JP2006294745A - Semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device which can suppress the peak of an NFP end and improve its uniformity. <P>SOLUTION: A semiconductor layer 20 including an active layer 22 is formed on a substrate 10, and a p-side electrode 31 is provided on the semiconductor layer 20. A projected line 40 is formed in the semiconductor layer 20, and a refractive index waveguide 50 is formed corresponding to the projected line 40. The width W0 of the refractive index waveguide 50 is made uniform in the extending direction of the projected line 40, 10 μm or more for example. A current non-injection area 53 is provided corresponding to boundary vicinity areas 51 and 52 in the refractive index waveguide 50. The current non-injection area 53 is formed by providing notches 31A and 24A to the p-side electrode 31 and a p-side contact layer 24. The width of the current non-injection area 53 is 2 μm or more and 10 μm or less from the boundary of the refractive index waveguide 50, for example, and its length is preferably 10 μm or more, for example. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a refractive index waveguide type semiconductor laser element, and more particularly to a semiconductor laser element suitable for a broad area type.

  Semiconductor lasers (laser diodes; LDs) are used not only as light sources in optical disk devices such as CDs (Compact Disks) or DVDs (Digital Versatile Disks), but also in various fields such as displays, printing equipment, material processing or medical treatment. Applied. In these application fields, high output is often desirable, and there is an increasing demand for high-power semiconductor lasers.

  As one method for increasing the output, in the case of a semiconductor laser having a stripe-shaped current injection region, it is effective to increase the width of the current injection region, that is, the stripe width. For example, in a semiconductor laser for an optical disc, the typical value of the stripe width is about 2 μm to 3 μm, whereas in a semiconductor laser developed for high output, the stripe width is increased to 50 μm to 100 μm. Things have also appeared. Such a semiconductor laser having a wide stripe width is called a broad area type semiconductor laser. In addition, although a clear numerical value of the stripe width as a reference for the “broad area type” here is not defined, it is assumed in this specification to be 10 μm or more.

FIG. 15 shows an example of a conventional broad area type semiconductor laser device. This semiconductor laser device has a semiconductor layer 220 in which an n-type cladding layer 221, an active layer 222, a p-type cladding layer 223 and a p-side contact layer 224 are sequentially stacked on a substrate 210. A p-side electrode 231 is provided on the semiconductor layer 220, and an n-side electrode 232 is formed on the back side of the substrate 210. A part of the p-side contact layer 223 and the p-type cladding layer 224 is removed by etching to form a ridge 240, and n-type buried layers (not shown) are formed on both sides of the ridge 240. Is provided. A refractive index difference Δn is provided between the buried layer and the protrusion 240, and a refractive index waveguide 250 is formed corresponding to the protrusion 240 having a high refractive index. The width W0 of the refractive index waveguide 250, that is, the stripe width is as wide as, for example, 10 μm or more, and many higher-order modes other than the fundamental mode may appear.
JP 2000-174385 A JP 2000-183463 A

  An NFP (Near Field Pattern) of such a conventional broad area type semiconductor laser usually has a shape having peaks near both ends as shown in FIG. This was one of the main causes of unevenness in strength. Furthermore, this peak tends to become higher as the refractive index difference Δn shown in FIG. The ideal NFP has a uniform intensity distribution as shown in FIG. 16C, a so-called top hat shape, and the cause of separation from this ideal shape is the presence of peaks at both ends. Suppressing this peak and bringing the NFP closer to the top hat shape is desired for applications that require spatially uniform irradiation and processing, such as display applications.

  For example, Patent Document 1 describes that the width of the protrusion is constant, and the width of the separation groove on both sides of the protrusion is narrow at the center of the resonator and wider than the center near the end face. Yes. In this configuration, light spreads in the lateral direction at the center of the resonator, and the light is focused to the center near the end face. That is, the essence of the configuration of Patent Document 1 is to modulate the waveguide state of light in the direction of the resonator by changing the width of the separation groove.

  For example, in Patent Document 2, the width of the protrusion is wide at the center of the resonator and narrow near the end face. In this configuration, since the width of the ridge portion itself is changed, it is clear that the shape of the waveguide is also deformed accordingly.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a semiconductor laser device that can suppress the peak at the end of NFP and improve the uniformity of NFP.

