JP4933930B2 - Laser chip, laser module, laser module manufacturing method, and projector - Google Patents

Description

  The present invention relates to a laser chip, a laser module, a laser module manufacturing method, and a projector.

In general, the semiconductor laser element is a GaAs end face emission type semiconductor laser element formed on a GaAs substrate. Such a semiconductor laser element is not limited to one having a single light emitting portion, but may be a plurality of light emitting portions arranged in an array. In particular, in the case of a semiconductor laser element having a plurality of light emitting portions, the semiconductor laser element is bonded onto the submount in order to reinforce mechanical strength. As the submount, an aluminum nitride substrate or a multilayer substrate having very high thermal conductivity and excellent heat dissipation is used. A semiconductor assembly in which a semiconductor laser element is bonded to such a submount via an indium solder layer has been proposed (see, for example, Patent Document 1).
In the semiconductor assembly described in Patent Document 1, in order to avoid the occurrence of thermal stress in the semiconductor laser element due to the difference in thermal expansion coefficient between the semiconductor laser element and the submount, the thickness of the submount is reduced. It is thick.
JP 2002-299744 A

However, in the semiconductor assembly described in Patent Document 1, the thickness of the submount is increased to reduce the stress applied to the semiconductor laser element, but the thermal resistance increases as the thickness of the submount increases. . This causes a problem that it is difficult to dissipate heat generated by the semiconductor laser element.
Further, although the semiconductor laser element is bonded to the submount via indium solder, indium (In) solder has a problem that it is easily oxidized, easily diffused, and expensive. Accordingly, a method of joining the semiconductor laser element to the submount through gold tin (Au—Sn) instead of indium solder is conceivable. Gold tin is a hard material, although it has good electrical and thermal conductivity and is chemically stable. Thereby, when mounting a semiconductor laser element on a submount, even if a stress is generated between the semiconductor laser element and the submount, the gold-tin solder cannot absorb this stress. This may cause damage to the semiconductor laser element.

  SUMMARY An advantage of some aspects of the invention is to provide a highly reliable laser chip, a laser module, a laser module manufacturing method, and a projector.

In order to achieve the above object, the present invention provides the following means.
The laser chip of the present invention has a plurality of light emitting portions for emitting laser light, and at least a portion of the light emitting portion between the light emitting portions is formed with a weakened portion having a lower strength than other portions. It is characterized by that.

  The laser chip according to the present invention is effective when mounted on a substrate (submount) having a linear expansion coefficient smaller than that of the laser chip. Generally, the linear expansion coefficient is different between a laser chip and a submount on which the laser chip is mounted. As a result, when the laser chip is mounted on the submount, distortion may occur due to stress generated in the laser chip, and the laser chip may be damaged. However, in the present invention, since a weak portion having a lower strength than other portions is formed in a part of the laser chip in the thickness direction between the light emitting portions, the stress applied to the laser chip is concentrated on the weak portion. As a result, when stress is applied to the laser chip, the fragile portion is easily cracked, so that the light emitting portion of the laser chip can be avoided from being damaged, and thus a highly reliable laser chip can be provided. .

  In the laser chip of the present invention, it is preferable that the fragile portion is a portion whose thickness is reduced by forming a groove in the thickness direction.

  In the laser chip according to the present invention, the fragile portion is a portion whose thickness is reduced by forming a groove in the thickness direction, and therefore the laser chip is easily broken without affecting the light emitting portion. Therefore, it is possible to manufacture a highly reliable laser chip.

  In the laser chip of the present invention, it is preferable that the strength of the fragile portion between the light emitting portions varies depending on the position.

  In the laser chip according to the present invention, the strength of the fragile portion between the light emitting portions having a large stress applied to the laser chip is increased in the fragile portion, and the strength of the fragile portion between the light emitting portions having a small stress applied to the laser chip is increased in the fragile portion. Weaken. As described above, by forming the fragile portion according to the stress applied to the laser chip, the stress applied to the fragile portion between any of the light emitting portions becomes substantially uniform. Therefore, since a burden is not applied to a place where the stress applied to the laser chip is large, it is possible to avoid damage to the light emitting portion even when the laser chip is broken.

