Multibeam semiconductor laser element and semiconductor laser device

Abstract

Provided is a semiconductor laser in which the difference in characteristics between beams is small. A plurality of laser waveguides 200 are formed adjacent to each other in the x direction in a laser region 902. Each laser waveguide 200 has a stripe-shaped power supply electrode 150 extending in the z direction. Power supply pads Pe are formed in a pad region 904 adjacent to the laser region 902 in the x direction. Connection wiring Lc connects the power supply electrode 150 of a corresponding laser waveguide 200 and a corresponding power supply pad Pe. When the length in the z direction of a multibeam semiconductor laser element 100 is denoted by Lchip, the length in the z direction of a part where an i-th (i = 1, 2, ..., M) laser waveguide 200_i intersects a j-th piece of connection wiring Lcj is denoted by Lij, and the total overlap length is denoted by Li=Σj=1 to MLij, all the laser waveguides satisfy the expression Li ≥ 0.5Lchip.

Description

Multibeam semiconductor laser element and semiconductor laser device

[0001] This disclosure relates to a multi-beam semiconductor laser device.

[0002] Semiconductor lasers are used as light sources in electronic devices such as printers and head-mounted displays (HMDs). To accommodate the increasing resolution of such image-handling electronic devices, multi-beam semiconductor laser elements, which have multiple laser waveguides formed in a single semiconductor laser element, are being adopted.

[0003] To miniaturize lenses and MEMS mirrors, it is necessary to narrow the beam pitch. When the beam pitch becomes narrower than the width of the pad (also called the pad electrode or electrode pad), the pad needs to be formed closer to the wire bonding (WB) region at the edge of the chip (semiconductor substrate).

[0004] Patent No. 5521411

[0005] To enable independent driving of multiple laser waveguides (emitters), a structure is employed in which an interlayer insulating film is partially formed on the emitter, and electrodes are formed so as to span across other emitters from the ridge to the WB region located at the tip edge.

[0006] In this structure, thermal crosstalk between adjacent emitters causes a temperature difference between the centrally located emitter and the outerly located emitters, resulting in variations in characteristics such as wavelength and optical output due to the temperature difference between emitters. In response to this, Patent Document 1 proposes a technique that reduces wavelength variations between emitters even when they are simultaneously lit by adjusting the heat dissipation of each emitter by opening the interlayer insulating film and changing the area in which the first electrode is exposed for each emitter.

[0007] As a result of various studies conducted by the present inventors regarding multi-beam semiconductor lasers, the following problems were identified.

[0008] As described in Patent Document 1, in a structure where the heat dissipation performance is adjusted for each emitter, it has been found that when each beam is lit independently, differences in light output and wavelength occur for each beam even under equivalent driving conditions. This is because the structure itself, which was designed to eliminate variations in characteristics between emitters during simultaneous operation, results in differences in the thermal resistance of each emitter. For example, in display applications, it is required that there be no difference in characteristics between beams not only during simultaneous operation but also when each beam is lit independently, which poses a significant practical challenge.

[0009] Some aspects of this disclosure have been made in view of such problems, and one exemplary objective is to provide a semiconductor laser with small differences in characteristics between beams.

[0010] A multibeam semiconductor laser element in one aspect of the present disclosure comprises a plurality of M (M≧3) laser waveguides formed adjacent to each other in the x-direction within the laser region of an epitaxial stacked structure, where the stacking direction of the epitaxial stacked structure is the y-direction, the direction of laser light guidance is the z-direction, and the direction orthogonal to the y-direction and z-direction is the x-direction, wherein each laser waveguide comprises M laser waveguides having stripe-shaped power supply electrodes extending in the z-direction, M power supply pads formed in pad regions adjacent to the laser region in the x-direction and corresponding to the M laser waveguides, and M connecting wires, each connecting the power supply electrode of the corresponding laser waveguide to the corresponding power supply pad. The length of the multibeam semiconductor laser element in the z-direction is L ｃｈｉｐ The length in the z-direction of the portion where the i-th (i = 1, 2, ..., M) laser waveguide intersects with the j-th connecting wire is L. ｉｊ In this case, in all (i=1 to M) laser waveguides, L ｉ = Σ ｊ＝１～Ｍ L ｉｊ ≥0.5L ｃｈｉｐ (However, i = 1, 2, ..., M) is satisfied. ｉ This represents the total overlap length, which is the sum of the lengths of the portions where the i-th laser waveguide overlaps with the connecting wiring.

