Quantum cascade semiconductor laser single light spot focusing space beam combining system

Abstract

The invention belongs to the technical field of quantum cascade semiconductor lasers, and discloses a quantum cascade semiconductor laser single light spot focusing space beam combining system which comprises a space beam combining crystal, a longitudinal light beam unit and a multi-path transverse light beam unit. The space beam combining crystal is in a polygon frustum shape, the lower bottom face of the space beam combining crystal serves as an incident face, the upper bottom face serves as an emergent face, and the side face serves as a reflecting face. The longitudinal light beam unit is coaxially arranged on one side of the incident surface, and the multiple transverse light beam units are arranged on one side of the reflecting surface in a one-to-one correspondence manner; a mid-infrared laser beam emitted by the longitudinal beam unit passes through the beam combining crystal, is emitted from the emergent surface, and is focused behind the beam combining crystal; the mid-infrared laser beams emitted by the multi-path transverse beam unit are reflected by the reflecting surface, and after the transmission direction is changed, the mid-infrared laser beams are focused at the same position where the longitudinal laser beams are focused. The system stability can be improved, and the overall light spot size is small; the focusing light spot surface type can be effectively improved, and the symmetry is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of quantum cascade semiconductor lasers and relates to a quantum cascade semiconductor laser single-spot focusing spatial beam combining system. Background Art

[0002] Compared with the current technical solutions such as gain medium and optical parametric oscillation (OPO) in medium-wave infrared lasers, quantum cascade medium-wave infrared devices can achieve compact medium-wave infrared laser output with smaller size, lighter weight and higher conversion efficiency. The sub-cascade semiconductor laser is directly driven by the injected current to obtain the current wavelength laser. The system has a small number of components, which makes it easy to achieve miniaturization and low power consumption. In addition, there are the natural advantages of semiconductor lasers with high reliability and good stability, which are suitable for miniaturized medium-wave infrared systems on various platforms. As the requirements for power consumption, volume and weight of laser light sources become higher and higher, the existing optical parametric oscillation (OPO) equipment technology route is difficult to meet the requirements. Therefore, quantum cascade lasers have unique advantages and become the best choice for future mid- and far-infrared and terahertz band systems.

[0003] The current single-core output power of quantum cascade semiconductor lasers is relatively low. In order to meet the demand for high-power output, spatial beam combining technology is usually used to achieve high-power output. The combined light obtained by ordinary spatial beam combining is a group of collimated beam lattices. Since multiple reflectors are used for beam combining, the size of the front beam reflector limits the rear beam. The multiple light spots used for beam combining are widely spaced. After beam combining, a single light spot cannot be formed within a short distance. The light spot size is large, the beam quality is severely degraded, the application scenarios and application scope are limited, and it is not conducive to practical application scenarios such as back-end fiber bundle coupling, laser processing, and detection tests.

[0004] In order to solve the above problems and obtain a short-distance, small-size single focused light spot, the present invention proposes a quantum cascade semiconductor laser single-spot focusing spatial beam combining system. Summary of the Invention

[0005] (1) Purpose of the invention

[0006] The purpose of the present invention is to propose a quantum cascade semiconductor laser single-spot focusing spatial beam combining system, which aims to solve the technical problems faced by the current mid-infrared quantum cascade semiconductor laser spatial beam combining and the problems of multiple spots, large intervals and reduced beam quality in the spatial beam combining of quantum cascade semiconductor lasers.

[0007] (2) Technical solution

[0008] In order to solve the above technical problems, the present invention provides a quantum cascade semiconductor laser single-spot focusing spatial beam combining system, comprising: a spatial beam combining crystal 7, a longitudinal beam unit, and a multi-path transverse beam unit; the spatial beam combining crystal 7 is in the shape of a polygonal pyramid, the lower bottom surface of the spatial beam combining crystal 7 serves as an incident surface 8, the upper bottom surface serves as an exit surface 9, and the side surfaces serve as reflection surfaces; the longitudinal beam unit is coaxially arranged on one side of the incident surface 8, and the multi-path transverse beam units are arranged one-to-one on one side of the reflection surface; the mid-infrared laser beam emitted by the longitudinal beam unit passes through the beam combining crystal 7, is emitted from the exit surface 9, and is focused behind the beam combining crystal 7; the mid-infrared laser beam emitted by the multi-path transverse beam unit is reflected by the reflection surface, changes the transmission direction, and is focused on the same position where the longitudinal laser beam is focused.

[0009] Furthermore, the longitudinal beam unit includes a longitudinal quantum cascade semiconductor laser 1, a longitudinal collimating lens 2, and a longitudinal focusing lens 3. The mid-infrared divergent laser beam emitted by the longitudinal quantum cascade semiconductor laser 1 becomes a collimated beam after passing through the longitudinal collimating lens 2, and is incident on the incident surface 8 of the spatial beam combining crystal 7 after passing through the longitudinal focusing lens 3.