  The laser module of the present invention has a plurality of light emitting portions for emitting laser light, and at least a portion of the light emitting portions between the light emitting portions is broken due to a weak portion having a lower strength than other portions. And a support substrate on which the laser element is mounted, wherein the linear expansion coefficient of the support substrate is smaller than the linear expansion coefficient of the laser element.

  For example, when a laser element is used for a long time, the amount of heat generated by the laser element increases, and stress may be generated in the laser element. If no measures are taken, the laser element may be damaged by stress. In the laser module of this invention, it has the fracture | rupture part resulting from a weak part. As a result, damage to the light emitting portion of the laser element can be avoided, so that a highly reliable laser module can be provided. In addition, the rupture portion can also be formed due to the fragile portion during the manufacturing process when the laser chip is mounted on the submount.

  In the laser module of the present invention, it is preferable that the fragile portion is a portion whose thickness is reduced by forming a groove in the thickness direction.

In the laser module according to the present invention, the fragile portion is a portion where the thickness is reduced by forming a groove in the thickness direction, so that the laser element is easily broken without affecting the light emitting portion. Therefore, it becomes possible to manufacture a highly reliable laser module.
Even when the laser element is broken for each light emitting portion, the portion is referred to as a groove.

  In the laser module of the present invention, it is preferable that the groove of the laser element is formed on the mounting surface of the laser element on the support substrate side.

  In the laser module according to the present invention, since the groove is formed on the mounting surface side in contact with the support substrate of the laser element, the tensile stress of the laser element is easily concentrated on the weak part. Thereby, it becomes easy to crack in the thickness direction of the laser element in which the weak part was formed. Therefore, when stress is applied to the laser element, the fragile portion is actively cracked, so that damage to the light emitting portion can be avoided.

  In the laser module of the present invention, it is preferable that the bonding material is a material containing a hard brazing material.

  In general, when a material containing a brazing filler metal is used as the bonding material, even if a stress is generated between the laser element and the support substrate, the bonding material cannot absorb this stress. However, in the laser module according to the present invention, the linear expansion coefficient of the support substrate is smaller than the linear expansion coefficient of the laser element, and the weak part is formed in the laser element. concentrate. Therefore, even if the bonding material is a material containing a brazing filler metal, the laser element can be firmly mounted on the support substrate without damaging the light emitting portion of the laser element.

  The method for manufacturing a laser module according to the present invention is a method for manufacturing a laser module in which a laser chip having a plurality of light emitting portions for emitting laser light is mounted on a support substrate, wherein at least a part of the light emitting portions of the laser chip. The method includes a step of forming a fragile portion in a part in a thickness direction between the step and a step of bonding the laser chip to the support substrate by a heated bonding material.

  In the method for manufacturing a laser module according to the present invention, first, a fragile portion is formed in a part in the thickness direction between at least some light emitting portions on the surface of the laser chip on the support substrate side. Thereafter, the laser chip is bonded to the support substrate with the heated bonding material. As the bonding material cools, stress is generated in the laser chip due to the difference between the linear expansion coefficient of the laser chip and the linear expansion coefficient of the support substrate. At this time, since the linear expansion coefficient of the support substrate is smaller than the linear expansion coefficient of the laser chip, the stress applied to the laser chip concentrates on the fragile portion. Therefore, since the stress is concentrated on the fragile portion of the laser chip due to the shrinkage of the laser chip, the laser chip on which the fragile portion is formed easily breaks in the thickness direction. With such a manufacturing method, when stress is applied to the laser chip, the fragile portion is easily cracked, so that it is possible to avoid damage to the light emitting portion. That is, it becomes possible to manufacture a highly reliable laser module.

  In the laser module manufacturing method of the present invention, the weakened portion is formed on the mounting surface of the laser chip on the support substrate side, and the thickness is reduced by forming a groove in the thickness direction. A part is preferred.

  In the laser module manufacturing method according to the present invention, a groove is formed on the mounting surface of the laser chip on the support substrate side. Thereby, the part where thickness became thin by the groove | channel being formed in the thickness direction turns into a weak part. Therefore, even if the linear expansion coefficient of the support substrate is smaller than the linear expansion coefficient of the laser chip, the laser chip is easily broken by the fragile portion without affecting the light emitting portion, so that a highly reliable laser module can be manufactured. It becomes.

