Semiconductor laser device

Abstract

To provide a semiconductor laser device capable of preventing a short-circuit between channels configured so as to be driven independently to each other and accurately aligning a plurality of luminous points.SOLUTION: A semiconductor laser device 1A comprises a semiconductor laser element 10 including a plurality of mesa parts 12, and a submount 20 including a recess 21 in which a plurality of mesa parts 12 is arranged. A wiring part W is provided in the recess 21. An electrode 35 corresponding to each mesa part 12 is electrically connected to the wiring part W via a solder member 33. The wiring part W includes first wiring 31A and second wiring 31B electrically separated adjacent to each other. A reference surface R1 of the semiconductor laser element 10 has surface contact with a reference surface R2 of the submount 20. A distance d2 from a first base end part P1 of a first mesa part 12A corresponding to the first wiring 31A to a second base end part P2 of a second mesa part 12B corresponding to the second wiring 31B is longer than a length d1 of a contact area CA of the mesa part 12.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to a semiconductor laser device.

Background Art

[0002] Conventionally, an end-emitting semiconductor laser element is known. For example, Patent Document 1 discloses a configuration in which the back surface opposite to the surface of a semiconductor laser element having a plurality of channels (light-emitting points) (the surface on the side where the active layer forming the light-emitting points is provided) is mounted on a mounting member by the junction-up method. Further, conventionally, as a mounting method other than the junction-up method, a junction-down method in which the surface of a semiconductor laser element is mounted on a mounting member is also known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional mounting methods as described above, when mounting the surface or the back surface of a semiconductor laser element on a mounting member via a solder member by, for example, reflow soldering, there is a problem that the thickness of the solder member is not uniform and the height positions of a plurality of light-emitting points vary.

[0005] Further, when configured to include at least a first channel and a second channel capable of driving a plurality of channels independently of each other, it is required to reliably prevent a short circuit between the first channel and the second channel.

[0006] Therefore, one aspect of this disclosure aims to provide a semiconductor laser device that can accurately align multiple light-emitting points while preventing short circuits between channels configured to be independently drivable. [Means for solving the problem]

[0007] This disclosure includes the following semiconductor laser devices [1] to

[18] .

[0008] [1] A semiconductor laser element comprising a substrate having a first surface and a second surface located opposite each other in a first direction, and a plurality of mesa portions having light-emitting end faces that intersect a second direction perpendicular to the first direction, and which are formed to protrude in the first direction and extend in the second direction relative to a first reference plane formed on the second surface, A mounting member comprising a third surface forming a second reference surface opposite to a first reference surface, and recesses formed on the third surface where a plurality of mesa portions are arranged, The mesa portion has a top surface facing the bottom surface of the recess, and a pair of sides located opposite each other in a third direction perpendicular to the first and second directions. A first electrode is provided on the top surface of the mesa portion, which is electrically connected to a contact layer located on the top surface side of the mesa portion. In the recess, wiring sections are provided at positions corresponding to each of the multiple mesa sections. Each of the multiple mesa sections, corresponding to the first electrode, is electrically connected to the wiring section via a soldering component. The wiring section includes a first wiring and a second wiring that are arranged adjacent to each other in a third direction and are electrically isolated from each other. The soldering member electrically connected to the first wiring is positioned so as not to come into contact with the soldering member electrically connected to the second wiring. Thus, the first mesa portion electrically connected to the first wiring is electrically isolated from the second mesa portion electrically connected to the second wiring. The first reference surface is in surface contact with the second reference surface. The distance in the third direction from the first proximal end, which is the boundary between the side surface of the first mesa portion on the side where the second mesa portion is located relative to the first mesa portion and the first reference plane, to the second proximal end, which is the boundary between the side surface of the second mesa portion on the side where the first mesa portion is located relative to the second mesa portion and the first reference plane, is longer than the length in the third direction of the contact region of the contact layer that is in contact with the first electrode. Semiconductor laser device.

[0009] In the above semiconductor laser device, the first reference surface of the semiconductor laser element is in surface contact with the second reference surface of the mounting member. This allows for precise alignment of the positions of multiple light-emitting points (e.g., the center of the light-emitting end face in the first direction) relative to the second reference surface of the mounting member. The semiconductor laser device also has a first mesa section and a second mesa section that are electrically isolated from each other (i.e., configured to be drivable independently of each other) and are arranged adjacent to each other. Here, the amount of solder material required (e.g., the width of the solder material in the third direction) may change depending on the width of the contact area (length in the third direction), but in the above semiconductor laser device, the distance between the first mesa section and the second mesa section (i.e., the distance from the first base end to the second base end in the third direction) is longer than the width of the contact area. This ensures that the distance between the first mesa section and the second mesa section is sufficient for the amount of solder material required according to the width of the contact area. As a result, when mounting the semiconductor laser element to the mounting member by reflow soldering, it is possible to effectively prevent the solder member corresponding to the first mesa portion and the solder member corresponding to the second mesa portion from melting and coming into contact with each other. Therefore, with the above semiconductor laser device, it is possible to accurately align multiple light-emitting points while preventing short circuits between channels that are configured to be driven independently of each other.

[0010] [2] The recess has a first recess in which the first mesa portion is located, and a second recess in which the second mesa portion is located. The length in the third direction of the second reference plane of the partition wall portion formed between the first recess and the second recess and extending in the second direction to separate the first recess and the second recess is longer than the length in the third direction of the contact region. [1] A semiconductor laser device. According to the above configuration, by arranging the first mesa portion and the second mesa portion in different recesses (first recess and second recess) and ensuring a sufficient width of the partition wall between the first recess and the second recess, it is possible to effectively prevent the solder member corresponding to the melted first mesa portion (or second mesa portion) from crossing the partition wall and short-circuiting with the solder member corresponding to the second mesa portion (or first mesa portion) during reflow soldering.

[0011] [3] The recess is composed of multiple recesses, each of which is individually positioned within a group of mesa sections. Between adjacent recesses, a partition wall is provided that extends in a second direction and has a predetermined length in a third direction, and has a second reference plane. A semiconductor laser device [1] or [2]. The above configuration, compared to a configuration including a single recess in which two or more mesa sections are arranged, effectively prevents short circuits between adjacent mesa sections and improves the reliability of independent driving of multiple channels. Furthermore, since the contact area between the first reference plane and the second reference plane can be increased at the partition wall provided between each recess, the stress on the semiconductor laser element (mainly the substrate) can be reduced, and the occurrence of warping of the semiconductor laser element can be suppressed. In particular, when the length of the substrate in the third direction increases due to the arrangement of multiple mesa sections in the third direction, warping of the substrate in the third direction becomes more likely. The above configuration is particularly effective in such cases.

[0012] [4] A single second electrode common to multiple mesa portions is provided on the first surface. A semiconductor laser device of any of the following types: [1] to [3]. According to the above configuration, by making the electrode member (second electrode) arranged on the back side (first surface) of the substrate of the semiconductor laser element common among multiple mesa portions, the number of wires connected to the electrode member by wire bonding can be reduced, thereby suppressing damage to the semiconductor laser element due to wire bonding.

[0013] [5] The recess has a first side surface facing the side surface of the mesa portion in the third direction, The first side surface is inclined with respect to the bottom surface such that the opening width along the third direction of the recess on the third surface is larger than the width along the third direction of the bottom surface of the recess. The semiconductor laser device according to any one of [1] to [4]. According to the above configuration, by configuring the first side surface of the recess as an inclined surface that widens from the bottom surface side toward the opening end side, it is possible to appropriately secure a space for discharging the solder member melted during reflow within the recess.

[0014] [6] The wiring portion extends from the inside of the recess to the third surface outside the recess. The semiconductor laser device according to any one of [1] to [5]. According to the above configuration, since the electrode on the mesa portion side of the semiconductor laser element can be drawn out to the surface (third surface) of the mount member via the first electrode and the wiring portion, it is easy to implement the configuration for flowing a current through the semiconductor laser element.

[0015] [7] The wiring portion extends along the second direction from the inside of the recess to the outside of the recess. The recess has a second side surface that intersects the second direction and along which the wiring portion extends. The second side surface is inclined with respect to the bottom surface such that the opening width along the second direction of the recess on the third surface is larger than the width along the second direction of the bottom surface of the recess. The semiconductor laser device according to [6]. If the second side surface is not inclined as described above (for example, if the second side surface is a surface perpendicular to the bottom surface of the recess), the wiring portion will bend in a stepped manner, making it easy for disconnection to occur. On the other hand, by configuring the second side surface as an inclined surface as described above and arranging the wiring portion along the inclined second side surface, it is possible to avoid the wiring portion from bending in a stepped manner and suppress the occurrence of disconnection.

[0016] [8] Each of the multiple mesa regions has one or more active layers independently provided for each mesa region. A semiconductor laser device from [1] to [7]. With the above configuration, the active layers are spatially separated between multiple mesa sections, thus reliably preventing optical crosstalk between mesa sections. Furthermore, if multiple active layers are provided in each mesa section, each mesa section can function as a stacked semiconductor laser element, thereby increasing the laser output.

