Optical device for semiconductor laser and laser device having such an optical device

Abstract

More specifically, the present invention relates to an optical device 12 for a semiconductor laser 10, which is a single emitter semiconductor laser, comprising a fast axis collimating lens 13, the optical device 12 being designed such that the laser radiation 11 emitted from the semiconductor laser 10 passes through the fast axis collimating lens 13, and a slow axis collimating lens 14 including an entrance surface 15 and an exit surface 16, the optical device 12 being designed such that the laser radiation 11 passing through the fast axis collimating lens 13 enters the slow axis collimating lens 14 through the entrance surface 15 and exits the slow axis collimating lens 14 through the exit surface 16, the entrance surface 15 being at least partially concave and the exit surface 16 being at least partially convex.

Description

[Technical Field]

[0001] The present invention relates to an optical device for a semiconductor laser and a laser device having such an optical device.

[0002] According to the preamble of claim 1, the invention relates to an optical arrangement of a semiconductor laser, in particular a single-emitter semiconductor laser, and to a laser device comprising such an optical arrangement. [Background technology]

[0003] Optical and laser devices of the above-mentioned type are known. Figure 1 shows an example of such a laser device with such an optical device. The laser device according to Figure 1 comprises a single-emitter semiconductor laser 1 having an output face from which laser radiation 2 emerges. The laser radiation 2 propagating in the z-direction has different divergences in a first direction x and a second direction y, where the first direction x corresponds to the slow axis direction of the laser radiation 2 and the second direction y extends into the plane of Figure 1 and corresponds to the fast axis direction of the laser radiation 2. The divergence in the fast axis direction is significantly greater than in the slow axis direction.

[0004] The optical device according to Fig. 1 comprises a fast axis collimating lens 3. The fast axis collimating lens 3 is designed as a cylindrical lens, the cylindrical axis of which extends in a first direction x. The optical device according to Fig. 1 further comprises a slow axis collimating lens 4, which includes an entrance surface 5 and an exit surface 6. The entrance surface 5 is flat, and the exit surface 6 is designed as a convex cylindrical lens, the cylindrical axis of which extends in a second direction y. The fast axis collimating lens 3 significantly reduces the divergence of the laser radiation 2 in the fast axis direction, or the laser radiation 2 in the fast axis direction is largely collimated. The slow axis collimating lens 4 significantly reduces the divergence of the laser radiation 2 in the slow axis direction, or the laser radiation 2 is largely collimated in the slow axis direction.

[0005] It turns out that the large distance a1 between the exit facet of the semiconductor laser 1 and the exit facet 6 of the slow-axis collimating lens 4 is a disadvantage in such optical devices or such laser devices. In the prior art, this distance a1 is between 10 mm and 20 mm. When several of these laser devices are combined in one housing, the large distance results in a lot of unused space in the housing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 101717 Summary of the Invention [Problem to be solved by the invention]

[0007] Based on this prior art, the present invention has the task of creating an optical and laser device of the type mentioned at the outset which requires less installation space. [Means for solving the problem]

[0008] This object is achieved according to the invention by an optical device of the type mentioned at the beginning having the features of claim 1 and by a laser device of the type mentioned at the beginning having the features of claim 10. The dependent claims relate to preferred embodiments of the invention.

[0009] According to claim 1, the entrance surface is at least partially concave and the exit surface is at least partially convex. With such a design, the distance between the exit surface of the semiconductor laser and the exit surface of the slow-axis collimating lens can be significantly reduced. For example, the distance between the exit surface of the semiconductor laser and the exit surface of the slow-axis collimating lens can be between 3 mm and 15 mm, particularly between 5 mm and 11 mm, and preferably between 7 mm and 8 mm. This results in less unused space in the housing when combining several laser devices in one housing.

[0010] The slow axis collimating lens comprises a transparent substrate on which both the entrance surface and the exit surface are formed, and in particular, it can be realized that the slow axis collimating lens is a monolithic component, which makes the optical device relatively compact and robust.

[0011] It can be realized that the size of the concave section of the entrance surface or entrance surface in a first direction corresponding to the slow axis direction of the laser radiation emitted by the semiconductor laser is smaller than the size of the convex section of the exit surface or exit surface in the first direction, in particular the size of the concave portion of the entrance surface or entrance surface in the first direction is 0.3 to 0.7 times larger than the size of the convex portion of the exit surface or exit surface in the first direction.