[0011] It should be noted that arbitrary combinations of the above constituent elements, and mutual replacements of constituent elements and expressions among methods, devices, systems, etc., are also effective as aspects of the present invention or the present disclosure. Furthermore, the description of this section (Means for Solving the Problems) does not describe all the essential features of the present invention, and therefore, subcombinations of these described features can also constitute the present invention.

[0012] According to an aspect of the present disclosure, the characteristic difference between individual beams can be reduced.

[0013] It is a perspective view of a semiconductor laser device according to an embodiment. It is a plan view of the semiconductor laser device of FIG. 1. It is a cross-sectional view taken along line A-A of the semiconductor laser device of FIG. 1. It is a diagram showing I-L characteristics of samples with different wiring occupation ratios. Wiring occupation rate L ｉ / L ＣＨＩＰ and the maximum optical output. It is a plan view of the semiconductor laser device according to Modification 1. It is a plan view of the semiconductor laser device according to Modification 2. It is a plan view of the semiconductor laser device according to Modification 3. It is a plan view of the semiconductor laser device according to Modification 4. It is a plan view of the semiconductor laser device according to Modification 5. It is a cross-sectional view of a semiconductor laser device. It is a cross-sectional view of a semiconductor laser device.

[0014] (Summary of Embodiment) An outline of several exemplary embodiments of the present disclosure will be described. This summary is intended as a preview of the detailed description given below, or for the purpose of providing a basic understanding of the embodiments. This summary briefly describes some concepts of one or more embodiments, and does not limit the scope of the invention or the disclosure. In addition, this summary is not a comprehensive overview of all conceivable embodiments, and does not limit essential constituent elements of the embodiments. For convenience, "one embodiment" may be used to refer to one embodiment (example or modification) or a plurality of embodiments (examples or modifications) disclosed in this specification.

[0015] A multibeam semiconductor laser element in one aspect of the present disclosure comprises a plurality of M (M≧3) laser waveguides formed adjacent to each other in the x-direction within the laser region of an epitaxial stacked structure, where the stacking direction of the epitaxial stacked structure is the y-direction, the direction of laser light guidance is the z-direction, and the direction orthogonal to the y-direction and z-direction is the x-direction, wherein each laser waveguide comprises M laser waveguides having stripe-shaped power supply electrodes extending in the z-direction, M power supply pads formed in pad regions adjacent to the laser region in the x-direction and corresponding to the M laser waveguides, and M connecting wires, each connecting the power supply electrode of the corresponding laser waveguide to the corresponding power supply pad. The length of the multibeam semiconductor laser element in the z-direction is L ｃｈｉｐ The length in the z-direction of the portion where the i-th (i = 1, 2, ..., M) laser waveguide intersects with the j-th connecting wire is L. ｉｊ The total overlap length L is defined as the sum of the lengths of the portion where the i-th laser waveguide overlaps with the connecting wiring. ｉ = Σ ｊ＝１～Ｍ L ｉｊ Let's assume that in all waveguides, L ｉ ≥0.5L ｃｈｉｐ (where i = 1, 2, ..., M) is satisfied. Note that each laser waveguide does not necessarily need to intersect with all connection lines; it is sufficient for it to intersect with two or more connection lines. If the k-th laser waveguide and the l-th connection line do not intersect, L ｋｌ You can treat it as equal to 0.