The semiconductor laser device according to the present invention improves the uniformity of NFP by having the following structural requirements (A) to (D).
(A) A semiconductor layer including at least a first cladding layer, an active layer, a second cladding layer, and a contact layer sequentially formed on a substrate (B) An electrode provided in contact with the contact layer (C) A contact layer of the semiconductor layer A protrusion (D) having a depth from the side to reach at least the second cladding layer and forming a refractive index waveguide having a uniform width in the extending direction (D) A region in the vicinity of the boundary line in the refractive index waveguide Here, the “width” refers to a dimension in a direction perpendicular to both the extending direction of the ridge, that is, the resonator direction and the stacking direction of the semiconductor layers. .

  In the semiconductor laser device of the present invention, since the current non-injection region is provided corresponding to the region near the boundary line in the refractive index waveguide, the amount of current flowing into the region near the boundary line of the refractive index waveguide is reduced. Gain decreases.

  According to the semiconductor laser device of the present invention, since the current non-injection region is provided corresponding to the region near the boundary line in the refractive index waveguide, the gain in the region near the boundary line of the refractive index waveguide can be lowered. it can. Therefore, the appearance of a peak at the end of the NFP can be suppressed, and the uniformity can be improved.

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

  Each of the following embodiments is different in the position and shape of the current non-injection region, but pays attention to the difference in the waveguide mode depending on the position in the refractive index waveguide, and uses this to make the end of the NFP. It is common in the point which tries to suppress the peak of. Therefore, before entering into the description of the embodiment, as a premise that forms the basis of the present invention in common with these, the difference in the waveguide mode depending on the position in the refractive index waveguide will be described based on the NFP measurement result.

  A broad area type semiconductor laser device having a refractive index waveguide 150 having a width W0 of 100 μm as shown by hatching in FIG. At this time, the width W0 of the refractive index waveguide 150 is uniform in the extending direction (resonator direction) A of the protrusion. Note that the element structure and the constituent materials are general GaAs-based refractive index waveguide types.

  With respect to this broad area type semiconductor laser device, the change in NFP was examined while increasing the injection current. 2A shows NFP measurement results near the oscillation start threshold value. FIGS. 2B and 2C show FIGS. 2A, 2B, and 2C. The NFP measurement results when the injection current is further increased in this order are shown.

  As can be seen from FIG. 2A, a strong refractive index guided mode is generated on the inner side by about several μm from both ends, and this shows a characteristic like a so-called refractive index guided mode. Near the oscillation start threshold, the refractive index guided modes at both ends are strongly excited.

  On the other hand, as can be seen from FIG. 2B, in the central region several μm or more from both ends, a gain-guided transverse mode composed of relatively fine ripples appears so as to be prompted by the modes at both ends. In other words, the threshold value of the mode in the central region is slightly higher.

  When the injection current is increased to further increase the output, as shown in FIG. 2 (C), the NFP has peaks at both ends, and the central region becomes a slightly lower strength NFP.

  Thus, in the broad area type semiconductor laser, it can be seen that the borderline vicinity regions 151 and 152 having a width of about 10 μm at both ends of the refractive index waveguide 150 function as a refractive index waveguide. In other words, if the gain is reduced by reducing the amount of current flowing into the borderline vicinity regions 151 and 152 of the refractive index waveguide 150, the peak at the end of the NFP can be suppressed without changing the shape of the striped refractive index waveguide 150. can do. If the current non-injection region is provided in this way, it is not necessary to modulate the light guiding state in the resonator direction as in Patent Document 1, or the width of the protrusion is resonated as in Patent Document 2. It is not necessary to differentiate between the central part of the vessel and the vicinity of the end face.

  Hereinafter, specific embodiments and modifications thereof will be described based on the NFP measurement results and the analysis thereof.

  FIG. 3 shows a cross-sectional configuration of a semiconductor laser device according to an embodiment of the present invention. This semiconductor laser element is used for a display, for example, and has a semiconductor layer 20 on a substrate 10 in which an n-type cladding layer 21, an active layer 22, a p-type cladding layer 23, and a contact layer 24 are sequentially stacked. ing. A p-side electrode 31 is provided on the semiconductor layer 20, and an n-side electrode 32 is formed on the back side of the substrate 10. A part of the contact layer 24 and the p-type cladding layer 23 is removed by etching to form a protrusion 40, and n-type buried layers (not shown) are provided on both sides of the protrusion 40. A refractive index difference Δn is provided between the buried layer and the protrusion 40, and a refractive index waveguide 50 is formed corresponding to the protrusion 40 having a high refractive index. The width W0 of the refractive index waveguide 50 is, for example, 10 μm or more. That is, this semiconductor laser element is of a broad area type.

