WO2019155668A1

WO2019155668A1 - Semiconductor laser device

Info

Publication number: WO2019155668A1
Application number: PCT/JP2018/032700
Authority: WO
Inventors: 藤川　周一; 智毅桂; 正人河▲崎▼; 菊池　弘
Original assignee: 三菱電機株式会社
Priority date: 2018-02-07
Filing date: 2018-09-04
Publication date: 2019-08-15
Also published as: JPWO2019155668A1

Abstract

A semiconductor laser device (10) is provided with: a semiconductor laser element (100) which outputs a laser beam; a fast-axis correction lens (2) which is disposed on the light path of the laser beam to correct the divergence angle in the fast-axis direction of the laser beam; and an output mirror (300) that reflects a portion of the laser beam from the fast-axis correction lens (2) by changing the reflectance with respect to the laser beam in a manner depending on the slow-axis direction position of the laser beam and that returns the reflected laser beam to the semiconductor laser element (100) while allowing the remainder of the laser beam to pass therethrough as an output beam.

Description

Semiconductor laser device

The present invention relates to a semiconductor laser device including a semiconductor laser element and an external resonator.

Conventional semiconductor lasers have a condensing property in the slow axis direction by installing a high reflector narrower than the width of the light emitting point in the slow axis direction directly or close to the light emitting point to suppress the generation of higher-order modes. (For example, refer to Patent Document 1). In the semiconductor laser disclosed in Patent Document 1, a high reflection region is formed by a coating technique at the center of the light emitting point in the slow axis direction in order to suppress the generation of higher order modes in the slow axis direction.

Japanese Patent Laid-Open No. 2-100391

However, the thickness of the semiconductor laser element is usually about 100 μm, and the width of the light emitting point in the slow axis direction is about several tens μm to several hundreds μm. In this way, applying a high-reflectance coating as in Patent Document 1 to a precise position in the region of the light emitting point having a small width in the slow axis direction to make the remaining region have a low reflectance is a coating. Technical difficulty is high from the viewpoint of uniformity and adhesion. Furthermore, since the number of steps related to coating increases, there is a problem that the manufacturing cost increases.

The present invention has been made in view of the above, and an object thereof is to obtain a semiconductor laser device capable of easily improving the light condensing property in the slow axis direction.

In order to solve the above-described problems and achieve the object, the present invention corrects the divergence angle of the laser beam in the first axis direction, which is disposed on the optical path of the laser beam and the semiconductor laser element that emits the laser beam. A first axis correction lens. The present invention further reflects a part of the laser beam from the first axis correction lens by changing the reflectance of the laser beam depending on the position of the laser beam in the slow axis direction, and reflects the reflected laser beam. An output coupling element that returns to the semiconductor laser element and passes the remainder as output light is provided.

According to the present invention, there is an effect that the light condensing property in the slow axis direction can be easily improved.

1 is a schematic top view showing a configuration of a semiconductor laser device according to a first embodiment of the present invention. Side surface schematic diagram which shows the structure of the semiconductor laser apparatus concerning Embodiment 1. FIG. Schematic diagram showing the configuration of the output mirror according to the first embodiment. Schematic diagram showing the configuration of the output mirror according to the second embodiment of the present invention. Schematic diagram showing the configuration of the output mirror according to the third embodiment of the present invention. Schematic top view showing the configuration of the semiconductor laser device according to the fourth embodiment of the present invention. Side surface schematic diagram which shows the structure of the semiconductor laser apparatus concerning Embodiment 4. FIG. Schematic diagram showing the configuration of the output mirror according to the fourth embodiment. Schematic top view showing the configuration of the semiconductor laser device according to the fifth embodiment of the present invention. Side surface schematic diagram showing the configuration of the semiconductor laser device according to the fifth embodiment. Schematic top view showing the configuration of the semiconductor laser device according to the sixth embodiment of the present invention. Side surface schematic diagram which shows the structure of the semiconductor laser apparatus concerning Embodiment 6. FIG. Schematic diagram showing the configuration of the output mirror according to the sixth embodiment. A perspective view showing an example of composition of a rotation optical element concerning Embodiment 6. Schematic top view showing a configuration of a semiconductor laser device according to a seventh embodiment of the present invention. The figure which shows the refractive index distribution of the slow axis direction formed in the inside of the semiconductor laser element concerning Embodiment 8 of this invention. Schematic top view showing the configuration of the semiconductor laser apparatus according to the ninth embodiment of the present invention. Side surface schematic diagram showing the configuration of the semiconductor laser device according to the ninth embodiment. Schematic top view showing the configuration of the semiconductor laser apparatus according to the tenth embodiment of the present invention. Side surface schematic diagram showing the configuration of the semiconductor laser device according to the tenth embodiment. Schematic top view showing the configuration of the semiconductor laser apparatus according to the eleventh embodiment of the present invention. Side surface schematic diagram showing the configuration of the semiconductor laser apparatus according to the eleventh embodiment. A perspective schematic view showing a configuration of an output mirror according to an eleventh embodiment. Schematic diagram showing the configuration of the output mirror according to the eleventh embodiment. Another schematic diagram showing the configuration of the output mirror according to the eleventh embodiment Schematic top view showing the configuration of the semiconductor laser apparatus according to the twelfth embodiment of the present invention.

Hereinafter, a semiconductor laser device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Moreover, in the following drawings, the same or equivalent components are denoted by the same reference numerals, and the direction of the coordinate system indicating the x direction, the y direction, and the z direction is clearly shown.

Embodiment 1 FIG.
FIG. 1 is a schematic top view showing the configuration of the semiconductor laser device 10 according to the first embodiment of the present invention. FIG. 2 is a schematic side view illustrating the configuration of the semiconductor laser device 10 according to the first embodiment. The semiconductor laser device 10 according to the first embodiment includes a semiconductor laser element 100, a first axis correction lens 2, and an output mirror 300 that is an output coupling element. The semiconductor laser element 100, the first axis correction lens 2, and the output mirror 300 constitute an external resonator for laser light, and this external resonator outputs laser light from the semiconductor laser element 100. The semiconductor laser device 10 uses an edge-emitting semiconductor laser element 100 that oscillates at a center wavelength of 975 nm.

1 is a schematic diagram viewed from the y direction, which is a direction perpendicular to the bonding surface of the active layer 103 of the semiconductor laser element 100. FIG. The schematic side view of FIG. 2 is a schematic diagram viewed from the x direction, which is a direction parallel to the bonding surface of the active layer 103 of the semiconductor laser device 100. The bonding surface of the active layer 103 is a bonding surface where the active layer 103 is bonded to another layer by a junction such as a pn junction or a hetero junction. Here, the direction perpendicular to the bonding surface of the active layer 103 of the semiconductor laser element 100 is called the first axis direction of the laser light, and corresponds to the y direction in FIGS. 1 and 2. Further, the direction parallel to the bonding surface of the active layer 103 of the semiconductor laser element 100 is perpendicular to the fast axis direction and is called the slow axis direction of the laser beam, and corresponds to the x direction in FIGS. To do. Here, the optical axis of the laser light is along the z direction, and both the fast axis direction and the slow axis direction are directions perpendicular to the optical axis of the laser light, that is, directions perpendicular to the z direction.

The semiconductor laser element 100 includes a semiconductor laser medium 104 that constitutes an active layer 103. Although not clearly shown in FIG. 1, an appropriate electrode or the like is provided on the semiconductor laser element 100 and current is injected in the y direction, which is a direction orthogonal to the bonding surface of the active layer 103, so that light near the center wavelength of 975 nm is obtained. On the other hand, the amplifying action works, and the semiconductor laser element 100 emits laser light. In the following description, the semiconductor laser medium 104 is not an area determined only by the layer structure of the semiconductor laser element 100 but an area to which a current is applied and has a laser amplification function. The width of the semiconductor laser medium 104 in the slow axis direction, that is, in the x direction is substantially equal to the emission point width on the front end face 101 from which the laser light is emitted. In the present embodiment, a semiconductor laser element 100 having a light emitting point width of 200 μm is used. Further, an antireflection coating for a wavelength of 975 nm is applied to the front end face 101 from which laser light is emitted, and a total reflection film for a wavelength of 975 nm is applied to the rear end face 102 of the semiconductor laser element 100. Here, the reflectance of the antireflection coating applied to the front end face 101 of the semiconductor laser element 100 is desirably 1% or less in order to suppress self-oscillation in the semiconductor laser element 100 alone.

In the semiconductor laser device 10, the first axis correction lens 2 is arranged so as to face the front end face 101 of the semiconductor laser element 100. That is, the first axis correction lens 2 is disposed on the optical path of the laser light between the semiconductor laser element 100 and the output mirror 300. The first axis correction lens 2 has a function of correcting the divergence angle of the laser beam in the first axis direction. Specifically, the first axis correction lens 2 reduces the divergence angle of the laser beam in the first axis direction. Here, the first axis correction lens 2 is constituted by a cylindrical convex lens. The first axis correction lens 2 is disposed so that the direction of the generatrix of the cylindrical convex lens coincides with the slow axis direction (x direction) and the focal point of the cylindrical convex lens substantially coincides with the front end face 101. Thereby, the beam divergence angle with respect to the first axis direction (y direction) of the laser light emitted from the front end face 101 can be effectively reduced.

The laser beam that has passed through the first axis correction lens 2 enters the output mirror 300. Here, the output mirror 300 is constituted by a cylindrical plano-concave mirror. The concave surface of the cylindrical plano-concave mirror is the incident surface 301 of the output mirror 300. The output mirror 300 is disposed so that the concave incident surface 301 faces the semiconductor laser element 100 and the direction of the generatrix of the cylindrical plano-concave mirror coincides with the first axis direction (y direction). . The optical distance between the principal point of the output mirror 300 and the front end face 101 of the semiconductor laser element 100 is set to approximately ½ of the radius of curvature of the concave surface of the cylindrical plano-concave mirror constituting the output mirror 300. . Therefore, the external resonator in the semiconductor laser device 10 according to the first embodiment constitutes a semi-conical resonator in the xz plane including the slow axis direction (x direction).