[0017] [9] The wiring section is arranged at each of the positions corresponding to each of the multiple mesa sections and includes multiple wires that are electrically isolated from each other. Any two wires among multiple wires that are adjacent to each other in a third direction correspond to the first wire and the second wire. A semiconductor laser device from [1] to [8]. According to the above configuration, the distance between any two adjacent mesa sections (i.e., the distance from the first base end to the second base end in the third direction) is longer than the width of the contact area. This makes it possible to drive multiple mesa sections (channels) independently while preventing short circuits between channels.

[0018]

[10] The mounting member is made of silicone. A semiconductor laser device from [1] to [9]. According to the above configuration, recesses can be formed with high precision, for example, by an etching process.

[0019]

[11] The mounting member has a third surface connected to a fourth surface that intersects in the second direction, The recess extends to the fourth surface and opens onto the fourth surface. A semiconductor laser device from [1] to

[10] . According to the above configuration, the light-emitting end faces of each mesa portion arranged in the recess can be exposed to the outside through the portion of the recess that opens to the fourth surface, thereby improving the efficiency of extracting light emitted from the light-emitting end faces along the second direction.

[0020]

[12] The third surface is provided with alignment marks for aligning the semiconductor laser element with respect to the mounting member. A semiconductor laser device from [1] to

[11] . According to the above configuration, when mounting the semiconductor laser element on the mounting member, it becomes possible to easily and accurately align the semiconductor laser element with respect to the mounting member.

[0021]

[13] The thickness of the substrate in the first direction is smaller than the thickness of the mounting member in the first direction. A semiconductor laser device from [1] to

[12] . With the above configuration, by using a mounting member that is thicker than the semiconductor laser element, the occurrence of distortion of the mounting member relative to the semiconductor laser element (i.e., distortion of the second reference plane) can be effectively suppressed. As a result, the positions of multiple light-emitting points with respect to the second reference plane of the mounting member can be aligned with even greater precision.

[0022]

[14] The substrate has a fifth surface that intersects in a third direction, In the third direction, the distance from the edge of the recess closest to the fifth surface to the fifth surface is longer than the distance from the first reference plane to the top surface of the mesa in the first direction. A semiconductor laser device of any of the following types: [1] to

[13] . According to the above configuration, in the area of ​​the substrate outside the region where the recess is provided in the third direction, the area of ​​contact between the first reference surface and the second reference surface can be secured to a certain extent or more, thereby improving the support stability of the semiconductor laser element with respect to the mounting member.

[0023]

[15] An optical element positioned in a second direction opposite to the semiconductor laser element and mounting member, which guides the light emitted from each of the multiple mesa portions toward the outside, A support substrate that supports the mounting member and optical element, Furthermore, The support substrate has a first support surface that supports the mounting member by making surface contact with a sixth surface opposite to the third surface of the mounting member, and a second support surface that supports the optical element by making surface contact with the optical element. A semiconductor laser device of any of the following types: [1] to

[14] . With the above configuration, the mounting member on which the semiconductor laser element is mounted and the optical element are supported by surface contact with the first and second support surfaces of the support substrate. Therefore, the height positions of the semiconductor laser element and the optical element (i.e., the height positions of each element relative to the support surfaces (first and second support surfaces) of the support substrate) can be easily and accurately aligned.

[0024]

[16] The optical element has a light incident surface into which light emitted from each of the light-emitting end faces of the multiple mesa portions is incident. The mounting member has a fourth surface facing the light incident surface, The light incident surface is in surface contact with the fourth surface.

[15] A semiconductor laser device. According to the above configuration, by bringing the fourth surface of the mounting members, which are opposite to each other in the second direction, into surface contact with the light incident surface of the optical element, the distance between the light emission end surface and the light incident surface in the second direction can be precisely adjusted. In other words, when mounting a semiconductor laser element on a mounting member, the distance from the light emission end surface to the light incident surface can be adjusted by adjusting the distance from the light emission end surface to the fourth surface in the second direction.

[0025]

[17] The length of the recess in the second direction is longer than the length of the semiconductor laser element in the second direction. A semiconductor laser device from [1] to

[16] . According to the above configuration, it is possible to release the molten solder material during reflow into the space within the recess that does not overlap with the semiconductor laser element (mesa portion) in the second direction. Furthermore, when the optical element is a lens, it is possible to adjust the position of the semiconductor laser element in the second direction relative to the mounting member according to the focal length of the lens.

[0026]

[18] The support substrate further comprises a molded resin formed to cover the optical element, the mounting member, and the semiconductor laser element. A semiconductor laser device of any of the following types:

[15] to

[17] . According to the above configuration, the positional relationship of each component (optical element, mounting member, and semiconductor laser element) placed on the support substrate can be fixed by the molded resin, thereby preventing misalignment of the components. Furthermore, each component can be properly protected by the molded resin. [Effects of the Invention]

[0027] According to one aspect of this disclosure, it is possible to provide a semiconductor laser device that can accurately align multiple light-emitting points while preventing short circuits between channels that are configured to be driven independently of each other. [Brief explanation of the drawing]

[0028] [Figure 1] Figure 1 is a perspective view showing a semiconductor laser device according to the first embodiment. [Figure 2] Figure 2 is a perspective view of the semiconductor laser element of the semiconductor laser apparatus shown in Figure 1, viewed from the side where the mesa section is located. [Figure 3] Figure 3 is a cross-sectional view along the line III-III in Figure 2. [Figure 4] Figure 4 is a perspective view showing the submount of the semiconductor laser device in Figure 1 before the semiconductor laser elements are mounted. [Figure 5] Figure 5 is an enlarged view of region A in Figure 4. [Figure 6]Figure 6(A) is a cross-sectional view along the line VIa-VIa in Figure 5. Figure 6(B) is a cross-sectional view along the line VIb-VIb in Figure 5. [Figure 7] Figure 7 shows the process of mounting a semiconductor laser element onto a submount. [Figure 8] Figure 8 is a plan view showing the semiconductor laser element mounted on the submount. [Figure 9] Figure 9 is a side view of a region containing two adjacent mesa areas. [Figure 10] Figure 10 is a side view showing a modified example of the recess. [Figure 11] Figure 11 is a partial side view showing another variation of the recess. [Figure 12] Figure 12 is a perspective view showing a semiconductor laser device according to the second embodiment. [Figure 13] Figure 13 is a side view showing the semiconductor laser device shown in Figure 12. [Figure 14] Figure 14 is a perspective view showing a semiconductor laser apparatus according to the third embodiment. [Figure 15] Figure 15 is a side view showing the semiconductor laser device shown in Figure 14. [Modes for carrying out the invention]

[0029] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0030] [First Embodiment] Referring to Figures 1 to 9, the semiconductor laser apparatus 1A of the first embodiment will be described. As shown in Figure 1, the semiconductor laser apparatus 1A comprises a semiconductor laser element 10 and a submount 20 (mounting member). The semiconductor laser element 10 is mounted on the submount 20 using a junction-down method. That is, the semiconductor laser element 10 is mounted on the submount 20 such that the surface (bottom surface 11b) on which the active layer 13 (see Figure 3) is provided faces the submount 20.

[0031] In this embodiment, the side on which the semiconductor laser element 10 is mounted on the submount 20 is defined as the upper side, and the side from which the laser light L is emitted outward from the semiconductor laser element 10 is defined as the front side. Based on the above definition, the vertical direction is represented as the Z-axis direction (first direction), the front-to-back direction is represented as the Y-axis direction (second direction), and the left-to-right direction is represented as the X-axis direction (third direction). The Z-axis direction coincides with the direction in which the semiconductor laser element 10 and the submount 20 face each other. The Y-axis direction is perpendicular to the Z-axis direction and coincides with the direction in which each of the multiple mesa portions 12 of the semiconductor laser element 10 extends (i.e., the laser emission direction). The X-axis direction is perpendicular to both the Z-axis direction and the Y-axis direction and coincides with the arrangement direction of the multiple mesa portions 12.

[0032] The semiconductor laser element 10 is an end-face emission type semiconductor laser element. The semiconductor laser element 10 has a substrate 11 and a plurality (eight in this embodiment) of mesa portions 12. The semiconductor laser element 10 may be a single-channel type having only one channel, or a multi-channel type having multiple channels. Here, "channel" refers to a unit that emits light simultaneously. In other words, a channel is an independently drivable unit. One channel is composed of one or more mesa portions 12. For example, if two or more mesa portions 12 are electrically connected, then one channel is composed of these two or more mesa portions 12. In this embodiment, as an example, each of the plurality of mesa portions 12 is electrically isolated from each other, so there is a "1:1" relationship between the mesa portions 12 and the channels. That is, in this embodiment, the semiconductor laser element 10 is configured as a multi-channel (8-channel) type semiconductor laser element, and the number of mesa portions 12 (eight) matches the number of channels.

