Semiconductor laser element

Abstract

The reflectance of an end surface protective film of this semiconductor laser element is 1% or less in a wide wavelength range. The semiconductor laser element (1) comprises: a semiconductor laminate (50) having a front-side end surface (50F) and a rear-side end surface (50R); and an end surface protective film (1F) disposed on the front-side end surface (50F) of the semiconductor laminate (50). The end surface protective film (1F) has a first dielectric layer (10) disposed on the front-side end surface (50F), and a second dielectric layer (20) laminated on the outside of the first dielectric layer (10). The second dielectric layer (20) has a first layer (21) laminated on the first dielectric layer (10), a second layer (22) laminated on the first layer (21), and a third layer (23) laminated on the second layer (22). With respect to the wavelength λ of laser light, the refractive index n2 of the second layer (22) is higher than the refractive index n1 of the first layer (21) and the refractive index n3 of the third layer (23), and the film thickness of the second layer (22) is λ / (8n2) to 3λ / (4n2).

Description

Technical Field

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

Background Art

[0002] Conventionally, laser processing has been put into practical use. In order to expand the applications of laser processing, an increase in the output power of laser light is required. As one method for realizing an increase in the output power and narrowing of the beam of laser light, a method of using a semiconductor laser device (that is, a laser array device) having a plurality of emission points as a light source has been proposed. In this method, a synthetic optical system for synthesizing a plurality of laser lights from the semiconductor laser device is constructed, and an external resonator is formed by the semiconductor laser device and a mirror disposed separately from the semiconductor laser device. By disposing the synthetic optical system in such an external resonator, a laser device that emits high-output and high-beam-quality laser light can be realized.

[0003] In a semiconductor laser device used in such an external resonator type laser device, in order to suppress the resonance (that is, internal resonance) of laser light inside the semiconductor laser device, it is required to reduce the reflectivity of the front end face (the main emission end face of laser light) of the semiconductor laser device as much as possible. The reflectivity is required to be, for example, 1% or less.

[0004] As a method for synthesizing a plurality of laser lights, for example, there are a spatial synthesis method for spatially synthesizing a plurality of laser lights and a wavelength synthesis method for condensing a plurality of laser lights having different wavelengths on the same optical axis. In order to synthesize a plurality of laser lights to realize beam narrowing, the wavelength synthesis method of condensing a plurality of laser lights on the same optical axis is more advantageous than the spatial synthesis method in which a plurality of optical axes are different from each other.

[0005] On the one hand, in the above external resonator, in order to achieve wavelength synthesis, it is necessary to generate laser light of a plurality of different wavelengths by a semiconductor laser element. For example, by utilizing a laser array element as the semiconductor laser element, laser light of a plurality of different wavelengths can be generated. Furthermore, in order to generate a large number of laser lights, it is also possible to use a plurality of laser array elements.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] The reflectance of the front end face of such a laser array element is required to be 1% or less for a plurality of different wavelengths. However, in the documents showing the prior art (such as Patent Document 1), an end face protective film that can be 1% or less in a wide wavelength range of 50 nm or more has not been reported. For this reason, the same end face protective film cannot be used for all the light emitting points of the laser array element.

[0008] The present disclosure solves such problems and provides a semiconductor laser element including an end face protective film capable of achieving a reflectance of 1% or less in a wide wavelength range.

[0009] One aspect of the semiconductor laser device according to the present disclosure includes a semiconductor laminate. The semiconductor laminate has a front-side end face and a rear-side end face, and further includes an end-face protective film. The end-face protective film is formed on the front-side end face of the semiconductor laminate. The end-face protective film has a first dielectric layer disposed on the front-side end face and a second dielectric layer laminated outside the first dielectric layer. The second dielectric layer has a first layer laminated on the first dielectric layer, a second layer laminated on the first layer, and a third layer laminated on the second layer. With respect to the wavelength λ of the laser light emitted by the semiconductor laser device, the refractive index n2 of the second layer is higher than the refractive index n1 of the first layer and the refractive index n3 of the third layer. The film thickness of the second layer is λ / (8n2) or more and 3λ / (4n2) or less.

[0010] With the end-face protective film having such a configuration, a reflectance of 1% or less can be realized in a wide wavelength range of 50 nm or more. Therefore, for example, when the semiconductor laser device according to the present disclosure is used in an external resonator type semiconductor laser device that performs wavelength synthesis, it is not necessary to change the configuration of the end-face protective film for each light-emitting point that emits laser light. For this reason, the configuration of the semiconductor laser device can be simplified. Along with this, since the manufacturing process of the semiconductor laser device can be simplified, the manufacturing of the semiconductor laser device can be stabilized, and the cost reduction of the semiconductor laser device can be realized.

[0011] In one aspect of the semiconductor laser device according to the present disclosure, the first dielectric layer may include at least one dielectric film made of at least one of a nitride film and an oxynitride film.

[0012] Thereby, oxygen diffusion from the outside of the end-face protective film to the semiconductor laminate can be reduced. For this reason, deterioration of the front-side end face of the semiconductor laminate can be suppressed. Therefore, long-term operation of the semiconductor laser device becomes possible.

[0013] In one aspect of the semiconductor laser device according to the present disclosure, the end-face protective film may include at least two dielectric films made of at least one of a nitride film and an oxynitride film.

[0014] As a result, oxygen diffusion from the outside of the end face protective film into the semiconductor laminate can be further reduced. Therefore, deterioration of the front end face of the semiconductor laminate can be further suppressed.

[0015] In one aspect of the semiconductor laser device according to the present disclosure, the first dielectric layer may include at least one of a SiN film, an AlN film, a SiON film, an AlON film, an Al2O3 film, and a SiO2 film.

[0016] In one aspect of the semiconductor laser device according to the present disclosure, each of the first layer and the third layer may include at least one of a SiO2 film and an Al2O3 film.

[0017] As a result, the first layer and the third layer having a relatively low refractive index can be realized.

[0018] In one aspect of the semiconductor laser device according to the present disclosure, the second layer may include at least one of an AlN film, an AlON film, a TiO2 film, a Nb2O5 film, a ZrO2 film, a Ta2O5 film, and a HfO2 film.

[0019] As a result, the second layer having a relatively high refractive index can be realized.

[0020] In one aspect of the semiconductor laser device according to the present disclosure, the reflectance of the end face protective film is preferably 1.0% or less in a wavelength range of 50 nm or more including the wavelength of the laser light.