FIG. 3 is a schematic diagram illustrating a configuration of the output mirror 300 according to the first embodiment. The output mirror 300 is constituted by the cylindrical plano-concave mirror as described above, and has the incident surface 301 on which the laser beam from the semiconductor laser element 100 is incident and the emission surface 303 that emits the laser beam. The concave incident surface 301 is a reflection having a reflectance of 0% or almost 0% with respect to a laser beam having a wavelength of 975 nm, except for the high reflection portion 302 provided in the center in the slow axis direction (x direction) of the laser beam. A protective coating is applied. Note that the high reflection portion 302 is provided only in a region having a width w1 with respect to the x direction in the center of the incident surface 301, and the other region is a low reflection portion to which an antireflection coating is applied. Yes. That is, the high reflection portion 302 is provided in a region having a width w1 including the center line 350 extending in the fast axis direction (y direction) at the center in the slow axis direction (x direction) of the laser light. The reflectance of the laser beam 301 is changed at the boundary between the high reflection portion 302 and the low reflection portion depending on the position of the laser beam in the slow axis direction. Therefore, the reflectance of the incident surface 301 with respect to the laser light does not increase even if it decreases from the reflectance at the center line 350 as it moves away from the center line 350 that is the center in the slow axis direction along the slow axis direction. Further, an antireflection coating for laser light having a wavelength of 975 nm is also applied to the emission surface 303 formed of a flat surface over the entire surface. With the above configuration, the output mirror 300 reflects a part of the laser light from the semiconductor laser element 100 at the incident surface 301, passes the rest, and outputs it from the output surface 303. The laser light reflected by the incident surface 301 returns to the semiconductor laser element 100.

High incidence part 302 is provided in the entrance plane 301 of output mirror 300 concerning Embodiment 1 only in the field which has width w1 to the x direction which is the slow axis direction. Therefore, as shown in FIG. 1, in the slow axis direction (x direction), the main oscillation light 401 corresponding to the width w1 of the high reflection portion 302 is formed by light feedback by the high reflection portion 302. In addition, around the main oscillation light 401, peripheral amplification light 402 is generated in the semiconductor laser medium 104, which is amplified using the diffracted light of the main oscillation light 401 as a seed.

Here, when a general output mirror having a uniform reflectance is used as the output mirror 300, the incident surface 301 determined by the eigenmode passively selected according to the configuration of the external resonator. The beam diameter in the slow axis direction (x direction) above is set to w2. The eigenmode is an eigenmode of the transverse mode in the slow axis direction (x direction). The width w1 of the high reflection portion 302 provided on the incident surface 301 of the output mirror 300 according to the first embodiment is set to a smaller value than the beam diameter w2 in the slow axis direction (x direction) on the incident surface 301. Therefore, the high reflection portion 302 functions as an opening that restricts the order of the transverse mode to the low order in the slow axis direction (x direction) of the external resonator. As a result, the order of the transverse mode in the slow axis direction of the main oscillation light 401 formed corresponding to the width w1 of the high reflection portion 302 is an external resonator using a general output mirror having a uniform reflectance. As compared with the case of, the value becomes lower and the light condensing property can be improved. Further, since the peripheral amplified light 402 is amplified by the stimulated emission phenomenon using the diffracted light of the main oscillation light 401 as a seed, the coherency with the main oscillation light 401 is maintained, and the peripheral oscillation light 402 is also the main oscillation light. The light condensing property equivalent to 401 can be obtained.

In addition, with respect to the first axis direction (y direction), although the light condensing performance close to the diffraction limit can be easily obtained due to the high confinement action of the semiconductor laser device 100, the laser light emitted from the light emitting point on the front end face 101 is easily In principle, the divergence full angle is very large, about 30 ° to 60 °. In the first embodiment, as shown in FIG. 2, since the first axis correction lens 2 is disposed so as to face the front end face 101 of the semiconductor laser element 100, the laser light emitted from the front end face 101 is The divergence angle with respect to the first axis direction (y direction) can be effectively reduced. As a result, it is not necessary to dispose the output mirror 300 constituting the external resonator close to the semiconductor laser element 100, and the external resonator according to the target beam characteristics can be appropriately designed. Therefore, the output mirror 300 can be installed by being separated from the semiconductor laser element 100 by a significant distance. Here, the significant distance is, for example, a distance of 10 mm or more.

When the output mirror 300 can be installed at a significant distance from the semiconductor laser element 100, the beam diameter in the slow axis direction (x direction) on the incident surface 301 of the output mirror 300 is set to the front side of the semiconductor laser element 100. Compared to the width of the light emitting point on the end face 101, it is possible to sufficiently expand. For example, if the distance between the output mirror 300 and the front end face 101 of the semiconductor laser element 100 is 10 mm, the width of the light emitting point in the slow axis direction on the front end face 101 is 200 μm, and the beam divergence angle in the slow axis direction is 5 in all angles. In the case of °, the beam diameter in the slow axis direction on the incident surface 301 is about 1.1 mm, which allows an enlargement of about 5 times. If the distance between the output mirror 300 and the semiconductor laser element 100 is further increased, the beam diameter can be further expanded. Thereby, in the first embodiment in which the high reflection portion 302 is provided in the center portion of the incident surface 301 in the slow axis direction (x direction), there is an effect that the design and manufacture of the output mirror 300 can be facilitated. Since the reflectance of the incident surface 301 of the output mirror 300 is constant with respect to the first axis direction (y direction), the external resonator of the semiconductor laser device 10 according to the first embodiment has a normal external resonance. Functions like a vessel.

Here, the design of the high reflection portion 302 provided on the incident surface 301 of the output mirror 300 may be performed as described below. The equivalent reflectivity R _eq of the output mirror 300 in which the reflectivity in the slow axis direction shown in FIG. 3 according to the first embodiment is changed can be calculated according to the following formula (1). In Equation (1), R _h is the reflectance of the high reflection portion 302, and R _l is the reflectance of the region of the incident surface 301 excluding the high reflection portion 302. Here, R _h > R ₁ holds. It should be noted that the reflectance distribution viewed from the center line 350, which is the center in the slow axis direction, in the x direction or the -x direction is symmetric with respect to the center line 350.

When a normal output mirror having a constant reflectance along the slow axis direction of the incident surface is used, the output is the optimum value that maximizes the output of the semiconductor laser device 10 according to the gain of the semiconductor laser medium 104. There is an optimal reflectivity. In the output mirror 300 according to the first embodiment, as described above, w2 is calculated from the eigenmode in the slow axis direction (x direction) of the external resonator, and based on the target order of the transverse mode in the slow axis direction. Thus, the width w1 of the high reflection portion 302 is determined. Then, if the values of R _h and R _l are set so that the value of the equivalent reflectance R _eq calculated by Equation (1) substantially matches the optimum reflectance, the high reflection portion 302 according to the first embodiment. Even when the output mirror 300 provided with is used, the laser light can be efficiently extracted from the semiconductor laser medium 104. That is, even when the output mirror 300 according to the first embodiment in which the reflectivity in the slow axis direction is changed by providing the high reflection portion 302 in order to improve the light collecting property, the laser from the semiconductor laser medium 104 is used. Light can be output efficiently.

In the above description, the configuration in which the antireflection coating is applied to the incident surface 301 of the output mirror 300 except for the high reflection portion 302 is shown, but the configuration of the output mirror 300 is not limited to this. Even if a coating having a certain value of reflectance is applied to a region other than the high reflection portion 302, an appropriate width corresponding to the order of the transverse mode in the target slow axis direction at a position on the incident surface of the appropriate output mirror If the value of R _h and R _l is set so that the high reflection part of w1 is provided and the value of the equivalent reflectance R _eq shown in the equation (1) substantially matches the optimum reflectance, The optical property can be easily improved, and the laser beam can be efficiently extracted from the semiconductor laser medium 104.

In the above description, a configuration using a cylindrical plano-concave lens is shown for the output mirror 300 of the external resonator. However, the configuration of the output mirror 300 is not limited to this, and the external resonance depends on the target beam mode. The shape of the entrance surface and the exit surface of the output mirror 300 may be determined by designing the device appropriately.

In the above description, the high reflection portion 302 is provided in the region of the width w1 at the center of the incident surface 301 of the output mirror 300 in the slow axis direction, and the antireflection coating is provided in the region other than the high reflection portion 302 of the incident surface 301. The structure which gave is shown. However, the incident surface and the exit surface having the same radius of curvature as the entrance surface 301 and the exit surface 303 of the output mirror 300 according to the first embodiment are provided, and the reflectivity of the entrance surface is the same as the reflectivity of the high reflection portion 302 and the width. It goes without saying that the same effect can be obtained even if the mirror of w1 is used instead of the output mirror 300.

As described above, according to the semiconductor laser device 10 according to the first embodiment, the first laser beam is positioned at the position on the optical path of the laser beam between the semiconductor laser element 100 and the output mirror 300 and facing the semiconductor laser element 100. By installing the axis correction lens 2, the beam divergence angle of the laser beam in the first axis direction is reduced. As a result, the output mirror 300 constituting the external resonator can be installed without being close to the semiconductor laser element 100, the adjustment of the configuration of the external resonator is facilitated, and laser light is stably generated. Can be made. Since the output mirror 300 does not need to be installed close to the semiconductor laser element 100, the beam diameter in the slow axis direction on the output mirror 300 is larger than the width of the light emitting point in the slow axis direction of the semiconductor laser element 100. Therefore, the positional accuracy of the change in reflectance provided in the slow axis direction of the output mirror 300 can be relaxed. As a result, the manufacturing cost of the output mirror 300 can be reduced and the adjustment margin of the output mirror 300 can be increased. Since the reflectance of the output mirror 300 with respect to the laser light incident on the output mirror 300 is changed in the slow axis direction, the target transverse mode is selectively amplified in the slow axis direction, and The light collecting property can be improved efficiently and easily.