  According to another aspect of the invention, a projector includes: a light source device including the laser module; and an image forming device that displays an image having a desired size on a display surface using light from the light source device. .

  In the projector according to the present invention, the light emitted from the light source device enters the image forming apparatus. Then, an image having a desired size is displayed on the display surface by the image forming apparatus. At this time, as described above, by providing the projector with the light source device having the highly reliable laser module, the reliability of the projector itself can be improved.

  Hereinafter, embodiments of a laser chip, a laser module, a laser module manufacturing method, and a projector according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

[First Embodiment]
A method for manufacturing the laser module according to this embodiment will be described.
First, the configuration of a laser module manufactured by the laser module manufacturing method of the present embodiment will be described with reference to FIG.
As shown in FIG. 1, the laser module 1 includes a plurality of divided laser elements 15, a submount (support substrate) 20, and a current supply substrate 30.
The submount 20 supports the laser element 15 and reinforces the mechanical strength.

First, the laser chip 10 mounted on the submount 20 will be described.
As shown in FIG. 2, the laser chip 10 is an end face emission type semiconductor laser in which a plurality of emitters (light emitting portions) 12 for emitting laser light are arranged in a one-dimensional direction.
Specifically, as shown in the enlarged view of FIG. 2, the laser chip 10 has a plurality of layers including an active layer 13 a including a quantum well structure stacked on one surface 11 a of the semiconductor substrate 11. The active layer 13a serves as the emitter 12 that emits laser light. The active layer 13 a is formed with insulating layers 13 b on both sides, and the active layers 13 a and insulating layers 13 b are alternately formed in the length direction of the laser chip 10. Further, the termination layer side of the plurality of layers formed on the semiconductor substrate 11 is a mounting surface 10 a mounted on the submount 20. A groove 14 is formed in the thickness direction of the laser chip 10 in a region including the insulating layer 13b from the mounting surface 10a of the laser chip 10. And the area | region (part where thickness became thin) P between the edge part 14a of the groove | channel 14 of the thickness direction of the laser chip 10 and the end surface 10b opposite to the mounting surface 10a is a weak part.
That is, a groove 14 is formed between each of the plurality of emitters 12. The groove 14 can be formed by, for example, photolithography and etching. The depth of the groove 14 is a depth that reaches the semiconductor substrate 11 and is preferably formed so as to divide the light emitting portion at least. Further, the depth of the groove 14 between the emitters 12 is substantially the same.

The laser chip 10 is made of a semiconductor material made of gallium (Ga) and arsenic (As). The linear expansion coefficient of the laser chip 10 is about 6 × 10 ⁻⁶ / K.
The submount 20 is made of diamond having a linear expansion coefficient of about 1 × 10 ⁻⁶ / K.

  As shown in FIG. 1, the current supply substrate 30 is a flexible substrate, and a wiring pattern 31 for supplying current is formed. An electrode (not shown) is provided for each emitter 12 on the upper and lower surfaces of the laser element 15. A bonding wire 32 is bonded to the wiring pattern 31 from the electrode on the upper surface of the laser chip 10.

Next, a method for manufacturing the laser module 1 in which the laser chip 10 of the present embodiment configured as described above is mounted on the submount 20 will be described.
First, as shown in FIG. 3, in the region L where the laser chip 10 is mounted on the upper surface 20a of the submount 20, as shown in FIG. 4, a die attach of Au—Sn (gold-tin) alloy material (bonding material). The film 21 is placed. Note that the melting point of the die attach film 21 made of Au—Sn (gold tin) used in the present embodiment is 287 ° C.
Then, as shown in FIG. 4, when the submount 20 is heated to about 300 ° C., the die attach film 21 is melted, and the laser chip 10 expands outward as indicated by arrows A1 and B1, and the submount 20 also As shown by arrows C1 and D1, it expands outward. Thereafter, the submount 20 on which the laser chip 10 is mounted is naturally cooled to room temperature, and the laser chip 10 is fixed onto the submount 20.