[0012] The effective focal length of the slow-axis collimating lens formed by the entrance and exit faces can be between 5 mm and 50 mm, particularly between 10 mm and 30 mm, preferably between 13 mm and 20 mm, e.g., about 15 mm high. An advantage of the optical device according to the invention is that a relatively large effective focal length, e.g., about 15 mm, can be maintained despite a very small distance between the exit face of the semiconductor laser and the exit face of the slow-axis collimating lens, e.g., 7 mm to 8 mm. This is achieved by the concave entrance face, which expands the laser radiation impinging on it before it is largely collimated by the convex exit face.

[0013] It can be provided that the fast axis collimating lens is designed as a cylindrical lens, the cylindrical axis of which extends in the first direction.

[0014] Both the entrance surface and the exit surface of the slow axis collimating lens are designed as cylindrical lenses, and it can be realized that the cylindrical axes of the entrance surface and the exit surface are parallel to each other, in particular that the cylindrical axes extend in a second direction that is perpendicular to the first direction and corresponds to the fast axis direction of the laser radiation emitted from the semiconductor laser.

[0015] Furthermore, the cross section of the cylindrical shape of the entrance surface and / or the cross section of the cylindrical shape of the exit surface deviates from a circular shape, and in particular, the cylindrical lens forming the entrance surface and / or the cylindrical lens forming the exit surface has an aspherical shape.

[0016] The deviation from a circular shape of the cross section of the cylindrical shape of the entrance surface may be different from the deviation from a circular shape of the cross section of the cylindrical shape of the exit surface.

[0017] The optical device can be configured such that the intensity distribution of the laser radiation emitted from the exit surface deviates from a homogeneous intensity distribution by the aspherical shape of the entrance and / or exit surface. This allows the light distribution of collimated laser radiation to be influenced by targeted adjustment of the aspherical shape. Compared to the prior art, this distribution can be advantageously improved for applications other than collimation. For example, fiber coupling of laser radiation can be performed more efficiently by concentrating the energy in the center of the fiber core. In addition, the arrangement of two cylindrical lenses in one optical component offers the possibility of beam shaping with a certain number of surfaces in the beam path.

[0018] According to claim 10, a laser device comprises a semiconductor laser, in particular a single-emitter semiconductor laser, and an optical device according to the invention.

[0019] Further features and advantages of exemplary embodiments of the present invention are described below with reference to the drawings, in which the same reference numbers are used for the same or similar parts and parts with the same or similar functions. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic side view of a prior art laser device. [Figure 2] 1 is a schematic side view of a laser device according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0021] The drawings are depicted in a Cartesian coordinate system, with the y direction extending into the drawing plane of the drawing.

[0022] It is not necessary for a device according to the invention to have all of the features described below, and it is also possible for a device according to the invention to have only individual features of the exemplary embodiments described below.

[0023] The laser device according to FIG. 2 comprises a semiconductor laser 10, in particular a single-emitter semiconductor laser, having an exit surface from which laser radiation 11 emerges. The laser radiation 11 propagating in the z direction has different divergences in a first direction x and a second direction y, where the first direction x corresponds to the slow axis direction of the laser radiation 11, and the second direction y extends in the plane of FIG. 2 and corresponds to the fast axis direction of the laser radiation 2. The divergence in the fast axis direction is significantly greater than in the slow axis direction. The laser device shown in FIG. 2 further comprises an optical device 12 according to the present invention. This optical device 12 comprises a fast axis collimating lens 13. The fast axis collimating lens 13 is designed as a cylindrical lens, with its cylindrical axis extending in the first direction x. The optical device 12 further comprises a slow axis collimating lens 14, which includes an entrance surface 15 and an exit surface 16. The entrance surface 15 is designed as a concave cylindrical lens and the exit surface 16 is designed as a convex cylindrical lens, the cylinder axes of which extend in the second direction y.

[0024] The fast axis collimating lens 13 significantly reduces the divergence of the laser radiation 11 in the fast axis direction, or the laser radiation 11 is highly collimated in the fast axis direction. The slow axis collimating lens 14 significantly reduces the divergence of the laser radiation 11 in the slow axis direction, or the laser radiation 11 is highly collimated in the slow axis direction.

[0025] The concave entrance surface 15 has an extent in the x-direction of only about half the extent in the x-direction of the exit surface 16. Alternatively, it is possible to choose the extent of the entrance surface 15 in the x-direction to be exactly the same as the extent of the exit surface 16 in the x-direction. However, in that case, since the beam diameter of the laser radiation 11 is relatively small when it strikes the entrance surface 15, it is sufficient to provide a concave curvature only in the central section.