Embodiment 2. FIG.
FIG. 4 is a schematic diagram illustrating a configuration of the output mirror 310 according to the second embodiment of the present invention. The configuration of the semiconductor laser device according to the second embodiment is the same as that in which the output mirror 300 that is the output coupling element in FIGS. 1 and 2 is replaced with the output mirror 310, and external resonance with respect to the laser light in the second embodiment. The configuration of the vessel is the same as that of the first embodiment.

In the output mirror 310 of FIG. 4, a first high reflection portion 304 having a width w <b> 3 is provided at the center of the incident surface 301 in the slow axis direction (x direction). In the output mirror 310, a second high reflection portion 305 is further provided on both sides of the first high reflection portion 304 in the region of the width w4 (> w3) in the slow axis direction (x direction). The width w3 of the first high reflection portion 304 is set to a smaller value than the beam diameter w2 in the slow axis direction (x direction) on the incident surface 301.

Note that the output surface 303 of the output mirror 310 in FIG. 4 is provided with an antireflection coating for laser light having a wavelength of 975 nm, as in the first embodiment. Then, the reflectance of the first high reflecting portion 304 and _{R h1,} the reflectance of the second high reflective portion 305 and _{R h2,} except for the first high-reflective portion 304 and the second high reflecting portion 305 Assuming that the reflectance of the incident surface 301 is R _l , R _h1 , R _h2, and R _l satisfy the relationship expressed by the following formula (2).

As shown in FIG. 4, in addition to the first high reflection portion 304, the second high reflection portion 305 having different reflectivity is arranged along the slow axis direction (x direction) on the incident surface 301 of the output mirror 310. Thus, the incident surface 301 of the output mirror 310 has a higher level of reflectance in the slow axis direction than the incident surface 301 of the output mirror 300 of the first embodiment provided with only one high reflection portion 302. Can be changed. Even in the output mirror 310, the reflectance of the incident surface 301 with respect to the laser light does not increase even though it decreases as the distance from the center line 350, which is the center in the slow axis direction, increases along the slow axis direction. The reflectance distribution viewed from the center line 350, which is the center in the slow axis direction, in the x direction or the -x direction is a symmetric distribution with respect to the center line 350. Accordingly, the output mirror 310 can set the spatial distribution of the resonator loss with respect to the slow axis direction more precisely according to the target order of the transverse mode with respect to the slow axis direction. An effect is obtained that generation of laser light having the target order of the transverse mode can be realized more easily.

The equivalent reflectivity R _eq of the output mirror 310 according to the second embodiment can be calculated according to the following mathematical formula (3).

First, according to the target order of the transverse mode in the slow axis direction, the width w3 and the reflectance R _{h1 of} the first high reflection portion 304, the width w4 and the reflectance R _{h2 of} the second high reflection portion 305, Is selected. As described above, when a normal output mirror having a constant reflectance along the slow axis direction of the incident surface is used, an optimum reflectance exists for the reflectance. Therefore, if the reflectance R _l of the incident surface 301 is set so that the value of the equivalent reflectance R _eq calculated by the equation (3) substantially matches the optimum reflectance, the output mirror 310 according to the second embodiment can be obtained. Even when it is used, laser light can be efficiently extracted from the semiconductor laser medium 104. That is, when the output mirror 310 according to the second embodiment in which the first high reflection portion 304 and the second high reflection portion 305 are provided to change the reflectivity in the slow axis direction in order to improve the light collecting property is used. Even so, it is possible to efficiently generate laser light having a target order for the transverse mode in the slow axis direction.

In the output mirror 310 according to the second embodiment, the first high reflection portion 304 and the second high reflection portion 305 having different reflectivities are arranged in the slow axis direction (x direction) and provided on the incident surface 301. However, the configuration in which the high reflection portion is provided on the incident surface of the output mirror is not limited to this. For example, the third and fourth high-reflecting parts, which have different reflectivities from the first high-reflecting part 304 and the second high-reflecting part 305 and have different reflectivities, are arranged on the incident surface of the output mirror in the slow axis direction If arranged in an array, the spatial distribution of the resonator loss in the slow axis direction can be set more finely, and laser light having the target order for the transverse mode in the slow axis direction can be more easily obtained. Can be generated.

Embodiment 3 FIG.
FIG. 5 is a schematic diagram showing the configuration of the output mirror 320 according to the third embodiment of the present invention. The configuration of the semiconductor laser device according to the third embodiment is the same as that in which the output mirror 300 which is the output coupling element in FIGS. 1 and 2 is replaced by the output mirror 320, and external resonance with respect to the laser light in the third embodiment. The configuration of the vessel is the same as that of the first embodiment. The shape of the output mirror 320 is the same as that of the output mirror 300.

The incident surface 301 of the output mirror 320 according to the third embodiment has a constant reflectance along the fast axis direction (y direction), and the reflectance at the center in the slow axis direction (x direction). A coating exhibiting a Gaussian-distributed reflectivity with a maximum is applied. That is, also in the output mirror 320, the reflectance of the incident surface 301 with respect to the laser light does not increase even though it decreases as the distance from the center line 350, which is the center in the slow axis direction, increases along the slow axis direction. The reflectance distribution viewed from the center line 350, which is the center in the slow axis direction, in the x direction or the -x direction is a symmetric distribution with respect to the center line 350. At the bottom of FIG. 5, the reflectance with respect to the position along the slow axis direction (x direction) is shown in a graph. Although not shown in the figure, an antireflection coating for a wavelength of 975 nm is also applied to the output surface consisting of a plane of the output mirror 320 over the entire surface.

When the output mirror 320 having the incident surface 301 whose reflectivity continuously changes in the slow axis direction as shown in FIG. 5 is used, the output mirror 300 according to the first embodiment and the second embodiment are used. In addition to the same effects as the output mirror 310, the degree of freedom in designing the resonator loss distribution in the slow axis direction is further improved. Thereby, since it is possible to set an optimal reflectance distribution according to the target order of the transverse mode in the slow axis direction, the laser beam having the target order of the transverse mode in the slow axis direction can be efficiently used. In addition, it can be generated more easily.

In the third embodiment, the configuration using the output mirror 320 having a Gaussian distribution type reflectance distribution with respect to the slow axis direction is shown, but the shape of the reflectance distribution is not limited to this, and the slow axis is not limited to this. Needless to say, it may be designed as appropriate according to the target order of the transverse mode of direction.

In each of the first to third embodiments, the reflectance of the incident surface 301 of the output mirror changes with respect to the slow axis direction, and the output surface 303 of the output mirror has a wavelength corresponding to the wavelength of the laser beam. Although the configuration in which the antireflection coating is applied is shown, the configuration of the output mirror is not limited to these. Specifically, even if the antireflection coating for the wavelength of the laser beam is applied to the incident surface 301 and the reflectance of the emission surface 303 is changed with respect to the slow axis direction, the first embodiment can be applied. The same effect as in the third embodiment can be obtained.

Embodiment 4 FIG.
FIG. 6 is a schematic top view showing the configuration of the semiconductor laser apparatus 20 according to the fourth embodiment of the present invention. FIG. 7 is a schematic side view showing the configuration of the semiconductor laser apparatus 20 according to the fourth embodiment. FIG. 8 is a schematic diagram illustrating a configuration of the output mirror 330 according to the fourth embodiment. The configuration of the semiconductor laser element 100 according to the fourth embodiment is the same as the configuration of the semiconductor laser element 100 according to the first embodiment.

The semiconductor laser device 20 according to the fourth embodiment includes a semiconductor laser element 100, a first axis correction lens 2, a first horizontal cylindrical lens 5, a first vertical cylindrical lens 6, and a second horizontal direction. A cylindrical lens 7 and an output mirror 330 that is an output coupling element are provided. The first axis correction lens 2 is a cylindrical lens having a focal length f1 in which a bus is arranged in the slow axis direction (x direction) of the semiconductor laser element 100 which is the horizontal direction. The first horizontal cylindrical lens 5 is a cylindrical lens having a focal length f3 in which a bus is arranged in the vertical direction (y direction). The first vertical cylindrical lens 6 is a cylindrical lens having a focal length f2 in which a bus is arranged in the horizontal direction (x direction). The second horizontal cylindrical lens 7 is a cylindrical lens having a focal length f4 in which a bus is arranged in the vertical direction (y direction). The semiconductor laser element 100, the first axis correction lens 2, the first horizontal cylindrical lens 5, the first vertical cylindrical lens 6, the second horizontal cylindrical lens 7, and the output mirror 330 are external resonators for laser light. The external resonator causes the semiconductor laser element 100 to output laser light having a wavelength of 975 nm.

The output mirror 330 according to the fourth embodiment is configured by a plane mirror. On the incident surface 301 of the output mirror 330, the width w1 is narrower than the beam diameter w2 of the laser light incident on the incident surface 301 at the center in the x direction, which is the slow axis direction of the laser light incident on the incident surface 301. A highly reflective portion 302 is provided. The width w1 of the high reflection portion 302 is determined based on the target order of the transverse mode in the slow axis direction. An antireflection coating for a wavelength of 975 nm is applied to the region of the incident surface 301 excluding the high reflection portion 302. Even in the output mirror 330, the reflectance of the incident surface 301 with respect to the laser light does not increase even though it decreases as the distance from the center line 350, which is the center in the slow axis direction, increases along the slow axis direction. The reflectance distribution viewed from the center line 350, which is the center in the slow axis direction, in the x direction or the -x direction is a symmetric distribution with respect to the center line 350. Although not shown, the output surface 303 opposite to the incident surface 301 of the output mirror 330 is provided with an antireflection coating for the wavelength of 975 nm over the entire surface.

In the semiconductor laser device 20 according to the fourth embodiment, the first axis correction lens 2 having a focal length f1 with a bus line arranged in the slow axis direction (x direction) is positioned at a distance f1 from the front end face 101 of the semiconductor laser element 100. And a first vertical cylindrical lens 6 with a focal length f2 having a bus line arranged in the slow axis direction (x direction) is arranged at a distance f1 + f2 from the first axis correction lens 2, and an output mirror 330 is disposed at a distance f2 from the first vertical cylindrical lens 6. Here, it is assumed that the distances indicated by f1 and f2 are optical distances between principal points of the respective optical elements. Thus, an afocal imaging optical system with respect to the first axis direction (y direction) is configured between the front end face 101 of the semiconductor laser element 100 and the incident surface 301 of the output mirror 330. Therefore, the front end surface 101 of the semiconductor laser element 100 and the incident surface 301 of the output mirror 330 are optically conjugate with respect to the fast axis direction (y direction).

