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 with an exit face from which laser radiation 2 emerges. The laser radiation 2 propagating in the z direction has different divergence in a first direction x and in a second direction y, the first direction x corresponding to the slow axis direction of the laser radiation 2 and the second direction y extending into the plane of Figure 1 and corresponding 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 face 5 and an exit face 6. The entrance face 5 is flat and the exit face 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 a large distance a1 between the exit face of the semiconductor laser 1 and the exit face 6 of the slow axis collimating lens 4 is a disadvantage in such an optical device or in such a laser device. In the prior art, this distance ai is between 10 mm and 20 mm. If several of these laser devices are combined in one housing, due to the large distance there is 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 invention has the task of creating an optical and laser arrangement 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 characteristic features of claim 1 and by a laser device of the type mentioned at the beginning having the characteristics of claim 10. The dependent claims relate to preferred embodiments of the invention.

[0009] According to claim 1, it is realized that the entrance surface is at least partially concave and the exit surface is at least partially convex. In the case of 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, in particular between 5 mm and 11 mm, 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 and exit surfaces 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 entrance surface or the concave section of the 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 exit surface or the convex section of the exit surface in the first direction, in particular that the size of the entrance surface or the concave portion of the entrance surface in the first direction is 0.3 to 0.7 times larger than the size of the exit surface or the convex portion of the 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, in particular between 10 mm and 30 mm, preferably between 13 mm and 20 mm, for example about 15 mm high. An advantage of the optical device according to the invention is that a relatively large effective focal length, for example about 15 mm, can be maintained despite the very small distance between the exit face of the semiconductor laser and the exit face of the slow-axis collimating lens, for example 7 mm to 8 mm. This is achieved by the concave entrance face, which spreads 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 a first direction.

[0014] It can be realized that both the entrance surface and the exit surface of the slow axis collimating lens are designed as cylindrical lenses, the cylindrical axes of the entrance surface and the exit surface are parallel to each other, in particular the cylindrical axes extend in a second direction which 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 is realized to have an aspheric shape.

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

[0017] The optical device can be set such that the intensity distribution of the laser radiation emerging from the exit surface deviates from a homogeneous intensity distribution by the morphology of the aspheric shape of the entrance and / or exit surface. This allows the light distribution in the collimated laser radiation to be influenced by targeted adjustment of the aspheric shape. Compared to the prior art, this distribution can be advantageously improved for applications other than collimation as well. For example, fiber coupling of the 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 for parts with the same or similar functions. [Brief description of the drawings]

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

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

[0022] It is not necessary for the device according to the invention to have all the features described below: it is also possible for the 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 face from which the laser radiation 11 emerges. The laser radiation 11 propagating in the z-direction has different divergence in a first direction x and in a second direction y, the first direction x corresponding to the slow axis direction of the laser radiation 11 and the second direction y extending in the plane of Fig. 2 and corresponding 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 invention. This optical device 12 comprises a fast axis collimating lens 13. The fast axis collimating lens 13 is designed as a cylindrical lens, the cylindrical axis of which extends in the first direction x. The optical device 12 further comprises a slow axis collimating lens 14, which includes an entrance face 15 and an exit face 16. The entrance face 15 is designed as a concave cylindrical lens and the exit face 16 is designed as a convex cylindrical lens, the cylinder axes of which extend in a 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 face 15 has only about half the extent in the x direction of the exit face 16. It is also possible to choose the extent of the entrance face 15 in the x direction to be exactly the same as the extent of the exit face 16 in the x direction instead. However, in that case, since the beam diameter of the laser radiation 11 is relatively small when it strikes the entrance face 15, it is sufficient to provide a concave curvature only in the central section.

[0026] The slow axis collimating lens 14 is a monolithic optical component formed with an entrance surface 15 and an exit surface 16. The entrance surface 15 and the exit surface 16 each have a cylindrical cross section that deviates from a circular shape; in particular, the cylindrical lens forming the entrance surface 15 and the cylindrical lens forming the exit surface 16 have an aspheric shape. The deviation of the cylindrical cross section of the entrance surface 15 from a circular shape may be different from the deviation of the cylindrical cross section of the exit surface 16 from a circular shape.

[0027] The distance a2 between the emission surface of the semiconductor laser 10 and the emission 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), the fast axis collimating lens (13) being configured such 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), the optical device (12) being configured such 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), characterized in that the entrance surface (15) is at least partially concave and the exit surface (16) is at least partially convex.

2. 2. The optical device (12) of 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, in particular characterized in that the slow axis collimating lens (14) is a monolithic component.

3. 3. The optical device (12) according to claim 1 or 2, characterized in that 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. 4. The optical device (12) according to claim 1, characterized in that 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, more preferably about 15 mm.

5. 5. 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 the first direction (x).

6. 6. The optical device (12) according to claim 1, characterized in that both the entrance surface (15) and the exit surface (16) of the slow axis collimating lens (14) are designed as cylindrical lenses, the cylindrical axes of the entrance surface (15) and the exit surface (16) are parallel to each other, in particular the cylindrical axes extend in a second direction (y) perpendicular to the first direction (x) and corresponding to the fast axis direction of the laser radiation (11) emitted by the semiconductor laser (10).

7. 7. An optical device (12) according to claim 6, characterized in that 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, in particular the cylindrical lens forming the entrance surface (15) and / or the cylindrical lens forming the exit surface (16) have an aspherical shape.

8. 8. The optical device (12) of claim 7, characterized in that the deviation of the cross-section of the cylindrical shape of the entrance surface (15) from the circular shape is different from the deviation of the cross-section of the cylindrical shape of the exit surface (16) from the circular shape.

9. 9. The optical device (12) according to claim 7 or 8, characterized in that the aspheric 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.

10. 10. A laser arrangement, comprising a semiconductor laser (10), in particular a single-emitter semiconductor laser, and an optical device (12) according to any one of claims 1 to 9.

11. 11. The laser device according to claim 10, characterized in that 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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