[0016] In this configuration, the M laser waveguides (emitters) are thermally coupled to each other by connecting wiring. The inventors have found that the total chip length L ＣＨＩＰ The total overlap length L of each laser waveguide. ｉ Ratio L ｉ / L ＣＨＩＰ By varying the ratio L and investigating its relationship with the output of multiple laser waveguides, the following findings were obtained. ｉ / L ＣＨＩＰ In the range of 0-50%, the laser light output increases with increasing ratio L. ｉ / L ＣＨＩＰ When the ratio exceeds 50%, the light output saturates relative to the ratio. In other words, ratio Lｉ / L ＣＨＩＰ By setting this ratio to 50% or more, sufficient heat dissipation can be obtained through the connection wiring without affecting the optical output. This reduces the difference in beam characteristics between the case where M laser waveguides are simultaneously illuminated and the case where one of the M laser waveguides is illuminated.

[0017] In one embodiment, the total overlap length L of the multiple laser waveguides １ ~L Ｍ They may be substantially equal. Specifically, L １ , L ２ ,...L Ｍ The maximum value among them is max(L １ , L ２ ,...L Ｍ ), the minimum value min(L １ , L ２ ,...L Ｍ When ) max(L １ , L ２ ,...L Ｍ ) - min(L １ , L ２ ,...L Ｍ ) ≤ 0.1L ｃｈｉｐ This condition may also be met. This allows for equalization of thermal resistance between multiple laser waveguides, thereby uniformizing the output.

[0018] In one embodiment, the width of each connecting wire in the z direction may be greater than or equal to the length of the corresponding power supply pad in the z direction. By making the width of the connecting wire in the z direction greater than the length of the power supply pad in the z direction, the ratio L ｉ / L ＣＨＩＰ It can improve.

[0019] In one embodiment, all M connection wires may intersect with all M laser waveguides.

[0020] In one embodiment, the distance between the x-direction end of the connecting wiring and the closest of the M laser waveguides may be longer than half the distance between adjacent laser waveguides, and more preferably, may be greater than the substrate thickness. Since the heat generated in the emitter spreads in the x-direction through the connecting wiring and then spreads towards the substrate, if the distance between the laser waveguide and the end of the connecting wiring is small, a difference in thermal resistance occurs between the laser waveguide at the end and the laser waveguide in the center. On the other hand, if the distance between the laser waveguide and the end of the connecting wiring is greater than half the distance between adjacent laser waveguides, the electrode structure at the emitter pitch is made uniform between emitters, so the difference in thermal resistance between the laser waveguide located at the end and the adjacent laser waveguide is reduced and the difference in output is eliminated. Furthermore, since the spread of heat is thought to be concentric with the substrate thickness as the radius, the heat dissipation function towards the substrate is improved by making the distance between the laser waveguide and the end of the connecting wiring greater than or equal to the substrate thickness. This further homogenizes the thermal conditions between the emitter and the emitter, reduces the absolute value of the thermal resistance, and improves the optical output.

[0021] In one embodiment, the length in the z-direction of the contact region where the power supply electrode of each laser waveguide is connected to the corresponding connecting wiring may be substantially equal between each laser waveguide. This makes it possible to equalize the thermal resistance between each laser waveguide even when the heat dissipation differs between the contact region and the non-contact region, thereby equalizing the output.

[0022] In one embodiment, pad regions are formed on both sides of the laser region, and M power supply pads may be arranged in two pad regions. When a semiconductor laser element is mounted in a junction-down configuration relative to a submount, the semiconductor laser element can be supported on both sides of the chip.

[0023] In one embodiment, the width of the M connection wires in the z direction may be larger the closer they are to the output end face of the multi-beam semiconductor laser element. Since the heat generation density is higher closer to the output end face, increasing the width of the connection wires closer to the output end face can suppress the temperature rise at the output end face.

[0024] In one embodiment, the material of the guide layer or cladding layer is {Al ｘGa （１－ｘ）} １－ｙ In ｙ P may also be (0 ≤ x ≤ 1, 0 ≤ y ≤ 1). These materials have low thermal conductivity, and the output of semiconductor lasers is susceptible to heat, so the heat dissipation effect of connecting wiring is more pronounced.