Further, in the semiconductor laser device 20 according to the fourth embodiment, the first horizontal cylindrical lens 5 having the focal length f3 in which the bus is arranged in the vertical direction (y direction) is arranged from the front end face 101 of the semiconductor laser element 100. The second horizontal cylindrical lens 7 having a focal length f4, which is disposed at the position of the distance f3 and has a bus line arranged in the vertical direction (y direction), is positioned at a distance f3 + f4 from the first horizontal cylindrical lens 5. The output mirror 330 is disposed at a distance f4 from the second horizontal cylindrical lens 7. Here, it is assumed that the distances indicated by f3 and f4 are optical distances between principal points of the optical elements. Accordingly, an afocal imaging optical system is configured between the front end face 101 of the semiconductor laser element 100 and the incident surface 301 of the output mirror 330 in the slow axis direction (x direction). Therefore, also in the slow axis direction (x direction), the front end face 101 of the semiconductor laser element 100 and the incident face 301 of the output mirror 330 are optically conjugate.

As described above, in the semiconductor laser device 20 according to the fourth embodiment, the front end face 101 of the semiconductor laser element 100 is imaged on the output mirror 330. When the transfer magnification is M, the beam width w2 in the slow axis direction on the output mirror 330 is equal to a value obtained by multiplying the light emitting point width of the semiconductor laser element 100 in the slow axis direction by M.

According to the semiconductor laser device 20 according to the fourth embodiment, the front end face 101 of the semiconductor laser element 100 and the incident surface 301 of the output mirror 330 are optically conjugate with respect to at least the slow axis direction (x direction). Therefore, a configuration in which a high reflection portion is provided in a region having a width of w1 / w2 as compared with the width of the light emitting point in the slow axis direction (x direction) at the center of the light emitting point on the front end face 101 of the semiconductor laser element 100. Is optically equivalent. That is, the semiconductor laser device 20 according to the fourth embodiment has a configuration that is optically equivalent to a general Fabry-Perot type optical resonator in which a partial reflection coating is provided on the front end face 101 of the semiconductor laser element 100. Thereby, the selectivity of the order of the transverse mode with respect to the slow axis direction (x direction) is remarkably improved as compared with the semiconductor laser device 10 according to the first to third embodiments. It is possible to more efficiently generate laser light having the following order.

As described above, the semiconductor laser device 20 according to the fourth embodiment is optically equivalent to a configuration in which a high reflection portion is provided in a limited region of the light emitting point of the semiconductor laser element 100 in the slow axis direction. However, it is difficult to accurately form a high reflection portion in a minute region on the front end face 101 of the semiconductor laser element 100 because the technical difficulty is high and the coating process is complicated. There was a problem that the cost also increased. On the other hand, in the semiconductor laser device 20 according to the fourth embodiment, an external resonator is formed in which the front end face 101 of the semiconductor laser element 100 is imaged on the output mirror 330 at least in the slow axis direction. Therefore, the light emission point of the semiconductor laser element 100 can be enlarged and imaged on the output mirror 330. Thereby, in the semiconductor laser device 20, the high reflection portion formed on the incident surface 301 of the output mirror 330 is larger than the width of the high reflection portion when the high reflection portion is directly formed on the front end face 101 of the semiconductor laser element 100. The width w1 of 302 can be increased. As a result, the output mirror 330 can be manufactured easily technically and at a low cost.

Although the semiconductor laser device 20 according to the fourth embodiment has been described as configuring an external resonator using the output mirror 330 having the single high reflection portion 302 on the incident surface 301 shown in FIG. The configuration of the output mirror is not limited to this. As in the output mirror 310 according to the second embodiment, an output mirror in which a plurality of high reflection portions having different reflectivities are arranged in the slow axis direction may be used, or the output mirror according to the third embodiment. An output mirror in which the reflectance of the incident surface is continuously changed along the slow axis direction as in 320 may be used. By adopting the output mirror having these configurations, the transverse mode in the slow axis direction can be used. The order selectivity may be further improved.

Embodiment 5. FIG.
FIG. 9 is a schematic top view showing the configuration of the semiconductor laser device 30 according to the fifth embodiment of the present invention. FIG. 10 is a schematic side view illustrating the configuration of the semiconductor laser device 30 according to the fifth embodiment. The semiconductor laser device 30 according to the fifth embodiment uses the output mirror 330 shown in FIG. Further, the external resonator of the semiconductor laser device 30 according to the fifth embodiment includes the diffraction grating 8 as shown in FIG. 9, and the optical axis of the external resonator is bent by the diffraction effect. However, since the diffraction grating 8 does not exhibit a lens action, in the schematic side view shown in FIG. 10, in order to clarify the technical characteristics of the semiconductor laser device 30, an external part extending from the semiconductor laser element 110 to the output mirror 330 is used. The configuration of the resonator is schematically shown so that the optical axis is a straight line. Further, in order to clarify the direction after the optical axis is bent by the diffraction grating 8, FIG. 9 clearly shows the orientation of the coordinate system indicating the x ′ direction, the y ′ direction, and the z ′ direction.

The semiconductor laser device 30 according to the fifth embodiment includes a semiconductor laser element 110, a first axis correction lens 2, a first horizontal cylindrical lens 5, a first vertical cylindrical lens 6, a diffraction grating 8, A second horizontal cylindrical lens 7 and an output mirror 330 are provided.

The single semiconductor laser element 110 included in the semiconductor laser device 30 is configured by a semiconductor laser array including a plurality of semiconductor laser media. The semiconductor laser element 110 is a semiconductor laser array composed of three semiconductor laser media: a first semiconductor laser medium 1041, a second semiconductor laser medium 1042, and a third semiconductor laser medium 1043. Further, the front end face 101 of the semiconductor laser device 110 according to the fifth embodiment is provided with an antireflection coating for a broadband laser beam centered on a wavelength of 975 nm, and the rear end face 102 is centered on a wavelength of 975 nm. A total reflection coating for broadband laser light is applied. In FIG. 9, the semiconductor laser device 30 according to the fifth embodiment is illustrated as having a configuration using a semiconductor laser element 110 including a semiconductor laser array including three semiconductor laser media. The configuration of is not limited to this. That is, the number of semiconductor laser media may be a plurality of numbers other than three.

The first axis correction lens 2 is a cylindrical lens in which a bus is arranged in the slow axis direction (x direction) of the semiconductor laser element 110 which is the horizontal direction. The first horizontal cylindrical lens 5 is a cylindrical lens in which a bus is arranged in the vertical direction (y direction) that is the first axis direction. The first vertical cylindrical lens 6 is a cylindrical lens in which a bus is arranged in the horizontal direction (x direction). In the diffraction grating 8, grooves along the vertical direction (y direction) are formed in parallel. The second horizontal cylindrical lens 7 is a cylindrical lens in which a bus is arranged in the vertical direction (y ′ direction).

In FIG. 9, the y ′ direction is the same as the first axis direction (y direction). Further, the direction perpendicular to the plane of the plane mirror constituting the output mirror 330 is the z ′ direction, and the direction perpendicular to the y ′ direction and the z ′ direction is the x ′ direction. Therefore, the slow axis direction of the laser light diffracted by the diffraction grating 8 is the x ′ direction, and the first axis direction is the y ′ direction.

The semiconductor laser element 110, the first axis correction lens 2, the first horizontal cylindrical lens 5, the first vertical cylindrical lens 6, the diffraction grating 8, the second horizontal cylindrical lens 7 and the output mirror 330 are laser beams. And an external resonator for outputting the laser beam to the semiconductor laser device 110.

In the semiconductor laser device 30 according to the fifth embodiment, the first horizontal cylindrical lens 5 in which the bus is arranged in the vertical direction (y direction) is the focal length of the first horizontal cylindrical lens 5 from the semiconductor laser element 110. Are disposed at approximately the same distance. The diffraction grating 8 is also disposed at a distance substantially equal to the focal length of the first horizontal cylindrical lens 5 from the first horizontal cylindrical lens 5. Accordingly, the laser light emitted from each of the first to third

semiconductor laser media

1041, 1042, and 1043 has a divergence angle in the slow axis direction (x direction) made parallel by the first horizontal cylindrical lens 5, At the focal position of the first horizontal cylindrical lens 5 on the diffraction grating 8, the principal ray is condensed so as to substantially overlap one point. The output mirror 330 constituting the external resonator is common to the first to third

semiconductor laser media

1041, 1042, and 1043, and in the z ′ direction with respect to the output mirror 330 formed of a plane mirror. The cavity loss of vertically incident laser light is minimized. Accordingly, the laser oscillation wavelengths of the first to third

semiconductor laser media

1041, 1042, and 1043 are set so that the diffraction angle by the diffraction grating 8 coincides with the angle at which the diffracted laser light is perpendicularly incident on the output mirror 330. Passively selected. As a result, the plurality of laser beams emitted from the first to third

semiconductor laser media

1041, 1042, and 1043 are superimposed on the same axis in the optical path between the diffraction grating 8 and the output mirror 330. Therefore, by selecting the oscillation wavelength, the diffraction grating 8 is consequently arranged at a position where the optical axes of the plurality of laser beams are superimposed, and wavelength coupling of the plurality of laser beams into one beam. Then, the light is emitted toward the output mirror 330.