[0033] The substrate 11 is a semiconductor substrate, such as a compound semiconductor substrate. The substrate 11 is formed in the shape of a rectangular plate (cuboid). As shown in Figures 1 and 2, the substrate 11 has an upper surface 11a (first surface) and a lower surface 11b (second surface) located opposite each other in the Z-axis direction, a front surface 11c and a rear surface 11d located opposite each other in the Y-axis direction, and side surfaces 11e and 11f (fifth surface) located opposite each other in the X-axis direction.

[0034] An electrode 32 (second electrode), which is a cathode electrode, is provided on the upper surface 11a of the substrate 11. For example, the electrode 32 is configured as a single electrode common to multiple mesa portions 12. That is, the electrode 32 is provided over substantially the entire surface of the upper surface 11a so as to overlap with the multiple mesa portions 12 in the Z-axis direction. The electrode 32 may be formed from a metallic material such as AuGe, Ni, or Au. Wires for electrically connecting to a power supply circuit (not shown) may be connected to the upper surface of the electrode 32 by wire bonding or the like.

[0035] Each of the multiple mesa sections 12 has an independently emitting light end face 12a that emits laser light L. As shown in Figure 2, the multiple (eight in this embodiment) mesa sections 12 are arranged at approximately equal intervals along the X-axis. The light emitting end faces 12a of each mesa section 12 intersect in the Y-axis direction and emit laser light L along the Y-axis direction. Although the light emitting end faces 12a are provided on both sides (front and rear) of each mesa section 12 in the Y-axis direction, in this embodiment, the front light emitting end face 12a functions as the light emitting end face that emits laser light L outwards. Therefore, a reflective film or the like may be provided on the rear light emitting end face 12a to prevent laser light L from being emitted backwards. On the other hand, a low-reflectivity film may be provided on the front light emitting end face 12a to improve the efficiency of light extraction to the outside.

[0036] As shown in Figure 2, each mesa portion 12 is formed to protrude in the Z-axis direction with respect to a reference surface R1 (first reference surface) formed on the lower surface 11b of the substrate 11. Furthermore, each mesa portion 12 is formed to extend in the Y-axis direction. The reference surface R1 is a surface that is directly supported by the submount 20 by surface contact with the reference surface R2 (second reference surface) of the submount 20. As an example, an insulating layer 19 is continuously formed on the entire lower surface 11b (including the surface of the mesa portion 12) with a predetermined thickness. In this case, the surface 19a of the insulating layer 19 opposite to the side facing the substrate 11 functions as the reference surface R1.

[0037] Each mesa portion 12 has a top surface 12b and a pair of side surfaces 12c. The top surface 12b is the surface facing the recess 21 of the submount 20 (see Figure 4). In other words, the top surface 12b is the surface facing away from the side on which the substrate 11 is located relative to the mesa portion 12. For example, the top surface 12b is formed by the portion of the surface 19a of the insulating layer 19 that covers the surface 18a of the contact layer 18, which will be described later. The pair of side surfaces 12c are surfaces located on opposite sides in the X-axis direction. The side surfaces 12c are surfaces that connect the top surface 12b and the reference surface R1. The pair of side surfaces 12c are inclined with respect to the top surface 12b and the reference surface R1 such that the distance between the pair of side surfaces 12c in the X-axis direction widens from the top surface 12b toward the reference surface R1. That is, each mesa portion 12 is formed in a trapezoidal shape when viewed from the Y-axis direction.

[0038] An electrode 35 (first electrode), which is an anode electrode electrically connected to each mesa portion 12, is provided on the top surface 12b of each mesa portion 12. That is, an electrode 35 is provided for each mesa portion 12. The electrode 35 can be made of a metallic material such as Ti, Pt, or Au. As shown in Figure 2, as an example, the electrode 35 is provided so as to cover most of the top surface 12b of the mesa portion 12 (excluding the side edges in the Y-axis direction of the top surface 12b) and to extend in the Y-axis direction.

[0039] As shown in Figure 3, the mesa portion 12 has a laminated structure formed on the lower surface 11b of the substrate 11. For example, the mesa portion 12 includes four first laminated structures L1, three second laminated structures L2, and a contact layer 18. More specifically, the lowest (closest to the substrate 11) first laminated structure L1 is laminated on the lower surface 11b of the substrate 11. On top of that, three first laminated structures L1 and three second laminated structures L2 are laminated so as to form a repeating structure in which one second laminated structure L2 is sandwiched between two first laminated structures L1. A contact layer 18 is laminated on the uppermost (farthest from the substrate 11) first laminated structure L1.

[0040] The first stacked structure L1 includes an active layer 13, a first semiconductor layer 14, and a second semiconductor layer 15. The layers constituting the first stacked structure L1 are stacked in the order of first semiconductor layer 14, active layer 13, and second semiconductor layer 15 from the bottom surface 11b side. The active layer 13 is a layer that includes a quantum well structure in which quantum well layers and barrier layers are alternately stacked in the Z-axis direction, and is a layer that generates laser light L. The active layer 13 has a structure in which multiple InGaAs layers and InAlAs layers are alternately stacked along the stacking direction (Z-axis direction). The first semiconductor layer 14 may be formed by, for example, an n-type AlGaAs layer. The second semiconductor layer 15 may be formed by, for example, a p-type AlGaAs layer.

[0041] The second laminated structure L2 is a so-called tunnel junction and includes a first tunnel junction layer 16 and a second tunnel junction layer 17. The first tunnel junction layer 16 is located on the lower surface 11b side of the second tunnel junction layer 17. The first tunnel junction layer 16 may be formed, for example, by a highly doped GaAs layer of p-type dopant. The second tunnel junction layer 17 may be formed, for example, by a highly doped GaAs layer of n-type dopant.

[0042] The contact layer 18 can be formed, for example, by a highly concentrated p-type dopant GaAs layer. The contact layer 18 is the layer that contacts the electrode 35 described above. The insulating layer 19 covering the surface 18a of the contact layer 18 opposite to the side facing the substrate 11 is provided with an opening 19b to expose at least a portion of the surface 18a. As shown in Figures 2 and 3, the opening 19b is located in the center of the top surface 12b in the X-axis direction where the electrode 35 and the contact layer 18 overlap. When viewed from the Z-axis direction, the opening 19b is formed in a rectangular shape extending in the Y-axis direction. In this embodiment, the recessed portion of the electrode 35 in Figure 2 corresponds to the portion where the opening 19b is formed. At the opening 19b, the surface of the electrode 35 is recessed as the electrode 35 moves toward the contact layer 18 side. The region of the surface 18a of the contact layer 18 that overlaps with the opening 19b in the Z-axis direction (i.e., the region exposed to the outside) functions as the contact region CA that contacts the electrode 35. In this embodiment, since the insulating layer 19 covers both side edges of the surface 18a of the contact layer 18 in the X-axis direction, the length d1 of the contact region CA in the X-axis direction is shorter than the length of the top surface 12b in the X-axis direction.

[0043] The submount 20 is, for example, a silicon substrate formed of silicon. Circuits for driving the semiconductor laser element 10 may be built into the submount 20. As shown in Figure 4, the submount 20 is formed in the shape of a rectangular plate (cuboid). The submount 20 has an upper surface 20a (third surface) and a lower surface 20b (sixth surface) located opposite each other in the Z-axis direction, a front surface 20c (fourth surface) and a rear surface 20d located opposite each other in the Y-axis direction, and side surfaces 20e and 20f located opposite each other in the X-axis direction. The upper surface 20a is the surface facing the reference surface R1 of the semiconductor laser element 10 and forms a reference surface R2 that is in surface contact with the reference surface R1. In this embodiment, the reference surface R1 of the semiconductor laser element 10 is formed by the surface 19a of the insulating layer 19 provided on the lower surface 11b of the substrate 11, whereas the reference surface R2 of the submount 20 is formed by the surface of the submount 20 itself (upper surface 20a).

[0044] The submount 20 has a recess 21 formed on its upper surface 20a. The recess 21 is a portion formed to be recessed toward the lower surface 20b than the rest of the upper surface 20a in order to arrange (accommodate) a plurality of mesa portions 12 provided on the semiconductor laser element 10. The recess 21 can be formed, for example, by wet etching. As an example, the recess 21 is composed of a plurality of (eight in this embodiment) recesses 22, each of the plurality of mesa portions 12 individually accommodating one of them. That is, in this embodiment, a plurality of recesses 22 are provided on the upper surface 20a, arranged in the X-axis direction to correspond to each of the plurality of mesa portions 12. The length of each recess 22 in the Y-axis direction is longer than the length of the substrate 11 in the Y-axis direction. Partition walls 23 are provided between adjacent recesses 22. The partition walls 23 extend in the Y-axis direction and have a predetermined length (i.e., a certain width or more) in the X-axis direction and have a reference plane R2. In other words, adjacent recesses 22 are arranged with a certain distance or more between them in the X-axis direction, and the portion corresponding to this distance (i.e., the portion where no recesses 22 are formed) functions as a partition wall 23.