[0025] In one embodiment, the M laser waveguides may be transverse single-mode ridge waveguides. This configuration increases the heat density, thus enhancing the heat dissipation effect of the connecting wiring.

[0026] A semiconductor laser apparatus according to one embodiment comprises a submount and one of the above-described multi-beam semiconductor laser elements mounted on the submount either junction-up or junction-down.

[0027] (Embodiments) The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Furthermore, the embodiments are illustrative and not limiting to the disclosure, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure.

[0028] The dimensions (thickness, length, width, etc.) of each component shown in the drawing may be enlarged or reduced as appropriate for ease of understanding. Furthermore, the dimensions of multiple components do not necessarily represent their relative sizes; even if component A is depicted as thicker than component B in the drawing, component A may actually be thinner than component B.

[0029] (Embodiment) Figure 1 is a perspective view of a semiconductor laser element 100 according to an embodiment. The semiconductor laser element 100 is an end-face emitting type semiconductor laser element and is a multi-beam semiconductor laser having a plurality of M (M≧2) emitters. In this embodiment, the number of emitters M is 4.

[0030] In this specification, the beam emission direction is taken as the z-axis (z-direction), the stacking direction of the semiconductor laser elements is taken as the y-axis (y-direction), and the x-axis (x-direction) is taken as the direction perpendicular to the z-axis and y-axis.

[0031] The semiconductor laser element 100 comprises a substrate 110 and an epitaxial stacked structure (hereinafter simply referred to as the stacked structure) 120 formed on the substrate 110. The stacked structure 120 includes an N-type semiconductor layer 122, an emissive layer (active layer) 124, and a P-type semiconductor layer 126, which are sequentially stacked in the y-direction on the substrate 110 by epitaxial growth. The emissive layer 124 includes an N-type guide layer (lower guide layer), an active layer consisting of a quantum well layer, and a P-type guide layer (upper guide layer). The materials of the substrate 110 and the stacked structure 120 can be selected according to the required oscillation wavelength and are not particularly limited in this disclosure.

[0032] The application of this disclosure is not limited to specific wavelengths, but the material of the guide layer or cladding layer included in the laminated structure 120 is {Al ｘ Ga （１－ｘ）} １－ｙ In ｙ P may also be P(0≦x≦1, 0≦y≦1).

[0033] Furthermore, the M laser waveguides 200_1 to 200_4 may be transverse single-mode ridge waveguides.

[0034] The semiconductor laser element 100 has a central laser region 902 and a pad region 904. M adjacent laser waveguides 200_1 to 200_M are formed in the laser region 902 in the x direction. Each laser waveguide 200 has a stripe structure extending in the z direction perpendicular to the x direction and emits a beam in the z direction.

[0035] A waveguide structure for confining light is formed in the laminated structure 120, and the cleavage surfaces at both ends of this waveguide structure act as mirrors, forming a Fabry-Perot type laser waveguide 200. In this example, four laser waveguides 200_1 to 200_4 are formed, and beams BM1 to BM4 are emitted in the z direction from the exit end face (front end face) S1. The exit end face S1 and rear end face S2 of each laser waveguide 200 are coated to give a desired reflectivity.

[0036] The laser waveguide 200 may be an external resonator type laser, a distributed Bragg Reflector (DBR) laser, or a distributed feedback (DFB) laser.

[0037] The waveguide structure can be, for example, an embedded ridge waveguide.

[0038] Alternatively, the waveguide structure may be a CSP (Channeled Substrate Planar) structure in which grooves are formed in the substrate 110 along the waveguide, and the thickness of the N-type semiconductor layer 122 in the groove portion is relatively thicker.

[0039] While embedded ridge structures and CSP structures are waveguide structures that utilize refractive index distributions, this disclosure is not limited to these, and gain waveguide structures that utilize gain distributions may also be used. These structures can be understood as both optical confinement structures and current constriction structures.