In the semiconductor laser device 30 according to the fifth embodiment, as in the semiconductor laser device 20 according to the fourth embodiment, the horizontal direction of the slow axis (x direction, x ′ direction) is the first. By placing the horizontal cylindrical lens 5, the second horizontal cylindrical lens 7 and the output mirror 330 apart from each other by an appropriate distance, the front end surface 101 of the semiconductor laser element 110 is connected to the incident surface 301 of the output mirror 330. An optical system for imaging is configured. For the fast axis direction (y direction, y ′ direction) that is the vertical direction, the fast axis correction lens 2, the first vertical cylindrical lens 6, and the output mirror 330 are installed at an appropriate distance, An optical system that forms an image of the front end surface 101 of the semiconductor laser element 110 on the incident surface 301 of the output mirror 330 is configured. Accordingly, the front end face 101 of the semiconductor laser element 110 and the incident face 301 of the output mirror 330 are optically conjugate in both directions.

In the semiconductor laser device 30 according to the fifth embodiment, a semiconductor laser element 110 that is a semiconductor laser array including a plurality of semiconductor laser media such as first to third

semiconductor laser media

1041, 1042, and 1043 is used. External resonators corresponding to the first to third

semiconductor laser media

1041, 1042, and 1043 share a single output mirror 330, respectively. Furthermore, in the semiconductor laser device 30, a plurality of laser beams emitted from a plurality of semiconductor laser media including the first to third

semiconductor laser media

1041, 1042, and 1043 are obtained by wavelength coupling using the wavelength dispersion effect of the diffraction grating 8. Laser light is superimposed coaxially. As a result, the semiconductor laser device 30 according to the fifth embodiment increases the output without reducing the light condensing performance as compared with the case where the semiconductor laser device 100 including the single semiconductor laser medium 104 is used. Is easily possible.

Further, the incident surface 301 of the output mirror 330 according to the fifth embodiment is provided with the high reflection portion 302 only in the range set corresponding to the target order of the transverse mode in the slow axis direction. Even when the semiconductor laser element 110 including a plurality of semiconductor laser media is used, it is possible to simultaneously improve the light condensing properties in the slow axis direction corresponding to each of the plurality of semiconductor laser media. Also in the semiconductor laser device 30 according to the fifth embodiment, since the front end face 101 of the semiconductor laser element 110 and the incident surface 301 of the output mirror 330 are optically conjugate, the semiconductor laser device according to the fourth embodiment. As in the case of 20, the selectivity of the order of the transverse mode with respect to the slow axis direction (x direction) can be significantly improved as compared with the semiconductor laser device 10 according to the first to third embodiments.

Embodiment 6 FIG.
FIG. 11 is a schematic top view showing the configuration of the semiconductor laser apparatus 40 according to the sixth embodiment of the present invention. FIG. 12 is a schematic side view illustrating the configuration of the semiconductor laser device 40 according to the sixth embodiment. FIG. 13 is a schematic diagram illustrating a configuration of an output mirror 340 according to the sixth embodiment. The configuration of the semiconductor laser device 110 according to the sixth embodiment is the same as the configuration of the semiconductor laser device 110 according to the fifth embodiment, but is not limited to this configuration as in the fifth embodiment. Further, in the external resonator of the semiconductor laser device 40 according to the sixth embodiment, the optical axis is bent by the diffraction grating 8 as in the semiconductor laser device 30 according to the fifth embodiment. In FIG. 2, in order to clarify the technical characteristics of the semiconductor laser device 40, the optical axis is schematically shown as being linear. Further, in order to clarify the direction after the optical axis is bent by the diffraction grating 8, FIG. 11 clearly shows the direction of the coordinate system indicating the x ′ direction, the y ′ direction, and the z ′ direction. In the semiconductor laser device 40 according to the sixth embodiment, in addition to the configuration of the semiconductor laser device 30, the rotating optical element 11 is installed between the first axis correction lens 2 and the first vertical cylindrical lens 6. A second vertical cylindrical lens 9 is installed between the diffraction grating 8 and the second horizontal cylindrical lens 7. In the semiconductor laser device 40, the semiconductor laser element 110, the first axis correction lens 2, the rotating optical element 11, the first vertical cylindrical lens 6, the first horizontal cylindrical lens 5, the diffraction grating 8, the second The vertical cylindrical lens 9, the second horizontal cylindrical lens 7 and the output mirror 340 as an output coupling element constitute an external resonator for the laser light, and this external resonator causes the semiconductor laser element 110 to output the laser light. In the sixth embodiment, a plurality of laser beams having different optical axes are emitted from one semiconductor laser element 110, and the diffraction grating 8 emits the plurality of laser beams by wavelength coupling to one beam. .

FIG. 14 is a perspective view showing an example of the configuration of the rotating optical element 11 according to the sixth embodiment. The rotating optical element 11 is a 90 ° image rotating optical system array, and a pair of opposed cylindrical convex lenses are inclined by 45 ° with respect to the y direction that is the direction of the reference axis, and a plurality of light emitting points of the semiconductor laser element 110 are arranged. They are arranged at the same pitch as the interval. In the rotating optical element 11, if the focal length of the cylindrical convex lens is f, the interval L between the opposing cylindrical convex lenses is set to 2f. When the major axis or minor axis of the flat light is incident on the rotating optical element 11 at an angle parallel to the y direction which is the direction of the reference axis, the major axis and the minor axis are switched in the emitted light. That is, the rotating optical element 11 emits light obtained by rotating each incident laser beam by 90 ° with each optical axis as a rotation axis. Accordingly, the image of the light emitted from the rotating optical element 11 is obtained by rotating the image of the incident light on the rotating optical element 11 by 90 °. The rotating optical element 11 has been commercialized by, for example, LIMO Lissotschenko Mikropik GmbH of Germany, and can be easily obtained under the product name Beam Transformation System.

In the semiconductor laser device 40 according to the sixth embodiment, the laser beams emitted from the first to third

semiconductor laser media

1041, 1042, and 1043 of the semiconductor laser element 110 are transmitted in the first axis direction ( The divergence angle in the y direction is made substantially parallel. Next, each laser beam is rotated by 90 ° around the optical axis by passing through the rotating optical element 11. Therefore, the component in the slow axis direction (x direction) of each laser beam when emitted from the semiconductor laser element 110 is converted into the component in the vertical direction (y direction), and each component when emitted from the semiconductor laser element 110 is converted. The components in the first axis direction (y direction) of the laser light are converted into components in the horizontal direction (x direction), respectively. The laser light that has passed through the rotating optical element 11 has a divergence angle in the slow axis direction (y direction) substantially parallelized by the first vertical cylindrical lens 6 having a bus line arranged in the horizontal direction (x direction), and is vertical. The light enters the first horizontal cylindrical lens 5 in which the bus is arranged in the direction (y direction). The first horizontal cylindrical lens 5 condenses each laser beam on the diffraction grating 8 with respect to the fast axis direction (x direction) so that the chief ray overlaps almost one point. In the diffraction grating 8, grooves along the vertical direction (y direction) are formed in parallel.

As described above, since the first axis direction and the slow axis direction of each laser beam are interchanged by passing through the rotating optical element 11, in FIG. 11, the slow axis direction of the laser beam after diffraction by the diffraction grating 8 is y. In the 'direction, the fast axis direction is the x' direction. The y ′ direction is the same direction as the y direction, and the x ′ direction and the z ′ direction perpendicular to the y ′ direction are perpendicular to the plane of the plane mirror constituting the output mirror 340.

Also in the semiconductor laser device 40 according to the sixth embodiment, the first to third

semiconductor laser media

1041, 1042, and 1043 share a single output mirror 340, similarly to the semiconductor laser device 30 according to the fifth embodiment. Each of the first to third

semiconductor laser media

1041, 1042, and 1043 is oscillated so that the diffraction angle by the diffraction grating 8 coincides with the angle at which the diffracted laser light is perpendicularly incident on the output mirror 340. The wavelength is selected passively. As a result, as in the fifth embodiment, the laser beams emitted from the first to third

semiconductor laser media

1041, 1042, and 1043 are coaxial in the optical path between the diffraction grating 8 and the output mirror 340. Is superimposed on.

The laser beam superimposed coaxially by the diffraction grating 8 is condensed with respect to the slow axis direction (y ′ direction) by the second vertical cylindrical lens 9 having a bus line arranged in the horizontal direction (x ′ direction). Then, the light enters the second horizontal cylindrical lens 7 in which the bus is arranged in the vertical direction (y ′ direction). The laser light incident on the second horizontal cylindrical lens 7 is incident on the output mirror 340 with the divergence angle in the fast axis direction (x ′ direction) being substantially parallelized.

Also in the semiconductor laser device 40 according to the sixth embodiment, the first horizontal cylindrical lens 5, the second horizontal cylindrical lens 7 and the output mirror 340 are arranged in the horizontal direction (x direction, x ′ direction). An optical system that forms an image of the front end surface 101 of the semiconductor laser element 110 on the incident surface 301 of the output mirror 340 is configured by being separated by an appropriate distance. Further, in the vertical direction (y direction, y ′ direction), the first axis correction lens 2, the first vertical cylindrical lens 6, the second vertical cylindrical lens 9, and the output mirror 340 are separated by an appropriate distance. By doing so, an optical system is formed which images the front end face 101 of the semiconductor laser element 110 onto the incident surface 301 of the output mirror 340. Accordingly, the front end face 101 of the semiconductor laser element 110 and the incident face 301 of the output mirror 340 are optically conjugate in both directions.

Also in the semiconductor laser device 40 according to the sixth embodiment, the semiconductor laser element 110 which is a semiconductor laser array including a plurality of semiconductor laser media is used, and the first to third

semiconductor laser media

1041, 1042, and 1043 are used. Each corresponding external resonator shares a single output mirror 340. Further, in the semiconductor laser device 40, laser light emitted from a plurality of semiconductor laser media including the first to third

semiconductor laser media

1041, 1042, and 1043 is obtained by wavelength coupling using the wavelength dispersion effect of the diffraction grating 8. Coaxially superimposed. Therefore, as in the fifth embodiment, the semiconductor laser device 40 according to the sixth embodiment reduces the light condensing performance as compared with the case where the semiconductor laser element 100 including the single semiconductor laser medium 104 is used. Therefore, it is possible to easily increase the output.

