Compact semiconductor laser

Abstract

The utility model discloses a compact semiconductor laser, and mainly relates to the field of lasers. Comprising a light emitting unit, a shaping unit, a beam combining unit and a coupling unit which are sequentially arranged in the light beam propagation direction, the light emitting unit comprises multiple sets of laser chips, and the shaping unit comprises but is not limited to a fast axis collimating lens, a slow axis beam expanding collimating lens set, a small reflector and a large reflector. The slow-axis beam-expanding collimating lens group comprises a concave cylindrical mirror used for light spot beam expanding and a convex cylindrical mirror used for collimating after beam expanding, the beam combining unit comprises but is not limited to a polarization splitting prism and a fast-axis compression lens, and the coupling unit comprises but is not limited to a focusing lens. The beneficial effects of the utility model are that the laser can solve the technical problem that the size of a conventional laser cannot meet the requirements of the high-precision field, and greatly reduces the distance between the slow-axis collimating lens and the laser chip by expanding and collimating the slow-axis light spot in advance, thereby further reducing the size of the laser.

Description

Technical Field

[0001] The utility model relates to the field of lasers, in particular to a compact semiconductor laser. Background Art

[0002] Semiconductor lasers have the characteristics of small size, light weight, long life, low power consumption, and wide wavelength coverage, and are used in laser display, material processing, laser communication, and laser medicine. They have important applications in industrial processing, biological medicine, national defense and other fields. With the development of technology, whether as a pump source for fiber / solid-state lasers or for direct application, further requirements are put forward for semiconductor laser light sources. Under the demand for higher power, in order to maintain high beam quality, beam combining is necessary. The beam combining scheme is the basis and prerequisite for realizing the output of high-power semiconductor lasers. Under the demand for smaller volume, it is necessary to further compress the spatial distance in the fast axis direction;

[0003] In existing semiconductor lasers, multiple laser chips are arranged in two rows and the two rows of laser chips are arranged facing each other. The light beam emitted by each laser chip passes through a fast axis collimating lens, a volume Bragg grating, a slow axis collimating lens and a small mirror. After passing through the small mirror, the spatial position of the light beam will change, and a spot for verifying the superposition of the light beam in the fast axis direction is formed with other semiconductor laser chips in the same row, thereby forming spatial beam combining; To further increase the power, on the basis of spatial optical beam combining in one row, the light beam emitted by one row of the two rows of laser chips is changed in direction by a large mirror, and the polarization direction is changed by a polarization beam splitter prism. The light beam of the other row of laser chips enters the polarization beam splitter prism in an orthogonal direction, thereby realizing polarization beam combining; Due to the continuous superposition of laser chips in the fast axis direction, the size in the fast axis direction is larger than that in the slow axis direction after spatial beam combining, which affects the spot and NA output by the coupling lens. Through a fast axis compression lens, the light beam in the fast axis direction is compressed to achieve the purpose of making the spot sizes in the fast and slow axis directions basically the same. Finally, the combined spot is coupled into the optical fiber through a focusing lens;

[0004] Although existing semiconductor lasers are relatively perfect, the current technology has the following problems: In a semiconductor laser, the slow axis collimating lens and the small mirror are on the same side, that is, the spot in the slow axis direction needs to change the optical path direction through a cylindrical collimation and then a mirror. Due to the limitations of the focal length and working distance of the slow axis collimating lens, the optical path between the slow axis collimating lens and the laser chip occupies a large space, resulting in a large size of the semiconductor laser. At present, in high-end and high-precision application fields such as military industry, aerospace, etc., the volume requirements for semiconductor lasers are getting smaller and smaller. Therefore, there is still room for optimization in the volume of existing semiconductor lasers. Summary of the Utility Model

[0005] The purpose of the present utility model is to provide a compact semiconductor laser, which can solve the technical problem that the volume of the existing laser cannot meet the requirements of the high-precision field. By pre-expanding and collimating the slow-axis light spot, the distance between the slow-axis collimating lens and the laser chip is greatly reduced, and further the volume of the laser is reduced to meet the requirements of the high-precision field for the volume of the laser.