[0021] As a result, for example, when the semiconductor laser device according to the present disclosure is used in an external resonator type semiconductor laser device that performs wavelength synthesis, it is not necessary to change the configuration of the end face protective film for each light emitting point that emits laser light. Therefore, the configuration of the semiconductor laser device can be simplified. Along with this, the manufacturing process of the semiconductor laser device can be simplified, so that the manufacturing of the semiconductor laser device can be stabilized and the cost reduction of the semiconductor laser device can be realized.

[0022] In one aspect of the semiconductor laser device according to the present disclosure, it is more preferable that the reflectance of the end face protective film is 0.5% or less in a wavelength range of 50 nm or more including the wavelength of the laser light.

[0023] Thereby, for example, when the semiconductor laser device according to the present disclosure is used in an external resonator type semiconductor laser device that performs wavelength synthesis, it is not necessary to change the configuration of the end face protective film for each light emitting point that emits laser light. For this reason, the configuration of the semiconductor laser device can be simplified. Along with this, since the manufacturing process of the semiconductor laser device can be simplified, the manufacturing of the semiconductor laser device can be stabilized, and the cost reduction of the semiconductor laser device can be realized.

[0024] In one aspect of the semiconductor laser device according to the present disclosure, the semiconductor laminate may be formed of a gallium nitride-based material.

[0025] Thereby, a semiconductor laser device that emits laser light having a wavelength in a band of about 390 nm or more and 530 nm or less can be realized. In addition, although the gallium nitride-based material may have a problem of deterioration due to oxygen diffusion from the end face, the oxygen diffusion from the end face can be reduced by the end face protective film according to the present disclosure. For this reason, the reliability of the semiconductor laser device can be enhanced.

[0026] In one aspect of the semiconductor laser device according to the present disclosure, the semiconductor laminate may be formed of a gallium arsenide-based material.

[0027] Thereby, a semiconductor laser device that emits laser light having a wavelength in the infrared band of about 750 nm or more and 1100 nm or less can be realized.

[0028] One aspect of the semiconductor laser device according to the present disclosure has a plurality of light emitting points, and each of the plurality of light emitting points may emit laser light.

[0029] Thereby, a small laser light source that can emit a plurality of laser lights can be realized. By using such a semiconductor laser device in an external resonator type semiconductor laser device that performs wavelength synthesis, a small semiconductor laser device can be realized.

[0030] According to the present disclosure, a semiconductor laser element including an end face protective film capable of achieving a reflectance of 1% or less in a wide wavelength range can be provided.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Embodiments for Carrying Out the Invention

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, and the arrangement positions and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0033] In addition, each figure is a schematic diagram and is not necessarily drawn precisely. Therefore, the scales and the like in each figure do not necessarily match. In each figure, substantially the same components are denoted by the same reference numerals, and overlapping descriptions are omitted or simplified.

[0034] In addition, in this specification, the terms "upper" and "lower" do not refer to the upward direction (vertically upward) and the downward direction (vertically downward) in an absolute spatial recognition, but are used as terms defined by a relative positional relationship based on the stacking order in a stacked structure. Further, the terms "upper" and "lower" are applicable not only when two components are arranged at intervals from each other and there is another component between the two components, but also when the two components are arranged in contact with each other.

[0035] (First Embodiment) A semiconductor laser element according to the first embodiment will be described.

[0036] [1-1. Overall Configuration] First, the overall configuration of the semiconductor laser element according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing the configuration of the semiconductor laser element 1 according to the present embodiment. In FIG. 1, a cross-section along the stacking direction (vertical direction in FIG. 1) of the semiconductor stack 50 included in the semiconductor laser element 1 and the resonance direction of the laser light (left-right direction in FIG. 1) is shown.

[0037] The semiconductor laser element 1 is a semiconductor light-emitting element that emits laser light. As shown in FIG. 1, the semiconductor laser element 1 includes a semiconductor stack 50 and an end face protective film 1F. In the present embodiment, the semiconductor laser element 1 further includes an end face protective film 1R, a first electrode 56, and a second electrode 57.

[0038] [1-1-1. Configuration of Semiconductor Stack and Electrodes] The semiconductor laminate 50 is a laminate in which a plurality of semiconductor layers constituting the semiconductor laser element 1 are laminated. As shown in FIG. 1, the semiconductor laminate 50 has a front-side end face 50F and a rear-side end face 50R which are opposing end faces. End face protective films 1F and 1R are respectively disposed on the front-side end face 50F and the rear-side end face 50R.

[0039] The semiconductor laminate 50 has a substrate 51, a first semiconductor layer 52, an active layer 53, a second semiconductor layer 54, and a contact layer 55. In the present embodiment, the semiconductor laminate 50 is formed of a gallium nitride-based material. Thereby, a semiconductor laser element 1 that emits laser light having a wavelength in a band of about 390 nm or more and 530 nm or less can be realized.

[0040] The substrate 51 is a plate-like member that serves as a base material of the semiconductor laminate 50. In the present embodiment, the substrate 51 is a GaN single crystal substrate having a thickness of 100 μm. Note that the thickness of the substrate 51 is not limited to 100 μm, and may be, for example, 50 μm or more and 120 μm or less. Further, the material forming the substrate 51 is not limited to a GaN single crystal, and may be sapphire, SiC, or the like.

[0041] The first semiconductor layer 52 is a first-conductivity-type semiconductor layer disposed above the substrate 51. In the present embodiment, the first semiconductor layer 52 is an n-type semiconductor layer disposed on one main surface of the substrate 51 and includes an n-type cladding layer. The n-type cladding layer is a layer made of n-Al 0.2 Ga 0.8 N. Note that the configuration of the n-type cladding layer is not limited thereto. The thickness of the n-type cladding layer may be 0.5 μm or more, and the composition may be n-Al x Ga 1-x N (0 <x <1).

[0042] The active layer 53 is a light-emitting layer disposed above the first semiconductor layer 52. In the present embodiment, the active layer 53 is In 0.18 Ga 0.82It is a quantum well active layer in which well layers with a thickness of 5 nm made of N and barrier layers with a thickness of 10 nm made of GaN are alternately stacked, and it has two well layers. By providing such an active layer 53, the semiconductor laser element 1 can emit blue laser light with a wavelength of about 450 nm. The configuration of the active layer 53 is not limited to this, and it may be a quantum well active layer in which well layers made of In x Ga 1-x N (0 < x < 1) and barrier layers made of Al x In y Ga 1-x―y N (0 ≤ x + y ≤ 1) are alternately stacked. Note that the active layer 53 may include a guide layer formed on at least one of the upper and lower sides of the quantum well active layer. In this embodiment, the number of well layers is two, but it may be one or more and four or less. Also, the In composition of the well layer may be appropriately selected so as to generate light with a desired wavelength within the range of 390 nm or more and 530 nm or less.