[0040] In order to drive the laser waveguides 200_1 to 200_M independently, they must be electrically isolated. For this purpose, insulating means such as a separation groove are formed between two adjacent laser waveguides 200.

[0041] A contact insulating film (not shown) is formed on the upper surface of each laser waveguide 200. Rectangular openings extending in the z direction are formed in the contact insulating film on the upper surfaces of laser waveguides 200_1 to 200_M. Power supply electrodes (P-side electrodes) 150 are formed along these openings. In order to enable the laser waveguides 200 to be driven independently, the power supply electrodes 150 are electrically insulated from each other. In this embodiment, the power supply electrodes 150 are stripe-shaped electrodes extending along the z direction on the upper surface of the laser waveguide 200.

[0042] An N-side electrode 152 is formed on the back surface of the laser waveguide 200.

[0043] A metal layer is formed on top of the laser waveguides 200 to supply power to them. Specifically, the metal layer includes a plurality of power supply pads (hereinafter simply referred to as pads) Pe1 to Pe4 corresponding to the plurality of laser waveguides 200_1 to 200_4, and a plurality of connection wires Lc1 to Lc4.

[0044] Multiple pads Pe1 to Pe4 are formed in the laser region 902 and the adjacent pad region 904, aligned in the z direction. Bonding wires are connected to pads Pe1 to Pe4 in the case of junction-up mounting, and solder is connected in the case of junction-down mounting.

[0045] Each connecting wire Lci (i = 1, 2, 3, 4) extends in the x direction and electrically connects the power supply electrode 150 of the corresponding laser waveguide 200_i to the corresponding pad Pi. In this embodiment, each connecting wire Lc1 to Lc4 is formed to cross all of the power supply electrodes 150_1 to 150_4.

[0046] The insulating film 170 is formed to include the point where the connecting wiring Lc and the power supply electrode 150 intersect, thereby ensuring electrical insulation between the connecting wiring Lci and the power supply electrode 150_j (where i ≠ j).

[0047] The insulating film 170 is provided with an opening OPi that serves as an electrical contact at the connection point between the corresponding connecting wiring Lci and the power supply electrode 150_i (i=1 to 4). In this embodiment, openings OP1 to OP4 are formed in the insulating film 170. The connecting wiring Lc1 and the power supply electrode 150_1 are electrically connected via opening OP1, the connecting wiring Lc2 and the power supply electrode 150_2 are electrically connected via opening OP2, the connecting wiring Lc3 and the power supply electrode 150_3 are electrically connected via opening OP3, and the connecting wiring Lc4 and the power supply electrode 150_4 are electrically connected via opening OP4.

[0048] Organic materials such as polyimide can be used as the material for the insulating film 170. Polyimide has the advantage of being able to fill in irregularities in the substrate and easily flatten the surface, thus flattening the connecting wiring Lc and improving the coverage of the film. In addition, it has toughness and high durability against external forces, making it less susceptible to damage such as cracks, and can improve the electrical insulation between electrodes.

[0049] Figure 2 is a plan view of the semiconductor laser element 100 shown in Figure 1. The length of the semiconductor laser element 100 in the z direction is L. ｃｈｉｐ Let's assume that the length in the z direction (overlap length) of the portion where the i-th (i = 1, 2, ..., M) laser waveguide 200_i intersects with the j-th connecting wiring Lcj is L ｉｊ Let's assume that.

[0050] The total length of the portion where the i-th laser waveguide 200_i overlaps with any of the connecting wires Lc1 to Lc4 (total overlap length) L ｉ is, L ｉ = Σ ｊ＝１～Ｍ L ｉｊ That is the case.

[0051] In all laser waveguides 200_1 to 200_4, L ｉ = Σ ｊ＝１～Ｍ L ｉｊ ≥0.5L ｃｈｉｐ The following relationship is satisfied. In other words, when each laser waveguide 200 is viewed along the z-direction, more than half of it is covered by the connecting wiring Lc.