  When cooled in this way, as shown in FIG. 5, the amount of shrinkage differs due to the difference in the linear expansion coefficient between the laser chip 10 and the submount 20, so that stress is generated in the laser chip 10. That is, since the linear expansion coefficient of the laser chip 10 is larger than that of the submount 20, the central portion of the laser chip 10 is smaller than the contraction force (arrows C2 and D2 in FIG. 5) toward the central portion of the submount 20. The shrinking force (arrows A2 and B2 in FIG. 5) is larger. Therefore, tensile stress is generated in the laser chip 10 and compressive stress is generated in the submount 20.

At this time, as shown in the enlarged view of FIG. 5, tensile stress is generated in the laser chip 10 due to the stress concentration at the center of the laser chip 10. That is, when stress concentrates on the region (fragile portion) P of the laser chip 10, a crack (crack) K is generated from the end portion 14a of the groove 14 of the laser chip 10 to the end face 10b, and as shown in FIG. Each emitter 12 is divided. As a result, as shown in FIG. 7, a plurality of laser elements 15 each having one emitter 12 are formed.
In the example shown in FIG. 7, the laser chip 10 is shown in a state where it is all divided between the emitters 12, but depending on how stress is applied to the laser chip 10, there is a case where there are undivided emitters 12. There is also.

  Then, as shown in FIG. 1, bonding wires 32 are bonded from each laser element 15 to the wiring pattern 31. Each laser element 15 is electrically connected to the wiring pattern 31 by at least one bonding wire 32. In this way, current is supplied from the current supply substrate 30 to each laser element 15.

In the laser module manufacturing method according to the present embodiment, the laser chip 10 in which the grooves 14 are formed in the thickness direction is mounted on the submount 20 having a linear expansion coefficient smaller than that of the laser chip 10. As a result, the stress applied to the laser chip 10 is concentrated in the region P, which is a fragile portion formed by the groove 14, and the region P is easily cracked. Therefore, damage to the emitter 12 of the laser chip 10 can be avoided. Therefore, it becomes possible to provide the laser module 1 with high reliability.
Further, by forming the groove 14 on the mounting surface 10 a of the laser chip 10, stress is easily concentrated on the region P. As a result, the crack K is easily formed in the region P in the thickness direction of the laser chip 10 in which the groove 14 is formed. With such a manufacturing method, the stress applied to the laser chip 10 can be relaxed without affecting the emitter 12, and a highly reliable laser module can be manufactured.

  Furthermore, generally, when a bonding material made of Au—Sn (a material containing a hard brazing material) is used as a bonding material for bonding the laser chip 10 and the submount 20, a gap between the laser chip 10 and the submount 20 is used. Even if stress occurs, the bonding material made of Au—Sn cannot absorb this stress. However, in the laser chip manufacturing method according to the present invention, the linear expansion coefficient of the submount 20 is smaller than the linear expansion coefficient of the laser chip 10, and the groove 14 is formed in the laser chip 10. Stress applied to the chip 10 is concentrated. Therefore, even if the bonding material is made of Au—Sn, the laser chip 10 can be firmly fixed on the submount 20 without damaging the emitter 12 of the laser chip 10.

In this embodiment, the groove 14 is formed between all the emitters 12, but it is sufficient that the groove 14 is formed between at least one emitter 12.
Moreover, although the groove | channel 14 was formed from the mounting surface 10a of the laser chip 10, you may form toward the mounting surface 10a from the end surface 10b.
Moreover, although the groove | channel 14 was formed in order to form a weak part, it is not restricted to this. That is, a portion having a lower strength than other portions may be formed by performing a process such as modifying a part in the thickness direction so that the shape does not change in appearance. Furthermore, you may form a weak part compared with another part in the intermediate part which goes to the end surface 10b from the mounting surface 10a using a laser beam.
Further, although the edge emitting semiconductor laser is used as the laser chip 10, even if a surface emitting laser is used, the same effect can be obtained by forming a weak portion between the light emitting portions.
When a surface emitting laser is used, not only the laser chip 10 in which a plurality of emitters 12 are arranged in a one-dimensional direction, but also a laser chip 35 having light emitting portions 35a arranged in a matrix as shown in FIG. It may be. In this laser chip 35, a plurality of laser elements can be obtained in a matrix by forming grooves 36 in a lattice pattern between the light emitting portions 35a. In this case, as shown in FIG. 8, adjacent laser elements are electrically connected by bonding wires 37a, and bonding wires 37b are provided on the wiring pattern 31 of the current supply substrate 30 from the laser elements on the end face 35b side.
A single bonding wire may be provided from the laser element having one emitter to the wiring pattern 31 of the current supply substrate 30.