[0043] The second semiconductor layer 54 is a second-conductivity-type semiconductor layer disposed above the active layer 53. The second conductivity type is different from the first conductivity type. In this embodiment, the second semiconductor layer 54 is a p-type semiconductor layer and includes a p-type cladding layer. The p-type cladding layer is a superlattice layer in which layers with a thickness of 3 nm made of p-Al 0.2 Ga 0.8 N and layers with a thickness of 3 nm made of GaN are alternately stacked 100 layers each. The configuration of the p-type cladding layer is not limited to this, and it may be a layer with a thickness of 0.3 μm or more and 1 μm or less made of Al x Ga 1-x N (0 < x < 1).

[0044] Note that the p-type cladding layer may be formed of a material other than AlGaN. The p-type cladding layer may be formed of another material having a refractive index suitable for confining light in the active layer 53.

[0045] The contact layer 55 is a semiconductor layer of the second conductivity type that makes an ohmic contact with the second electrode 57. In the present embodiment, the contact layer 55 is a p-type semiconductor layer and is a layer made of p-GaN with a thickness of 10 nm. Note that the configuration of the contact layer 55 is not limited to this. The thickness of the contact layer 55 may be 5 nm or more.

[0046] Note that in the present embodiment, one or more ridge portions are formed in the second semiconductor layer 54 and the contact layer 55. The region of the active layer 53 corresponding to each ridge portion (that is, the region of the active layer 53 located below each ridge portion) serves as a light-emitting point and emits laser light.

[0047] The first electrode 56 is an electrode disposed on the main surface below the substrate 51 (that is, the main surface on which the first semiconductor layer 52 and the like are not disposed). In the present embodiment, the first electrode 56 is a laminated film in which Ti, Pt, and Au are laminated in this order from the substrate 51 side. The configuration of the first electrode 56 is not limited to this. The first electrode 56 may be a laminated film in which Ti and Au are laminated.

[0048] The second electrode 57 is an electrode disposed on the contact layer 55. In the present embodiment, the second electrode 57 includes a p-side electrode that makes an ohmic contact with the contact layer 55 and a pad electrode disposed on the p-side electrode.

[0049] The p-side electrode is a laminated film in which Pd and Pt are laminated in this order from the contact layer 55 side. The configuration of the p-side electrode is not limited to this. The p-side electrode may be, for example, a single-layer film or a multilayer film formed of at least one of Cr, Ti, Ni, Pd, Pt, and Au.

[0050] The pad electrode is a pad-shaped electrode disposed above the p-side electrode. In the present embodiment, the pad electrode is a laminated film in which Ti and Au are laminated in this order from the p-side electrode side and is disposed on the ridge portion and its periphery. The configuration of the pad electrode is not limited to this. The pad electrode may be, for example, a laminated film of Ti, Pt, and Au, a laminated film of Ni and Au, or a laminated film of other metals.

[0051] Although not shown in FIG. 1, the semiconductor laminate 50 may further include an insulating film such as a SiO2 film that covers the side walls of the ridge portion, etc., in addition to the above layers.

[0052] [1-1-2. Configuration of the end face protective films 1F and 1R] The end face protective film 1F is a protective film disposed on the front end face 50F of the semiconductor laminate 50. The end face protective film 1F protects the front end face 50F of the semiconductor laminate 50 and reduces the reflectance of the laser light at the front end face 50F. The end face protective film 1F has a first dielectric layer 10 and a second dielectric layer 20.

[0053] The first dielectric layer 10 is a dielectric layer disposed on the front end face 50F. The first dielectric layer 10 may include at least one dielectric film made of at least one of a nitride film and an oxynitride film. Thereby, oxygen diffusion from the direction of the front end face 50F to the semiconductor laminate 50 can be reduced. For this reason, deterioration of the front end face of the semiconductor laminate can be suppressed. Therefore, long-term operation of the semiconductor laser element becomes possible.

[0054] Also, the first dielectric layer 10 is directly connected to the front end face 50F of the semiconductor laminate 50 (that is, formed in contact with the front end face 50F). For this reason, by using a nitride film or an oxynitride film having the same crystallinity as the semiconductor laminate 50 as the first dielectric layer 10, the protection performance of the front end face 50F can be enhanced. In the present embodiment, the first dielectric layer 10 includes an AlON film. More specifically, the first dielectric layer 10 is a single-layer film made of an AlON film having a thickness of about 20 nm. Note that the configuration of the first dielectric layer 10 is not limited to this. The first dielectric layer 10 may be, for example, another oxynitride film such as SiON, or a nitride film such as an AlN film or a SiN film.

[0055] The second dielectric layer 20 is a dielectric layer laminated outside the first dielectric layer 10, and includes a first layer 21 laminated on the first dielectric layer, a second layer 22 laminated on the first layer 21, and a third layer 23 laminated on the second layer 22. With respect to the wavelength λ of the laser light emitted from the semiconductor laser element 1, the refractive index n2 of the second layer 22 is higher than the refractive index n1 of the first layer 21 and the refractive index n3 of the third layer 23, and the film thickness of the second layer 22 is λ / (8n2) or more and 3λ / (4n2) or less. Thereby, an end face protective film 1F having a reflectivity of 1% or less can be realized in a wide wavelength range. Here, the wavelength dependence of the reflectivity of the end face protective film 1F will be described with reference to FIG. 2. FIG. 2 is a graph showing the wavelength dependence of the reflectivity of the end face protective film 1F according to the present embodiment. The graph shown in FIG. 2 is obtained by calculation. The vertical axis and the horizontal axis of FIG. 2 indicate reflectivity and wavelength, respectively. As shown in FIG. 2, the reflectivity of the end face protective film 1F is 1% or less in a wavelength range of 50 nm or more including the wavelength of the laser light. More specifically, the reflectivity of the end face protective film 1F is 0.5% or less in a wavelength range of 50 nm or more including the wavelength of the laser light. In the example shown in FIG. 2, a reflectivity of 0.5% or less is obtained in a wavelength range of 100 nm or more, about 400 nm or more and 500 nm or less.

