JP7504702B2 - Semiconductor laser device and laser device - Google Patents

Description

The present invention relates to a semiconductor laser device and a laser device.

A semiconductor laser device generally comprises a semiconductor laser element, a collimating lens, and a focusing optical system, and the laser light emitted from the semiconductor laser is collimated by the collimating lens, then focused by the focusing optical system and output to the outside. A semiconductor laser device that requires high output is provided with a number of semiconductor laser elements and collimating lenses according to the required output.

The following Patent Documents 1 and 2 disclose a semiconductor laser device in which a semiconductor laser element, an F-axis (fast axis) collimating lens, and an S-axis (slow axis) collimating lens are provided on each step of a stepped mount. In this semiconductor laser device, the laser light emitted from the semiconductor laser element provided on each step is individually collimated by the collimating lens provided on each step, and then focused by a focusing optical system and coupled to a single optical fiber.

JP 2018-85493 A JP 2016-164671 A

However, in the semiconductor laser devices disclosed in Patent Documents 1 and 2, if one attempts to increase the number of semiconductor laser elements mounted in order to increase the output, it is necessary to increase the number of steps in the mount. This poses the problem of increasing the height dimension of the semiconductor laser device.

The present invention was made in consideration of the above circumstances, and aims to provide a semiconductor laser device and a laser device that can achieve high output while reducing the height dimension.

In order to solve the above problem, the semiconductor laser device (1, 2) according to the first aspect of the present invention comprises a stepped mount member (10) having a plurality of steps (ST), a plurality of semiconductor laser elements (11) mounted on each of the steps of the mount member and emitting laser light in a first direction (+Z direction), a plurality of collimating optical systems (12, 13) provided on each of the steps of the mount member corresponding to the semiconductor laser elements and collimating the laser light emitted from the corresponding semiconductor laser element while reflecting it in a second direction (+X direction) intersecting the first direction, and a combining optical system (14) that combines the laser light reflected by the collimating optical system.

In the semiconductor laser device according to the first aspect of the present invention, a plurality of semiconductor laser elements that emit laser light in a first direction are mounted on each step of a stepped mount member having a plurality of steps, and a plurality of collimating optical systems corresponding to the semiconductor laser elements are provided on each step of the mount member. The laser light emitted from the plurality of semiconductor laser elements mounted on each step of the mount member is collimated by the corresponding collimating optical system, reflected in a second direction intersecting the first direction, and combined by a combining optical system. In the semiconductor laser device according to the first aspect of the present invention, by mounting a plurality of semiconductor laser elements on the steps of the mount member, the number of steps can be reduced, making it possible to increase output while reducing the height dimension.

In addition, in the semiconductor laser device according to the first aspect of the present invention, at least one (12) of the collimating optical systems provided in a plurality of positions on each step of the mounting member includes a first collimating lens (12a) that collimates the components of the laser light emitted from the corresponding semiconductor laser element in a third direction (Y direction) perpendicular to the first direction and the second direction, and a collimating mirror (12b) that reflects the second direction component of the laser light emitted from the corresponding semiconductor laser element while collimating it toward the second direction.

In addition, in the semiconductor laser device according to the first aspect of the present invention, at least one (13) of the remaining collimating optical systems provided in multiple on each step of the mount member includes a first collimating lens (13a) that collimates the third direction component of the laser light emitted from the corresponding semiconductor laser element, a second collimating lens (13b) that collimates the second direction component of the laser light emitted from the corresponding semiconductor laser element, and a reflecting mirror (13c) that reflects the laser light collimated by the second collimating lens toward the second direction.

In addition, in the semiconductor laser device according to the first aspect of the present invention, the semiconductor laser elements are linearly arranged in the second direction.

Alternatively, in the semiconductor laser device according to the first aspect of the present invention, the collimating optical system provided in multiple on each step of the mount member includes the first collimating lens (12a, 13a) and the collimating mirror (12b, 13d), and the semiconductor laser element is arranged so that the distance from the laser light emission end to the collimating mirror is the same.

In order to solve the above problem, the semiconductor laser device (1) according to the second aspect of the present invention comprises a stepped mount member (10) having a plurality of steps (ST), a first semiconductor laser element (11a) mounted on each of the steps of the mount member, a second semiconductor laser element (11b) mounted on each of the steps of the mount member, a first fast axis collimator lens (12a) provided in correspondence with the first semiconductor laser element on each of the steps of the mount member, and a second fast axis collimator lens (12b) provided in correspondence with the second semiconductor laser element on each of the steps of the mount member. The device includes a fast axis collimating lens (13a), a slow axis collimating mirror (12b) provided on each step of the mount member corresponding to the first semiconductor laser element, a slow axis collimating lens (13b) provided on each step of the mount member corresponding to the second semiconductor laser element, a reflecting mirror (13c) provided on each step of the mount member corresponding to the second semiconductor laser element, and a combining optical system (14) that combines the laser light reflected by the slow axis collimating mirror and the reflecting mirror.

In addition, in the semiconductor laser device according to the second aspect of the present invention, the combining optical system includes a polarizing element (14a) that changes the polarization state of the laser light reflected by either the slow axis collimating mirror or the reflecting mirror, and a polarized combining optical system (14b, 14c) that combines the laser light that has passed through the polarizing element with the laser light reflected by the other of the slow axis collimating mirror and the reflecting mirror.

The semiconductor laser device according to the first and second aspects of the present invention also includes a focusing optical system (15) that focuses the laser light combined by the combining optical system onto the core of the optical fiber.

The laser device (70) according to the first aspect of the present invention comprises any one of the semiconductor laser devices (1, 2) described above, a combiner (72) that optically combines the laser light output from the semiconductor laser device, and an output end (74) that outputs the laser light combined by the combiner to the outside.