[0045] As shown in Figures 4, 5, and 6, the recess 22 is formed in the shape of a groove extending in the Y-axis direction. The recess 22 extends to the front surface 20c and opens onto the front surface 20c. The recess 22 has a bottom surface 22a that intersects in the Z-axis direction, a pair of side surfaces 22b (first side surfaces) that intersect in the X-axis direction, and a side surface 22c (second side surfaces) that intersects in the Y-axis direction. Figures 4, 5, and 6 show the state before the semiconductor laser element 10 is mounted on the submount 20.

[0046] The pair of side surfaces 22b are the surfaces facing the side surface 12c of the mesa portion 12 in the X-axis direction when the semiconductor laser element 10 is mounted on the submount 20. The side surfaces 22b are inclined with respect to the bottom surface 22a such that the opening width of the recess 22 on the top surface 20a along the X-axis direction is greater than the width of the bottom surface 22a of the recess 22 along the X-axis direction. That is, as shown in Figure 6(A), the inclination angle θ1 of the side surface 22b with respect to the bottom surface 22a is acute. On the other hand, the angle θ2 between the top surface 20a (reference surface R2) and the side surface 22b is obtuse. As an example, the side surfaces 22b are formed in a planar shape when the recess 22 is formed by wet etching. In this case, the inclination angle θ1 and the angle θ2 have the relationship "θ1 + θ2 = 180°".

[0047] The side surface 22c is a surface formed behind the recess 22. The side surface 22c is inclined with respect to the bottom surface 22a such that the opening width of the recess 22 along the Y-axis direction on the top surface 20a is greater than the width of the bottom surface 22a of the recess 22 along the Y-axis direction. That is, as shown in Figure 6(B), the inclination angle θ3 of the side surface 22c with respect to the bottom surface 22a is acute. For example, when the recess 22 is formed by wet etching, the inclination angle θ3 is approximately the same as the inclination angle θ1.

[0048] The recess 21 is provided with a wiring section W at a position corresponding to each of the multiple mesa sections 12. For example, the wiring section W includes multiple wires 31 arranged at each position corresponding to each of the multiple mesa sections 12. The wires 31 may be formed of a metallic material such as Au. In this embodiment, since an independent recess 22 is formed for each mesa section 12, an individual wire 31 is provided for each recess 22, as shown in Figure 5. In each recess 22, the wire 31 extends in the Y-axis direction along the bottom surface 22a. As shown in Figures 4 and 5, the wire 31 extends from the inside of the recess 22 to the top surface 20a outside the recess 22. For example, each wire 31 extends to an electrode pad 34 independently provided on the top surface 20a. That is, the multiple wires 31 are electrically isolated from each other. This makes it possible to independently supply current to each of the multiple mesa sections 12 (i.e., to independently drive each mesa section 12). As shown in Figures 5 and 6(B), the wiring 31 runs along the bottom surface 22a and the side surface 22c. That is, the side surface 22c guides the wiring 31 from inside the recess 22 to the outside of the recess 22. Wires for electrically connecting to a power supply circuit (not shown) may be connected to each electrode pad 34 by wire bonding or the like.

[0049] As shown in Figures 5 and 6(A), solder material 33 is provided on the wiring 31 within each recess 22 by vapor deposition or the like. The solder material 33 can be formed from a material suitable for reflow soldering, such as Sn, Ag, or Cu.

[0050] Referring to Figure 7, the process of mounting the semiconductor laser element 10 onto the submount 20 will be described. First, as shown in S1 of Figure 7, solder members 33 are placed on the wiring 31 in each recess 22. Next, as shown in S2 of Figure 7, the semiconductor laser element 10 is placed on the submount 20 so that the positions of each mesa portion 12 of the semiconductor laser element 10 are aligned with the positions of the recesses 22, and the reference surface R1 faces the reference surface R2. That is, the electrodes 35 provided on the top surface 12b of each mesa portion 12 are brought into contact with the upper surface of the solder members 33 placed in each recess 22. Subsequently, the semiconductor laser element 10 and submount 20 in the state shown in S2 of Figure 7 are heated in a reflow oven, causing the solder members 33 to melt and the semiconductor laser element 10 to adhere to the submount 20. Specifically, as the solder member 33 melts and its thickness in the Z-axis direction decreases, the semiconductor laser element 10 moves toward the submount 20 until the reference surface R1 of the semiconductor laser element 10 and the reference surface R2 of the submount 20 come into contact. As a result, as shown in S3 of Figure 7, each of the multiple mesa portions 12 is housed within the recess 22, and the reference surface R1 and the reference surface R2 are in surface contact. In addition, the electrodes 35 corresponding to each of the multiple mesa portions 12 are electrically connected to the corresponding wiring 31 via the solder member 33.

[0051] As shown in Figure 8, the upper surface 20a of the submount 20 is provided with alignment marks M for aligning the semiconductor laser element 10 with respect to the submount 20 during the mounting process shown in Figure 7. For example, the alignment marks M have a cross shape in plan view. The alignment marks M are located on both sides of the semiconductor laser element 10 in the X-axis direction in the mounted state. As shown in Figure 8, by aligning the inner ends of each alignment mark M in the X-axis direction along the sides 11e and 11f, it is possible to align the semiconductor laser element 10 with respect to the submount 20 in the X-axis direction. Also, as an example, both ends of the electrode 32 in the X-axis direction are provided with markers (recesses 32a) corresponding to the alignment marks M. By aligning the portion M1 of the alignment marks M that extends inward in the X-axis direction to overlap with the recesses 32a in the Y-axis direction, it is possible to align the semiconductor laser element 10 with respect to the submount 20 in the Y-axis direction. In this embodiment, by this alignment, the semiconductor laser element 10 is positioned relative to the submount 20 such that the front surface 11c of the semiconductor laser element 10 and the front surface 20c of the submount 20 are substantially flush. Therefore, the position of the semiconductor laser element 10 in the Y-axis direction relative to the submount 20 can also be determined by aligning the front surfaces 11c and 20c. However, if, for example, the semiconductor laser element 10 is positioned such that the front surface 11c of the substrate 11 is located in front of or behind the front surface 20c of the submount 20, the position of the semiconductor laser element 10 in the Y-axis direction can be appropriately determined by using the aforementioned portion M1 and recess 32a as markers.

[0052] Referring to Figure 9, the positional relationship of each mesa portion 12 in the implemented state will be explained. Figure 9 is a side view taken from the Y-axis direction (front) of a portion that includes two mesa portions 12 that are adjacent to each other in the X-axis direction, out of a plurality of mesa portions 12 (eight in this embodiment). Here, of the two mesa portions 12, the one on the left when viewed from the front is referred to as the first mesa portion 12A, and the one on the right is referred to as the second mesa portion 12B.

[0053] The first wiring 31A, which is a wiring 31 located in the recess 22 housing the first mesa portion 12A, is electrically isolated (insulated) from the second wiring 31B, which is a wiring 31 located in the recess 22 housing the second mesa portion 12B. In other words, the plurality of wirings 31 include the first wiring 31A and the second wiring 31B, which are arranged adjacent to each other in the X-axis direction and are electrically isolated from each other. Furthermore, since the solder member 33 electrically connected to the first wiring 31A is arranged so as not to come into contact with the solder member 33 electrically connected to the second wiring 31B, the first mesa portion 12A, which is electrically connected to the first wiring 31A, is electrically isolated from the second mesa portion 12B, which is electrically connected to the second wiring 31B. In this embodiment, as described above, the plurality of wirings 31 are electrically isolated from each other. Therefore, any two wirings 31 arranged adjacent to each other in the X-axis direction among the plurality of wirings 31 correspond to the first wiring 31A and the second wiring 31B.

[0054] Here, the boundary between the side surface 12c of the mesa portion 12 and the reference plane R1 is represented as the base end P, the base end P that is the boundary between the side surface 12c of the first mesa portion 12A on the side where the second mesa portion 12B is located relative to the first mesa portion 12A and the reference plane R1 is represented as the first base end P1, and the base end P that is the boundary between the side surface 12c of the second mesa portion 12B on the side where the first mesa portion 12A is located and the reference plane R1 is represented as the second base end P2. In this case, the distance d2 in the X-axis direction from the first base end P1 to the second base end P2 is longer than the length d1 in the X-axis direction of the contact region CA of the mesa portion 12.

[0055] Furthermore, when viewed from the Y-axis direction, the distance d4 in the X-axis direction between the side surface 22b of the recess 22 and the side surface 12c of the mesa portion 12 facing the side surface 22b becomes shorter along the Z-axis direction from the top surface 12b toward the base end P, which is the boundary between the side surface 12c of the mesa portion 12 and the reference plane R1.

[0056] [Effects and Effects] The following describes the effects and capabilities of the semiconductor laser device 1A mentioned above.