[0056] In the present embodiment, the first layer 21 is an Al2O3 film having a thickness of about 100 nm. The first layer 21 may be a dielectric film having a refractive index lower than that of the second layer 22, and may include at least one of, for example, a SiO2 film and an Al2O3 film. Thereby, the first layer 21 having a relatively low refractive index can be realized.

[0057] In the present embodiment, the second layer 22 is a ZrO2 film having a thickness of about 50 nm. The second layer 22 may be a dielectric film having a refractive index higher than that of the first layer 21 and the third layer 23. For example, when the first layer 21 and the third layer 23 are Al2O3 films or SiO2 films, the second layer 22 may include at least one of an AlN film, an AlON film, a TiO2 film, a Nb2O5 film, a ZrO2 film, a Ta2O5 film, and a HfO2 film. Further, the second layer 22 may include at least one of a SiN film and a SiON film. Thereby, the second layer 22 having a relatively high refractive index can be realized.

[0058] In this embodiment, the third layer 23 is a SiO2 film with a thickness of about 100 nm. The third layer 23 may be a dielectric film having a refractive index lower than that of the second layer 22, and may include, for example, at least one of a SiO2 film and an Al2O3 film. Thereby, the third layer 23 having a relatively low refractive index can be realized.

[0059] The end face protective film 1R is a protective film disposed on the rear end face 50R of the semiconductor laminate 50. The end face protective film 1R protects the rear end face 50R of the semiconductor laminate 50 and increases the reflectivity of the laser light at the rear end face 50R. In this embodiment, the end face protective film 1R is a multilayer film in which a plurality of pairs of SiO2 films and ZrO2 films with a thickness of about λ / (4n) are laminated, where λ is the wavelength of the laser light and n represents the refractive index of each dielectric film. Thereby, the reflectivity of the laser light in the end face protective film 1R can be made 90% or more. Note that the configuration of the end face protective film 1R is not limited to this, and as long as a desired reflectivity can be obtained, a configuration in which a plurality of pairs of a SiO2 film and a Ta2O5 film, a SiO2 film and an AlON film, a SiO2 film and an AlN film, a SiO2 film and a TiO2 film, a SiO2 film and a HfO2 film, a SiO2 film and a Nb2O5 film, etc. are laminated may be used. Also, among the above pairs, an Al2O3 film may be used as the low refractive index film. Also, in the end face protective film 1R as well, similar to the end face protective film 1F, it may include at least one of a nitride film and an oxynitride film.

[0060] [1-2. Action and effect of end face protective film 1F] Next, the operation and effects of the end face protective film 1F according to the present embodiment will be described with reference to FIGS. 3 and 4 while comparing with comparative examples. FIG. 3 is a graph showing the wavelength dependence of the reflectance of the second dielectric layer 20 of the end face protective film 1F according to the present embodiment. FIG. 4 is an enlarged graph of a part of FIG. 3. In FIGS. 3 and 4, graphs obtained by calculation are shown. The vertical axis and the horizontal axis in FIGS. 3 and 4 indicate reflectance and wavelength, respectively. In FIGS. 3 and 4, the wavelength dependence of the reflectance of the end face protective film of the comparative example is also shown. The solid line graphs shown in FIGS. 3 and 4 indicate the reflectance of the second dielectric layer 20 composed of a three-layer film according to the present embodiment. Also, the one-dot chain line and two-dot chain line graphs shown in FIGS. 3 and 4 indicate the reflectances of the single-layer film of the first comparative example and the two-layer film of the second comparative example, respectively.

[0061] In the case of the single-layer film of the first comparative example, as shown in FIGS. 3 and 4, a low reflectance of about 0.3% can be realized, but the wavelength range in which the low reflectance can be obtained is narrow. Specifically, the wavelength range in which the reflectance is 0.5% or less is about 10 nm, and the wavelength range in which the reflectance is 1% or less is about 20 nm. Also, in the case of the two-layer film of the second comparative example, a low reflectance of 0.1% or less can be realized, but in this case as well, as in the first comparative example, the wavelength range in which the low reflectance can be obtained is narrow.

[0062] On the other hand, in the case of a three-layer film using a high refractive index film as the second layer 22 like the second dielectric layer 20 according to the present embodiment, as shown in FIG. 4, the wavelength dependence of the reflectance in the low reflectance wavelength range can be reduced. Therefore, a low reflectance can be realized over a wide wavelength range. For this reason, for example, when the semiconductor laser element 1 according to the present embodiment is used in an external resonator type semiconductor laser device that performs wavelength synthesis, it is not necessary to change the configuration of the end face protective film for each light emitting point that emits laser light. Therefore, the configuration of the semiconductor laser device can be simplified. Along with this, since the manufacturing process of the semiconductor laser device can be simplified, the manufacturing of the semiconductor laser device can be stabilized and the cost reduction of the semiconductor laser device can be realized.

[0063] Here, the reason why a wide range of low reflectance can be realized in the second dielectric layer 20 according to the present embodiment will be described. In the second dielectric layer 20 according to the present embodiment, by increasing the optical path length (that is, the optical path length in the thickness direction of the second dielectric layer 20) compared to a single-layer film and a two-layer film, among the wavelengths at which the reflectance takes a minimum value, two wavelengths close to 450 nm can be brought closer to about 420 nm and about 480 nm. Here, the minimum value at the point where the wavelength λ is 420 nm is a minimum value generated when the optical path length in the thickness direction of the second dielectric layer 20 is a multiple of λ / 4, and the minimum value at the point where the wavelength λ is 480 nm is a minimum value generated when the optical path length in the thickness direction of the second dielectric layer 20 is a multiple of λ / 2.

[0064] Furthermore, in order to suppress the reflectance at wavelengths between 420 nm and 480 nm, a high refractive index film is used for the second layer 22.

[0065] By the above method, a second dielectric layer 20 capable of obtaining low reflectance in a wide wavelength range can be realized.

[0066] However, with only the second dielectric layer 20 having a three-layer structure, an end face protective film applicable to a high-output semiconductor laser element cannot be realized. The end face protective film applicable to a high-output semiconductor laser element needs to be able to reduce the breakage of the front end face 50F even in a long-term reliability test of the semiconductor laser element. Therefore, the end face protective film 1F according to the present embodiment includes a first dielectric layer 10 disposed between the second dielectric layer 20 and the front end face 50F. Thereby, in the end face protective film 1F, both reliability and the above reflectance characteristics can be realized.

[0067] Also, in the present embodiment, the semiconductor laminate 50 is formed of a gallium nitride-based material.