[0052] More preferably, in all laser waveguides 200_1 to 200_4, L ｉ ≥0.8L ｃｈｉｐ The relationship should be satisfied.

[0053] Figure 3 is a cross-sectional view of the semiconductor laser element 100 shown in Figure 1, taken along line A-A in Figure 2. Figure 3 shows a cross-section of the connecting wiring Lc3. An opening OP3 is formed in the insulating film 170, and the power supply electrode 150_3 and the connecting wiring Lc3 are electrically connected through this opening OP3. The connecting wiring Lc3 is insulated from the other power supply electrodes 150_1, 150_2, and 150_4 by the insulating film 170.

[0054] Furthermore, the semiconductor laser element 100 satisfies several additional design conditions 1 to 5 below.

[0055] (Design condition 1) Total overlap length L of multiple laser waveguides 200_1 to 200_4 １ ~L ４ It is preferable that they are substantially equal. Specifically, L １ , L ２ ,...L Ｍ The maximum value among them is max(L １ , L ２ ,...L Ｍ ), the minimum value min(L １ , L ２ ,...L Ｍ When ) max(L １ , L ２ ,...L Ｍ ) - min(L １ , L ２ ,...L Ｍ ) ≤ 0.1L ｃｈｉｐ It may satisfy the requirement.

[0056] (Design Condition 2) Refer to Figure 2. In this embodiment, the width Wci in the z direction of each connection wire Lci is equal to or greater than the length Wpi in the z direction of the corresponding power supply pad Pei. In this embodiment, Wci = Wpi. Wci ≥ Wpi

[0057] The length Wpi in the z-direction of the power supply pad Pei refers to the width of the metal layer in the pad region 904.

[0058] (Design condition 3) Refer to Figure 3. The distance d between the x-direction end of the connecting wiring Lc and the closest laser waveguide among the M (200_4 in this example) is longer than half the spacing (center-to-center distance) p of the laser waveguides 200.

[0059] (Design Condition 4) Refer to Figure 3. A distance d between an end of the connection wiring Lc in the x-direction and the one of the M laser waveguides closest to said end (200_4 in this example) is greater than a thickness t of the substrate 110 ｓｕｂ .

[0060] (Design Condition 5) Refer to Figure 2. Lengths in the z-direction of contact regions (openings), where the power feeding electrode 150 of each laser waveguide 200 is electrically connected to the corresponding connection wiring Lc, are substantially equal.

[0061] The above is the configuration of the semiconductor laser device 100.

[0062] In order to investigate the influence of the total overlap length, a chip length L ｃｈｉｐ , a ratio of a total overlap length L ｉ thereto (referred to as wiring occupation rate) L / L ｃｈｉｐ was varied to 16%, 33%, 50% and 66% to prepare samples, and I-L characteristics were measured.

[0063] FIG. 4 is a diagram showing I-L characteristics, which is a relationship between current and optical output, of samples having different wiring occupation rates. FIG. 5 is a diagram showing a relationship between the wiring occupation rate L ｉ / L ＣＨＩＰ and maximum optical output.

[0064] When the wiring occupation rate L ｉ / L ＣＨＩＰ is in a range of 0 to 50%, the optical output of the laser increases as the wiring occupation rate L ｉ / L ＣＨＩＰ increases. When the wiring occupation rate L ｉ / L ＣＨＩＰ is 50% or more, the optical output is saturated with respect to the wiring occupation rate L ｉ / L ＣＨＩＰ . In other words, by setting the wiring occupation rate L ｉ / L ＣＨＩＰ to 50% or more, a sufficient heat dissipation effect that does not affect optical output can be obtained by the connection wiring Lc. Accordingly, a difference in beam characteristics between a case where all M laser waveguides 200 emit light simultaneously and a case where one of the M laser waveguides 200 emits light can be reduced.

