display, printing equipment, optical disk initialization device, material processing Or it is used in various fields such as medical care. In general, in a semiconductor laser called a broad area type, the stripe width is at least 5 μm, most of which is 10 μm or more and about several hundred μm at the maximum.

  In particular, in fields such as projection displays, it is required to emit high-power laser light in a one-dimensional array. Therefore, for example, it is effective to configure a semiconductor laser array by arranging a plurality of strip-shaped waveguides one-dimensionally and to convert a plurality of laser beams emitted corresponding to the respective strip-shaped waveguides into parallel light using an illumination lens or the like. is there.

  By the way, in such a broad area type semiconductor laser array, if the respective strip-shaped waveguides are brought too close to each other, they interfere with each other and the NFP (Near Field Pattern) becomes non-uniform, or the energy conversion efficiency and light output due to heat storage It is known that laser characteristics are adversely affected, such as a reduction in lifetime. For this reason, the waveguides are usually arranged with sufficient intervals so that the width of the region where the band-shaped waveguides are not formed is wider than the width of the band-shaped waveguides.

  Also, if the semiconductor laser array is made of a material with low energy conversion efficiency, the heat of the semiconductor laser array cannot be dissipated sufficiently only by spacing the waveguides. In general, it is arranged below the semiconductor laser array via a submount (Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 01-181490 Japanese Patent Laid-Open No. 08-228044

  However, the thermal conductivity of AlN (aluminum nitride) commonly used for submounts is 230 W / mK, which is much higher than the thermal conductivity of Cu (copper) commonly used for heat sinks (390 W / mK). small. For this reason, if a large current is passed through the semiconductor laser array, thermal saturation is likely to occur, and the submount is a factor that hinders high output of the semiconductor laser array.

  Therefore, it is conceivable to bond the semiconductor laser array directly to the heat sink without using a submount. However, in this method, since the semiconductor laser array and the heat sink are joined via the solder layer, compression is caused by the difference in the thermal expansion coefficient between the semiconductor laser array (for example, 6 ppm / K) and the heat sink (for example, 17 ppm / K). Strain is applied to the semiconductor laser array, which adversely affects laser characteristics and reliability.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a semiconductor laser device capable of increasing the output.

  The semiconductor laser device of the present invention includes a semiconductor laser array having a plurality of strip-shaped waveguides arranged in parallel on a substrate, a heat sink, a solder layer and a stress relaxation layer provided between the semiconductor laser array and the heat sink, It is equipped with. Here, the heat sink has a thermal expansion coefficient larger than that of the strip-shaped waveguide. The stress relaxation layer has a thermal expansion coefficient smaller than that of the band-shaped waveguide, and is disposed in a part of a region facing the semiconductor laser array. A display device of the present invention includes the semiconductor laser device.

  In the semiconductor laser device and the display device of the present invention, the stress relaxation layer having a thermal expansion coefficient smaller than the thermal expansion coefficient of the strip waveguide is disposed in a part of the region facing the semiconductor laser array. As a result, the semiconductor laser array receives compressive strain from the heat sink while the semiconductor laser array receives stretch strain from the stress relaxation layer, so that the compressive strain received from the heat sink is reduced by the stretch strain received from the stress relaxation layer. The stress applied to the whole is relieved.

  According to the semiconductor laser device and the display device of the present invention, the compressive strain received from the heat sink is reduced by the stretching strain received from the stress relaxation layer, so that the stress applied to the entire semiconductor laser array is relaxed. It is possible to join the semiconductor laser array to the heat sink. Thereby, since heat dissipation improves, a semiconductor laser array can be increased in output.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration of a semiconductor laser device 1 according to an embodiment of the present invention. FIG. 2 is an enlarged view of a part of the semiconductor laser array 10 of FIG. FIG. 3 is an enlarged view of the upper surface in the vicinity of the semiconductor laser array 10 in the semiconductor laser device 1 of FIG. FIG. 4 shows a cross-sectional configuration when the semiconductor laser device 1 of FIG. 3 is cut in the direction of arrows AA. 1 to 4 are schematically shown and are different from actual dimensions and shapes.

  The semiconductor laser device 1 includes a semiconductor laser array 10 and a heat sink 20. A solder layer 30 is inserted between the semiconductor laser array 10 and the heat sink 20, and the semiconductor laser array 10 and the heat sink 20 are joined to each other by the solder layer 30 (see FIGS. 1 and 4).