[0006] To achieve the above object, the present utility model is realized through the following technical solutions:

[0007] A compact semiconductor laser includes a light-emitting unit, a shaping unit, a beam combining unit, and a coupling unit arranged in sequence along the light beam propagation direction. The light-emitting unit includes multiple groups of laser chips. The shaping unit includes, but is not limited to, a fast-axis collimating lens, a slow-axis expanding collimating lens group, a small reflector, and a large reflector. The slow-axis expanding collimating lens group includes a concave cylindrical mirror for light spot expansion and a convex cylindrical mirror for collimation after expansion. The beam combining unit includes, but is not limited to, a polarization beam splitter prism and a fast-axis compression lens. The coupling unit includes, but is not limited to, a focusing lens.

[0008] Further, the small reflector is located between the concave cylindrical mirror and the convex cylindrical mirror.

[0009] Further, two adjacent laser chips share one slow-axis expanding collimating lens group.

[0010] Further, two adjacent laser chips share the convex cylindrical mirror in one slow-axis expanding collimating lens group.

[0011] Further, the concave cylindrical mirror in one laser chip is located before the small reflector, and the concave cylindrical mirror in the other laser chip is located after the small reflector.

[0012] Further, there are two groups of laser chips, and the two groups of laser chips are arranged oppositely, and each group of laser chips is a plurality of chips located on the same side.

[0013] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0014] 1. The structure of the present utility model uses a slow-axis expanding collimating lens group composed of a concave cylindrical mirror and a convex cylindrical mirror to replace the slow-axis collimating lens of the traditional laser, realizing pre-expansion of the light beam, and thus greatly shortening the working distance under the same focal length, and greatly shortening the distance in the vertical direction of the laser chip while ensuring the same optical path, so that the overall volume of the laser is smaller, meeting the requirements of the high-precision field for the volume of the laser;

[0015] 2. The structure of the present utility model will not re-transform parts such as the light-emitting unit, beam-combining unit, and coupling unit of the existing laser. It only needs to transform the slow-axis collimating lens in the original shaping unit into a slow-axis beam-expanding collimating lens group composed of a concave cylindrical mirror and a convex cylindrical mirror. Thus, while making minor improvements to the inside of the laser, the distance in the vertical direction of the laser chip is greatly reduced, making it more convenient to improve the existing laser. After simple improvement, the existing laser can meet the requirements for the volume of the laser in the high-precision field, improving the practicability and convenience of transforming and applying the existing laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. Figure 1 is a schematic diagram of the usage scenario of the slow-axis collimating lens of the present utility model.

[0017] FIG. Figure 2 is a schematic structural diagram of the present utility model.

[0018] FIG. Figure 3 is a schematic structural diagram comparing the slow-axis beam-expanding collimating lens group and the slow-axis collimating lens of the present utility model.

[0019] FIG. Figure 4 is a schematic structural diagram of the distribution positions of adjacent laser chips of the present utility model.

[0020] FIG. Figure 5 is a schematic structural diagram of the distribution position of the convex cylindrical mirror of the present utility model.

[0021] Reference numerals shown in the drawings:

[0022] 1. Laser chip; 2. Fast-axis collimating lens; 3. Small mirror; 4. Large mirror; 5. Concave cylindrical mirror; 6. Convex cylindrical mirror; 7. Polarizing beam splitter prism; 8. Fast-axis compression lens; 9. Focusing lens; 10. Slow-axis collimating lens. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following further elaborates the present utility model in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present utility model and not to limit the scope of the present utility model. In addition, it should be understood that after reading the content taught by the present utility model, those skilled in the art can make various changes or modifications to the present utility model, and these equivalent forms also fall within the scope defined by this application.