  The substrate 10 is made of, for example, n-type GaAs having a thickness of about 100 μm and added with an n-type impurity such as silicon (Si). The n-type cladding layer 21 has a thickness of 3 μm, for example, and is composed of an n-type AlGaAs mixed crystal to which an n-type impurity such as silicon is added.

  The active layer 22 has, for example, a thickness of 30 nm and is composed of an AlGaAs mixed crystal to which no impurity is added.

  The p-type cladding layer 23 has, for example, a thickness of 2 μm and is made of a p-type AlGaAs mixed crystal to which a p-type impurity such as zinc (Zn) is added. The p-side contact layer 24 has, for example, a thickness of 0.5 μm and is made of p-type GaAs to which a p-type impurity such as zinc (Zn) is added.

  The p-side electrode 31 has, for example, a structure in which a titanium (Ti) layer, a platinum (Pt) layer, and a gold (Au) layer are stacked in this order from the semiconductor layer 20 side, and the p-side contact layer of the semiconductor layer 20 24 is electrically connected. The n-side electrode 32 has, for example, a structure in which an alloy layer of gold and germanium (Ge), a nickel (Ni) layer, and a gold (Au) layer are sequentially stacked from the substrate 10 side. And electrically connected to the semiconductor layer 20.

  Further, in this semiconductor laser element, the main emission side end face 11 and the rear end face 12 facing each other in the extending direction A of the protrusion 40 are a pair of resonator end faces, and the main emission side end face 11 and the rear end face 12. Each has a reflecting mirror film (not shown). The reflecting mirror film on the main emission side end face 11 is adjusted to have a low reflectance, and the reflecting mirror film on the rear end face 12 is adjusted to have a high reflectance. Thereby, the light generated in the active layer 22 is amplified by reciprocating between the pair of reflecting mirror films, and is emitted as a laser beam from the reflecting mirror film on the main emission side end face 11 side.

  FIG. 4 shows a planar shape of the refractive index waveguide 50 of the semiconductor laser device shown in FIG. The width W 0 of the refractive index waveguide 50 is uniform in the extending direction A of the protrusion 40. A current non-injection region 53 is provided corresponding to the borderline vicinity regions 51 and 52 in the refractive index waveguide 50. Here, the current non-injection region 53 is a p-side electrode 31 provided with a notch 31A (not shown in FIG. 4, refer to FIG. 3). As a result, in this semiconductor laser device, the gain of the boundary line vicinity regions 51 and 52 of the refractive index waveguide 50 can be lowered, and the peak at the end of the NFP can be suppressed.

  The width W1 of the current non-injection region 53 is preferably 2 μm or more and 10 μm or less from the boundary lines 51A and 52A of the refractive index waveguide 50, for example. If it is less than 2 μm, a sufficient effect cannot be obtained due to current diffusion, and if it is larger than 10 μm, the loss increases.

  The length L1 of the current non-injection region 53 in the extending direction of the refractive index waveguide 50 is preferably 10 μm or more. If the thickness is less than 10 μm, a sufficient effect cannot be obtained due to current diffusion. In particular, when the injection current is increased, the effect may be hardly obtained.

  In the current non-injection region 53, the contact layer 24 is also provided with a notch 24A (not shown in FIG. 4, see FIG. 3). By providing the notch 24A not only in the p-side electrode 31 but also in the contact layer 24, it is possible to prevent the drive current supplied from the p-side electrode 31 from spreading through the contact layer 24. An effect is obtained.

  The shape of the current non-injection region 53 is not particularly limited, and may be a step shape, a curved shape, a rectangular shape, or the like in addition to the triangle as shown in FIGS.

  This semiconductor laser can be manufactured, for example, as follows.

  5 and 6 show this semiconductor laser manufacturing method in the order of steps. First, as shown in FIG. 5, for example, an n layer made of the above-described thickness and material is formed on one surface of the substrate 10 made of the above-described material by, for example, MOCVD (Metal Organic Chemical Vapor Deposition) method. The semiconductor layer 20 is formed by sequentially stacking the mold cladding layer 21, the active layer 22, the p-type cladding layer 23, and the p-side contact layer 24.