A laser device (60) according to a second aspect of the present invention includes any one of the semiconductor laser devices (1, 2) described above, an amplification fiber (64) having a core doped with rare earth, a combiner (62) that couples the laser light output from the semiconductor laser device to the amplification fiber as excitation light, and an output end (67) that outputs the light amplified by the amplification fiber to the outside.

The present invention has the advantage of being able to achieve high output while reducing the height dimension.

1 is a perspective view of a semiconductor laser device according to a first embodiment of the present invention. 1 is a plan view of a semiconductor laser device according to a first embodiment of the present invention. 1 is a side view of a semiconductor laser device according to a first embodiment of the present invention. 1 is a plan view illustrating a characteristic portion of a semiconductor laser device according to a first embodiment of the present invention. FIG. 4 is a plan view of a semiconductor laser device according to a second embodiment of the present invention. FIG. 11 is a plan view illustrating a characteristic portion of a semiconductor laser device according to a second embodiment of the present invention. FIG. 2 is a side perspective view showing a first configuration example of the optical module. FIG. 11 is a perspective view showing a second configuration example of the optical module. FIG. 11 is a plan view perspective view of an optical module according to a second configuration example. 10 is a perspective view showing an optical module unit including a plurality of the optical modules shown in FIGS. 8 and 9. FIG. 1 is a diagram showing a configuration of a main part of a laser device according to a first embodiment of the present invention; FIG. 4 is a diagram showing a configuration of a main part of a laser device according to a second embodiment of the present invention.

The semiconductor laser device and laser device according to the embodiment of the present invention will be described in detail below with reference to the drawings. Note that, in order to facilitate understanding, the positional relationships of the various components will be described below with reference to the XYZ Cartesian coordinate system (the position of the origin will be changed as appropriate) set in the drawings as necessary. Also, in the drawings referred to below, the dimensions of the various components will be changed as appropriate as necessary to facilitate understanding.

[Semiconductor laser device]
First Embodiment
FIG 1 is a perspective view of a semiconductor laser device according to a first embodiment of the present invention, FIG 2 is a plan view of the semiconductor laser device, and FIG 3 is a side view of the semiconductor laser device. Also, FIG 4 is a plan view of a characteristic portion of the semiconductor laser device. As shown in FIG 1 to FIG 3, the semiconductor laser device 1 of this embodiment includes a mount 10 (mount member), 2N (N=6 in this embodiment) semiconductor laser elements 11, N collimating optical systems 12, N collimating optical systems 13, a synthesizing optical system 14, and a focusing optical system 15. Such a semiconductor laser device 1 outputs laser light emitted from the 2N semiconductor laser elements 11 to the outside via an optical fiber FB.

In the XYZ orthogonal coordinate system shown in Figures 1 to 3, the +Z direction (first direction) of the Z axis is set to the emission direction of the laser light emitted from the semiconductor laser element 11. In addition, the X axis (second direction) of this XYZ orthogonal coordinate system is set to be parallel to the direction (slow axis) parallel to the pn junction surface of the semiconductor laser element 11, and the Y axis (third direction) is set to be parallel to the direction (fast axis) perpendicular to the pn junction surface of the semiconductor laser element 11.

The mount 10 is a generally plate-like member having a rectangular planar shape and a first surface 10a on which the semiconductor laser element 11, collimating optical system 12, collimating optical system 13, synthesizing optical system 14, and focusing optical system 15 are mounted, and a second surface 10b on the opposite side. N step portions ST are formed in a staircase shape on the first surface 10a of the mount 10, and the second surface 10b is a flat surface.

The step ST formed in the mount 10 is configured so that it advances in the +Y direction (becomes higher) as it advances in the -X direction. In other words, the step ST formed in the mount 10 is configured so that it advances in the -Y direction (becomes lower) as it advances in the +X direction. The Y-directional spacing of the step ST is adjusted so that the collimating optical system 12, 13 provided in one step ST does not block the laser light that passes through the collimating optical system 12, 13 provided in the other step ST.

The mount 10 is formed using a material that has high thermal conductivity to increase the heat dissipation efficiency of the semiconductor laser element 11, and has a low thermal expansion coefficient to minimize stress caused by temperature changes. For example, ceramics such as aluminum nitride (AlN) or metals such as molybdenum (Mo) are suitable.

The semiconductor laser elements 11 are mounted two by two on the -Z side of the step ST of the mount 10 with the laser light emission end facing the +Z side. The reason why two semiconductor laser elements 11 are mounted on each step ST of the mount 10 is to reduce the dimension of the semiconductor laser device 1 in the height direction (Y direction) by reducing the number of steps ST on which the semiconductor laser elements 11 are mounted. The semiconductor laser elements 11 are linearly arranged in the X direction so that the positions of the laser light emission ends in the Z direction are consistent. The semiconductor laser elements 11 are connected in series.

When a drive current is supplied from a drive circuit (not shown), the semiconductor laser element 11 emits laser light in the +Z direction. The wavelength of the laser light emitted from the semiconductor laser element 11 is, for example, in the 0.9 μm band. When it is necessary to distinguish between the two semiconductor laser elements 11 mounted on one step ST of the mount 10, they are referred to as the "semiconductor laser element 11a" and the "semiconductor laser element 11b," respectively. The "semiconductor laser element 11a" emits laser light that is collimated by the collimating optical system 12, and the "semiconductor laser element 11b" emits laser light that is collimated by the collimating optical system 13.

The collimating optical system 12 is provided corresponding to the semiconductor laser element 11a (first semiconductor element) and collimates the laser light emitted from the corresponding semiconductor laser element 11a while reflecting it in the +X direction. The collimating optical system 12 includes a collimating lens 12a (first collimating lens, first fast-axis collimating lens) and a collimating mirror 12b (slow-axis collimating mirror).

The collimating lens 12a is disposed on the +Z side of the semiconductor laser element 11a and is a FAC lens (fast axis collimating lens) that collimates the fast axis component of the laser light emitted from the semiconductor laser element 11a. Note that the collimating lens 12a does not collimate the slow axis component of the laser light emitted from the semiconductor laser element 11a.