In the semiconductor laser element 110 having a plurality of semiconductor laser media, a deformation called “smile” due to the manufacturing process occurs, and the installation heights in the y direction of the first to third

semiconductor laser media

1041, 1042, and 1043 respectively. There may be differences. On the other hand, the semiconductor laser device 40 according to the sixth embodiment further uses the rotating optical element 11 so that the laser light emitted from each of the first to third

semiconductor laser media

1041, 1042, and 1043. Is rotated 90 ° around the optical axis. As a result, the direction of optical axis deviation that occurs during beam superimposition due to the difference in installation height can be converted from the y direction to the x direction. In other words, the direction of the optical axis deviation that occurs when the beam is superimposed is relatively low in the light condensing property compared to the first axis direction, and the rate of decrease in the light condensing property with respect to the amount of optical axis deviation is set to the slow axis direction. Therefore, it is possible to obtain an effect that the output can be stably increased while suppressing the reduction ratio of the light condensing property as compared with the semiconductor laser device 30 according to the fifth embodiment.

Further, as shown in FIG. 13, the incident surface 301 of the output mirror 340 according to the sixth embodiment has an area of the width w1 in the y ′ direction determined based on the target order of the transverse mode in the slow axis direction. Only the high reflection portion 302 is provided. Also in the output mirror 340, the reflectance of the incident surface 301 with respect to the laser light decreases as the distance from the center line 350, which is the center of the diffracted laser light in the slow axis direction (y ′ direction), increases along the slow axis direction. Will not increase. The reflectance distribution viewed from the center line 350, which is the center in the slow axis direction, in the y ′ direction or the −y ′ direction is symmetric with respect to the center line 350. Therefore, even when the semiconductor laser device 110 including the first to third

semiconductor laser media

1041, 1042, and 1043 is used by using the output mirror 340, the semiconductor laser device 30 according to the fifth embodiment and Similarly, it is possible to simultaneously improve the light condensing property in the slow axis direction corresponding to each of the plurality of semiconductor laser media. Further, also in the semiconductor laser device 40 according to the sixth embodiment, the front end face 101 of the semiconductor laser element 110 and the incident surface 301 of the output mirror 340 are optically conjugate, and therefore the semiconductor laser device according to the fourth embodiment. 20 and the semiconductor laser device 30 according to the fifth embodiment, the selectivity of the order of the transverse mode with respect to the slow axis direction (x direction) is markedly higher than that of the semiconductor laser device 10 according to the first to third embodiments. Can be improved.

Embodiment 7 FIG.
FIG. 15 is a schematic top view showing the configuration of the semiconductor laser apparatus 50 according to the seventh embodiment of the present invention. In the semiconductor laser device 50, the first semiconductor laser element 121 and the second semiconductor laser element 122, which are two semiconductor laser elements, are used, and the laser is generated using the diffraction grating 8 under the common output mirror 340. By superimposing the light, the output is increased while maintaining the light condensing property. Each of the first semiconductor laser element 121 and the second semiconductor laser element 122 has the same configuration as the semiconductor laser element 110 according to the fifth and sixth embodiments, and each includes a plurality of semiconductor laser media. That is, the first semiconductor laser element 121 includes first to third

semiconductor laser media

1051, 1052, and 1053, and the second semiconductor laser element 122 includes first to third

semiconductor laser media

1061, 1062, and so on. 1063. The configuration of the output mirror 340 according to the seventh embodiment is the same as that of the output mirror 340 according to the sixth embodiment. Therefore, the configuration of the external resonator for each of the first semiconductor laser element 121 and the second semiconductor laser element 122 is the same as that of the sixth embodiment.

As shown in the semiconductor laser device 50 of FIG. 15, a plurality of semiconductor laser elements, ie, a first semiconductor laser element 121 and a second semiconductor laser element 122 are used, and laser light is superimposed by a diffraction grating 8 and is shared. If the external resonator is configured using the output mirror 340, the same effect as the semiconductor laser device 40 according to the sixth embodiment can be obtained, and the output can be easily increased while maintaining the light condensing property. Is even more possible.

In the semiconductor laser device 50 according to the seventh embodiment shown in FIG. 15, the configuration in which wavelength coupling is performed using the diffraction grating 8 using two semiconductor laser elements is shown. The number of is not limited to this as long as it is plural. In addition, the plurality of semiconductor laser elements may not be formed of a semiconductor laser array that includes a plurality of semiconductor laser media. That is, a part of the plurality of semiconductor laser elements may be a semiconductor laser element having only a single semiconductor laser medium, such as the semiconductor laser element 100.

In the fifth to seventh embodiments, the laser light emitted from a plurality of semiconductor laser media is coaxially formed in the external resonator of the semiconductor laser element by using the wavelength dispersion effect of the diffraction grating 8. Although the superimposing structure is shown, the means for superimposing the laser beam is not limited to this. For example, using a plurality of semiconductor laser media having gains in different oscillation wavelength bands, utilizing the wavelength dependence of the coating reflectivity in a dichroic mirror or the like in an external resonator sharing a single output mirror, Even when laser beams emitted from a plurality of semiconductor laser media are coaxially superimposed, the same effects as those of the fifth to seventh embodiments can be obtained.

Further, in the fifth to seventh embodiments, it has been described that the external resonator is configured using the output mirrors 330 and 340 provided with the single high reflection portion 302 on the incident surface 301. The configuration is not limited to this. As in the output mirror 310 according to the second embodiment, an output mirror in which a plurality of high reflection portions having different reflectivities are arranged in the slow axis direction may be used, or the output mirror according to the third embodiment. An output mirror in which the reflectance of the incident surface is continuously changed along the slow axis direction as in 320 may be used. By adopting the output mirror having these configurations, the transverse mode in the slow axis direction can be used. The order selectivity may be further improved.

In the fifth to seventh embodiments, the external resonator that images the front end surface 101 of the semiconductor laser element onto the incident surface 301 of the output mirrors 330 and 340 is shown. However, the configuration of the external resonator is as follows. However, the present invention is not limited to this, and it may be appropriately designed according to the target beam characteristics.

Embodiment 8 FIG.
The light confinement in the slow axis direction of the edge-emitting semiconductor laser element in the semiconductor laser device according to the first to seventh embodiments is not limited to the gain guide function in which light is concentrated in a region having an optical amplification function, It is thought that the lens action by the refractive index distribution based on the distribution and the carrier concentration distribution works. These light confinement effects become stronger when the laser output is high. As a result, even if the external resonator is configured to improve the beam condensing property in the slow axis direction as in the first to seventh embodiments, the condensing property may not be improved in a region where the laser output is high. is there.

In the eighth embodiment of the present invention, the light emitting points of the

semiconductor laser elements

100, 110, 121, and 122 and the vicinity of the light emitting points, that is, each semiconductor laser medium, included in the semiconductor laser device according to the first to seventh embodiments. In addition, a refractive index distribution is formed to reduce the light confinement effect in the slow axis direction. That is, since the refractive index distribution in the slow axis direction of the semiconductor laser medium of the

semiconductor laser elements

100, 110, 121, and 122 is a distribution that suppresses the confinement effect of the laser light in the slow axis direction, The effect of light confinement in the direction can be suppressed. This makes it possible to obtain a high light collecting property even in a high output region.

FIG. 16 is a diagram showing a refractive index distribution in the slow axis direction formed inside the semiconductor laser device according to the eighth embodiment of the present invention. FIG. 16 is an example of a refractive index distribution in the slow axis direction of the semiconductor laser medium that suppresses the confinement effect of the laser light in the slow axis direction. As shown in FIG. 16, in the distribution in the slow axis direction of the refractive index with respect to the laser light of the semiconductor laser element in the non-energized state, the refractive index of the semiconductor laser medium that is the light emitting region is the refraction of the non-light emitting region around the light emitting region. It is lower than the rate. By forming such a refractive index distribution, the confinement effect of the laser light is lowered. If the semiconductor laser device according to the eighth embodiment is used, the action of suppressing higher-order mode confinement works both in the semiconductor laser device and in the external resonator. Can be further improved.

Embodiment 9 FIG.
FIG. 17 is a schematic top view showing the configuration of the semiconductor laser apparatus 60 according to the ninth embodiment of the present invention. FIG. 18 is a schematic side view illustrating the configuration of the semiconductor laser device 60 according to the ninth embodiment. The distribution along the slow axis direction of the ratio of the reflection of the laser beam by the output mirror 352 to the light emitting point of the semiconductor laser element 100 in the ninth embodiment is different from that in the first to eighth embodiments.

In the output coupling elements of the first to eighth embodiments, the laser beam in the central area in the slow axis direction is reflected more toward the light emitting point of the semiconductor laser element than in the peripheral area. The output mirror 352 that is the output coupling element of the ninth embodiment actively reflects the laser beam in the peripheral region as compared with the laser beam in the central region in the slow axis direction.

In FIG. 17, the output mirror 352 according to the ninth embodiment includes one of the peripheral amplified light 402 that is laser light that passes through the peripheral region in the slow axis direction (x direction) of the main oscillation light 401 and the peripheral amplified light 402. It is inserted so that only a part is reflected. The incident surface 351 of the output mirror 352 is coated with a high reflectance with respect to the laser light. The output surface 353 of the output mirror 352 may be coated with AR (Anti Reflection), which is a coating with low reflectance, or may be roughened such as a sanded surface without being coated. Good. By processing the emission surface 353 in this way, unnecessary oscillation due to the residual reflectance at the emission surface 353 can be suppressed, and the operation of the semiconductor laser device 60 can be effectively stabilized.

In the semiconductor laser device 60 according to the ninth embodiment, since the output mirror 352 reflects the peripheral amplified light 402, the rear end face 102 of the semiconductor laser element 100 and the output mirror 352 constitute a semiconductor laser resonator, All the main oscillation light 401 is output. This makes it possible to increase the ratio of the laser light output from the semiconductor laser device 60 to the main condensing light 401 having high condensing property as compared with the case where the output mirror 352 is not provided. That is, it is possible to improve the light condensing property of the laser beam output from the semiconductor laser device 60 in the slow axis direction.