[0068] As a result, a semiconductor laser element 1 that emits laser light having a wavelength in a band of about 390 nm or more and 530 nm or less can be realized. Further, in the gallium nitride-based material, deterioration due to oxygen diffusion from the end face may be a problem, but the end face protective film 1F according to the present embodiment can reduce oxygen diffusion from the front end face 50F. Therefore, the reliability of the semiconductor laser element 1 can be improved.

[0069] [1-3. Manufacturing method] Next, a method for manufacturing the semiconductor laser element 1 according to the present embodiment will be described.

[0070] First, a semiconductor laminate 50 is formed. When forming the semiconductor laminate 50, first, a substrate 51 is prepared, and a first semiconductor layer 52, an active layer 53, a second semiconductor layer 54, and a contact layer 55 are laminated in this order. In the present embodiment, an n-type clad layer, an active layer 53, a p-type clad layer, and a contact layer 55 are laminated on the substrate 51 in this order. The film formation of each layer can be performed, for example, by metalorganic chemical vapor deposition (MOCVD).

[0071] Subsequently, a ridge portion is formed in the second semiconductor layer 54 and the contact layer 55. The ridge portion can be formed, for example, by inductively coupled plasma (ICP) type reactive ion etching or the like.

[0072] As described above, the semiconductor laminate 50 of the semiconductor laser element 1 can be formed.

[0073] Subsequently, an insulating film such as an SiO2 film is formed, for example, by plasma CVD or the like. At least a part of the upper surface of the ridge portion in the insulating film is removed by wet etching or the like.

[0074] Subsequently, a second electrode 57 is formed on the ridge portion, for example, by vacuum evaporation or the like.

[0075] Subsequently, a first electrode 56 is formed on the lower surface of the substrate 51, for example, by vacuum evaporation or the like.

[0076] Next, an end face protective film 1F and an end face protective film 1R are formed on the front end face 50F and the rear end face 50R of the semiconductor laminate 50, respectively. For forming each dielectric film on each of the front end face 50F and the rear end face 50R, for example, a solid source ECR (Electron Cyclotron Resonance) sputtering plasma deposition apparatus is used. Thereby, damage to each end face when forming the dielectric film can be suppressed.

[0077] As described above, the semiconductor laser element 1 according to the present embodiment can be manufactured.

[0078] [1-4. Application examples] Next, application examples of the semiconductor laser element 1 according to the present embodiment will be described. The semiconductor laser element 1 according to the present embodiment can be applied to, for example, an external resonator type semiconductor laser device that performs wavelength synthesis. Hereinafter, the semiconductor laser device to which the semiconductor laser element 1 is applied will be described with reference to FIG. 5. FIG. 5 is a schematic plan view showing the configuration of a semiconductor laser device 2 to which the semiconductor laser element 1 according to the present embodiment is applied.

[0079] As shown in FIG. 5, the semiconductor laser device 2 includes semiconductor laser elements 1a and 1b, optical lenses 91a and 91b, a diffraction grating 95, and a partial reflection mirror 97.

[0080] Each of the semiconductor laser elements 1a and 1b is an example of the semiconductor laser element 1 according to the present embodiment. The semiconductor laser elements 1a and 1b are laser array elements, and each has N (N is an integer of 2 or more) light emitting points E 11 ~E 1N , and N light emitting points E 21 ~E 2N . Each of these light emitting points emits laser light. The wavelength of the laser light emitted from each light emitting point is determined by the wavelength selection action of an external resonator including a diffraction grating 95 described later. The semiconductor laser element 1a emits laser light from the light emitting points E 11 ~E 1N having mutually different wavelengths λ 11 ~λ 1Nemits laser light. The semiconductor laser element 1b has emission points E 21 ~E 2N respectively emit laser lights having mutually different wavelengths λ 21 ~λ 2N The semiconductor laser elements 1a and 1b are arranged such that each laser light propagates in the same plane.

[0081] The optical lenses 91a and 91b are optical elements that condense the laser lights emitted from the semiconductor laser elements 1a and 1b onto the diffraction grating 95. Note that the optical lenses 91a and 91b may have a function of collimating each laser light. Further, the semiconductor laser device 2 may separately include collimating lenses for collimating each laser light, in addition to the optical lenses 91a and 91b.

[0082] The diffraction grating 95 is a wavelength dispersion element that multiplexes a plurality of laser lights having different wavelengths. By appropriately setting the wavelengths and incident angles of the plurality of laser lights incident on the diffraction grating 95 and the interval between the slits of the diffraction grating 95, it is possible to synthesize laser lights having different propagation directions on substantially the same optical axis.

[0083] The partial reflection mirror 97 is a mirror that forms an external resonator with the rear end face of each semiconductor laser element and functions as an output coupler that emits laser light. The reflectivity and transmittance of the partial reflection mirror 97 may be appropriately set according to the gain of each semiconductor laser element and the like.

[0084] The operation of the semiconductor laser device 2 having the above configuration will be described. When current is supplied to each of the semiconductor laser elements 1a and 1b, N laser lights are emitted. The N laser lights emitted from the semiconductor laser element 1a are condensed by the optical lens 91a onto the condensing point on the diffraction grating 95, and the N laser lights emitted from the semiconductor laser element 1b are condensed by the optical lens 91b onto the said condensing point on the diffraction grating 95. Each laser light transmitted through the diffraction grating 95 is diffracted by the diffraction grating 95 and propagates on substantially the same optical axis toward the partial reflection mirror 97. A part of each laser light heading toward the partial reflection mirror 97 is reflected by the partial reflection mirror 97 and returns to the semiconductor laser element that emitted the laser light via the diffraction grating 95, the optical lens 91a or 91b. In this way, an external resonator is formed between the rear end face 50R of each semiconductor laser element and the partial reflection mirror 97. On the other hand, the laser light transmitted through the partial reflection mirror 97 becomes the output light of the semiconductor laser device 2, and it becomes possible to obtain a high-output laser light with, for example, an optical fiber arranged on the optical axis of the output light.

[0085] In forming an external resonator by utilizing the partial reflection mirror 97, it is necessary to suppress the internal resonance in each semiconductor laser element. In order to suppress the internal resonance in each semiconductor laser element, it is necessary to minimize the reflection of light at the front end face 50F of each semiconductor laser element. For this reason, it is necessary to make the reflectance of the end face protective film 1F arranged on the front end face 50F 1% or less. Note that it is even better if the reflectance of the end face protective film 1F is 0.5% or less. Thereby, the internal resonance in each semiconductor laser element can be suppressed even further.