  As shown in FIG. 2, the semiconductor laser array 10 includes a semiconductor layer 12 having a plurality of ridge portions 13 (band-shaped waveguides) arranged in parallel with each other on a substrate 11. This is a laser.

  The substrate 11 is made of, for example, n-type GaAs, and the semiconductor layer 12 is made of, for example, an AlGaInP-based semiconductor. Therefore, the semiconductor laser array 10 can emit red laser light from each light emitting spot 12A. Examples of the n-type impurity contained in the n-type GaAs (and the n-type cladding layer and n-type guide layer described below) include silicon (Si) and selenium (Se).

  The semiconductor layer 12 includes, for example, an n-type cladding layer, an n-type guide layer, an active layer, a p-type guide layer, a p-type cladding layer, and a p-type contact layer (all not shown) stacked in this order from the substrate 11 side. Is formed. In addition, a stripe-shaped ridge portion (projection portion) 13 extending in the laser beam emission direction (axial direction, y-axis direction) is formed in part of the p-type contact layer and the p-type cladding layer. . Here, examples of the p-type impurity contained in the p-type guide layer, the p-type cladding layer, and the p-type contact layer include zinc (Zn), magnesium (Mg), and beryllium (Be).

  Here, the n-type cladding layer is made of, for example, n-type AlInP, and the n-type guide layer is made of, for example, n-type AlInP. The active layer is made of undoped GaInP, for example. A region of the active layer facing the ridge portion 13 is a light emitting region 12B (see FIG. 4). The light emitting region 12B has a stripe width of the same size as the bottom of the opposing ridge portion 13 (p-type cladding layer portion), and a current injection region into which a current confined in the ridge portion 13 is injected. It corresponds to. Further, both ends of the light emitting region 12B are exposed to a pair of cleaved surfaces 16 facing each other in the extending direction of each ridge portion 13 in the light emitting region 12B, and these exposed portions become light emitting spots 12A (see FIG. 2). ). The p-type guide layer is made of, for example, p-type AlInP, and the p-type cladding layer 15 is made of, for example, p-type AlInP. The contact layer is made of p-type GaAs, for example, and is provided on the ridge portion 17.

  Hereinafter, a direction in which the layers included in the semiconductor layer 12 are stacked is referred to as a vertical direction (z-axis direction), and a laser beam emission direction (axial direction, y-axis direction) and a direction perpendicular to the vertical direction are defined as horizontal directions. It is called a direction (x-axis direction).

  Electrodes 14 are provided on the upper surface of each ridge portion 13 in the semiconductor layer 12, and electrodes 15 are separately provided on the back surface of the substrate 11 including regions facing the ridge portions 13. The semiconductor layer 12 has a pair of cleaved surfaces 16 that face each other in the extending direction (y-axis direction) of each ridge portion 13. A reflective film (not shown) having a high reflectivity is provided on one (the back side in FIG. 2) of the pair of cleavage surfaces 16, and a low reflectivity is provided on the other (the near side in FIG. 2). A membrane (not shown) is provided. The portion corresponding to the portion immediately below each ridge portion 13 of the cleavage plane 16 provided with the low-reflectance reflecting film is the above-described light emission spot 12A.

  Here, the electrode 14 is formed by, for example, laminating a titanium (Ti) layer, a platinum (Pt) layer, and a gold (Au) layer in this order from the p-type contact layer side, and is electrically connected to the p-type contact layer. Has been. The electrode 15 has, for example, a structure in which an alloy layer of Au and germanium (Ge), a nickel (Ni) layer, and an Au layer are stacked in this order from the back side of the substrate 11. It is connected.

  The heat sink 20 dissipates heat generated from the semiconductor laser array 10, and is, for example, a metal material having a thermal expansion coefficient larger than the thermal expansion coefficient (approximately 6 ppm / K) of each ridge portion 13, such as Cu (copper). (Approximately 17 ppm / K). The solder layer 30 is used to directly bond the semiconductor laser array 10 to the heat sink 20. For example, AuSn (approximately 17 .. 17) having a thermal expansion coefficient larger than the thermal expansion coefficient (approximately 6 ppm / K) of each ridge portion 13. 5 ppm / K).