Furthermore, the submount 20 is desirably placed on a heat sink having high thermal conductivity, such as copper (Cu). As a result, the heat generated from the laser element 15 is transferred from the submount 20 to the heat sink and dissipated.
Here, when the laser element 15 is used for a long time, the laser element 15 becomes high temperature, and the metal used as the wiring or the electrode moves on the insulator (migration phenomenon), and the insulation resistance value between the electrodes decreases. Defects may occur. However, by using a laser module in which the submount 20 is mounted on a heat sink having high thermal conductivity, the heat of the laser element 15 can be radiated more effectively, so that the occurrence of the above-described defects can be prevented. it can.
In the present embodiment, the heated submount 20 is naturally cooled, but may be forcibly cooled by a cooling device or the like.
Furthermore, although Au-Sn was used as a material containing a brazing filler metal, it is not limited to this.

[Modification of First Embodiment]
In the first embodiment shown in FIG. 2, it is assumed that the depth of the groove 14 between the emitters 12 is substantially the same, but the sub-chip is formed by using a laser chip 40 in which the depth of the groove 41 between the emitters 12 differs depending on the position. It may be mounted on the mount 20. Such a modification will be described with reference to FIG.
In the present embodiment, when the laser chip 40 is mounted on the submount 20, the stress applied to the end faces 40a and 40b is larger than that in the central portion.
Therefore, as shown in FIG. 9, the laser chip 40 is formed with a groove 41 having a depth Q deeper from the end faces 40a, 40b toward the center. Thereby, compared with the intensity | strength of the area | region P1 used as the weak part formed by the groove | channel 41 by the side of the end surface 40a of the laser chip 40 among the area | regions P which are the weak parts formed by the groove | channel 41 of the laser chip 40, The intensity | strength of the area | region P2 used as the weak part formed of the groove | channel 41 of the center part is weaker. That is, the strength of the region P1 between the emitters 12 on the side of the end faces 40a and 40b where the stress applied to the laser chip 40 is large is increased in the plurality of grooves 41, and the region between the emitters 12 in the central portion where the stress applied to the laser chip 40 is small. The strength of P2 is weakened among the plurality of grooves 41.
Using such a laser chip 40, it is mounted on the submount 20 as in the first embodiment.

  In the manufacturing method of the laser module according to the present embodiment, the depth of the groove 41 is set according to the stress applied to the laser chip 40, so that it is easy to crack in the regions P1 and P2 between all the emitters 12 when cooling. Is substantially uniform. Accordingly, since a burden is not applied to a place where the stress applied to the laser chip 40 is large, it is possible to divide the laser chip 40 without affecting the emitter 12.

In addition, the depth of the groove 41 is not limited to a depth that increases toward the center, and may be appropriately changed according to the shape of the submount 20 to be mounted.
That is, the depth of the groove 41 is not limited to a constant depth. For example, depending on the state of the submount 20 to be mounted, the weakened portion between the emitters 12 to be easily broken is weakened. The depth may be increased.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIG.
In FIG. 10, the casing constituting the projector 100 is omitted for simplification.

In the projector 100, the red laser light source (light source device) 101R that emits red light, green light, and blue light, the green laser light source (light source device) 101G, and the blue laser light source (light source device) 101B are the lasers of the first embodiment. The light source device 101 includes the module 1.
The projector 100 is formed by liquid crystal light valves (light modulation devices) 104R, 104G, and 104B that modulate laser beams emitted from the laser light sources 101R, 101G, and 101B, and liquid crystal light valves 104R, 104G, and 104B, respectively. An image forming apparatus having a projection lens (projection apparatus) 107 that enlarges an image and projects it on a screen (display surface) 110 is provided. The projector 100 further includes a cross dichroic prism (color light combining unit) 106 that combines the light emitted from the liquid crystal light valves 104R, 104G, and 104B and guides the light to the projection lens 107.