  Next, as shown in FIG. 5, a mask layer (not shown) made of a resist is formed on the p-side contact layer 24, and dry etching using this mask layer is performed to perform the p-side contact layer 24 and the p-side contact layer 24 and p A part of the mold cladding layer 23 in the thickness direction is selectively removed to form the protrusion 40. After that, the mask layer is removed.

  Subsequently, as shown in FIG. 6, another mask layer (not shown) made of a resist is formed on the p-side contact layer 24, and the p-side contact layer 24 is formed by dry etching using this mask layer. Is selectively removed, and a notch 24A is provided in a region to be the current non-injection region 53. After that, an n-type buried layer (not shown) is formed on both sides of the ridge 40 and a refractive index difference Δn is provided between the burying layer and the ridge 40, thereby providing a ridge having a high refractive index. A refractive index waveguide 50 is formed in the extending direction of the portion 40.

  After that, as shown in FIG. 3, the back side of the substrate 10 is wrapped to reduce the thickness of the substrate 10 to the above-described thickness, and an alloy layer of gold and germanium, a nickel layer, and a gold layer are sequentially deposited on the surface. Thus, the n-side electrode 32 is formed.

  Further, the p-side electrode 31 is formed on the upper surface of the protrusion 40 of the semiconductor layer 20 by sequentially depositing, for example, a titanium layer, a platinum layer, and a gold layer. At this time, the current non-injection region 53 is formed by providing the p-side electrode 31 with a notch 31A corresponding to the borderline vicinity regions 51 and 52 in the refractive index waveguide 50.

  After forming the n-side electrode 32 and the p-side electrode 31, the substrate 10 is adjusted to a predetermined size, and a reflecting mirror film (not shown) is formed on the main emission side end face 11 and the opposite end face 12. Thereby, the semiconductor laser shown in FIG. 3 is formed.

  In this semiconductor laser, when a predetermined voltage is applied between the n-side electrode 32 and the p-side electrode 31, the driving current supplied from the p-side electrode 31 is confined by the protrusion 40 and then the active layer. The light is emitted by electron-hole recombination. This light is reflected by a pair of reflecting mirror films (not shown) in the refractive index waveguide 50, reciprocates between them to generate laser oscillation, and is emitted to the outside as a laser beam. Here, since the current non-injection region 53 is provided corresponding to the boundary line vicinity regions 51 and 52 in the refractive index waveguide 50, as shown in FIG. The drive current L1 from the side electrode 31 is not supplied, and only the diffusion current L2 flows. Therefore, the amount of current flowing into the boundary line vicinity regions 51 and 52 of the refractive index waveguide 50 is reduced, the gain is reduced, and the peak at the end of the NFP is suppressed.

  As described above, in the present embodiment, the current non-injection region 53 is provided corresponding to the boundary line vicinity regions 51 and 52 in the refractive index waveguide 50, so the boundary line vicinity region 51 of the refractive index waveguide 50. , 52 can be reduced. Therefore, the appearance of a peak at the end of the NFP can be suppressed, and the uniformity of the NFP can be improved.

[Modification 1]
FIG. 8 shows a configuration of a semiconductor laser device according to the first modification of the above embodiment. This modification has the same configuration as that of the above embodiment except that the current non-injection region 53 is provided in the vicinity of the main emission side end face 11 in both ends in the extending direction of the refractive index waveguide 50. , Functions and effects, and can be manufactured in the same manner.

[Modification 2]
FIG. 9 shows a configuration of a semiconductor laser device according to the second modification of the above embodiment. This modified example has the same configuration, operation, and effects as those of the above-described embodiment except that the current non-injection region 53 is provided at an intermediate position in the extending direction of the refractive index waveguide 50. And can be manufactured in the same manner.

[Modification 3]
FIG. 10 shows the configuration of the semiconductor laser device according to Modification 3 of the above embodiment, and FIG. 11 shows the planar shape of the refractive index waveguide 50 of the semiconductor laser device shown in FIG. It is. This modification has the same configuration as that of the above embodiment except that the current non-injection region 53 is provided from one end to the other end in the extending direction of the refractive index waveguide 50. Yes. Accordingly, the corresponding components will be described with the same reference numerals.

  The width W1 of the current non-injection region 53 is preferably, for example, 2 μm or more and 10 μm or less from the boundary lines 51A and 52A of the refractive index waveguide 50, as in the above embodiment.

  This semiconductor laser element can be manufactured in the same manner as in the above-described embodiment, operates in the same way, and produces the same effects.