[0024] Referring to Figure 2 and Figure 3, the utility model relates to a compact semiconductor laser. The main structure includes a light-emitting unit, a shaping unit, a beam combining unit, and a coupling unit arranged in sequence along the light beam propagation direction. The light-emitting unit includes a plurality of laser chips 1 arranged in a straight line, and the strip widths, cavity lengths, and fast and slow axis divergence angles of the plurality of laser chips 1 are all different. The laser emitted by the light-emitting unit passes through the shaping unit, the beam combining unit, and the coupling unit in sequence and is coupled into the output optical fiber. The light-emitting unit is used to emit laser. The laser chips 1 are arranged in the order of the same-side chips and staggered on the opposite side. The shaping unit includes, but is not limited to, a fast-axis collimating lens 2, a slow-axis beam expanding and collimating lens group, a small mirror 3, and a large mirror 4. The shaping unit is used to shape the laser beam. Specifically, the fast-axis collimating lens 2 and the slow-axis beam expanding and collimating lens group are respectively used for collimation in the fast-axis and slow-axis directions, and the small mirror 3 and the large mirror 4 are used to change the direction of the light beam. The slow-axis beam expanding and collimating lens group includes a concave cylindrical mirror 5 for spot expansion and a convex cylindrical mirror 6 for collimation after expansion. In the shaping unit, the slow-axis beam expanding and collimating lens group uses the front concave cylindrical mirror 5 for expansion and then uses the rear convex cylindrical mirror 6 to collimate the optical path after changing the optical path through the mirror, compared with Figure 1 the prior art in which uses a common slow-axis collimating lens 10. By using the concave cylindrical mirror 5, beam expansion can be carried out in advance, the working distance is shortened under the same focal length, and the distance perpendicular to the laser chip 1 direction is shortened while ensuring the optical path remains unchanged. Since there is an interval of 5 mm to 8 mm between the two chips in the horizontal direction, it does not affect the spatial distance of the semiconductor laser in the horizontal direction either. Thus, the space perpendicular to the laser chip 1 direction is greatly shortened, and the overall volume of the laser is reduced. The beam combining unit includes, but is not limited to, a polarization beam splitting prism 7 and a fast-axis compression lens 8. The polarization beam splitting prism 7 is used to change the polarization direction of the light beam, and a polarization beam combiner can also be used instead. The light beam emitted by one row of laser chips 1 is directly combined by reflection of the small mirror 3 and then enters the polarization beam splitting prism 7. The light beam emitted by the other row of laser chips 1 enters the polarization beam splitting prism 7 after being reflected by the small mirror 3 and the large mirror 4 together, further realizing the combination of multiple groups of light beams and improving the output power of the laser. The fast-axis compression lens 8 is used to compress the combined light spot after passing through the polarization beam splitting prism 7 in the fast-axis direction to achieve the same size as the combined light spot in the slow-axis direction. The compression ratio in the fast-axis direction includes, but is not limited to, 0.4, 0.6. Or the beam combining unit further includes a slow-axis beam expanding lens, which is used to expand the combined light spot after passing through the polarization beam combiner or the polarization beam splitting prism 7 in the slow-axis direction to achieve the same size as the combined light spot in the fast-axis direction. The compression ratio in the fast-axis direction includes, but is not limited to, 1.25, 1.5. The coupling unit includes, but is not limited to, a focusing lens 9, which is used to couple the combined light beam, the fast-axis compressed light beam, and the slow-axis expanded light beam into the optical fiber.

[0025] Preferably, the small mirror 3 is located between the concave cylindrical mirror 5 and the convex cylindrical mirror 6. Such a structure can place the small mirror 3 in the air layer in the middle of the slow-axis beam expansion and collimation lens group, that is, the small mirror 3 is arranged between the concave cylindrical mirror 5 and the convex cylindrical mirror 6, shortening the distance perpendicular to the direction of the laser chip 1 while ensuring the unchanged optical path, which is more convenient and efficient for the improvement of the existing laser.

[0026] Preferably, two adjacent laser chips 1 share a slow-axis beam expansion and collimation lens group. Such a structure can group the two chips on the same side, so that the lasers of the two groups pass through the same slow-axis beam expansion and collimation lens group for beam expansion and collimation, thereby reducing the number of lenses, reducing the distance parallel to the direction of the laser chip 1, further reducing the volume of the laser, reducing the cost of the laser while reducing the number of lenses through which the beam passes, reducing the power loss, and increasing the output power of the laser.

[0027] Preferably, referring to Figure 4 , two adjacent laser chips 1 share the convex cylindrical mirror 6 in a slow-axis beam expansion and collimation lens group. Such a structure enables the two laser beams to be collimated by the same convex cylindrical mirror 6 after being expanded by the concave cylindrical mirrors 5 in their respective slow-axis beam expansion and collimation lenses, changing the number of lenses for adjacent laser chips 1 from 4 to 3, simplifying the process of lens bonding and fixing, so that a certain interval can still exist between adjacent laser chips 1, the lasers emitted by adjacent laser chips 1 do not interfere with each other, and the number of lenses is reduced on the premise of ensuring the laser beam expansion and collimation effect.