[0086] As a light combining method, for example, there are a wavelength combining method used in the semiconductor laser device 2 shown in FIG. 5 and a spatial combining method for spatially combining light. In order to achieve beam narrowing, the wavelength combining method that condenses light on the same optical axis is advantageous compared to the spatial combining method. As shown in FIG. 5, the wavelength λ of the laser light of the semiconductor laser element 1a 11 of the laser light and the wavelength λ 1NThe laser light emits light of different wavelengths due to differences in the optical path length and the incident angle on the diffraction grating 95. Also, in the semiconductor laser element 1b disposed at a position different from that of the semiconductor laser element 1a, since the optical path length and the incident angle on the diffraction grating 95 are different from those of the semiconductor laser element 1a, light of different wavelengths is emitted. Thus, in order to increase the optical output by synthesizing a plurality of laser lights by the wavelength synthesis method, laser lights of a large number of wavelengths are required.

[0087] In the semiconductor laser elements 1a and 1b according to the present embodiment, the reflectance of the end face protective film 1F can be set to 1% or less in a wide wavelength range including the wavelengths of the plurality of laser lights. For this reason, it is not necessary to change the configuration at each light emitting point of the end face protective film 1F of each semiconductor laser element. Furthermore, the configurations of the end face protective films of the semiconductor laser elements 1a and 1b can also be made common. For this reason, the configuration of the semiconductor laser device 2 can be simplified. Along with this, since the manufacturing process of the semiconductor laser device 2 can be simplified, the manufacturing of the semiconductor laser device can be stabilized and the cost reduction of the semiconductor laser device can be realized. Furthermore, in the end face protective film 1F according to the present embodiment, since the first dielectric layer 10 disposed between the second dielectric layer 20 and the front side end face 50F is provided, even when each semiconductor laser element is operated at a high output for a long time, the destruction of the front side end face 50F can be reduced. Therefore, a high-output and highly reliable semiconductor laser device can be realized.

[0088] Also, each of the semiconductor laser elements 1a and 1b is a laser array element, has a plurality of light emitting points, and each of the plurality of light emitting points emits laser light.

[0089] Thereby, a small laser light source capable of emitting a plurality of laser lights can be realized. By using the semiconductor laser elements 1a and 1b in an external resonator type semiconductor laser device 2 that performs wavelength synthesis, a small semiconductor laser device can be realized.

[0090] Note that the semiconductor laser device 2 includes two semiconductor laser elements 1a and 1b, but the number of semiconductor laser elements included in the semiconductor laser device 2 is not limited to this, and may be one, or may be three or more. Also, in the semiconductor laser device 2, each semiconductor laser element has a plurality of light emitting points, but each semiconductor laser element may have a single light emitting point.

[0091] (Second Embodiment) The semiconductor laser element according to the second embodiment will be described. The semiconductor laser element according to the present embodiment is mainly different from the semiconductor laser element 1 according to the first embodiment in the configuration of the first dielectric layer. Hereinafter, the semiconductor laser element according to the present embodiment will be described with reference to FIG. 6 centering on the differences from the semiconductor laser element 1 according to Embodiment 1.

[0092] FIG. 6 is a schematic cross-sectional view showing the configuration of the semiconductor laser element 101 according to the present embodiment. FIG. 6 shows a cross-section along the stacking direction of the semiconductor stack 50 included in the semiconductor laser element 101 and the resonance direction of the laser light.

[0093] As shown in FIG. 6, the semiconductor laser element 101 according to the present embodiment includes a semiconductor stack 50, end face protective films 101F and 1R, a first electrode 56, and a second electrode 57.

[0094] The end face protective film 101F according to the present embodiment has a first dielectric layer 110 and a second dielectric layer 120.

[0095] The first dielectric layer 110 according to the present embodiment includes a plurality of dielectric films. As shown in FIG. 6, the first dielectric layer 110 has a first protective layer 111, a second protective layer 112, and a third protective layer 113.

[0096] The first protective layer 111 is a dielectric film directly connected to the front end face 50F of the semiconductor laminate 50. The first protective layer 111 may include a dielectric film composed of at least one of a nitride film and an oxynitride film. In the present embodiment, the first protective layer 111 includes an AlON film. More specifically, the first protective layer 111 is a single-layer film made of an AlON film with a thickness of about 20 nm. Note that the configuration of the first protective layer 111 is not limited to this. The first protective layer 111 may be, for example, another oxynitride film such as SiON, or a nitride film such as an AlN film or a SiN film.

[0097] The second protective layer 112 is a dielectric film laminated on the first protective layer 111. In the present embodiment, the second protective layer 112 is a single-layer film made of an Al2O3 film with a thickness of about 10 nm. Note that the configuration of the second protective layer 112 is not limited to this. The second protective layer 112 may be, for example, another dielectric film such as SiO2.

[0098] The third protective layer 113 is a dielectric film laminated on the second protective layer 112. The third protective layer 113 may include a dielectric film composed of at least one of a nitride film and an oxynitride film. In the present embodiment, the third protective layer 113 is a single-layer film made of an AlN film with a thickness of about 15 nm. Note that the configuration of the third protective layer 113 is not limited to this. The third protective layer 113 may be, for example, another nitride film such as SiN, or an oxynitride film such as an AlON film or a SiON film.

[0099] As shown in FIG. 6, the second dielectric layer 120 has a first layer 121, a second layer 122, and a third layer 123. The first layer 121 according to the present embodiment is a single-layer film made of an SiO2 film with a thickness of about 100 nm. The second layer 122 according to the present embodiment is a single-layer film made of a Ta2O5 film with a thickness of about 50 nm. The third layer 123 according to the present embodiment has the same configuration as the third layer 23 according to Embodiment 1.

[0100] Note that the configuration of the second dielectric layer 120 is not limited to this. The first layer 121 and the third layer 123 may be dielectric films having a refractive index lower than that of the second layer 122, and may be other dielectric films such as an Al2O3 film. Further, the second layer 122 may be a dielectric film having a refractive index higher than that of the first layer 121 and the third layer 123, and may be a SiN film, a SiON film, a TiO2 film, a Nb2O5 film, a HfO2 film, an AlN film, an AlON film, or the like.

[0101] Even with the semiconductor laser element 101 having the above configuration, the same effects as those of the semiconductor laser element 1 according to the first embodiment are achieved.