[0057] (First effect) In the semiconductor laser device 1A, the reference surface R1 of the semiconductor laser element 10 (in this embodiment, the surface 19a of the insulating layer 19) is in surface contact with the reference surface R2 of the submount 20. This allows for precise alignment of the positions of multiple light-emitting points (for example, the center of the light-emitting end face 12a in the Z-axis direction) relative to the reference surface R2 of the submount 20. The semiconductor laser device 1A also has a first mesa portion 12A and a second mesa portion 12B that are electrically isolated from each other (i.e., configured to be drivable independently of each other) and arranged adjacent to each other. Here, the amount of solder material 33 required (for example, the width of the solder material 33 in the X-axis direction) may change depending on the width of the contact region CA (length d1 in the X-axis direction), but in the semiconductor laser device 1A, the distance between the first mesa portion 12A and the second mesa portion 12B (i.e., the distance d2 from the first base end P1 to the second base end P2 in the X-axis direction) is longer than the length d1 of the contact region CA. This ensures sufficient spacing between the first mesa portion 12A and the second mesa portion 12B for the amount of solder material 33 required according to the length d1 of the contact area CA. As a result, when mounting the semiconductor laser element 10 to the submount 20 by reflow soldering, it is possible to effectively prevent the solder material 33 corresponding to the first mesa portion 12A and the solder material 33 corresponding to the second mesa portion 12B from melting and coming into contact with each other. Therefore, the semiconductor laser device 1A can accurately align multiple light-emitting points while preventing short circuits between channels that are configured to be driven independently of each other.

[0058] Furthermore, the semiconductor laser apparatus 1A has the following configuration in relation to the first effect described above. That is, as shown in Figure 9, the recess 21 has a first recess 22A, which is a recess 22 in which the first mesa portion 12A is accommodated (placed), and a second recess 22B, which is a recess 22 in which the second mesa portion 12B is accommodated. Also, the length d3 in the X-axis direction of the reference plane R2 of the partition wall portion 23 formed between the first recess 22A and the second recess 22B (i.e., the portion that extends in the Y-axis direction to separate the first recess 22A and the second recess 22B) is longer than the length d1 in the X-axis direction of the contact region CA. As shown in Figure 9, in this embodiment, the boundary portion B between the reference plane R2 and the side surface 22b of the recess 22 is spaced apart from the base end portion P in the X-axis direction. Therefore, the relationship "d2>d3>d1" holds. The length d3 is the length in the X-axis direction between the boundary B of the reference plane R2 and the first recess 22A (boundary B on the second recess 22B side) and the boundary B of the reference plane R2 and the second recess 22B (boundary B on the first recess 22A side). With the above configuration, the first mesa portion 12A and the second mesa portion 12B are housed in different recesses 22 (first recess 22A and second recess 22B), and the width (length d3) of the partition wall portion 23 between the first recess 22A and the second recess 22B is sufficiently secured, thereby effectively preventing the solder member 33 corresponding to the melted first mesa portion 12A (or second mesa portion 12B) from crossing the partition wall portion 23 and coming into contact (short-circuiting) with the solder member 33 corresponding to the second mesa portion 12B (or first mesa portion 12A) during reflow soldering.

[0059] Furthermore, the recess 21 is composed of multiple recesses 22, each of which accommodates a plurality of mesa portions 12 individually, and partition walls 23 are provided between adjacent recesses 22. Compared to a configuration that includes a single recess 22 accommodating two or more mesa portions 12, this configuration effectively prevents short circuits between adjacent mesa portions 12 and improves the reliability of independent driving of multiple channels. Moreover, since the contact area between the reference surface R1 and the reference surface R2 can be increased in the partition walls 23 provided between each recess 22, the stress on the semiconductor laser element 10 (mainly the substrate 11) can be reduced, and the occurrence of warping of the semiconductor laser element 10 can be suppressed. In particular, when the length of the substrate 11 in the X-axis direction increases due to the arrangement of multiple mesa portions 12 in the X-axis direction as in this embodiment, warping of the substrate 11 in the X-axis direction becomes more likely. The above configuration is particularly effective in such cases.

[0060] In this embodiment, the first mesa portion 12A and the second mesa portion 12B are housed in separate recesses 22, which effectively prevents the solder member 33 corresponding to the first mesa portion 12A and the solder member 33 corresponding to the second mesa portion 12B from coming into contact with each other. However, it is not essential that the first mesa portion 12A and the second mesa portion 12B are housed in separate recesses 22 in order to obtain the above first effect. For example, as shown in Figure 10, the recess 21 may be composed of a single recess 22C that houses a plurality (in this case, eight) of mesa portions 12. In this case, a plurality of wirings 31 corresponding to each of the plurality of mesa portions 12 are provided on the bottom surface 22a of the single recess 22C. That is, the wiring W provided at the positions corresponding to each of the plurality of mesa portions 12 includes a plurality of wirings 31 that are arranged at the positions corresponding to each of the plurality of mesa portions 12 and are electrically isolated from each other. Alternatively, as shown in Figure 11, the recess 21 may have multiple recesses 22 (however, fewer than the total number of mesa portions 12) and at least one recess 22D that accommodates two or more (in this case, three) mesa portions 12. With the configuration in which "d2>d1" is satisfied as described above, even if the first mesa portion 12A and the second mesa portion 12B are housed in the same recess (i.e., no partition wall 23 is provided between the first mesa portion 12A and the second mesa portion 12B), it is possible to effectively prevent short circuits between the solder member 33 corresponding to the first mesa portion 12A and the solder member 33 corresponding to the second mesa portion 12B.

[0061] Furthermore, as shown in the example in Figure 11, the distance between adjacent mesa portions 12 (the distance corresponding to the distance d2 described above) does not have to be uniform among all mesa portions 12. In the example in Figure 11, the distance d21 between the rightmost mesa portion 12 housed in recess 22D and the leftmost mesa portion 12 housed in recess 22 adjacent to the right of recess 22D is longer than the distance d22 between the three mesa portions 12 housed in recess 22D. For example, the distance between mesa portions 12 that need to be electrically separated may be longer than the distance between mesa portions 12 that do not need to be electrically separated. Also, in the example in Figure 11, if the same channel is formed by the three mesa portions 12 housed in recess 22D, a single common wire (a wire formed wide in the X-axis direction so as to overlap the three mesa portions 12) may be provided in recess 22D. In this case, the three mesa portions 12 are electrically connected to each other via this single wire.

[0062] Furthermore, in this embodiment, the wiring section W includes a plurality of wires 31 that are arranged at positions corresponding to each of the plurality of mesa sections 12 and are electrically isolated from each other, and any two wires 31 that are arranged adjacent to each other in the X-axis direction correspond to the first wire 31A and the second wire 31B described above. With the above configuration, since the distance between any two adjacent mesa sections 12 (i.e., the distance d2) is longer than the width (length d1) of the contact area CA, it is possible to drive the plurality of mesa sections 12 (channels) independently while preventing short circuits between each channel.

[0063] Furthermore, some of the multiple wirings 31 may be electrically connected to one another. For example, as described above, a common wiring 31 may be formed on two or more mesa sections 12 belonging to the same channel. In this case, it is not a problem if the solder members 33 corresponding to some of the wirings 31 come into contact with each other. Therefore, when the mesa sections 12 corresponding to some of the wirings 31 are adjacent to each other in the X-axis direction, the distance between the mesa sections 12 (d2) may be shorter than the width (length d1) of the contact area CA. In other words, in order to obtain the first effect described above, the relationship "d2>d1" described above only needs to hold between the first mesa section 12A and the second mesa section 12B corresponding to two electrically separated wirings 31 (first wiring 31A and second wiring 31B).

[0064] (Second effect) In the semiconductor laser device 1A, the reference surface R1 of the semiconductor laser element 10 is in surface contact with the reference surface R2 of the submount 20. This allows for precise alignment of the positions of multiple light-emitting points (for example, the center of the light-emitting end face 12a in the Z-axis direction) relative to the reference surface R2 of the submount 20. Furthermore, in the semiconductor laser device 1A, the contact area between the reference surface R1 and the reference surface R2 can be increased in the partition wall portion 23 provided between adjacent recesses 22, thereby reducing the stress on the semiconductor laser element 10 (mainly the substrate 11) and suppressing the occurrence of warping of the semiconductor laser element 10. More specifically, in the semiconductor laser device 1A, in addition to the contact between the reference surface R1 and the reference surface R2 in both regions in the X-axis direction of the semiconductor laser element (the region to the left of the leftmost recess 22 and the region to the right of the rightmost recess 22), the reference surface R1 and the reference surface R2 also come into contact in the partition wall portion 23, thus effectively reducing the stress on the semiconductor laser element 10 (mainly the substrate 11). Here, from the viewpoint of suppressing the occurrence of warping of the semiconductor laser element 10, it is preferable to make the contact surface between the reference surface R1 and the reference surface R2 as large as possible. To achieve this, it is preferable to make the distance in the X-axis direction between the boundary B between the side surface 22b of the recess 22 and the reference surface R2 and the base end P of the mesa portion 12 facing the side surface 22b as short as possible. However, if the distance between the boundary B and the base end P is made short in this way, the side surface 22b of the recess 22 and the side surface 12c of the mesa portion 12 become more likely to come into contact, increasing the risk of damage to the mesa portion 12. Therefore, in the semiconductor laser apparatus 1A, the distance d4 in the X-axis direction between the side surface 22b of the recess 22 and the side surface 12c of the mesa portion 12 (see Figure 9) is configured to become shorter along the Z-axis direction from the top surface 12b toward the base end P. With the above configuration, the distance between the boundary B and the base end P can be made as short as possible while reducing the risk of contact between the side surface 22b of the recess 22 and the side surface 12c of the mesa portion 12. As a result, the contact surface between the reference surface R1 and the reference surface R2 can be made as large as possible while suppressing damage to the semiconductor laser element 10. Therefore, the semiconductor laser device 1A can accurately align multiple light-emitting points while suitably suppressing the occurrence of warping of the semiconductor laser element 10.