[Modification 4]
FIG. 12 shows the configuration of the semiconductor laser device according to Modification 4 of the above embodiment, and FIG. 13 shows the planar shape of the refractive index waveguide 50 of the semiconductor laser device shown in FIG. It is. This modification has the same configuration as that of the above embodiment except that the current non-injection region 53 is provided on one side of the refractive index waveguide 50. Accordingly, the corresponding components will be described with the same reference numerals.

  The semiconductor layer 20 is configured in the same manner as in the above embodiment except that the semiconductor layer 20 is formed with an off angle of 10 °, for example. The p-side electrode 31 and the n-side electrode 32 are configured in the same manner as in the above embodiment.

  One of the pair of side surfaces of the protrusion 40 has a steep slope 40A and the other has a gentle slope 40B, and the current non-injection region 53 is provided on the steep slope 40A side of the refractive index waveguide 50. Thereby, in this semiconductor laser, it is possible to suppress a peak from appearing at the end of the NFP on the steep slope 40A side.

  This semiconductor laser can be manufactured in the same manner as in the above embodiment except that the current non-injection region 53 is provided on the steep slope 40A side of the refractive index waveguide 50.

  In this semiconductor laser, when a predetermined voltage is applied between the n-side electrode 32 and the p-side electrode 31, laser oscillation occurs as in the above embodiment, and a laser beam is emitted to the outside. Here, since the current non-injection region 53 is provided on the steep slope 40A side of the refractive index waveguide 50, the gain of the region 51 in the vicinity of the boundary line of the refractive index waveguide 50 decreases, and the peak at the end of the NFP on the steep slope 40A side. Is suppressed.

  As described above, in this modification, the current non-injection region 53 is provided on one side of the refractive index waveguide 50, specifically, on the steep slope 40A side of the ridge 40, so that the peak at the end of the NFP on the steep slope 40A side is obtained. Can be suppressed. Therefore, the uniformity of NFP can also be improved in the case of a semiconductor laser element formed on an off substrate.

  Note that Modifications 1 to 3 described above can also be applied to this modification.

  Further, in this modification, the semiconductor laser element formed on the off substrate has been described as an example, but the application target of this modification is not limited to the semiconductor laser element on the off substrate. For example, a semiconductor laser element is formed on the substrate 10 having no off-angle, and after measuring the NFP and examining the light intensity distribution, the current non-injection region 53 is formed only on the side where a high peak appears at the end of the NFP. It may be provided to correct the asymmetry of NFP.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the case where the p-side electrode 31 is provided with the notch 31A in the current non-injection region 53 has been described. For example, as illustrated in FIG. An insulating film 60 may be provided between the semiconductor layer 20 and the p-side electrode 31 so as not to be electrically connected to the semiconductor layer 20 by the insulating film 60.

  Further, the material and thickness of each layer described in the above embodiment, or the film formation method and film formation conditions are not limited, and other materials and thicknesses may be used, or other film formation methods and film formation. It is good also as conditions. For example, in the above embodiment, silicon is used as the n-type impurity, but other n-type impurities such as selenium (Se) may be used.

  Further, for example, in the above-described embodiment, the material constituting the semiconductor laser has been described with a specific example. However, the present invention is not limited to the GaAs-based device described in the above-described embodiment, but may be an AlGaInP-based, InGaAs-based device. Other III-V compound semiconductors such as InGaAs, InGaAsP or InP, nitride-based III-V compound semiconductors such as InGaN, GaN or GaInNAs used for communication lasers, or II-VI compounds The present invention can be widely applied to cases where other semiconductor materials such as semiconductors are used. In the case of a blue laser such as InGaN, the width W0 of the refractive index waveguide 50 is, for example, 10 μm, and the width W1 of the current non-injection region 53 is, for example, about 20 to 30% of the width W0, that is, 2 μm to 3 μm. It is preferable to do.

  In addition, for example, in the above-described embodiment, the case where the semiconductor layer 20 is formed by the MOCVD method has been described. However, an MBE (Molecular Beam Epitaxy) method or the like may be used.

  Furthermore, for example, in the above embodiment, a semiconductor laser having a configuration in which an n-type cladding layer 21, an active layer 22, a p-type cladding layer 23, and a p-side contact layer 24 are sequentially stacked on an n-type substrate 10. Although the element has been described, a p-type substrate may be used, and a reverse conductivity type structure in which a p-type semiconductor layer, an active layer, and an n-type semiconductor layer are stacked on a p-type substrate may be used.