The collimating mirror 12b is disposed on the +Z side of the collimating lens 12a, at a fixed distance from the emission end of the semiconductor laser element 11a. The collimating mirror 12b collimates the slow axis component of the laser light that passes through the collimating lens 12a, while reflecting it in the +X direction. As shown in FIG. 4, for example, the collimating mirror 12b is a mirror whose reflecting surface is an emission surface (a surface whose cross-sectional shape in the ZX plane is a parabola). Note that the collimating mirror 12b does not collimate the fast axis component of the laser light emitted from the semiconductor laser element 11a.

The collimating optical system 13 is provided corresponding to the semiconductor laser element 11b (second semiconductor element) and collimates the laser light emitted from the corresponding semiconductor laser element 11b while reflecting it in the +X direction. The collimating optical system 13 includes a collimating lens 13a (first collimating lens, second fast-axis collimating lens), a collimating lens 13b (second collimating lens, slow-axis collimating lens), and a reflecting mirror 13c.

The collimating lens 13a is disposed on the +Z side of the semiconductor laser element 11b and is a FAC lens (fast axis collimating lens) that collimates the fast axis component of the laser light emitted from the semiconductor laser element 11b. Note that, like the collimating lens 12a, the collimating lens 13a does not collimate the slow axis component of the laser light emitted from the semiconductor laser element 11b.

The collimating lens 13b is disposed on the +Z side of the collimating lens 13a, at a fixed distance from the emission end of the semiconductor laser element 11b. This distance is approximately the same as the distance from the emission end of the semiconductor laser element 11a to the collimating mirror 12b. The collimating lens 13b collimates the slow axis component of the laser light that passes through the collimating lens 13a. Note that, like the collimating mirror 12b, the collimating lens 13b does not collimate the fast axis component of the laser light emitted from the semiconductor laser element 11b.

Reflection mirror 13c is disposed on the +Z side of collimator lens 13b, and reflects the laser light that passes through collimator lens 13b in the +X direction. Here, reflection mirror 13c is disposed on the +Z side of collimator mirror 12b so that the laser light reflected in the +X direction by reflection mirror 13c is not blocked by collimator mirror 12b. Note that reflection mirror 13c is a mirror with a planar reflection surface that is inclined at 45° from the Z axis to the X axis, as shown in FIG. 4.

The synthesis optical system 14 is provided on the first surface 10a on the +Z side of the mount 10, and synthesizes the laser light reflected by the collimating optical system 12 (collimating mirror 12b) and the laser light reflected by the collimating optical system 13 (reflection mirror 13c). The synthesis optical system 14 includes, for example, a half-wave plate 14a (polarizing element), a reflection mirror 14b (polarized wave combining optical system), and a polarizing beam splitter 14c (polarized wave combining optical system), and performs polarization synthesis of the above-mentioned laser light.

The half-wave plate 14a is disposed on the +X side of the collimating mirror 12b on the first surface 10a of the mount 10, and changes the polarization state of the laser light reflected by the collimating mirror 12b. For example, if the polarization state of the laser light reflected in the +X direction by the collimating mirror 12b is linearly polarized parallel to the Z axis, the half-wave plate 14a rotates the polarization direction by 90 degrees to change the polarization state to linearly polarized parallel to the Y axis.

The reflection mirror 14b is disposed on the +X side of the 1/2 wavelength plate 14a, and reflects the laser light that passes through the 1/2 wavelength plate 14a in the +Z direction. As shown in FIG. 4, the reflection mirror 14b is a mirror having a flat reflection surface that is inclined at 45° from the X axis to the Z axis.

The polarizing beam splitter 14c is disposed on the first surface 10a of the mount 10, on the +X side of the reflecting mirror 13c and on the +Z side of the reflecting mirror 14b. The polarizing beam splitter 14c transmits or reflects the incident light depending on its polarization state. For example, the polarizing beam splitter 14c transmits linearly polarized light parallel to the Z axis and reflects linearly polarized light parallel to the Y axis.

Here, assume that the polarization state of the laser light reflected in the +X direction by the collimator mirror 12b and the reflecting mirror 13c is both linearly polarized parallel to the Z axis. The laser light reflected in the +X direction by the collimator mirror 12b is linearly polarized parallel to the Y axis by the half-wave plate 14a, then reflected by the reflecting mirror 14b and enters the polarizing beam splitter 14c, so it is reflected by the polarizing beam splitter 14c and travels in the +X direction. On the other hand, the laser light reflected in the +X direction by the reflecting mirror 13c passes through the polarizing beam splitter 14c and travels in the +X direction. In this way, the laser light reflected in the X direction by the collimator mirror 12b and the reflecting mirror 13c is combined.

The focusing optical system 15 is disposed on the first surface 10a of the mount 10 between the synthesis optical system 14 and the incident end surface of the optical fiber FB, and focuses the laser light combined by the synthesis optical system 14 onto the core of the optical fiber FB. The focusing optical system 15 includes a cylindrical lens 15a and a cylindrical lens 15b. The cylindrical lens 15a is disposed on the +X side of the polarized beam splitter 14c of the synthesis optical system 14, and focuses the fast axis component (Y direction component) of the laser light combined by the synthesis optical system 14. The cylindrical lens 15b is disposed on the +X side of the cylindrical lens 15a, and focuses the slow axis component (Z direction component) of the laser light that passes through the cylindrical lens 15a.

The optical fiber FB is arranged in a direction perpendicular to the traveling direction of the laser light emitted from the semiconductor laser element 11, and is positioned so that its incident end face is located, for example, at the focal position of the cylindrical lens 15b. This optical fiber FB guides the laser light emitted from each of the semiconductor laser elements 11 to the outside of the semiconductor laser device 1. Any optical fiber FB can be used depending on the application. For example, a single-core fiber, a multi-core fiber, a single-clad fiber, a double-clad fiber, or other optical fibers can be used.