[0065] Furthermore, the semiconductor laser device 1A has the following configuration in relation to the second effect described above. That is, each of the multiple recesses 22 individually accommodates each of the multiple mesa portions 12. With this configuration, the contact area between the reference surface R1 and the reference surface R2 can be increased in the multiple partition walls 23 provided between each recess 22, so that the stress on the semiconductor laser element 10 (mainly the substrate 11) can be further reduced, and the occurrence of warping of the semiconductor laser element 10 can be effectively suppressed.

[0066] Furthermore, the wiring section W includes multiple wires 31 that are arranged at positions corresponding to each of the multiple mesa sections 12 and are electrically isolated from one another. With the above configuration, by separating any two adjacent mesa sections 12 with a partition wall 23 provided between the recesses 22, it becomes possible to drive multiple mesa sections 12 (channels) independently while preventing short circuits between each channel.

[0067] Furthermore, as shown in Figure 9, the inclination angle θ4 of the side surface 12c of the mesa portion 12 with respect to the reference plane R1 is smaller than the inclination angle θ1 of the side surface 22b of the recess 22 with respect to the bottom surface 22a (see Figure 6(A)). In other words, in this embodiment, both the side surface 12c of the mesa portion 12 and the side surface 22b of the recess 22 are provided in a planar shape, and the inclination angle θ4 of the side surface 12c and the inclination angle θ1 of the side surface 22b have the relationship "θ4 < θ1", thereby realizing a configuration in which the distance d4 decreases as it moves from the top surface 12b toward the base end P. With the above configuration, a configuration in which the distance d4 between the side surface 22b of the recess 22 and the side surface 12c of the mesa portion 12 decreases as it moves from the top surface 12b toward the base end P can be easily and reliably realized.

[0068] Furthermore, as shown in Figure 6(A), the angle θ2 between the reference surface R2 and the side surface 22b of the recess 22 is obtuse. With the above configuration, even if the side surface 12c of the mesa portion 12 comes into contact with the point where the reference surface R2 and the side surface 22b intersect (i.e., boundary B) when mounting the semiconductor laser element 10 onto the submount 20, the impact on the side surface 12c of the mesa portion 12 can be reduced compared to when the angle between the reference surface R2 and the side surface 22c is set to 90 degrees or less (i.e., when the sharpness of boundary B is large). Therefore, with the above configuration, the risk of damage to the semiconductor laser element 10 during mounting can be reduced.

[0069] Furthermore, the boundary B between the reference surface R2 and the side surface 22b of the recess 22 is spaced apart from the base end P in the X-axis direction. With the above configuration, the semiconductor laser element 10 is mounted on the submount 20 so that the boundary B and the base end P do not come into contact. This reduces the risk of the side surface 12c of the mesa portion 12 coming into contact with the boundary B during mounting, and effectively prevents damage to the semiconductor laser element 10.

[0070] It should be noted that, in order to obtain the second effect described above, it is not essential to provide multiple recesses 22 that individually accommodate the mesa portion 12. To obtain the second effect described above, it is sufficient to provide at least two recesses 22 and at least one partition wall portion 23 positioned between them.

[0071] (Other effects and benefits) A single electrode 32 common to multiple mesa portions 12 is provided on the upper surface 11a of the substrate 11 of the semiconductor laser element 10. With this configuration, by making the cathode electrode (electrode 32) located on the back side (upper surface 11a) of the substrate 11 common to multiple mesa portions 12, the number of wires connected to the electrode 32 by wire bonding can be reduced, thereby suppressing damage to the semiconductor laser element 10 due to wire bonding. More specifically, if the electrode 32 were separated for each channel, at least as many wires as there are channels would be required, but according to this embodiment, at least one wire needs to be connected to the electrode 32.

[0072] As shown in Figure 6(A), the side surface 22b of the recess 22 is inclined with respect to the bottom surface 22a such that the opening width of the recess 22 along the X-axis direction on the upper surface 20a of the submount 20 is greater than the width of the bottom surface 22a of the recess 22 along the X-axis direction. In other words, the inclination angle θ1 of the side surface 22b with respect to the bottom surface 22a is acute. With the above configuration, by configuring the side surface 22b of the recess 22 as an inclined surface that widens from the bottom surface 22a side to the opening end side, it is possible to appropriately secure space within the recess 22 for the molten solder material 33 to escape during reflow.

[0073] As shown in Figures 4 and 5, the wiring 31 extends from inside the recess 22 to the upper surface 20a outside the recess 22. With this configuration, the electrode (anode electrode) on the mesa portion 12 side of the semiconductor laser element 10 can be brought out to the surface (upper surface 20a) of the submount 20 via the electrode 35 and the wiring 31, making it easier to implement the configuration for supplying current to the semiconductor laser element 10. More specifically, the electrode pad 34, which is electrically connected to the electrode 35, which is the anode electrode, can be exposed on the same side as the electrode 32, which is the cathode electrode (the side facing the upper surface 20a of the submount 20). This improves the workability of wire bonding to the electrode 32 and the electrode pad 34.

[0074] As shown in Figure 5, the wiring 31 (wiring section W) extends along the Y-axis from the inside of the recess 22 to the outside of the recess 22. Also, as shown in Figure 6(B), the recess 22 has a side surface 22c that intersects with the Y-axis and along which the wiring 31 follows. Furthermore, the side surface 22c is inclined with respect to the bottom surface 22a such that the opening width of the recess 22 along the Y-axis at the top surface 20a is greater than the width of the bottom surface 22a of the recess 22 along the Y-axis. That is, the inclination angle θ3 of the side surface 22c with respect to the bottom surface 22a is acute. If the side surface 22c were not inclined as described above (for example, if the side surface 22c were a surface perpendicular to the bottom surface 22a of the recess 22), the wiring 31 would bend in a stepped manner at the boundary between the bottom surface 22a and the side surface 22c, and at the boundary between the side surface 22c and the top surface 20a, making it prone to breakage. On the other hand, by configuring the side surface 22c as an inclined surface as described above, and running the wiring 31 along the inclined side surface 22c, it is possible to avoid the wiring 31 bending in a stepped manner and suppress the occurrence of wire breakage.

[0075] As shown in Figure 3, each of the multiple mesa portions 12 has one or more active layers 13 provided independently for each mesa portion 12. With this configuration, the active layers 13 are spatially separated between the multiple mesa portions 12, so that optical crosstalk between the mesa portions 12 can be reliably prevented. Furthermore, when multiple (four in this embodiment) active layers 13 are provided in each mesa portion 12, as in this embodiment, each mesa portion 12 can function as a stacked semiconductor laser element, thereby increasing the laser output.

[0076] The submount 20 is formed of silicon. With the above configuration, the recess 21 can be formed with high precision, for example, by an etching process.

[0077] The submount 20 is connected to the upper surface 20a and has a front surface 20c that intersects in the Y-axis direction, and the recess 22 extends to the front surface 20c and opens to the front surface 20c. With the above configuration, the portion of the recess 22 that opens to the front surface 20c allows the light-emitting end surface 12a of each mesa portion 12 housed in the recess 22 to be exposed to the outside, thereby improving the extraction efficiency of the laser light L emitted from the light-emitting end surface 12a along the Y-axis direction.

[0078] Alignment marks M are provided on the upper surface 20a of the submount 20 for aligning the semiconductor laser element 10 with respect to the submount 20. With this configuration, when mounting the semiconductor laser element 10 on the submount 20, it is possible to easily and accurately align the semiconductor laser element 10 with respect to the submount 20.

[0079] The thickness of the substrate 11 in the Z-axis direction (length from the top surface 11a to the bottom surface 11b) is smaller than the thickness of the submount 20 in the Z-axis direction (length from the top surface 20a to the bottom surface 20b). With the above configuration, by using a submount 20 that is thicker than the semiconductor laser element 10, the occurrence of distortion of the submount 20 relative to the semiconductor laser element 10 (i.e., distortion of the reference plane R2) can be suitably suppressed. As a result, the positions of the multiple light-emitting points of the submount 20 with respect to the reference plane R2 can be aligned with even greater precision.