[0102] Further, the end face protective film 101F according to the present embodiment includes at least two dielectric films made of at least one of a nitride film and an oxynitride film. More specifically, the first dielectric layer 110 of the end face protective film 101F includes at least two dielectric films made of at least one of a nitride film and an oxynitride film. Thereby, oxygen diffusion from the front side end face 50F direction to the semiconductor laminate 50 can be further reduced compared to the end face protective film 1F according to the first embodiment. For this reason, deterioration of the front side end face 50F of the semiconductor laminate 50 can be further suppressed. Therefore, a semiconductor laser element 101 capable of more long-term operation can be realized.

[0103] (Third Embodiment) A semiconductor laser element according to the third embodiment will be described. The semiconductor laser element according to the present embodiment is different from the semiconductor laser element 101 according to the second embodiment in that the second dielectric layer of the end face protective film includes a dielectric film made of at least one of a nitride film and an oxynitride film. Hereinafter, the semiconductor laser element according to the present embodiment will be described with reference to FIG. 7 centering on the differences from the semiconductor laser element 101 according to the second embodiment.

[0104] FIG. 7 is a schematic cross-sectional view showing the configuration of the semiconductor laser element 201 according to the present embodiment. FIG. 7 shows a cross section along the stacking direction of the semiconductor laminate 50 included in the semiconductor laser element 201 and the resonance direction of the laser light.

[0105] As shown in FIG. 7, the semiconductor laser element 201 according to the present embodiment includes a semiconductor laminate 50, end face protective films 201F and 1R, a first electrode 56, and a second electrode 57.

[0106] The end face protective film 201F according to the present embodiment has a first dielectric layer 210 and a second dielectric layer 220.

[0107] The first dielectric layer 210 according to the present embodiment includes a plurality of dielectric films. As shown in FIG. 7, the first dielectric layer 210 includes a first protective layer 211 and a second protective layer 212.

[0108] The first protective layer 211 is a dielectric film directly connected to the front end face 50F of the semiconductor laminate 50. The first protective layer 211 includes a dielectric film made of at least one of a nitride film and an oxynitride film. In the present embodiment, the first protective layer 211 includes an AlON film. More specifically, the first protective layer 211 is a single-layer film made of an AlON film having a thickness of about 20 nm. Note that the configuration of the first protective layer 211 is not limited to this. The first protective layer 211 may be, for example, another oxynitride film such as SiON, or a nitride film such as an AlN film or a SiN film.

[0109] The second protective layer 212 is a dielectric film laminated on the first protective layer 211. In the present embodiment, the second protective layer 212 is a single-layer film made of an Al2O3 film having a thickness of about 10 nm. Note that the configuration of the second protective layer 212 is not limited to this. The second protective layer 212 may be, for example, another dielectric film such as SiO2.

[0110] As shown in FIG. 7, the second dielectric layer 220 has a first layer 221, a second layer 222, and a third layer 223. The first layer 221 according to the present embodiment is a single-layer film made of an SiO2 film having a thickness of about 100 nm. The second layer 222 according to the present embodiment is a single-layer film made of an AlN film having a thickness of about 30 nm. The third layer 223 according to the present embodiment has the same configuration as the third layer 23 according to Embodiment 1.

[0111] Note that the configuration of the second dielectric layer 220 is not limited to this. The first layer 221 and the third layer 223 may be dielectric films having a refractive index lower than that of the second layer 222, and may be other dielectric films such as an Al2O3 film. Also, the second layer 222 may be a nitride film or an oxynitride film having a refractive index higher than that of the first layer 221 and the third layer 223, and may be a SiN film, a SiON film, an AlON film, or the like.

[0112] Even with the semiconductor laser element 201 having the above configuration, the same effects as those of the semiconductor laser element 1 according to the first embodiment are achieved.

[0113] Also, the end face protective film 201F according to the present embodiment includes at least two dielectric films made of at least one of a nitride film and an oxynitride film. More specifically, in the present embodiment, each of the first dielectric layer 210 and the second dielectric layer 220 includes a dielectric film made of at least one of a nitride film and an oxynitride film. Thereby, oxygen diffusion from the end face protective film 101F to the semiconductor laminate 50 can be further reduced as compared with the end face protective film 1F according to the first embodiment. For this reason, deterioration of the front end face 50F of the semiconductor laminate 50 can be further suppressed. Therefore, a semiconductor laser element 201 capable of more long-term operation can be realized.

[0114] (Modifications, etc.) As described above, the semiconductor laser element according to the present disclosure has been described based on each embodiment, but the present disclosure is not limited to the above-described embodiments.

[0115] For example, in the first embodiment above, the first dielectric layer 10 was an AlN film, but the configuration of the first dielectric layer 10 is not limited to this. The first dielectric layer 10 may include, for example, at least one of a SiN film, an AlN film, a SiON film, an AlON film, an Al2O3 film, and a SiO2 film.

[0116] Further, each of the first dielectric layer, the first layer, the second layer, and the third layer may include a plurality of layers of different materials. When the first dielectric layer is a single-layer film, a nitride film or an oxynitride film may be used as the first dielectric layer in order to protect the end face of the semiconductor laminate. Specifically, an AlN film, an AlON film, a SiN film, a SiON film, or the like may be used as the first dielectric layer.

[0117] Also, in each of the above embodiments, an example is shown in which the semiconductor laminate is formed of a gallium nitride-based material and the end face protective film has a low reflectance in the vicinity of the 400 nm wavelength band. However, the configuration of the end face protective film is not limited to this. For example, the semiconductor laminate may be formed of an AlGaInP-based material and the end face protective film may have a low reflectance in the red wavelength band (band of 600 nm or more and 700 nm or less). Further, the semiconductor laminate may be formed of a gallium arsenide-based material and the end face protective film may have a low reflectance in the infrared wavelength band (band of 750 nm or more and 1100 nm or less).

[0118] Also, each end face protective film may be formed using a sputtering apparatus, an evaporation apparatus, or the like other than a solid source ECR sputtering plasma deposition apparatus, or may be formed using an ablation deposition apparatus using PLD (Pulse Laser Deposition), ALD (Atomic Layer Deposition), or the like, an epitaxial growth apparatus using MOCVD, or the like.

[0119] Also, in the semiconductor laser device 2, although the transmissive diffraction grating 95 is used as the wavelength dispersion element, the wavelength dispersion element is not limited to this. For example, a prism, a reflective diffraction grating, or the like may be used as the wavelength dispersion element.