The laser light entrance and exit surfaces of the transmissive optical components provided in the collimating optical systems 12 and 13, the synthesis optical system 14, and the focusing optical system 15 described above are provided with an anti-reflection coating (AR coating) made of a dielectric multilayer film. In addition, the reflective surfaces of the reflective optical components provided in the collimating optical systems 12 and 13, the synthesis optical system 14, and the focusing optical system 15 are provided with a reflective coating made of a dielectric multilayer film or a metal thin film.

For example, anti-reflection coatings are formed on the laser light entrance and exit surfaces of the collimating lens 12a of the collimating optical system 12, the collimating lenses 13a and 13b of the collimating optical system 13, the half-wave plate 14a and the polarizing beam splitter 14c of the synthesis optical system 14, and the cylindrical lenses 15a and 15b of the focusing optical system 15. In addition, reflective coatings are formed on the reflective surfaces of the collimating mirror 12b of the collimating optical system 12, the reflective mirror 13c of the collimating optical system 13, and the reflective mirror 14b of the synthesis optical system 14.

When a drive current is supplied from a drive circuit (not shown) to the semiconductor laser device 1 configured as described above, the supplied drive current flows to the semiconductor laser elements 11 connected in series, and laser light is emitted from these semiconductor laser elements 11 in the +Z direction. As shown in FIG. 4, the laser light emitted from the semiconductor laser element 11a of the semiconductor laser elements 11 in the +Z direction is incident on the collimating lens 12a constituting the collimating optical system 12, where the fast axis component is collimated. The laser light that passes through the collimating lens 12a is incident on the collimating mirror 12b constituting the collimating optical system 12, where the slow axis component is collimated and is reflected in the +X direction.

As shown in FIG. 4, the laser light emitted from semiconductor laser element 11b of semiconductor laser element 11 in the +Z direction is incident on collimating lens 13a constituting collimating optical system 13, where the fast axis component is collimated. The laser light that has passed through collimating lens 13a is incident on collimating lens 13b constituting collimating optical system 13, where the slow axis component is collimated. The laser light that has passed through collimating lens 13b is reflected in the +X direction by reflecting mirror 13c constituting collimating optical system 13.

When the laser light reflected in the +X direction by the collimating mirror 12b of the collimating optical system 12 enters the 1/2 wavelength plate 14a of the synthesis optical system 14, the polarization state changes. The laser light that passes through the 1/2 wavelength plate 14a is reflected by the reflecting mirror 14b and enters the polarizing beam splitter 14c, where it is reflected in the +X direction. In contrast, the laser light reflected in the +X direction by the reflecting mirror 13c of the collimating optical system 13 passes through the polarizing beam splitter 14c and travels in the +X direction. In this way, the laser light reflected in the X direction by the collimating mirror 12b and the reflecting mirror 13c is synthesized.

The laser light combined by the combining optical system 14 enters the focusing optical system 15, where the fast axis component (component in the Y direction) is focused by the cylindrical lens 15a, and the slow axis component (component in the Z direction) is focused by the cylindrical lens 15b. The laser light thus focused enters the core from the incident end face of the optical fiber FB and propagates through the core. In this way, the laser light emitted from each of the semiconductor laser elements 11 is guided to the outside of the semiconductor laser device 1 via the optical fiber FB.

As described above, in this embodiment, semiconductor laser elements 11a and 11b that emit laser light in the +Z direction are mounted on each of the step portions ST provided on the mount 10, and collimating optical systems 12 and 13 are provided corresponding to the semiconductor laser elements 11a and 11b, respectively. The laser light reflected in the +X direction by the collimating optical systems 12 and 13 is then combined by the combining optical system 14, and focused by the focusing optical system 15 to be incident on the core of the optical fiber FB. This allows the number of step portions ST on the mount 10 to be reduced, making it possible to increase output while reducing the height dimension.

Second Embodiment
Fig. 5 is a plan view of a semiconductor laser device according to a second embodiment of the present invention. Fig. 6 is a plan view of a characteristic portion of the semiconductor laser device. In Figs. 5 and 6, the same reference numerals are used for components corresponding to those shown in Figs. 1 to 4. The semiconductor laser device 2 of this embodiment differs from the semiconductor laser device 1 shown in Figs. 1 to 4 in the configuration of the collimating optical system 13 and the arrangement of the semiconductor laser element 11b.

As shown in Figures 5 and 6, the collimating optical system 13 provided in the semiconductor laser device 2 of this embodiment has a configuration similar to that of the collimating optical system 12, and includes a collimating lens 13a and a collimating mirror 13d. The collimating mirror 13d is similar to the collimating mirror 12b shown in Figures 1 to 4, and reflects the slow axis component of the laser light that passes through the collimating lens 13a in the +X direction while collimating it.

Collimating mirror 13d is disposed on the +Z side of collimating lens 13a, at a fixed distance from the emission end of semiconductor laser element 11b. If collimating mirror 13d has the same characteristics as collimating mirror 12b, the distance to the light source (point light source) required to collimate the slow axis component will be the same. For this reason, semiconductor laser element 11b is disposed so that the distance from the emission end of semiconductor laser element 11b to collimating mirror 13d is the same as the distance from the emission end of semiconductor laser element 11a to collimating mirror 12b.

As described above, the semiconductor laser device 2 of this embodiment is the same as the semiconductor laser device 1 shown in Figures 1 to 4, except for the configuration of the collimating optical system 13 and the arrangement of the semiconductor laser element 11b. Therefore, in this embodiment as well, the number of steps ST of the mount 10 can be reduced, making it possible to increase output while reducing the height dimension. In addition, in this embodiment, the collimating optical system 13 is composed of a collimating lens 13a and a collimating mirror 13d, and the collimating lens 13b shown in Figures 1 to 4 is not required, so the number of optical components can be reduced compared to the first embodiment. As a result, it is possible to reduce the number of steps required for mounting, aligning, etc. the optical components.