[0065] During the manufacturing process, poor coverage of the connecting wiring may occur at the intersections with the laser waveguides. In such areas, the wiring occupancy may be ineffective or effectively reduced. In these situations, the wiring occupancy rate falls below the design value, which poses a risk to the uniformity of the characteristics between emitters. Considering such manufacturing variations, it is desirable that the wiring occupancy rate be 75% or higher. For example, if three connecting wires are equally divided among three laser waveguides, the design ensures that each connecting wire occupies 25% of the total intersection area. In this case, even if one connecting wire becomes ineffective, the remaining two wires can still occupy 50% of the total, thus ensuring an intersection area ratio of 50% or higher. This effect is similar for four or more laser waveguides, and even if poor coverage of the connecting wiring occurs due to manufacturing variations, the uniformity of the characteristics between emitters is maintained.

[0066] Next, a modified example of the semiconductor laser element 100 will be described.

[0067] (Modification 1) Figure 6 is a plan view of the semiconductor laser element 100A according to Modification 1. In this modification, design conditions 1, 2, 4, and 5 of the above-mentioned design conditions 1 to 5 are satisfied.

[0068] (Modification 2) Figure 7 is a plan view of the semiconductor laser element 100B according to Modification 2. In this modification, design conditions 2 to 4 are satisfied, and the widths Wc1 to Wc4 in the z direction of the multiple connection wires Lc1 to Lc4 further satisfy design condition 6.

[0069] (Design condition 6) The value is larger closer to the output end face of the multi-beam semiconductor laser element. That is, the relationship Wc1 > Wc2 > Wc3 > Wc4 holds true.

[0070] Since the heat generation density is higher closer to the exit end face, the temperature rise at the exit end face can be suppressed by increasing the width of the connecting wiring closer to the exit end face.

[0071] (Modification 3) Figure 8 is a plan view of the semiconductor laser element 100C according to Modification 3. In this modification, pad regions 904 and 906 are provided on both sides of the semiconductor laser element 100C, and multiple pads Pe1 to Pe4 are distributed and formed in the two pad regions 904 and 906. This modification satisfies design conditions 1, 2, and 5.

[0072] (Modification 4) Figure 9 is a plan view of the semiconductor laser element 100D according to Modification 4. In this modification, pad regions 904 and 906 are provided on both sides of the semiconductor laser element 100C, and multiple pads Pe1 to Pe4 are distributed and formed in the two pad regions 904 and 906. This modification satisfies design conditions 1 and 2.

[0073] (Modification 5) Figure 10 is a plan view of the semiconductor laser element 100E according to Modification 5. In this modification, the width Wci of the connecting wiring Lci is greater than the length Wpi of the pad Pe in the z direction.

[0074] Next, we will describe a semiconductor laser device 400 equipped with a semiconductor laser element 100.

[0075] Figure 11 is a cross-sectional view of the semiconductor laser device 400. The semiconductor laser device 400 comprises a submount 420 and a semiconductor laser element 100. The semiconductor laser element 100 is junction-up mounted to the submount 420. Specifically, the N-side electrode 152 of the semiconductor laser element 100 is connected to a wiring 422 on the submount 420 via solder 424.

[0076] Figure 12 is a cross-sectional view of a semiconductor laser device 400. The semiconductor laser device 400 comprises a submount 420 and a semiconductor laser element 100. The semiconductor laser element 100 is mounted to the submount 420 using a junction-down mounting method. Specifically, the pads Pe of the semiconductor laser element 100 are connected to the wiring 422 on the submount 420 via solder 424. When using junction-down mounting, the semiconductor laser elements 100C and 100D shown in Figures 8 and 9, in which the pad electrodes Pe are present on both sides of the chip, can be used to support the semiconductor laser element 100 on both sides of the chip.

[0077] The embodiments merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are permitted in the embodiments, without departing from the spirit of the present invention as defined in the claims.