  In addition, for example, in the above-described embodiment, the configuration of the semiconductor laser element has been specifically described, but it is not necessary to include all layers, and other layers may be further included. For example, a light guide layer may be provided between the active layer 22 and the n-type cladding layer 21 or the p-type cladding layer 23.

  Furthermore, for example, in the above-described embodiment, a case of a so-called buried ridge type in which the protrusion 40 has a depth from the p-side contact layer 24 side of the semiconductor layer 20 to the p-type cladding layer 23 has been described. However, the present invention is not limited to this, and is also applicable to other refractive index waveguide type semiconductor laser elements such as a so-called buried hetero type in which the depth of the protrusion 40 reaches the active layer 22. can do.

It is a figure for demonstrating the basic principle of this invention. It is a figure showing NFP of the semiconductor laser element which has a refractive index waveguide shown in FIG. 1 is a perspective view illustrating a configuration of a semiconductor laser element according to an embodiment of the present invention. It is a figure for demonstrating the planar shape of the refractive index waveguide of the semiconductor laser element shown in FIG. FIG. 4 is a cross-sectional view illustrating a method of manufacturing the semiconductor laser element illustrated in FIG. FIG. 6 is a cross-sectional view illustrating a process following FIG. 5. It is sectional drawing for demonstrating the effect | action of the semiconductor laser element shown in FIG. It is a figure for demonstrating the planar shape of the refractive index waveguide of the semiconductor laser element which concerns on the modification 1 of this invention. It is a figure for demonstrating the planar shape of the refractive index waveguide of the semiconductor laser element which concerns on the modification 2 of this invention. It is a perspective view showing the structure of the semiconductor laser element which concerns on the modification 3 of this invention. It is a figure for demonstrating the planar shape of the refractive index waveguide of the semiconductor laser element shown in FIG. It is sectional drawing showing the structure of the semiconductor laser element which concerns on the modification 4 of this invention. It is a figure for demonstrating the planar shape of the refractive index waveguide of the semiconductor laser element shown in FIG. FIG. 10 is a cross-sectional view illustrating another modification of the semiconductor laser illustrated in FIG. 1. It is sectional drawing showing the example of 1 structure of the conventional broad area type semiconductor laser element. FIG. 16 is a view for explaining an NFP shape of the conventional broad area type semiconductor laser device shown in FIG. 15.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... Main emission side end surface, 12 ... Back end surface, 20 ... Semiconductor layer, 21 ... N-type cladding layer, 22 ... Active layer, 23 ... P-type cladding layer, 24 ... P-side contact layer, 24A, 31A ... notch, 31 ... p-side electrode, 32 ... n-side electrode, 40 ... projection, 40A ... steep slope, 40B ... slow slope, 50 ... refractive index waveguide, 51,52 ... border boundary region, 51A, 52A ... boundary line, 53 ... current non-injection region, 60 ... insulating film.

Claims (9)

A semiconductor layer including at least a first cladding layer, an active layer, a second cladding layer, and a contact layer sequentially formed on the substrate;
An electrode provided in contact with the contact layer;
A protrusion having a depth from the contact layer side of the semiconductor layer to at least the second cladding layer and forming a refractive index waveguide having a uniform width in the extending direction;
And a current non-injection region provided corresponding to a region near the boundary line in the refractive index waveguide. 2. The semiconductor laser device according to claim 1, wherein the current non-injection region is a notch provided in a contact layer of the protrusion. 2. The semiconductor laser device according to claim 1, wherein the current non-injection region is provided in the vicinity of at least a main emission side end face in both end portions in the extending direction of the refractive index waveguide. The semiconductor laser device according to claim 1, wherein the current non-injection region is provided at an intermediate position in the extending direction of the refractive index waveguide. The semiconductor laser device according to claim 1, wherein the current non-injection region is provided from one end to the other end in the extending direction of the refractive index waveguide. The semiconductor laser device according to claim 1, wherein the current non-injection region has a width of 2 μm to 10 μm from a boundary line of the refractive index waveguide. The semiconductor laser device according to claim 1, wherein a length of the current non-injection region in the extending direction of the refractive index waveguide is 10 μm or more. The semiconductor laser device according to claim 1, wherein the current non-injection region is provided on one side of the refractive index waveguide. The semiconductor laser device according to claim 1, wherein the refractive index waveguide has a width of 10 μm or more.

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