[Optical module]
The semiconductor laser device 1 according to the first embodiment and the semiconductor laser device 2 according to the second embodiment described above are often modularized by being housed in a housing for the purposes of facilitating handling, improving reliability, increasing robustness, and other purposes. Hereinafter, a configuration example of an optical module in which a semiconductor laser device is modularized will be described.

First Configuration Example
7 is a side perspective view showing a first configuration example of an optical module. The optical module M1 according to the first configuration example is modularized by housing the semiconductor laser device 1 according to the first embodiment described above in a housing. Note that the optical module M1 may also be modularized by housing the semiconductor laser device 2 according to the second embodiment described above in a housing.

The optical module M1 is a roughly rectangular parallelepiped module that includes a housing body 21, a cover member 22, and a pair of connectors 23. The housing body 21 is made up of a mount 10 for the semiconductor laser device 1, and a frame body 24 that is integrated with the mount 10 and surrounds the outer periphery of the mount 10. The frame body 24 is made of a metal such as copper (Cu) that has high thermal conductivity in order to improve heat dissipation efficiency. It is preferable that the surface of the frame body 24 is gold plated to improve the wettability of the solder.

The frame 24 has a notch 24a around the entire circumference on the inner surface at the end on the side (+Y side) where the lid member 22 is arranged. The outer periphery of the lid member 22 fits into this notch 24a. The frame 24 also has a through hole for leading the optical fiber FB from the inside of the housing body 21 to the outside of the housing body 21, and a through hole for leading the pair of connectors 23 from the inside of the housing body 21 to the outside of the housing body 21.

The frame 24 also has a protrusion 24b that protrudes in the ±Z direction at the end on the opposite side (-Y side) from the side where the cover member 22 is arranged. Three protrusions 24b that protrude in the -Z direction are shown in FIG. 7. These protrusions 24b have insertion holes for bolts BT1, and are used to fix the frame 24 to the support member by tightening the bolts.

The lid member 22 is a rectangular plate-like member whose planar shape is the same as that of the frame body 24, and whose size in planar view is slightly smaller than that of the frame body 24. Like the frame body 24, the lid member 22 is made of a metal such as copper (Cu) that has high thermal conductivity in order to improve heat dissipation efficiency. When the outer periphery of the lid member 22 is fitted into the notch 24a of the frame body 24, the various optical components of the semiconductor laser device 1 are housed in the space partitioned by the housing body 21 and the lid member 22.

The pair of connectors 23 supply drive current to the multiple semiconductor laser elements 11 provided in the semiconductor laser device 1. As described above, the multiple semiconductor laser elements 11 are connected in series. Therefore, one of the pair of connectors 23 is a connector that supplies the drive current supplied from the outside to the inside of the housing body 21, and the other is a connector that guides the drive current that has flowed through the serially connected semiconductor laser elements 11 to the outside.

The optical module M1 having such a configuration is used in a state where it is bolted to a cooling mechanism such as a cooling plate CP by bolts BT1 as shown in FIG. 7, for example. When a drive current is supplied to the semiconductor laser element 11 via the pair of connectors 23, laser light is emitted from the semiconductor laser element 11, and the semiconductor laser element 11 generates heat. The heat generated from the semiconductor laser element 11 is transferred to the cooling plate CP via the housing body 21 (mount 10 and frame 24). In this manner, heat is dissipated from the semiconductor laser element 11.

Second Configuration Example
Fig. 8 is a perspective view showing a second configuration example of the optical module, and Fig. 9 is a plan view perspective view of the same optical module. The optical module M2 according to the second configuration example is a modularization in which the semiconductor laser device 1 according to the first embodiment described above is housed in a housing and water-cooled. The optical module M2 may also be a modularization in which the semiconductor laser device 2 according to the second embodiment described above is housed in a housing and water-cooled.

The optical module M2 is a generally rectangular parallelepiped module that includes a housing body 31, a first cover member (not shown), a second cover member 32, and a pair of connectors 33. The housing body 31 is composed of a mount 10 for the semiconductor laser device 1, and a frame 34 that is integrated with the mount 10 and surrounds the outer periphery of the mount 10. As shown in FIG. 9, a flow path WP1 for circulating a cooling medium (e.g., temperature-controlled cooling water) is formed on the second surface 10b side (see FIGS. 1 and 3) of the mount 10 that forms part of the housing body 31. This flow path WP1 is a flow path that bends multiple times and has an inlet E1 at one end and an outlet E2 at the other end.

The frame 34, which is part of the housing main body 31, is made of a metal such as copper (Cu) with high thermal conductivity to improve heat dissipation efficiency. The surface of the frame 34 is preferably gold plated to improve solder wettability. The frame 34 has a notch 34a around the entire circumference on the inner surface at the end on the side (+Y side) where the first lid member (a member similar to the lid member 22 shown in FIG. 7) is placed. The outer periphery of the first lid member is fitted into this notch 34a.

The frame 34 is also formed with a through hole for leading the optical fiber FB from inside the housing body 31 to outside the housing body 31, and a through hole for leading the pair of connectors 33 from inside the housing body 31 to outside the housing body 31. In addition, the frame 34 is formed with a through hole for arranging a joint 35 attached to the inlet E1 of the flow path WP1, and a through hole for arranging a joint 36 attached to the outlet E2 of the flow path WP1.

The second cover member 32 is, for example, a triangular prism made of the same metal as the frame body 34. This second cover member 32 is fitted into a recess 31a formed in the housing body 31 while covering the flow path WP1 formed on the second surface 10b side of the mount 10, and is fixed to the housing body 31 with an adhesive such as phosphorus copper solder or silver solder. By covering the flow path WP1 with the second cover member 32, leakage of the cooling medium from the flow path WP1 is suppressed.