[0080] The substrate 11 has sides 11e and 11f that intersect in the X-axis direction. Furthermore, the distance d5 in the X-axis direction from the edge (boundary B) of the recess 22 located closest to the sides 11e and 11f in the X-axis direction to the sides 11e and 11f (see Figure 7) is longer than the distance d6 in the Z-axis direction from the reference plane R1 to the top surface 12b of the mesa portion 12 (see Figure 9). With the above configuration, in the area of ​​the substrate 11 outside the region where the recess 22 is provided in the X-axis direction, a certain area or more can be secured where the reference plane R1 and the reference plane R2 are in contact, thereby improving the support stability of the semiconductor laser element 10 with respect to the submount 20.

[0081] As an example, the distance d6 (i.e., the height of the mesa portion 12) may be set to be shorter than half the depth of the recess 22 (i.e., the length in the Z-axis direction from the reference surface R2 to the bottom surface 22a). In this case, a suitable space not occupied by the mesa portion 12 can be secured in the recess 22, so that, for example, a space for accumulating molten solder material 33 during reflow can be appropriately secured. In addition, by making the recess 22 deeper than the height of the mesa portion 12, the risk of contact between the mesa portion 12 and the recess 22 can be reduced, but if the recess 22 is made too deep relative to the height of the mesa portion 12, the amount (height) of solder material 33 required to ensure reliable contact between the wiring 31 and the electrode 35 will increase. From the above viewpoint, the distance d6 may be set to be longer than one-third of the depth of the recess 22.

[0082] [Second Embodiment] Referring to Figures 12 and 13, the semiconductor laser apparatus 1B of the second embodiment will be described. The semiconductor laser apparatus 1B differs from the semiconductor laser apparatus 1A of the first embodiment in that, in addition to the semiconductor laser apparatus 1A, it further comprises a support substrate 40 and a lens member 50 (optical element). In Figure 13, only the elements necessary to explain the positional relationship of the semiconductor laser element 10, submount 20, support substrate 40, and lens member 50 are shown, and elements unnecessary for the above explanation (wiring 31, electrode pad 34, etc.) are omitted as appropriate.

[0083] The support substrate 40 is a member that supports the submount 20 and the lens member 50. For example, the support substrate 40 is formed in the shape of a rectangular plate whose length in the X-axis direction matches that of the submount 20 and whose length in the Y-axis direction is longer than that of the submount 20. For example, the submount 20 is positioned on the support substrate 40 such that a pair of sides of the support substrate 40 that intersect in the X-axis direction are substantially flush with the sides 20f and 20e of the submount 20, and the side of the support substrate 40 facing the rear is substantially flush with the rear surface 20d of the submount 20.

[0084] The lens member 50 is positioned in the Y-axis direction opposite to the semiconductor laser element 10 and the submount 20. The lens member 50 guides the laser light L emitted from each of the optical emission end faces 12a (see Figure 1) of the multiple mesa portions 12 toward the outside. In this embodiment, as shown in Figure 13, the lens member 50 plays the role of focusing or collimating the laser light L emitted from each optical emission end face 12a of the mesa portion 12 with a certain divergence angle. The lens member 50 has a main body portion 51 having a lens function, a lower flange 52 provided on the lower side of the main body portion 51 (the side where the support substrate 40 is located), and an upper flange 53 provided on the upper side of the main body portion 51. The lower flange 52 and the upper flange 53 have a similar rectangular plate shape. The lens member 50 has a lower surface 50a formed by the rectangular lower surface of the lower flange 52, a light incident surface 50b formed by the rear surfaces of the main body 51, the lower flange 52, and the upper flange 53, and a light emission surface 50c formed on the main body 51 opposite to the light incident surface 50b. Both the lower surface 50a and the light incident surface 50b are flat surfaces. The light emission surface 50c is a lens surface that has a curved shape that is convex outward (forward) when viewed from the X-axis direction. The light incident surface 50b is the surface to which the laser light L emitted from each of the light emission end faces 12a of the multiple mesa portions 12 is incident. The light incident surface 50b is in surface contact with the front surface 20c of the submount 20.

[0085] The support substrate 40 has a support surface 40a that supports the submount 20 and the lens member 50. The support surface 40a has a first support surface 40a1 that supports the submount 20 by surface contacting the lower surface 20b of the submount 20, and a second support surface 40a2 that supports the lens member 50 by surface contacting the lower surface 50a of the lens member 50. In this embodiment, the first support surface 40a1 and the second support surface 40a2 are continuous and flush with each other, but the height position (position in the Z-axis direction) of the first support surface 40a1 and the height position of the second support surface 40a2 may be different from each other. That is, the support substrate 40 may have a connecting surface parallel to the XZ plane that connects the first support surface 40a1 and the second support surface 40a2.

[0086] In the semiconductor laser device 1B, the submount 20 on which the semiconductor laser element 10 is mounted and the lens member 50 are supported by surface contact with the first support surface 40a1 and the second support surface 40a2 of the support substrate 40. Therefore, the height positions of the semiconductor laser element 10 and the lens member 50 (i.e., the height positions of each member relative to the support surface 40a of the support substrate 40 (first support surface 40a1 and second support surface 40a2)) can be easily and accurately aligned. Here, as shown in Figure 13, the thickness of the submount 20 in the Z-axis direction is represented as T, and the height of the lens member 50 from the lower surface 50a of the central axis is represented as H. In this case, by adjusting the thickness T so that the relationship "H = T - d6 / 2" holds between the distance d6 in the Z-axis direction from the reference surface R1 to the top surface 12b of the mesa portion 12 (see Figure 9) and the thickness T and height H described above, the height positions of multiple light-emitting points (centers in the Z-axis direction of the light-emitting end surface 12a) can be easily aligned with the center position of the lens member 50. The height adjustment described above may also be performed by adjusting the height of the second support surface 40a2 relative to the first support surface 40a1 of the support substrate 40. In any case, simply by placing the submount 20 and the lens member 50 on the support surface 40a of the support substrate 40, the height positions of the semiconductor laser element 10 and the lens member 50 can be easily and appropriately aligned.

[0087] Furthermore, in the semiconductor laser device 1B, by bringing the front surfaces 20c of the submounts 20 facing each other in the Y-axis direction into surface contact with the light incident surface 50b of the lens member 50, the distance between the light emission end surface 12a and the light incident surface 50b in the Y-axis direction can be precisely adjusted. That is, when mounting the semiconductor laser element 10 on the submount 20, the distance from the light emission end surface 12a to the light incident surface 50b can be adjusted by adjusting the distance from the light emission end surface 12a to the front surface 20c in the Y-axis direction. For example, if the light emission end surface 12a of each mesa portion 12 is configured to be flush with the front surface 11c of the substrate 11, and the semiconductor laser element 10 is mounted on the submount 20 such that the front surface 11c of the substrate 11 and the front surface 20c of the submount 20 are flush, then the light emission end surface 12a will be flush with the front surface 20c of the submount 20. In this case, by bringing the front surface 20c of the submount 20 into surface contact with the light incident surface 50b, the light-emitting end surface 12a of each mesa portion 12 can be brought into surface contact with the light incident surface 50b.

[0088] Furthermore, as described when explaining the semiconductor laser device 1A, in this embodiment, the length of the recess 21 in the Y-axis direction is longer than the length of the semiconductor laser element 10 in the Y-axis direction. With the above configuration, it is possible to release the molten solder member 33 during reflow into the space within the recess 21 that does not overlap with the semiconductor laser element 10 (mesa portion 12) in the Y-axis direction. In addition, it is possible to adjust the position of the semiconductor laser element 10 in the Y-axis direction relative to the submount 20 according to the focal length of the lens member 50. That is, with the above configuration, it is possible to position the semiconductor laser element 10 relative to the submount 20 such that the front surface 11c of the semiconductor laser element 10 is located behind the front surface 20c of the submount 20, within the range in which the mesa portion 12 does not interfere with the submount 20. This makes it possible to appropriately adjust the distance between the front light-emitting end surface 12a of each mesa portion 12 and the light-incident surface 50b.

[0089] [Third Embodiment] Referring to Figures 14 and 15, the semiconductor laser apparatus 1C of the third embodiment will be described. The semiconductor laser apparatus 1C differs from the semiconductor laser apparatus 1B of the second embodiment in that it further includes a molding resin 60 in addition to the semiconductor laser apparatus 1B of the second embodiment. In Figure 15, as with Figure 13, only the elements necessary to explain the positional relationship of the semiconductor laser element 10, submount 20, support substrate 40, lens member 50, and molding resin 60 are shown, and elements unnecessary for the above explanation (wiring 31, electrode pads 34, etc.) are omitted as appropriate.

[0090] The molded resin 60 is formed on the support substrate 40 so as to cover the lens member 50, the submount 20, and the semiconductor laser element 10. The semiconductor laser device 1C has a rectangular parallelepiped shape overall due to the inclusion of such molded resin 60. The molded resin 60 can be formed by resin molding techniques such as transfer molding and compression molding. Examples of materials for the molded resin 60 include epoxy resin and silicone resin.

[0091] In the semiconductor laser device 1C, the mold resin 60 can fix the positional relationship of each component (lens member 50, submount 20, and semiconductor laser element 10) placed on the support substrate 40, thereby preventing misalignment of the positional relationship of each component. Furthermore, the mold resin 60 can appropriately protect each component.