Here, the region in the laser beam into which the output mirror 352 is inserted is a region on one side where the energy of the laser beam is included in the profile that is the spatial distribution of the energy of the laser beam along the slow axis. To do. The profile of the laser beam in the slow axis direction is substantially symmetric with respect to the laser beam axis. In the ninth embodiment, the output mirror 352 is inserted only on one side of the symmetrical beam profile. By arranging the output mirror on one side of one of the symmetrical beam profiles, the reflectivity of the central part in the slow axis direction is at least one of the reflectivities of the peripheral parts existing on both sides in the slow axis direction of the central part. It becomes a value lower than either. Then, by adjusting the position of the output mirror 352 in the slow axis direction, the ratio of the reflection of the laser light by the output mirror 352 can be adjusted. By moving the output mirror 352 toward the center of the laser optical axis, more laser light energy can be reflected. Increasing the energy of the laser light reflected by the output mirror 352 can improve the light condensing performance, but the power of the laser light output from the semiconductor laser device 60 is reduced. According to the experiment by the inventors of the present invention, when the ratio of the energy of the laser beam reflected by the output mirror 352 is 5% to 10% of the whole, the power reduction is suppressed and the light condensing property in the slow axis direction is improved. I was able to.

Embodiment 10 FIG.
FIG. 19 is a schematic top view showing the configuration of the semiconductor laser apparatus 70 according to the tenth embodiment of the present invention. FIG. 20 is a schematic side view illustrating the configuration of the semiconductor laser device 70 according to the tenth embodiment. In the tenth embodiment, the output mirrors inserted in one side of the profile along the slow axis of the laser beam in the ninth embodiment are inserted in both sides.

As shown in FIG. 19, the output mirror 360 and the output mirror 370 constituting the output coupling element of the tenth embodiment are arranged symmetrically with respect to the laser optical axis in the slow axis direction (x direction). Thereby, the reflectance of the central part in the slow axis direction becomes a value lower than the reflectance of the peripheral part existing on both sides of the central part in the slow axis direction. Further, the reflectance has a symmetrical distribution with respect to the center in the slow axis direction. Since the reflectance distribution is symmetric, the spatial symmetry of the beam output from the semiconductor laser device 70 can be improved, and the anisotropy of laser processing can be suppressed.

The incident surface 361 of the output mirror 360 and the incident surface 371 of the output mirror 370 are coated with a high reflectivity with respect to the laser beam, similarly to the incident surface 351 of the output mirror 352 of the ninth embodiment. The output surface 363 of the output mirror 360 and the output surface 373 of the output mirror 370 have the same configuration as the output surface 353 of the output mirror 352 of the ninth embodiment.

According to the semiconductor laser device 70 according to the tenth embodiment, the output mirror 360 and the output mirror 370 are inserted in symmetrical positions with the laser optical axis as the central axis along the slow axis direction. It is possible to make the beam profile along the slow axis direction of the output laser light symmetrical with the laser optical axis as the center.

Also in the tenth embodiment, as in the ninth embodiment, the output mirror 360 and the output mirror 370 to the semiconductor laser element 100 are adjusted by adjusting the positions of the output mirror 360 and the output mirror 370 in the slow axis direction of the laser light. It is possible to adjust the ratio of the reflection of the laser beam by.

In the tenth embodiment, the total ratio of reflection by the output mirror 360 and the output mirror 370 is 2% to 40% of the energy of the laser beam. Also in the tenth embodiment, when the energy of the laser light reflected by the output mirror 360 and the output mirror 370 is increased, the light condensing performance can be improved, but the power of the laser light output from the semiconductor laser device 70 is reduced. To do. According to the experiment by the inventors of the present invention, when the sum of the ratios of the energy of the laser beams reflected by the output mirror 360 and the output mirror 370 is 5% to 10% of the whole, the power reduction is suppressed, Condensation was improved.

The laser light output from the semiconductor laser device 70 according to the tenth embodiment may be used after being guided to an optical fiber, or may be directly condensed and used for laser processing. Due to the high symmetry of the profile of the laser beam from the semiconductor laser device 70, the former has the effect of improving the light guiding efficiency to the optical fiber, and the latter has the effect of suppressing the anisotropy of laser processing. It is done.

The beam profile in the slow axis direction of the laser beam output from the semiconductor laser element 100 has a substantially symmetric shape with respect to the laser beam axis. However, the laser beam profile is not perfectly symmetric, and is a distorted laser beam profile due to a minute assembly error in mounting the semiconductor laser device 100. As in the semiconductor laser device 70 according to the tenth embodiment, a configuration in which the symmetry of the profile of the laser beam is improved by the output mirrors 360 and 370 that can easily perform the orientation adjustment or the position control of the arrangement spatially greatly. By doing so, the symmetry of the profile of the laser beam can be improved regardless of the assembly error.

Embodiment 11 FIG.
FIG. 21 is a schematic top view showing the configuration of the semiconductor laser apparatus 80 according to the eleventh embodiment of the present invention. FIG. 22 is a schematic side view showing the configuration of the semiconductor laser apparatus 80 according to the eleventh embodiment. FIG. 23 is a schematic perspective view illustrating the configuration of the output mirror 380 according to the eleventh embodiment.

In the ninth embodiment and the tenth embodiment, by inserting a high-reflectance output mirror from the peripheral portion in the slow axis direction of the laser beam into the path of the laser beam, the peripheral in the profile in the slow axis direction of the laser beam In this configuration, the laser beam in the portion is reflected more than the laser beam in the center portion. In the ninth and tenth embodiments, the reflectance of the laser light in the incident surface of the output mirror has not changed spatially. However, in the semiconductor laser device 80 according to the eleventh embodiment, due to the reflectance distribution on the incident surface of the output mirror 380 as the output coupling element, the semiconductor laser device 100 has more in the periphery of the profile in the slow axis direction than in the center. It is set as the structure which reflects a laser beam toward.

A high reflection portion 382 and a low reflection portion 386 are formed on the incident surface 381 of the output mirror 380 in the eleventh embodiment. The exit surface 383 is provided with an AR coating for suppressing reflectivity.

FIG. 24 is a schematic diagram illustrating a configuration of the output mirror 380 according to the eleventh embodiment. As shown in FIGS. 23 and 24, the high reflection portion 382 is disposed on both sides of the low reflection portion 386 in the slow axis direction (x direction) of the laser light. As shown in FIG. 21, the peripheral amplified light 402 of the laser light is reflected toward the light emitting point of the semiconductor laser element 100 by the high reflection portion 382 of the output mirror 380.

Similarly to the ninth and tenth embodiments, according to the semiconductor laser device 80 according to the eleventh embodiment, the laser light outputted by reflecting the peripheral amplified light 402 of the laser light to constitute the semiconductor laser resonator. The ratio of the main oscillation light 401 can be increased. Thereby, the effect of improving the condensing property of the laser beam output from the semiconductor laser device 80 in the slow axis direction can be obtained.

According to the output mirror 380 according to the eleventh embodiment, a large amount of the peripheral amplified light 402 is reflected by a single output mirror whose reflectance distribution in the slow axis direction is changed by coating. Scattering and absorption of the laser light generated at the boundary between the low reflection portion 386 and the high reflection portion 382 of the output mirror 380 are in a region corresponding to the boundary of the output mirrors 352, 360, and 370 according to the ninth and tenth embodiments. Compared to the scattering and absorption of laser light generated at a certain mechanical edge portion, it can be remarkably reduced. Therefore, when the laser beam has a high output, the output mirror 380 according to the eleventh embodiment can suppress adverse effects such as breakage or abnormal oscillation of the output mirror due to scattering and absorption of the laser beam. It is.

Further, the output coupling element is constituted by the two output mirrors 360 and 370 in the tenth embodiment, but is constituted by the output mirror 380 which is a single mirror in the eleventh embodiment. . According to the eleventh embodiment, not only the adjustment of the output coupling element is further facilitated, but also the reflectance distribution of the incident surface 381 of the output mirror 380 is designed so that the semiconductor laser element will be described below. The semiconductor laser device 80 can obtain a stable output characteristic of the laser beam in a wide operating region of 100.

24, the reflectance distribution in the slow axis direction of the incident surface 381 of the output mirror 380 is shown. In the example of FIG. 24, the reflectance of the high reflection portion 382 is close to 100%, and the reflectance of the low reflection portion 386 is almost 0%. When output mirror 380 has such a reflectance distribution, the effect of output mirror 380 is close to the effect of the output coupling element configured by output mirror 360 and output mirror 370 having high reflectivity in the tenth embodiment. It will be a thing.

FIG. 25 is another schematic diagram showing the configuration of the output mirror 380 according to the eleventh embodiment. The reflectance distribution in the slow axis direction of the incident surface 381 of the output mirror 380 shown in FIG. 25 is different from the example of FIG. In the example of FIG. 25, the reflectance of the high reflection portion 382 is about 80%, and the reflectance of the low reflection portion 386 is about 5%. The beam divergence angle in the slow axis direction of the laser light emitted from the semiconductor laser element 100 is small when the applied current to the semiconductor laser element 100 is small, and increases when the applied current is increased. For this reason, as the applied current increases, the ratio of the peripheral amplified light 402 in the laser light emitted from the semiconductor laser element 100 increases. Therefore, if the reflectance distribution of the output mirror 380 is designed so as to have an optimum reflectance distribution when the value of the applied current is in a high current region, the semiconductor is used when the applied current is small and the ratio of the peripheral amplified light 402 is small. The ratio of reflected light to the laser element 100 may be too low. As a result, the external resonator constituted by the rear end face 102 of the semiconductor laser element 100 and the output mirror 380 may not operate. When the applied current is small in this way, as shown in the example of FIG. 25, by setting the reflectance of the low reflective portion 386 to a value of several percent without making the value close to zero, stable oscillation even when a low current is applied. Is possible. In the example of FIG. 25, the reflectance of the high reflection portion 382 is reduced in order to maintain the ratio of the energy of the laser light reflected by the entire incident surface 381 of the output mirror 380, but the low reflection portion 386 is used. It is also possible to adjust by the area ratio between the high reflection portion 382 and the high reflection portion 382.