  Further, in this semiconductor laser device 1, as shown in FIG. 1, an electrode member 40 is provided on the heat sink 20 behind the semiconductor laser array 10 (on the side opposite to the light emission side). An insulating plate 41 made of an insulating material is inserted between the heat sink 20 and the heat sink 20. The electrode member 40 is made of, for example, copper (Cu), and is fixed to the heat sink 20 by an insulating fixing member 42. The electrode member 40 is provided with a stepped portion 40A in which the upper surface on the semiconductor laser array 10 side is cut out, and the stepped portion 40A and each electrode 14 of the semiconductor laser array 10 are electrically connected via a wire 43. It is connected. A protective member 44 that covers the wire 43 via a predetermined gap is provided on the stepped portion 40A.

  By the way, in this embodiment, as shown in FIGS. 3 and 4, the stress relaxation layer 31 is embedded in the solder layer 30 provided between the semiconductor laser array 10 and the heat sink 20. Specifically, as shown in FIG. 3, the stress relaxation layer 31 is sandwiched between the solder layer 30 </ b> A on the heat sink 20 side and the solder layer 30 </ b> B on the semiconductor laser array 1 side in the solder layer 30.

  The stress relaxation layer 31 is disposed in a part of a region facing the semiconductor laser array 10. Specifically, the stress relaxation layer 31 has a comb-like shape having a plurality of comb teeth extending in the extending direction of the ridge portion 13, and the tip portion of each comb tooth is each of the semiconductor laser array 10. It is disposed in a region including a region facing the ridge portion 13. That is, the comb-tooth portion of the stress relaxation layer 31 is longer than the length of each ridge portion 13 in the extending direction. The thickness of the stress relaxation layer 31 is preferably 0.1 μm or more and 50 μm or less. Moreover, it is preferable that the width W of the comb-tooth portion (portion facing the semiconductor laser array 10) of the stress relaxation layer 31 satisfies the following formula (1). In addition, the width W of each comb tooth of the stress relaxation layer 31 is preferably equal to each other, but is different from each other, such as widening or narrowing from the central portion to the end of the semiconductor laser array 10. May be.

P−D <W <P (1)

  Here, P is the distance between the center lines of each ridge portion 13, and D is the width of the ridge portion 13.

  The stress relaxation layer 31 is formed by, for example, processing a material having a thermal expansion coefficient smaller than the thermal expansion coefficient (approximately 6 ppm / K) of each ridge portion 13, such as a graphite sheet, or by CVD (Chemical Vapor Deposition; chemical vapor phase). Graphite (approx. 1 ppm / K) formed by growth) method, sintered AiN (approx. 4.2 ppm / K), diamond formed by CVD method (approx. 2.0 ppm / K), sintered SiC (Approximately 3.0 ppm / K) or Si (approximately 3.0 ppm / K).

For reference, the thermal expansion coefficient of each material and the thermal conductivity of some materials are shown in Table 1 below.

  The semiconductor laser device 1 having such a configuration can be manufactured, for example, as follows. Since the semiconductor laser array 10 can be formed by a known method, the description of the manufacturing method is omitted, and the method of mounting the semiconductor laser array 10 on the heat sink 20 will be mainly described below. To do.

  First, about 3 μm of a solder layer 30A is formed on the heat sink 20 by, for example, vapor deposition (see FIG. 5A). Next, for example, after a mask (not shown) having a comb-like opening is formed on the solder layer 30A, a comb-like graphite layer having a thickness of about 1 μm is formed by CVD, and the mask is removed. . Thereby, the stress relaxation layer 31 is formed on the solder layer 30A (see FIG. 5B). By forming the stress relaxation layer 31 in a comb shape in this way, it is possible to suppress the gap between the comb teeth in the subsequent steps.

  Next, the solder layer 30B is formed to a thickness of about 3 μm on the strip-like portion including the tip portion of each comb tooth of the stress relaxation layer 31 among the solder layer 30A and the stress relaxation layer 31 (see FIG. 5C). ).

  Next, after placing the semiconductor laser array 10 on the solder layer 30B, pressure is applied from the semiconductor laser array 10 side, and the temperature of the solder layers 30A, 30B exceeds the melting point of the solder layers 30A, 30B. The heat sink 20 and the semiconductor laser array 10 are bonded together by raising the temperature from the side. In this way, the semiconductor laser device 1 of the present embodiment is manufactured.

  Next, the operation and effect of the semiconductor laser device 1 of the present embodiment will be described.