The pair of connectors 33 supply drive current to the multiple semiconductor laser elements 11 provided in the semiconductor laser device 1. As described above, the multiple semiconductor laser elements 11 are connected in series. Therefore, one of the pair of connectors 33 is a connector that supplies the drive current supplied from the outside to the inside of the housing body 31, and the other is a connector that guides the drive current that has flowed through the serially connected semiconductor laser elements 11 to the outside.

The optical module M2 configured in this manner is used, for example, in a state in which the cooling medium is supplied to the inlet E1 of the flow path WP1 via the joint 35, while the cooling medium that has circulated through the flow path WP1 is discharged from the outlet E2 to the outside via the joint 36. When a drive current is supplied to the semiconductor laser element 11 via the pair of connectors 33, laser light is emitted from the semiconductor laser element 11, and the semiconductor laser element 11 generates heat. The heat generated by the semiconductor laser element 11 is transferred to the cooling medium via the mount 10. In this manner, heat is dissipated from the semiconductor laser element 11.

Figure 10 is a perspective view showing an optical module unit including a plurality of the optical modules shown in Figures 8 and 9. Note that Figure 10 shows a portion as a cross-sectional view. The optical module unit MU shown in Figure 10 includes a plurality of optical modules M2 (12 in the example shown in Figure 10) and a manifold 40. The optical modules M2 are arranged in parallel in the height direction (Y direction) so that adjacent ones are spaced apart from each other. Each of the optical modules M2 is fixed to the manifold 40 by a bolt BT2.

As shown in FIG. 10, the manifold 40 is a substantially rectangular parallelepiped member having a first flow path 41 and a second flow path 42 formed therein through which the cooling medium flows. The first flow path 41 is a flow path through which the cooling medium flows that is supplied to the flow path WP1 of the optical module M2. The second flow path 42 is a flow path through which the cooling medium flows after flowing through the flow path WP1 of the optical module M2.

The first flow path 41 is a linear flow path extending in the Y direction. A through hole is formed on the side of the center of the longitudinal direction of the first flow path 41, and a joint 51 is attached to this through hole. The joint 51 is formed in a cylindrical shape, and a cooling medium flows into the first flow path 41 from the outside through the joint 51. In addition, a plurality of through holes 43 are formed on the side of the first flow path 41 opposite the side on which the joint 51 is provided. The joints 35 attached to each of the optical modules M2 are inserted into the respective through holes 43, thereby connecting the first flow path 41 and the inlet E1 of the flow path WP1 of the optical module M2. That is, the flow paths WP1 of each of the optical modules M2 are connected in parallel by the first flow path 41.

The second flow path 42 is a linear flow path extending in the Y direction, parallel to the first flow path 41. A through hole is formed on the side of the center of the longitudinal direction of the second flow path 42, and a joint 52 is attached to this through hole. The joint 52 is formed in a cylindrical shape, and the cooling medium flows out from the second flow path 42 to the outside through the joint 52. In addition, a plurality of through holes 44 are formed on the side of the second flow path 42 opposite to the side on which the joint 52 is provided. The joints 36 attached to each of the optical modules M2 are inserted into the respective through holes 44, thereby connecting the second flow path 42 and the outlet E2 of the flow path WP1 of the optical module M2. That is, the flow paths WP1 of each of the optical modules M2 are connected in parallel by the second flow path 42.

In the optical module unit MU having such a configuration, for example, the cooling medium supplied from the outside flows into the first flow path 41 of the manifold 40 through the joint 51. The cooling medium that flows into the first flow path 41 is supplied to the inlet E1 of the flow path WP1 of each optical module M2 through the joint 35 inserted into the multiple through holes 43 formed in the first flow path 41. The cooling medium supplied to the inlet E1 circulates through the flow path WP1 of each optical module M2 and is discharged from the outlet E2. The cooling medium discharged from the outlet E2 flows into the second flow path 42 through the joint 36 inserted into the multiple through holes 44 formed in the second flow path 42 of the manifold 40. The cooling medium that flows into the second flow path 42 flows out to the outside through the joint 52.

As described above, the optical module unit MU is used with the cooling medium circulating through the flow path WP1 of each optical module M2. When a drive current is supplied to the semiconductor laser element 11 via a pair of connectors 33 provided in each optical module M2 provided in the optical module unit MU, laser light is emitted from the semiconductor laser element 11 and the semiconductor laser element 11 generates heat. The heat generated from the semiconductor laser element 11 is transferred to the cooling medium via the mount 10. In this way, heat is dissipated from the semiconductor laser element 11 in each optical module M2.

[Laser device]
First Embodiment
Fig. 11 is a diagram showing the main configuration of a laser device according to a first embodiment of the present invention. As shown in Fig. 11, a laser device 60 of this embodiment includes a pumping light source 61, a combiner 62, a resonator fiber 63, an amplification fiber 64, a resonator fiber 65, a delivery fiber 66, and an output end 67. Such a laser device 60 is a so-called forward pumping type fiber laser device.

Here, the resonator fiber 63, the amplification fiber 64, and the resonator fiber 65 constitute the resonator R. The resonator R generates signal light, which is laser light, using the excitation light output by the excitation light source 61. Note that in this specification, the excitation light source 61 side from the amplification fiber 64 may be referred to as the "front" and the output end 67 side may be referred to as the "rear."

In addition, in FIG. 11, the fusion spliced portions of the various fibers are indicated by an x mark. In reality, this fusion spliced portion is disposed inside a reinforcing portion (not shown) for protection. The reinforcing portion, for example, comprises a fiber housing having a groove formed therein capable of housing an optical fiber, and a resin for fixing the various fibers to the fiber housing with the fusion spliced portion housed in the groove of the fiber housing. Note that in figures other than FIG. 11, the fusion spliced portions of the various fibers are also indicated by an x mark.