Embodiment 12 FIG.
FIG. 26 is a schematic top view showing the configuration of the semiconductor laser apparatus 90 according to the twelfth embodiment of the present invention. The semiconductor laser device 90 has a configuration in which the output mirror 340 in the semiconductor laser device 50 according to the seventh embodiment is replaced with the output mirror 380 according to the eleventh embodiment. In the twelfth embodiment, the laser beam from the first semiconductor laser element 121 and the second semiconductor laser element 122, which are a plurality of semiconductor laser elements, using the rotating optical element 11, the diffraction grating 8, and the output mirror 380. Are coupled by chromatic dispersion.

In the semiconductor laser device 90 according to the twelfth embodiment, the output mirror 380 is arranged so that the direction of the center line 350 in FIGS. 24 and 25 is the x ′ direction in FIG. That is, the semiconductor laser device 90 uses, as an output coupling element, an output mirror 380 that reflects a large amount of peripheral amplified light in the slow axis direction (y ′ direction in FIG. 26) at the light emitting point of the semiconductor laser element.

In the first semiconductor laser element 121, the slow axis direction is the x direction, and the fast axis direction is the y direction. The slow axis direction in the second semiconductor laser element 122 is a direction different from the x direction, and the fast axis direction is the y direction. However, in the optical path downstream from the rotating optical element 11, the slow axis directions of the laser beams from the first semiconductor laser element 121 and the second semiconductor laser element 122 are both the y direction or the y 'direction. That is, at the position of the output mirror 380, the slow axis direction is the y 'direction.

Also in the semiconductor laser apparatus 90 according to the twelfth embodiment, the first horizontal cylindrical lens 5, the second horizontal cylindrical lens 7, the first axis correction lens 2, the first vertical cylindrical lens 6, and the second vertical cylinder. By placing the directional cylindrical lens 9 and the output mirror 380 apart by an appropriate distance, in the horizontal direction (x direction, the above direction different from the x direction, x ′ direction) and in the vertical direction (y direction, y ′ direction) An optical system that forms an image of the front end face 101 of the first semiconductor laser element 121 and the second semiconductor laser element 122 on the incident surface 381 of the output mirror 380 can be configured. That is, in both directions, the front end face 101 of the first semiconductor laser element 121 and the second semiconductor laser element 122 and the incident face 381 of the output mirror 380 have an optically conjugate relationship in the slow axis direction.

According to the semiconductor laser device 90 according to the twelfth embodiment, similar to the semiconductor laser device 50 according to the seventh embodiment, the light output from the light emitting points of the plurality of semiconductor laser elements can be collected by one output mirror. In addition to improving the output, the following effects can be obtained.

The laser light reflected by the high reflection portion 382 of the output mirror 380 is emitted from the first semiconductor laser element 121 and the second semiconductor laser element 122 even if the direction of the output mirror 380 is shifted in the slow axis direction. To reach. Therefore, no trouble occurs in the operation of the external resonators of the first semiconductor laser element 121 and the second semiconductor laser element 122. This is because the light emitting point located on the front end face 101 of the first semiconductor laser element 121 and the second semiconductor laser element 122 and the output mirror 380 have an optically conjugate relationship in the slow axis direction. is there. In the case of an optically conjugate positional relationship, light generated from one specific point reaches a specific point on the other regardless of the emission angle.

The angular deviation in the first axis direction (x ′ direction in FIG. 26) of the output mirror 380 is an angular deviation in the direction in which the wavelength dispersion due to the diffraction grating 8 exists. Even when the angle of the output mirror 380 in the fast axis direction is deviated, the oscillation wavelength of the external resonator is changed to compensate automatically.

As described above, according to the semiconductor laser device 90 according to the twelfth embodiment, it is possible to operate robustly against the angular deviation of the output mirror 380.

Also, the beam divergence angle in the slow axis direction of the laser beam emitted from the semiconductor laser varies depending on the current applied to the semiconductor laser element and the operating temperature of the semiconductor laser element. That is, as the applied current increases and the operating temperature increases, the beam divergence angle in the slow axis direction increases. Further, when there are a plurality of semiconductor laser elements and light emission points as in the semiconductor laser device 90 according to the twelfth embodiment, the beam divergence angle varies for each light emission point of the semiconductor laser elements.

Although the configuration in which the output mirror 380 reflects a large amount of the peripheral amplified light in the slow axis direction and improves the beam condensing property of the output laser light, the effect of improving the beam condensing property is high, but at the light emitting point of the semiconductor laser element As the beam divergence angle in the slow axis direction varies and varies, the feedback amount of the external resonator of the semiconductor laser may vary. As a result, there is a problem that the target external resonator operation cannot be performed and the operation of the semiconductor laser device 90 becomes unstable. However, in the semiconductor laser device 90 according to the twelfth embodiment, the front end face 101 of the first semiconductor laser element 121 and the second semiconductor laser element 122 and the incident face 381 of the output mirror 380 are optically conjugate. By doing so, the above problem can be avoided.

That is, the front end face 101 of the first semiconductor laser element 121 and the second semiconductor laser element 122 and the incident surface 381 of the output mirror 380 are in an optically conjugate relationship, so that the incident surface 381 of the output mirror 380 The width of the profile of the laser beam in the slow axis direction at the position becomes a constant size regardless of the fluctuation of the beam divergence angle caused by the change in the applied current or the variation of the elements. Here, the transfer magnification from the front end face 101 of the first semiconductor laser element 121 and the second semiconductor laser element 122 to the output mirror 380 is M. Further, the width of the light emitting point in the slow axis direction of the first semiconductor laser element 121 and the second semiconductor laser element 122 is defined as W. Then, the width of the profile in the slow axis direction of the laser light in the output mirror 380 becomes WM, and is constant regardless of the beam divergence angle as described above. Since the profile width of the laser beam is constant, the ratio of the energy of the laser beam irradiated to the high reflection portion 382 of the output mirror 380 to the entire laser beam does not depend on the beam divergence angle in the slow axis direction of the semiconductor laser element. Constant.

As a result, according to the semiconductor laser device 90 according to the twelfth embodiment, after realizing a robust operation that is not affected by variations in the beam divergence angle in the slow axis direction due to changes in applied current or variations in semiconductor laser elements. Thus, it is possible to easily reflect the peripheral region of the laser beam profile in the slow axis direction and improve the light condensing property in the slow axis direction.

The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

2 First axis correction lens, 5 First horizontal cylindrical lens, 6 First vertical cylindrical lens, 7 Second horizontal cylindrical lens, 8 Diffraction grating, 9 Second vertical cylindrical lens, 10, 20, 30, 40, 50, 60, 70, 80, 90 semiconductor laser device, 11 rotating optical element, 100, 110 semiconductor laser element, 101 front side end face, 102 rear side end face, 103 active layer, 104 semiconductor laser medium, 121 first Semiconductor laser element, 122, second semiconductor laser element, 1041, 1051, 1061, first semiconductor laser medium, 1042, 1052, 1062, second semiconductor laser medium, 1043, 1053, 1063, third semiconductor laser medium, 300 , 310, 320, 330, 340, 352, 360, 370, 380 Force mirror, 301, 351, 361, 371, 381 entrance surface, 302, 382 high reflection portion, 303, 353, 363, 373 exit surface, 304 first high reflection portion, 305 second high reflection portion, 350 center Line, 386 low reflection part, 401 main oscillation light, 402 peripheral amplification light.

Claims

A semiconductor laser element that emits laser light;
A first axis correction lens disposed on the optical path of the laser beam to correct a divergence angle in the first axis direction of the laser beam;
By changing the reflectance of the laser beam depending on the position of the laser beam in the slow axis direction, a part of the laser beam from the first axis correction lens is reflected, and the reflected laser beam is An output coupling element that returns to the semiconductor laser element and passes the remainder as output light;
A semiconductor laser device comprising:
2. The semiconductor laser device according to claim 1, wherein the front end face of the semiconductor laser element from which the laser beam is emitted and the output coupling element have an optically conjugate relationship with respect to the slow axis direction.
A plurality of the laser beams having different optical axes are emitted from one or a plurality of the semiconductor laser elements, arranged on the optical path between the first axis correction lens and the output coupling element, and a plurality of the plurality of the laser beams The semiconductor laser device according to claim 1, further comprising a diffraction grating that wavelength-couples laser light into one beam and emits the laser light.
The semiconductor laser device according to claim 3, wherein the semiconductor laser element is a semiconductor laser array having a plurality of semiconductor laser media.
A rotating optical element is provided on the optical path between the semiconductor laser element and the diffraction grating, and rotates a plurality of incident laser beams by 90 ° about the optical axis of each laser beam as a rotation axis. The semiconductor laser device according to claim 4.
The output coupling element is an output mirror having an incident surface on which the laser light is incident, and the reflectivity of the incident surface decreases or becomes constant as the distance from the center of the incident surface in the slow axis direction increases. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is any one of the following.
The output coupling element is an output mirror having an incident surface on which the laser beam is incident, and a width in the slow axis direction is smaller than a beam diameter of the laser beam in a part including the center in the slow axis direction of the incident surface. The high reflectance part is provided, The said reflectance of the area | region except the said highly reflective part of the said incident surface is lower than the said reflectance of the said high reflective part. The any one of Claim 1 to 6 characterized by the above-mentioned. The semiconductor laser device described.
The said reflectance of the center part of the said slow axis direction is lower than at least any one of the said reflectance of the peripheral part which exists in the both sides of the said slow axis direction of the said center part. The semiconductor laser device according to any one of the above.
The semiconductor laser device according to claim 1, wherein the reflectance has a distribution that is symmetrical with respect to a center in the slow axis direction.
The semiconductor laser device according to any one of claims 1 to 9, wherein the output coupling element is configured by a single mirror.
In the distribution of the refractive index of the semiconductor laser element in the non-energized state with respect to the laser beam in the slow axis direction, the refractive index of the semiconductor laser medium that is a light emitting region is the refractive index of the non-emitting region around the light emitting region. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is lower.