  In the semiconductor laser device 1 of the present embodiment, when a predetermined voltage is applied between the electrodes 14 and 15, current is confined by the ridge portions 13, and current is injected into the current injection region of the active layer. This causes light emission due to recombination of electrons and holes. This light is reflected by a pair of reflecting films (not shown), causes laser oscillation at a predetermined wavelength, and is emitted to the outside as a laser beam from each light emitting spot 12A.

  By the way, in the present embodiment, the stress relaxation layer 31 having a thermal expansion coefficient smaller than the thermal expansion coefficient (approximately 6 ppm / K) of each ridge portion 13 is disposed in a part of the region facing the semiconductor laser array 10. ing. Specifically, the tip portion of each comb tooth in the stress relaxation layer 31 is embedded in the solder layer 30 so as to be disposed in a region including a region facing each ridge portion 13 of the semiconductor laser array 10. Thereby, while the semiconductor laser array 10 receives compressive strain from the heat sink 20, the semiconductor laser array 10 receives stretching strain from the stress relaxation layer 31, so that the compressive strain received from the heat sink 20 depends on the stretching strain received from the stress relaxation layer 31. As a result, the stress applied to the entire semiconductor laser array 10 can be relieved. As a result, the semiconductor laser array 10 can be bonded to the heat sink without using a submount as in the present embodiment, and the heat dissipation is improved, so that the output of the semiconductor laser array 10 can be increased.

  When the stress relaxation layer 31 is disposed over the entire region facing the semiconductor laser array 10, it is possible to prevent the compressive strain received from the heat sink 20 from reaching the semiconductor laser array 10, but instead. In addition, the semiconductor laser array 10 is subjected to stretching strain from the stress relaxation layer 31, which adversely affects laser characteristics and reliability. On the other hand, in the present embodiment, the stress relaxation layer 31 is disposed only in a part of the region facing the semiconductor laser array 10, and the compressive strain received from the heat sink 20 is reduced by the stretching strain received from the stress relaxation layer 31. The semiconductor laser array 10 is not subjected to stress that adversely affects the laser characteristics and reliability.

  In the present embodiment, when the stress relaxation layer 31 is made of graphite, the thermal anisotropy of graphite (see Table 1) causes the semiconductor laser array 10 (more specifically, each light emitting region 12B) to The generated heat can be effectively dissipated not only in the stacking direction but also in the stacking plane direction. That is, the stress relaxation layer 31 does not become an obstacle from the viewpoint of heat dissipation. As a result, heat is not accumulated locally in the semiconductor laser device 1, so that the exhaust heat performance is improved.

[First Modification]
In the above embodiment, the stress relaxation layer 31 is disposed in the region including the region facing each ridge portion 13 of the semiconductor laser array 10. For example, as shown in FIG. It is also possible to arrange the laser array 10 in a region other than the region facing each ridge portion 13. At this time, it is preferable that the width W of the comb-tooth portion (portion facing the semiconductor laser array 10) of the stress relaxation layer 31 satisfies the following formula (2).

0 <W <P-D (2)

In this case, the heat generated from each light emitting region 12B is drawn into the stress relaxation layer 31 provided on the side of each ridge portion 13, so that the stress relaxation layer 31 is formed on the semiconductor laser array 10. Compared with the case where the light emitting regions 12B are arranged in the region including the region facing each ridge portion 13, the heat generated from each light emitting region 12B can be further dissipated in the in-layer direction. Thereby, exhaust heat property improves further.
[Second Modification]

Moreover, in the said embodiment, although the stress relaxation layer 31 was embedded in the solder layer 30, you may provide on the surface of the heat sink 20, as shown, for example in FIG.7, FIG.8. In this case, in order to improve the adhesion between the stress relaxation layer 31 and the heat sink 20, for example, a Ni layer or the like may be inserted between them.
[Third Modification]

  In the above embodiment, one comb-like stress relaxation layer 31 is disposed. However, for example, as shown in FIG. 9, a plurality of stress relaxation layers 31 that are separated and independent from each other may be disposed in parallel. Good.

[Example]
Next, an example of the semiconductor laser device 1 according to the first modification will be described as a representative of the above-described embodiment and the first and second modifications. In this example, the width W and the thickness Y of the stress relaxation layer 31 were set so as to satisfy the following expressions (3) and (4).