[0092] [Differentiation] While embodiments and several modifications of this disclosure have been described above, this disclosure is not limited to the configurations shown in the embodiments and each modification. The materials and shapes of each configuration are not limited to the specific materials and shapes described above, but a variety of other materials and shapes can be used. Furthermore, some of the configurations included in the embodiments and each modification may be omitted or modified as appropriate, or can be combined in any way.

[0093] For example, the recess 22 may be formed by a method other than wet etching. In this case, the inclination angles θ1 and θ3 may be different. Also, the inclination angle θ1 of the side surface 22b of the recess 22 does not have to be constant over the entire Z-axis direction of the side surface 22b. For example, the side surface 22b may be formed such that the inclination angle with respect to the bottom surface 22a changes in steps as you move from the top surface 20a side towards the bottom surface 22a side. Also, the side surface 22b does not have to be planar; for example, it may be curved. The above description regarding the side surface 22b also applies to the side surface 22c.

[0094] Furthermore, although a lens member 50 was described as an example of an optical element in the second and third embodiments, the optical element may be a member other than a lens, such as an optical filter or a volume holographic diffraction grating (VBG). In other words, the optical element only needs to have a lower surface (corresponding to the lower surface 50a) that can be supported by surface contact with the second support surface 40a2 of the support substrate 40, and the type of optical element incorporated into the semiconductor laser device is not particularly limited.

[0095] Furthermore, in the above embodiment, each mesa portion 12 is completely housed within the recess 22, but a portion of the mesa portion 12 may be located outside the recess 22. That is, it is sufficient that at least a portion of the mesa portion 12 is located in the recess 22. For example, the front light-emitting end face 12a of the mesa portion 12 may protrude forward beyond the front surface 20c of the submount 20. Also, for example, if the reference surface R1 of the semiconductor laser element 10 is formed lower than in the above embodiment (for example, if the reference surface R1 is formed by the surface of another member provided on the surface 19a of the insulating layer 19), a portion of the mesa portion 12 (a portion on the base end P side in the Z-axis direction) may be located outside the recess 22. [Explanation of Symbols]

[0096] 1A, 1B, 1C... Semiconductor laser device, 10... Semiconductor laser element, 11... Substrate, 11a... Top surface (first surface), 11b... Bottom surface (second surface), 11e, 11f... Side surface (fifth surface), 12... Mesa portion, 12a... Light emission end surface, 12A... First mesa portion, 12B... Second mesa portion, 12b... Top surface, 12c... Side surface, 13... Active layer, 18... Contact layer, 20... Submount (mounting member), 20a... Top surface (third surface), 20b... Bottom surface (sixth surface), 20c... Front surface (fourth surface), 21, 22, 22C, 22D... Recess, 22a... Bottom surface, 22b... Side surface (first Side view), 22c...Side view (second side view), 22A...First recess, 22B...Second recess, 23...Partition wall, 31...Wiring, 31A...First wiring, 31B...Second wiring, 32...Electrode (second electrode), 33...Soldering material, 35...Electrode (first electrode), 40...Support substrate, 40a1...First support surface, 40a2...Second support surface, 50...Lens material (optical element), 50b...Light incident surface, 60...Molding resin, CA...Contact area, M...Alignment mark, P1...First base end, P2...Second base end, R1...Reference surface (first reference surface), R2...Reference surface (second reference surface), W...Wiring section. .

Claims

1. A semiconductor laser element comprising: a substrate having a first surface and a second surface located opposite each other in a first direction; and a plurality of mesa portions having a light-emitting end surface that intersects a second direction perpendicular to the first direction, and which are formed to protrude in the first direction and extend in the second direction relative to a first reference plane formed on the second surface; A mounting member having a third surface that forms a second reference surface opposite to the first reference surface, and at least one recess formed on the third surface where the plurality of mesa portions are arranged, Equipped with, The first reference surface is a surface facing the third surface in the portion where the plurality of mesa portions are not provided. The second reference surface is a surface facing the second surface in the portion where the at least one recess is not provided. The mesa portion has a top surface facing the bottom surface of at least one recess, and a pair of sides located opposite each other in a third direction perpendicular to the first and second directions, A first electrode is provided on the top surface of the mesa portion, which is electrically connected to a contact layer provided on the top surface side of the mesa portion. At least one of the recesses is provided with a wiring section at a position corresponding to each of the plurality of mesa sections. Each of the multiple mesa portions is electrically connected to the wiring portion via a soldering member. The wiring section includes a first wiring and a second wiring that are arranged adjacent to each other in the third direction and are electrically separated from each other. The soldering member electrically connected to the first wiring is positioned so as not to come into contact with the soldering member electrically connected to the second wiring, thereby the first mesa portion electrically connected to the first wiring is electrically isolated from the second mesa portion electrically connected to the second wiring. The first reference surface is in surface contact with the second reference surface. The distance in the third direction from the first base end, which is the boundary between the side surface of the first mesa portion on the side where the second mesa portion is located relative to the first mesa portion and the first reference plane, to the second base end, which is the boundary between the side surface of the second mesa portion on the side where the first mesa portion is located and the first reference plane, is longer than the length of the contact region in the third direction that contacts the first electrode within the contact layer. Semiconductor laser device.

2. The at least one recess comprises a first recess in which the first mesa portion is disposed, and a second recess in which the second mesa portion is disposed. The length in the third direction of the second reference surface of the partition wall portion formed between the first recess and the second recess and extending in the second direction to separate the first recess and the second recess is longer than the length in the third direction of the contact region. The semiconductor laser apparatus according to claim 1.

3. The at least one recess is composed of a plurality of recesses in which each of the plurality of mesa portions is individually arranged. Between the adjacent recesses, a partition wall is provided that extends in the second direction and has a predetermined length in the third direction, and has a second reference plane. The semiconductor laser apparatus according to claim 1.

4. A single second electrode common to the plurality of mesa portions is provided on the first surface. The semiconductor laser apparatus according to claim 1.

5. The at least one recess has a first surface facing the side surface of the mesa in the third direction, The first side surface is inclined with respect to the bottom surface such that the opening width of the at least one recess in the third surface along the third direction is greater than the width of the bottom surface of the at least one recess along the third direction. The semiconductor laser apparatus according to claim 1.

6. The wiring portion extends from inside the at least one recess to the third surface outside the at least one recess. The semiconductor laser apparatus according to claim 1.

7. The wiring portion extends along the second direction from inside the at least one recess to outside the at least one recess, The at least one recess intersects the second direction and has a second side surface along which the wiring portion is aligned. The second side surface is inclined with respect to the bottom surface such that the opening width of the at least one recess in the third surface along the second direction is greater than the width of the bottom surface of the at least one recess along the second direction. The semiconductor laser apparatus according to claim 6.

8. Each of the plurality of mesa portions has one or more active layers provided independently for each mesa portion. The semiconductor laser apparatus according to claim 1.

9. The wiring section includes a plurality of wires arranged at each position corresponding to each of the plurality of mesa sections and electrically separated from each other. Any two of the aforementioned plurality of wires that are arranged adjacent to each other in the third direction correspond to the first wire and the second wire. The semiconductor laser apparatus according to claim 1.

10. The mounting member is made of silicon. The semiconductor laser apparatus according to claim 1.

11. The mounting member is connected to the third surface and has a fourth surface that intersects the second direction. The at least one recess extends to the fourth surface and opens to the fourth surface. The semiconductor laser apparatus according to claim 1.

12. The third surface is provided with alignment marks for aligning the semiconductor laser element with respect to the mounting member. The semiconductor laser apparatus according to claim 1.

13. The thickness of the substrate in the first direction is smaller than the thickness of the mounting member in the first direction. The semiconductor laser apparatus according to claim 1.

14. The substrate has a fifth surface that intersects the third direction, The distance in the third direction from the end of the at least one recess provided closest to the fifth surface to the fifth surface is longer than the distance in the first direction from the first reference plane to the top surface of the mesa portion. The semiconductor laser apparatus according to claim 1.

15. An optical element is positioned in the second direction opposite to the semiconductor laser element and the mounting member, and guides the light emitted from the light-emitting end face of each of the plurality of mesa portions toward the outside, The mounting member and the support substrate that supports the optical element, Furthermore, The support substrate has a first support surface that supports the mount member by making surface contact with the sixth surface of the mount member opposite to the third surface, and a second support surface that supports the optical element by making surface contact with the optical element. The semiconductor laser apparatus according to claim 1.

16. The optical element has a light incident surface to which the light emitted from each of the light-emitting end faces of the plurality of mesa portions is incident. The mounting member has a fourth surface facing the light incident surface, The light incident surface is in surface contact with the fourth surface. The semiconductor laser apparatus according to claim 15.

17. The length of the at least one recess in the second direction is longer than the length of the semiconductor laser element in the second direction. The semiconductor laser apparatus according to claim 1 or 15.

18. The support substrate further comprises a molded resin formed to cover the optical element, the mounting member, and the semiconductor laser element. The semiconductor laser apparatus according to claim 15 or 16.

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