The excitation light source 61 includes a plurality of optical module units MU, and outputs excitation light (forward excitation light). For example, the optical module units MU shown in FIG. 10 can be used. The number of optical module units MU provided in the excitation light source 61 can be any number depending on the power of the laser light output from the output end 67 of the laser device 60. The combiner 62 couples the excitation light output from each of the optical module units MU provided in the excitation light source 61 to the front end of the resonator R (the front end of the resonator fiber 63).

The front end of the resonator fiber 63 is fusion-spliced to the combiner 62, and the rear end of the resonator fiber 63 is fusion-spliced to the front end of the amplification fiber 64. An HR-FBG (High Reflectivity-Fiber Bragg Grating) 63a is formed in the core of the resonator fiber 63. The HR-FBG 63a is adjusted to reflect light of the signal light wavelength emitted by the active element of the excited amplification fiber 64 with a reflectivity of almost 100%. The HR-FBG 63a has a structure in which high refractive index portions are repeated at a constant interval along its longitudinal direction.

The amplification fiber 64 has a core doped with one or more types of active elements, a first cladding covering the core, a second cladding covering the first cladding, and a protective coating covering the second cladding. In other words, the amplification fiber 64 is a double-clad fiber. The active elements doped in the core are, for example, rare earth elements such as erbium (Er), ytterbium (Yb), or neodymium (Nd). These active elements emit light in an excited state.

The core and the first cladding can be made of silica glass or the like. The second cladding can be made of a resin such as a polymer. The protective coating can be made of a resin material such as an acrylic resin or a silicone resin. The amplification fiber 64 is a single-mode fiber. Note that a multimode fiber or a few-mode fiber can also be used as the amplification fiber 64. The number of modes that propagate through the few-mode fiber is, for example, 2 to 25.

The front end of the resonator fiber 65 is fusion-spliced to the rear end of the amplification fiber 64, and the rear end of the resonator fiber 65 is fusion-spliced to the front end of the delivery fiber 66. An OC-FBG (Output Coupler-Fiber Bragg Grating) 65a is formed in the core of the resonator fiber 65. The OC-FBG 65a has a structure similar to that of the HR-FBG 63a, but is adjusted to reflect light with a lower reflectance than the HR-FBG 63a. For example, the OC-FBG 65a is adjusted so that the reflectance for light of the signal light wavelength is about 10 to 20%.

In the amplification fiber 64, the signal light reflected by the HR-FBG 63a and the OC-FBG 65a travels back and forth in the longitudinal direction of the amplification fiber 64. As the signal light travels back and forth, it is amplified and becomes laser light. In this way, in the resonator R, the light is amplified and signal light (laser light) is generated.

The delivery fiber 66 transmits the laser light generated in the resonator R. The delivery fiber 66 includes a core, a cladding surrounding the core, and a coating covering the cladding. For example, a single-mode fiber can be used as the delivery fiber 66. Note that the delivery fiber 66 may also be, for example, a multimode fiber or a few-mode fiber.

The output end 67 is connected to the rear end of the delivery fiber 66 and emits the laser light transmitted by the delivery fiber 66. The output end 67 has a columnar body (light-transmitting columnar member) that transmits the laser light transmitted by the delivery fiber 66. This member is called an end cap.

The laser device 60 of this embodiment includes, for example, a plurality of optical module units MU as shown in FIG. 10. Each optical module unit MU includes, for example, a plurality of optical modules M2 that are modularized from the semiconductor laser device 1 of the first embodiment that allows high output while reducing the height dimension. Therefore, in the laser device 60 of this embodiment, the excitation light source 61 can be made compact while providing high output.

Second Embodiment
12 is a diagram showing the main configuration of a laser device according to a second embodiment of the present invention. As shown in FIG. 12, a laser device 70 of this embodiment includes a laser light source 71, a combiner 72, a delivery fiber 73, and an output end 74.

The laser light source 71 includes a plurality of optical module units MU and outputs laser light. For example, the optical module units MU shown in FIG. 10 can be used. The number of optical module units MU provided in the laser light source 71 can be any number depending on the power of the laser light output from the output end 74 of the laser device 70. The combiner 72 combines the laser light output from each of the optical module units MU provided in the laser light source 71 into the delivery fiber 73.

The delivery fiber 73 transmits the laser light combined by the combiner 72. The delivery fiber 73 has a core, a cladding surrounding the core, and a coating covering the cladding. For example, a single-mode fiber can be used as the delivery fiber 73. Note that the delivery fiber 73 may be, for example, a multimode fiber or a few-mode fiber. The output end 74 is connected to the rear end of the delivery fiber 73 and emits the laser light transmitted by the delivery fiber 73.

The laser device 70 of this embodiment includes, for example, a plurality of optical module units MU as shown in FIG. 10. Each optical module unit MU includes, for example, a plurality of optical modules M2 that are modularized semiconductor laser device 1 of the first embodiment that can achieve high output while reducing the height dimension. Therefore, in the laser device 70 of this embodiment, the laser light source 71 can be made compact while achieving high output.

Although an embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be freely modified within the scope of the present invention. For example, in the above embodiment, an example was described in which the mount 10 is formed with six steps ST. However, the number of steps ST formed on the mount 10 may be less than six steps or more than six steps.

In the above embodiment, an example has been described in which two semiconductor laser elements 11 are mounted on each of the step portions ST provided on the mount 10. However, three or more semiconductor laser elements 11 may be mounted on each of the step portions ST provided on the mount 10. Even if three or more semiconductor laser elements 11 are mounted on each of the step portions ST of the mount 10, the laser light emitted from each semiconductor laser element 11 is combined into one by the combining optical system 14.

In the above-described embodiment, an example has been described in which the synthesis optical system 14 performs polarization synthesis of the laser light reflected by the collimating optical system 12 (collimating mirror 12b) and the laser light reflected by the collimating optical system 13 (reflection mirror 13c). However, the method of synthesizing the laser light performed by the synthesis optical system 14 is not limited to polarization synthesis, and other synthesis methods such as wavelength synthesis can be used.