−ε2 <ε (W, Y) <+ ε1 (3)
ε (W, Y) = (X / 2 + 1/2) × {(κ−α) × ΔT × (P−W) + [γ × (Y / (Y + Z)) − α] × ΔT × W} / P ... (4)

  In Equation (4), (κ−α) × ΔT × (P−W) represents the amount of strain due to the heat sink 20, and [γ × (Y / (Y + Z)) − α] × ΔT × W is The amount of strain due to the stress relaxation layer 31 is shown. In the equation (4), {(κ−α) × ΔT × (P−W) + [γ × (Y / (Y + Z)) − α] × ΔT × W} / P is one ridge portion 13. Represents the amount of strain accumulated in the laser structure formed by. In Expression (4), (X / 2 + 1/2) is the number of ridge portions 13 included from the end portion to the center portion of the semiconductor laser array 10. Therefore, Expression (4) represents the amount of strain accumulated in the semiconductor laser array 10.

  Here, + ε1 is the upper limit value of the compressive strain accumulated in the semiconductor laser array 10 when the wavelength range of the light output from the semiconductor laser array 10 is 10 nm. The plus sign means that the stress is in the compression direction. -Ε2 is the upper limit value of the stretching strain accumulated in the semiconductor laser array 10 when the wavelength range of the light output from the semiconductor laser array 10 is 10 nm. The minus sign means that the stress is in the stretching direction. ε (W, Y) represents the amount of strain accumulated in the semiconductor laser array 10, and this strain amount is a function of the width W and the thickness Y of the stress relaxation layer 31. ΔT is a difference between the melting point of the solder layer 30 and normal temperature (for example, 25 ° C.). P is the distance between the center lines of the ridge portions 13. X is the total number of ridge portions 13 in the semiconductor laser array 10. Y is the thickness of the stress relaxation layer 31. Z is the distance between the stress relaxation layer 31 and the semiconductor laser array 10. α is a thermal expansion coefficient of the ridge portion 13 (substantially the same as the thermal expansion coefficient of the substrate 10 of the semiconductor laser array 10). β is a thermal expansion coefficient of the heat sink 20. γ is a thermal expansion coefficient of the stress relaxation layer 31. κ is a thermal expansion coefficient of the solder layer 30.

  In this embodiment, the substrate of the semiconductor laser array 10 is made of GaAs and the active layer is made of GaInP, and the parameters are set as follows.

ε1 = 5.0 × 10 ⁻³
ε2 = 2.6 × 10 ⁻³
ΔT = 280 ° C.−25 ° C. = 255 ° C.
P = 400 μm
X = 25
0.1 ≦ Y ≦ 50μm
Z = 3μm
227 μm <W <281 μm
α = 6.0 ppm / K
β = 17.0 ppm / K
γ = 1.0ppm / K
κ = 17.5ppm / K

  Thereby, the compressive strain received from the heat sink 20 was reduced by the stretching strain received from the stress relaxation layer 31, and the stress applied to the entire semiconductor laser array 10 could be relaxed. As a result, the wavelength range of light output from the semiconductor laser array 10 could be within 10 nm. Further, in this example, since the semiconductor laser array 10 was joined to the heat sink without using a submount, the heat dissipation was improved and the semiconductor laser array 10 could be increased in output.

[Application example]
Next, a case where the semiconductor laser device 1 of the above-described embodiment is applied to, for example, a projection type display device 100 as shown in FIG.

  A display device 100 according to this application example includes a semiconductor laser device 1, an illumination lens 2, a GLV (Grating Light Valve) 3, a projection lens 4, a scanning mirror 5, and a screen 6. Here, the illumination lens 2 converts the one-dimensional laser beam emitted from the semiconductor laser device 1 into parallel light and makes it incident on the GLV 3. GLV3 is produced by using MEMS elemental technology, and performs light modulation by changing the reflectance of a mirror according to a pixel signal. The projection lens 4 is composed of a plurality of lenses and the like, and projects image light modulated by reflection on the GLV 3 onto the screen 6 via the scanning mirror 5 to display an image. The scanning mirror 5 scans image light on the screen 6 to display an image.

  In the display device 100 having such a configuration, when the semiconductor laser device 1 of the above-described embodiment or the like is used, a high-power laser beam can be output from the semiconductor laser device 1, so that a high-luminance image is displayed. can do.