[0028] Preferably, referring to Figure 5 , the concave cylindrical mirror 5 in one laser chip 1 is located before the small mirror 3, and the concave cylindrical mirror 5 in the other laser chip 1 is located after the small mirror 3. By pre-defining the position of the convex cylindrical mirror 6 and adjusting the spatial positions of the two concave mirrors, the optical paths of the two beams reaching the convex cylindrical mirror 6 are ensured to be equal, and the beam expansion and collimation effects are the same, realizing the simultaneous collimation of the two beams, so that the beam expansion and collimation of multiple beams are more accurate.

[0029] Preferably, there are two groups of laser chips 1, and the two groups of laser chips 1 are arranged oppositely. Each group of laser chips 1 is a plurality of them located on the same side. The lasers emitted by the plurality of laser chips 1 in each group are separately combined and collimated to form a light spot. The beam of one group is turned and then becomes the same direction as the beam of the other group. The spatial beam combination by the beam combination unit greatly increases the output power of the laser, meeting the requirements of different laser powers.

[0030] Working principle: The structure of the present utility model uses a slow-axis beam expansion and collimation lens group composed of a concave cylindrical mirror 5 and a convex cylindrical mirror 6 to replace the slow-axis collimation lens 10 of a traditional laser, achieving early beam expansion, thereby greatly shortening the working distance under the same focal length and greatly shortening the distance in the vertical direction of the laser chip 1 while ensuring the same optical path, so that the overall volume of the laser is smaller, meeting the requirements for the volume of lasers in the high-precision field; the structure of the present utility model does not require re-transformation of parts such as the light-emitting unit, beam-combining unit, and coupling unit of the existing laser. Only the slow-axis collimation lens 10 in the original shaping unit needs to be transformed into a slow-axis beam expansion and collimation lens group composed of a concave cylindrical mirror 5 and a convex cylindrical mirror 6, thereby greatly reducing the distance in the vertical direction of the laser chip 1 while making minor improvements to the inside of the laser, making it more convenient to improve the existing laser, enabling the existing laser to meet the requirements for the volume of lasers in the high-precision field after simple improvement, and improving the practicability and convenience of transforming and applying the existing laser.

Claims

1. A compact semiconductor laser, comprising a light emitting unit, a shaping unit, a beam combining unit, and a coupling unit sequentially arranged along the light beam propagation direction, characterized in that: The light-emitting unit includes multiple groups of laser chips (1), the shaping unit includes but is not limited to a fast-axis collimating lens (2), a slow-axis beam-expanding and collimating lens group, a small mirror (3), and a large mirror (4), the slow-axis beam-expanding and collimating lens group includes a concave cylindrical mirror (5) for beam expansion and a convex cylindrical mirror (6) for collimation after beam expansion, the beam-combining unit includes but is not limited to a polarization beam-splitting prism (7) and a fast-axis compression lens (8), and the coupling unit includes but is not limited to a focusing lens (9).

2. The compact semiconductor laser according to claim 1, wherein: The small mirror (3) is located between the concave cylindrical mirror (5) and the convex cylindrical mirror (6).

3. The compact semiconductor laser according to claim 1, wherein: Two adjacent laser chips (1) share one slow-axis beam-expanding and collimating lens group.

4. The compact semiconductor laser according to claim 3, characterized in that: Two adjacent laser chips (1) share the convex cylindrical mirror (6) in one slow-axis beam-expanding and collimating lens group.

5. The compact semiconductor laser according to claim 4, wherein: The concave cylindrical mirror (5) in one of the laser chips (1) is located before the small mirror (3), and the concave cylindrical mirror (5) in the other laser chip (1) is located after the small mirror (3).

6. The compact semiconductor laser according to claim 1, characterized in that: There are two groups of the laser chips (1), the two groups of laser chips (1) are arranged oppositely, and each group of laser chips (1) includes multiple ones located on the same side.

Images