In the above-described first embodiment, an example has been described in which the polarization direction of the laser light reflected in the +X direction by the collimating mirror 12b provided in the semiconductor laser device 1 is changed by the 1/2 wavelength plate 14a and combined with the laser light reflected in the +X direction by the reflecting mirror 13c. However, conversely, the polarization direction of the laser light reflected in the +X direction by the reflecting mirror 13c provided in the semiconductor laser device 1 may be changed by the 1/2 wavelength plate 14a and combined with the laser light reflected in the +X direction by the collimating mirror 12b.

Similarly, in the above-mentioned second embodiment, an example has been described in which the polarization direction of the laser light reflected in the +X direction by the collimating mirror 12b provided in the semiconductor laser device 2 is changed by the 1/2 wavelength plate 14a and combined with the laser light reflected in the +X direction by the collimating mirror 13d. However, conversely, the polarization direction of the laser light reflected in the +X direction by the collimating mirror 13d provided in the semiconductor laser device 2 may be changed by the 1/2 wavelength plate 14a and combined with the laser light reflected in the +X direction by the collimating mirror 12b.

The laser device 60 shown in FIG. 11 and the laser device 70 shown in FIG. 12 each have a single output end 67, 74, but an optical fiber or the like may be further connected to the output end 67, 74. Also, a beam combiner may be connected to the output end 67, 74, and the laser light from multiple laser devices may be bundled.

The laser device may also be a fiber laser device of the MOPA (Master Oscillator Power Amplifier) type. Furthermore, the laser device may be a laser device in which the resonator is composed of something other than an optical fiber, such as a semiconductor laser (DDL: Direct Diode Laser) or a disk laser, and the laser light emitted from the resonator is focused into an optical fiber.

1, 2...semiconductor laser device, 10...mount, 11...semiconductor laser element, 12...collimating optical system, 12a...collimating lens, 12b...collimating mirror, 13...collimating optical system, 13a, 13b...collimating lens, 13c...reflecting mirror, 13d...collimating mirror, 14...combining optical system, 14a...half-wave plate, 14b...reflecting mirror, 14c...polarizing beam splitter, 15...focusing optical system, 60...laser device, 62...combiner, 64...amplifying fiber, 67...output end, 70...laser device, 72...combiner, 74...output end, ST...step

Claims (10)

A stepped mount member having a plurality of steps;
a plurality of semiconductor laser elements mounted on each of the step portions of the mount member, the semiconductor laser elements emitting laser light in a first direction;
a plurality of collimating optical systems provided on each of the step portions of the mount member corresponding to the semiconductor laser elements, the collimating optical systems reflecting laser light emitted from the corresponding semiconductor laser elements toward a second direction intersecting the first direction;
a combining optical system that combines the laser beams reflected by the collimating optical system;
Equipped with
The first direction is a direction along both a surface of the step portion and a step surface located between two adjacent step portions among the plurality of step portions.
Semiconductor laser device. At least one of the collimating optical systems provided on each of the step portions of the mount member is
a first collimating lens that collimates a component of a laser beam emitted from a corresponding semiconductor laser element in a third direction perpendicular to the first direction and the second direction;
a collimating mirror that collimates a component of the laser light emitted from the corresponding semiconductor laser element in the second direction and reflects the component in the second direction;
The semiconductor laser device according to claim 1 . At least one of the remaining collimating optical systems provided on each of the step portions of the mount member is
a first collimating lens that collimates a component of the laser light emitted from the corresponding semiconductor laser element in the third direction;
a second collimating lens that collimates a component of the laser light emitted from the corresponding semiconductor laser element in the second direction;
a reflecting mirror that reflects the laser light collimated by the second collimating lens toward the second direction;
3. The semiconductor laser device according to claim 2, comprising: The semiconductor laser device according to claim 3, wherein the semiconductor laser elements are linearly arranged in the second direction. the collimating optical system provided in each of the step portions of the mount member includes the first collimating lens and the collimating mirror,
The semiconductor laser element is disposed so that the distance from the laser light emission end to the collimating mirror is the same.
3. The semiconductor laser device according to claim 2. A stepped mount member having a plurality of steps;
a first semiconductor laser element mounted on each of the steps of the mount member;
a second semiconductor laser element mounted on each of the steps of the mount member;
a first fast axis collimator lens provided on each step of the mount member in correspondence with the first semiconductor laser element;
a second fast axis collimator lens provided on each step of the mount member in correspondence with the second semiconductor laser element;
a slow-axis collimating mirror provided on each step of the mount member in correspondence with the first semiconductor laser element;
a slow axis collimator lens provided on each step of the mount member in correspondence with the second semiconductor laser element;
a reflecting mirror provided on each step of the mount member in correspondence with the second semiconductor laser element;
a combining optical system that combines the laser light reflected by the slow axis collimator mirror and the laser light reflected by the reflecting mirror;
A semiconductor laser device comprising: The combining optical system includes a polarizing element that changes the polarization state of the laser light reflected by either the slow axis collimator mirror or the reflecting mirror;
a polarization combining optical system that combines the laser light passing through the polarizing element with the laser light reflected by the other of the slow axis collimator mirror and the reflecting mirror;
7. The semiconductor laser device according to claim 6, comprising: The semiconductor laser device according to any one of claims 1 to 7, further comprising a focusing optical system that focuses the laser light combined by the combining optical system onto the core of an optical fiber. A semiconductor laser device according to any one of claims 1 to 8,
a combiner that optically combines laser beams output from the semiconductor laser devices;
an output end that outputs the laser light combined by the combiner to an outside;
A laser device comprising: A semiconductor laser device according to any one of claims 1 to 8,
an amplifying fiber having a core doped with rare earth;
a combiner that couples the laser light output from the semiconductor laser device as pumping light to the amplification fiber;
an output end for outputting the light amplified by the amplifying fiber to the outside;
A laser device comprising:

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