1 is a schematic configuration diagram of a semiconductor laser device according to an embodiment of the present invention. FIG. 2 is a perspective view of the semiconductor laser array of FIG. 1. FIG. 2 is a top view of the vicinity of a semiconductor laser array in the semiconductor laser device of FIG. 1. It is a cross-sectional block diagram of the AA arrow direction of FIG. FIG. 8 is a top view for illustrating the manufacturing process for the semiconductor laser device of FIG. 1. It is a section lineblock diagram of a semiconductor laser device concerning one modification. It is a cross-sectional block diagram of the semiconductor laser apparatus which concerns on another modification. It is a section lineblock diagram of a semiconductor laser device concerning other modifications. It is a section lineblock diagram of a semiconductor laser device concerning other modifications. It is a schematic block diagram of the display apparatus which concerns on one application example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser apparatus, 2 ... Illumination lens, 3 ... GLV, 4 ... Projection lens, 5 ... Scanning mirror, 6 ... Screen, 10 ... Semiconductor laser array, 11 ... Substrate, 12 ... Semiconductor layer, 12A ... Light emission spot, 12B DESCRIPTION OF SYMBOLS ... Light-emitting region, 13 ... Ridge part, 14, 15 ... Electrode, 20 ... Heat sink, 30, 30A, 30B ... Solder layer, 31 ... Stress relaxation layer, 40 ... Electrode member, 40A ... Step part, 41 ... Insulating plate, 42 ... Fixing member, 43 ... Wire, 44 ... Protection member, 100 ... Display device.

Claims (9)

A semiconductor laser array having a plurality of strip-shaped waveguides arranged in parallel with each other on a substrate;
A heat sink,
A solder layer and a stress relaxation layer provided between the semiconductor laser array and the heat sink;
The heat sink has a thermal expansion coefficient larger than that of the strip-shaped waveguide,
The said stress relaxation layer has a thermal expansion coefficient smaller than the thermal expansion coefficient of the said strip | belt-shaped waveguide, and is arrange | positioned in a part of area | region facing the said semiconductor laser array. The semiconductor laser apparatus characterized by the above-mentioned. The semiconductor laser device according to claim 1, wherein the stress relaxation layer extends in an extending direction of the strip-shaped waveguide in a region facing the semiconductor laser array. The semiconductor laser device according to claim 1, wherein the stress relaxation layer is disposed in a region facing the region where the strip-shaped waveguide is not formed. The semiconductor laser device according to claim 1, wherein the stress relaxation layer is disposed in a region including a region facing the region where the band-shaped waveguide is formed. The semiconductor laser device according to claim 1, wherein the stress relaxation layer is embedded in the solder layer. The semiconductor laser device according to claim 1, wherein the stress relaxation layer is in contact with the heat sink. The array type semiconductor laser according to claim 1, wherein a width W and a thickness Y of the stress relaxation layer satisfy the following expressions (1) and (2).
−ε2 <ε (W, Y) <+ ε1 (1)
[epsilon] (W, Y) = [Delta] T * (X / 2 + 1/2) * {([kappa]-[alpha]) * (P-W) + [[gamma] * (Y / (Y + Z))-[alpha]] * W} / P ... ( 2)
+ Ε1: Upper limit value of compressive strain accumulated in the semiconductor laser array when the wavelength range of light output from the semiconductor laser array is a predetermined value -ε2: Wavelength range of light output from the semiconductor laser array Is an upper limit value ε (W, Y) of the stretching strain accumulated in the semiconductor laser array when Δ is a predetermined value: Stress ΔT at the center of the semiconductor laser array: Difference P between the melting point of the solder layer and room temperature : Distance between center lines of each waveguide X: Total number of waveguides Y: Thickness of the stress relaxation layer Z: Distance between the stress relaxation layer and the semiconductor laser array α: Heat of the band-shaped waveguide Expansion coefficient β: Thermal expansion coefficient of the heat sink γ: Thermal expansion coefficient of the stress relaxation layer κ: Thermal expansion coefficient of the solder layer The semiconductor laser device according to claim 1, wherein the stress relaxation layer is made of graphite. A display device including a semiconductor laser device,
The semiconductor laser device includes:
A semiconductor laser array having a plurality of strip-shaped waveguides arranged in parallel with each other on a substrate;
A heat sink,
A solder layer and a stress relaxation layer provided between the semiconductor laser array and the heat sink;
The heat sink has a thermal expansion coefficient larger than that of the strip-shaped waveguide,
The display device, wherein the stress relaxation layer has a thermal expansion coefficient smaller than a thermal expansion coefficient of the strip-shaped waveguide, and is disposed in a part of a region facing the semiconductor laser array.

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