[0026] Slow-axis collimating lens 14 is a monolithic optical component formed with entrance surface 15 and exit surface 16. Entrance surface 15 and exit surface 16 each have a cylindrical cross section that deviates from a circular shape; specifically, the cylindrical lenses that form entrance surface 15 and exit surface 16 have aspheric shapes. The deviation from a circular shape of the cylindrical cross section of entrance surface 15 may be different from the deviation from a circular shape of the cylindrical cross section of exit surface 16.

[0027] The distance a2 between the exit surface of the semiconductor laser 10 and the exit surface 16 of the slow axis collimating lens 14 is between 7 mm and 8 mm.

Claims

1. 1. An optical device (12) for a semiconductor laser (10), in particular a single-emitter semiconductor laser, comprising a fast-axis collimating lens (13), configured so that laser radiation (11) emitted by the semiconductor laser (10) passes through the fast-axis collimating lens (13), and a slow-axis collimating lens (14) having an entrance surface (15) and an exit surface (16), wherein the optical device (12) is configured so that the laser radiation (11) having passed through the fast-axis collimating lens (13) enters the slow-axis collimating lens (14) through the entrance surface (15) and exits the slow-axis collimating lens (14) through the exit surface (16), wherein the entrance surface (15) is at least partially concave and the exit surface (16) is at least partially convex; Both the entrance surface (15) and the exit surface (16) of the slow axis collimating lens (14) are designed as cylindrical lenses, and the cylindrical axes of the entrance surface (15) and the exit surface (16) are parallel to each other; the entrance surface (15) and / or the exit surface (16) have an aspherical shape in which the cylindrical cross section of the entrance surface (15) and / or the cylindrical cross section of the exit surface (16) deviates from a circular shape, 1. An optical device (12) characterized in that the aspherical shape of the entrance surface (15) and / or the exit surface (16) is configured to generate an intensity distribution in the laser radiation (11) emerging from the exit surface (16) that deviates from a homogeneous intensity distribution.

2. 2. The optical device (12) according to claim 1, wherein the slow axis collimating lens (14) comprises a transparent substrate on which both the entrance surface (15) and the exit surface (16) are formed, and in particular, the slow axis collimating lens (14) is a monolithic component.

3. 2. The optical device (12) according to claim 1, wherein the size of the concave portion of the entrance surface (15) or the entrance surface (15) in a first direction (x) is smaller than the size of the convex portion of the exit surface (16) or the exit surface (16) in the first direction (x), in particular the size of the concave portion of the entrance surface (15) or the entrance surface (15) in the first direction (x) is 0.3 to 0.7 times the size of the convex portion of the exit surface (16) or the exit surface (16) in the first direction (x), and the first direction (x) corresponds to the slow axis direction of the laser radiation (11) emitted by the semiconductor laser (10).

4. 2. The optical device (12) of claim 1, wherein the effective focal length of the slow axis collimating lens (14) formed by the entrance surface (15) and the exit surface (16) is between 5 mm and 50 mm, in particular between 10 mm and 30 mm, preferably between 13 mm and 20 mm, and more preferably about 15 mm.

5. 2. The optical device (12) according to claim 1, characterized in that the fast axis collimating lens (13) is designed as a cylindrical lens, the cylindrical axis of which extends in a first direction (x) corresponding to the slow axis direction of the laser radiation (11) emitted by the semiconductor laser (10).

6. 2. The optical device (12) according to claim 1, characterized in that the cylindrical axes of the entrance surface (15) and the exit surface (16) extend in a second direction (y) perpendicular to a first direction (x) corresponding to a slow axis direction of the laser radiation (11) emitted by the semiconductor laser (10) and corresponding to a fast axis direction of the laser radiation (11) emitted by the semiconductor laser (10).

7. 2. The optical device (12) according to claim 1, wherein the cylindrical lens forming the entrance surface (15) and / or the cylindrical lens forming the exit surface (16) have an aspherical shape.

8. 2. The optical device (12) of claim 1, wherein the deviation of the cylindrical shape of the entrance surface (15) from the circular shape of the cross section is different from the deviation of the cylindrical shape of the exit surface (16) from the circular shape of the cross section.

9. 9. A laser device, characterized in that it comprises a semiconductor laser (10), in particular a single-emitter semiconductor laser, and an optical device (12) according to any one of claims 1 to 8.

10. 10. The laser device according to claim 9, wherein the semiconductor laser (10) has an exit surface for laser radiation (11) generated by the semiconductor laser (10), and the distance (a2) between the exit surface of the semiconductor laser (10) and the exit surface (16) of the slow axis collimating lens (14) is between 3 mm and 15 mm, in particular between 5 mm and 11 mm, preferably between 7 mm and 8 mm.

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