[0078] 100 Semiconductor laser element 902 Laser region 904, 906 Pad region 110 Substrate 120 Stacked structure 122 N-type semiconductor layer 124 Light-emitting layer 126 P-type semiconductor layer Pe Pad OP Aperture 150 Power supply electrode 152 N-side electrode 170 Insulating film 200 Laser waveguide 400 Semiconductor laser device 420 Submount

Claims

1. A multibeam semiconductor laser element, wherein the stacking direction of the epitaxial stacked structure is the y-direction, the direction of laser light guidance is the z-direction, and the direction perpendicular to the y-direction and the z-direction is the x-direction, and a plurality of M (M≧3) laser waveguides are formed adjacent to each other in the x-direction in the laser region of the epitaxial stacked structure, each laser waveguide comprising: M laser waveguides having stripe-shaped power supply electrodes extending in the z-direction; M power supply pads formed in the pad region adjacent to the laser region in the x-direction and corresponding to the M laser waveguides; and M connecting wires, each connecting the power supply electrode of the corresponding laser waveguide to the corresponding power supply pad, wherein the length of the multibeam semiconductor laser element in the z-direction is L ｃｈｉｐ The length in the z-direction of the portion where the i-th (i = 1, 2, ..., M) laser waveguide intersects with the j-th connecting wire is L. ｉｊ The total overlap length L is defined as the sum of the lengths of the portions in which the i-th laser waveguide overlaps with the connecting wiring. ｉ = Σ ｊ＝１～Ｍ L ｉｊ In this case, L ｉ ≥0.5L ｃｈｉｐ A multi-beam semiconductor laser element characterized by satisfying the condition i = 1, 2, ..., M.

2. A maximum value among the total overlap lengths L １ , L ２ , ... L Ｍ of the M laser waveguides is defined as max(L １ , L ２ , ... L Ｍ ), and a minimum value is defined as min(L １ , L ２ , ... L Ｍ ), wherein max(L １ , L ２ , ... L Ｍ ) - min(L １ , L ２ , ... L Ｍ ) ≤ 0.1 L ｃｈｉｐ The multi-beam semiconductor laser device according to claim 1, which satisfies 3. The multi-beam semiconductor laser element according to claim 1 or 2, characterized in that the width of each connection wire in the z direction is greater than or equal to the length of the corresponding power supply pad in the z direction.

4. The multibeam semiconductor laser element according to claim 1 or 2, characterized in that all M connection wires intersect with all M laser waveguides.

5. The multibeam semiconductor laser element according to claim 1 or 2, characterized in that the distance between the end of the connecting wiring in the x-direction and the closest of the M laser waveguides to the end is longer than half the distance between adjacent laser waveguides.

6. The multibeam semiconductor laser element according to claim 1 or 2, characterized in that the distance between the end of the connecting wiring in the x-direction and the one of the M laser waveguides closest to the end is greater than the thickness of the substrate.

7. The multi-beam semiconductor laser element according to claim 1 or 2, characterized in that the length in the z direction of the contact region where the power supply electrode of each laser waveguide is electrically connected to the corresponding connecting wiring is substantially equal.

8. The multi-beam semiconductor laser element according to claim 1 or 2, characterized in that the pad regions are formed on both sides of the laser region, and the M power supply pads are arranged in two pad regions.

9. The multibeam semiconductor laser element according to claim 1 or 2, characterized in that the width of the M connection wires in the z direction is larger as it approaches the laser beam emission end face of the multibeam semiconductor laser element.

10. The material of the guide layer or cladding layer included in the epitaxial laminated structure is {Al ｘ Ga （１－ｘ） } １－ｙ In ｙ A multibeam semiconductor laser element according to claim 1 or 2, characterized in that P is (0 ≤ x ≤ 1, 0 ≤ y ≤ 1).

11. The multi-beam semiconductor laser element according to claim 1 or 2, characterized in that the M laser waveguides are transverse single-mode ridge waveguides.

12. The multi-beam semiconductor laser element according to claim 1 or 2, characterized in that the ratio of the difference in thermal resistance among the M laser waveguides is 10% or less.

13. A semiconductor laser device comprising: a submount; and a multi-beam semiconductor laser element according to claim 1 or 2, which is junction-up mounted or junction-down mounted on the submount.

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