[0120] Also, forms obtained by applying various modifications conceivable by those skilled in the art to each of the above embodiments, and forms realized by arbitrarily combining the components and functions in each of the above embodiments without departing from the spirit of the present disclosure are also included in the present disclosure.

Industrial Applicability

[0121] The semiconductor laser device of the present disclosure can be used, for example, as a light source for industrial laser devices such as industrial lighting, facility lighting, in-vehicle headlamps, and laser processing machines that particularly require high output in the W class (watt class), and for image display devices such as laser displays and projectors.

Explanation of Signs

[0122] 1, 1a, 1b, 101, 201 Semiconductor laser device 1F, 1R, 101F, 201F End face protective film 2 Semiconductor laser device 10, 110, 210 First dielectric layer 20, 120, 220 Second dielectric layer 21, 121, 221 First layer 22, 122, 222 Second layer 23, 123, 223 Third layer 50 Semiconductor laminate 50F Front side end face 50R Rear side end face 51 Substrate 52 First semiconductor layer 53 Active layer 54 Second semiconductor layer 55 Contact layer 56 First electrode 57 Second electrode 91a, 91b Optical lens 95 Diffraction grating 97 Partial reflection mirror 111, 211 First protective layer 112, 212 Second protective layer 113 Third protective layer

Claims

1. A semiconductor laser element that emits laser light, comprising a semiconductor laminate having a front-side end face and a rear-side end face, and an end face protective film disposed on the front-side end face of the semiconductor laminate, wherein the end face protective film has a first dielectric layer disposed on the front-side end face, and a second dielectric layer laminated outside the first dielectric layer, and the second dielectric layer has a first layer laminated on the first dielectric layer, a second layer laminated on the first layer, and a third layer laminated on the second layer, wherein, with respect to the wavelength λ of the laser light, the refractive index n2 of the second layer is higher than the refractive index n1 of the first layer and the refractive index n3 of the third layer, the film thickness of the second layer is not less than λ / (8n2) and not more than 3λ / (4n2), the second layer contains at least one of an AlN film, a TiO ２ film, a Nb ２ O ５ film, a ZrO ２ film, a Ta ２ O ５ film, a HfO ２ film, a SiN film, and a SiON film, the first dielectric layer includes at least one dielectric film made of at least one of a nitride film and an oxynitride film semiconductor laser element.

2. A semiconductor laser element that emits laser light, comprising a semiconductor laminate having a front-side end face and a rear-side end face, and an end face protective film disposed on the front-side end face of the semiconductor laminate, wherein the end face protective film has a first dielectric layer disposed on the front-side end face, and a second dielectric layer laminated outside the first dielectric layer, and the second dielectric layer has a first layer laminated on the first dielectric layer, A second layer laminated on the first layer, and a third layer laminated on the second layer. For the wavelength λ of the laser light, the refractive index n2 of the second layer is higher than the refractive index n1 of the first layer and the refractive index n3 of the third layer. The film thickness of the second layer is not less than λ / (8n2) and not more than 3λ / (4n2). The second layer includes at least one of an AlN film, a TiO ２ film, a Nb ２ O ５ film, a ZrO ２ film, a Ta ２ O ５ film, a HfO ２ film, a SiN film, and a SiON film. The end face protective film includes at least two dielectric films made of at least one of a nitride film and an oxynitride film. A semiconductor laser element.

3. The reflectivity of the end face protective film is 1.0% or less in a wavelength range of 50 nm or more including the wavelength of the laser light. The semiconductor laser element according to claim 1 or 2.

4. A semiconductor laser element that emits laser light, a semiconductor laminate having a front end face and a rear end face, and an end face protective film disposed on the front end face of the semiconductor laminate. The end face protective film includes a first dielectric layer disposed on the front end face, and a second dielectric layer laminated outside the first dielectric layer. The second dielectric layer has a first layer laminated on the first dielectric layer, a second layer laminated on the first layer, and a third layer laminated on the second layer. For the wavelength λ of the laser light, the refractive index n2 of the second layer is higher than the refractive index n1 of the first layer and the refractive index n3 of the third layer. The film thickness of the second layer is not less than λ / (8n2) and not more than 3λ / (4n2), The reflectance of the end face protective film is 1.0% or less in a wavelength range of 50 nm or more including the wavelength of the laser light, The first dielectric layer includes at least one dielectric film made of at least one of a nitride film and an oxynitride film Semiconductor laser element.

5. A semiconductor laser element that emits laser light, A semiconductor laminate having a front-side end face and a rear-side end face, An end face protective film disposed on the front-side end face of the semiconductor laminate, The end face protective film includes a first dielectric layer disposed on the front-side end face, And a second dielectric layer laminated outside the first dielectric layer, The second dielectric layer, A first layer laminated on the first dielectric layer, A second layer laminated on the first layer, And a third layer laminated on the second layer, With respect to the wavelength λ of the laser light, the refractive index n2 of the second layer is higher than the refractive index n1 of the first layer and the refractive index n3 of the third layer, The film thickness of the second layer is not less than λ / (8n2) and not more than 3λ / (4n2), The reflectance of the end face protective film is 1.0% or less in a wavelength range of 50 nm or more including the wavelength of the laser light, The end face protective film includes at least two dielectric films made of at least one of a nitride film and an oxynitride film Semiconductor laser element.

6. The second layer includes at least one of an AlN film, an AlON film, a TiO ２ film, Nb ２ O ５ film, ZrO ２ film, Ta ２ O ５ film, HfO ２ film, a SiN film, and a SiON film The semiconductor laser device according to claim 4 or 5.

7. The reflectance of the end face protective film is 0.5% or less in a wavelength range of 50 nm or more including the wavelength of the laser light. The semiconductor laser device according to any one of claims 3 to 6.

8. The first dielectric layer includes at least one of a SiN film, an AlN film, a SiON film, an AlON film, an Al ２ O ３ film, and a SiO ２ film. The semiconductor laser device according to any one of claims 1 to 7.

9. Each of the first layer and the third layer includes at least one of a SiO ２ film and an Al ２ O ３ film. The semiconductor laser device according to any one of claims 1 to 8.

10. The semiconductor laminate is formed of a gallium nitride-based material. The semiconductor laser device according to any one of claims 1 to 9.

11. The semiconductor laminate is formed of a gallium arsenide-based material. The semiconductor laser device according to any one of claims 1 to 9.

12. Having a plurality of light emitting points, Each of the plurality of light emitting points emits the laser light. The semiconductor laser device according to any one of claims 1 to 11.

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