  Further, in order to make the illuminance distribution of the laser light emitted from the laser light sources 101R, 101G, and 101B uniform, the projector 100 is arranged on the downstream side of the optical path from the laser light sources 101R, 101G, and 101B, and the uniformizing optical systems 102R and 102G. , 102B are provided, and the liquid crystal light valves 104R, 104G, 104B are illuminated by light having a uniform illuminance distribution. For example, the uniformizing optical systems 102R, 102G, and 102B are configured by, for example, a hologram 102a and a field lens 102b.

  The three color lights modulated by the respective liquid crystal light valves 104R, 104G, and 104B are incident on the cross dichroic prism 106. This prism is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 110 by the projection lens 107, which is a projection optical system, and an enlarged image is displayed.

  In the projector 100 of the present embodiment described above, the red laser light source 101R, the green laser light source 101G, and the blue laser light source 101B have the highly reliable laser module 1, so that the reliability of the projector 1 itself is also improved. Is possible.

  In the projector according to this embodiment, the red, green, and blue laser light sources 101R, 101G, and 101B have been described using the laser module 1 according to the first embodiment. It is also possible to use a module on which the above-described laser chip 40 is mounted. At this time, a light source device having a different laser module can be adopted for each light source device 101, or a light source device of the same laser module can be adopted.

Further, although a transmissive liquid crystal light valve is used as the light modulator, a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such a light valve include a reflective liquid crystal light valve and a digital micromirror device. The configuration of the projection optical system is appropriately changed depending on the type of light valve used.
An image forming apparatus for displaying an image of a desired size on a display surface by causing the laser module (including the modification) of the first embodiment to scan the screen with laser light from a laser light source (light source device). The present invention can also be applied to a light source device of a scanning type image display device (projector) having a scanning means.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the second embodiment, the cross dichroic prism is used as the color light combining means, but the present invention is not limited to this. As the color light synthesizing means, a dichroic mirror having a cross arrangement to synthesize color light, or a dichroic mirror arranged in parallel to synthesize color light can be used.

1 is a perspective view showing a laser module according to a first embodiment of the present invention. It is a top view which shows the laser chip concerning this invention. It is a top view which shows the process of mounting the laser chip concerning this invention on a support substrate. It is a top view which shows the process of mounting the laser chip concerning this invention on a support substrate. It is a top view which shows the process of mounting the laser chip concerning this invention on a support substrate. It is a top view which shows the process of mounting the laser chip concerning this invention on a support substrate. It is a top view which shows a part of laser module concerning this invention. It is a top view which shows the modification of the laser chip concerning this invention. It is a top view which shows the modification of the laser chip used for the laser module which concerns on 1st Embodiment of this invention. It is a schematic block diagram which shows the projector which concerns on 2nd Embodiment of this invention.

Explanation of symbols

  P ... area (fragile part), 1 ... laser module, 10, 35, 40 ... laser chip, 12 ... emitter (light emitting part) 20 ... submount (support substrate), 35a ... light emitting part, 100 ... projector

Claims (1)

The laser beam have a plurality of light emitting portions for emitting, in a portion between the light emitting portion of the part even without low, the laser chip weak plurality of fragile portions strength is formed as compared with other portions, A bonding material placing step of placing a bonding material between the laser chip and a support substrate;
A bonding step of heating and melting the bonding material to bond the support substrate and the laser chip;
A cooling step of naturally cooling the support substrate and the laser chip bonded to each other in the bonding step to room temperature;
A stress applying step of generating a tensile stress in the laser chip with a temperature difference generated in the cooling step, with a linear expansion coefficient of the support substrate smaller than the linear expansion coefficient of the laser chip; and
In the tensile stress, a dividing step of dividing the laser chip starting from the pre-formed the weakened portions on the laser chip to laser device, a method for manufacturing a including the laser module,
A plurality of the weak portion is a reduced thickness portion of the laser chip by the previous SL laser chip faces a groove formed,
The bonding material is a film-like Au- Sn (gold-tin) Ri alloy material der,
In the laser element, active layers and insulating layers are alternately stacked, and an insulating portion is formed on a side surface of the groove in the active layer,
The depth in the direction in which the groove is formed is the same,
The groove has a deepest substantially central portion in the region bonded by the bonding material,
The groove is formed such that the depth becomes shallower as it is separated from the substantially central portion in the direction in which the groove is formed and the direction perpendicular to the depth direction of the groove .
A method for manufacturing a laser module.

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