[0010] Furthermore, each transverse beam unit includes a transverse quantum cascade semiconductor laser 4, a transverse collimating lens 5, and a transverse focusing lens 6. The mid-infrared divergent laser beam emitted by the transverse quantum cascade semiconductor laser 4 is converted into a collimated beam after passing through the transverse collimating lens 5, and is incident on the reflection surface of the spatial beam combining crystal 7 after passing through the transverse focusing lens 6.

[0011] Furthermore, the incident surface 8 and the exit surface 9 of the longitudinal collimating lens 2, the longitudinal focusing lens 3, the transverse collimating lens 5, the transverse focusing lens 6, and the spatial beam combining crystal 7 are all coated with an anti-reflection film for the emission wavelength of the quantum cascade semiconductor laser.

[0012] Furthermore, the reflective surface of the spatial beam combining crystal 7 is coated with a total reflection film layer for the emission wavelength of the quantum cascade semiconductor laser.

[0013] Furthermore, the spatial beam combining crystal 7 is configured as a hexagonal pyramid having six reflection surfaces 10 - 15 .

[0014] Furthermore, the spatial beam combining crystal 7 is configured as a regular hexagonal pyramid.

[0015] Furthermore, the inclination angle of the reflecting surface and the incident angle of the laser beam of the transverse beam unit relative to the reflecting surface are set to ensure that the reflected beam and the longitudinal laser beam are focused at the same position.

[0016] (3) Beneficial effects

[0017] The quantum cascade semiconductor laser single-spot focusing spatial beam combining system provided by the above technical solution has the following beneficial effects:

[0018] (1) In the present invention, a spatial beam combining crystal is used to focus the beams of multiple quantum cascade semiconductor lasers together to form a single light spot.

[0019] (2) Compared with the common spatial beam combining scheme, the arrangement of the collimated beams of the multi-channel quantum cascade semiconductor lasers around the central spot in the present invention can effectively reduce the number of reflectors, improve the system stability, and reduce the overall spot size.

[0020] (3) In the present invention, the arrangement of the collimated light beams of the multi-channel quantum cascade semiconductor laser around the central light spot through the spatial beam combining crystal can effectively improve the focus spot surface shape and enhance the symmetry. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the optical path before the quantum cascade semiconductor laser spatial beam combining and focusing spatial beam combining crystal.

[0022] Figure 2 This is a schematic diagram of the optical path of the spatial beam combining of six longitudinal quantum cascade semiconductor lasers focusing light beams.

[0023] Figure 3 Figures I, II, and III are three-dimensional views of the spatial beam combining crystal in different directions.

[0024] Figure 4 This is a schematic diagram of the distribution of quantum cascade semiconductor laser beams as they pass through a spatial beam-combining crystal before focusing.

[0025] Figure 5 This is a schematic diagram of the optical path after the quantum cascade semiconductor laser spatial beam combining and focusing on the spatial beam combining crystal. DETAILED DESCRIPTION

[0026] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0027] In order to solve a series of problems in the spatial beam combining of numerous beams in ordinary semiconductors, such as the limitation of the size of the front beam reflector on the rear reflected beam (the more beams, the more serious the problem), the large spacing between multiple spots, the large spot size, the serious degradation of beam quality after beam combining and focusing, and the limited application scenarios and application scope, a single-spot spatial beam combining and focusing system of multiple quantum cascade lasers is proposed. Figure 1 This is a schematic diagram of the spatial beam combining optical path of quantum cascade semiconductor lasers. Figure 2 This is a schematic diagram of the optical path of six longitudinal quantum cascade semiconductor laser beams spatially combined. Figure 3 It is a three-dimensional view of the spatial beam combining crystal in different directions. Figure 4This is a schematic diagram of the distribution of quantum cascade semiconductor laser beams when they pass through a spatial beam combining crystal before focusing. Figure 5 This is a schematic diagram of the optical path after the quantum cascade semiconductor laser spatial beam combining and focusing on the spatial beam combining crystal.

[0028] The quantum cascade semiconductor laser single spot focusing spatial beam combining system of this embodiment is as follows Figure 1 、 Figure 2 As shown, it includes: a longitudinal quantum cascade semiconductor laser 1, a longitudinal collimating lens 2, a longitudinal focusing lens 3, a transverse quantum cascade semiconductor laser 4, a transverse collimating lens 5, a transverse focusing lens 6, a spatial beam combining crystal 7, an incident surface 8 of the longitudinal quantum cascade semiconductor laser collimated beam on the spatial beam combining crystal, an exit surface 9 of the longitudinal quantum cascade semiconductor laser collimated beam on the spatial beam combining crystal, and reflection surfaces 10-15 of the transverse quantum cascade semiconductor laser collimated beam on the spatial beam combining crystal.

[0029] The longitudinal collimating lens 2, longitudinal focusing lens 3, transverse collimating lens 5, and transverse focusing lens 6 are made of materials with high transmittance for the wavelength of quantum cascade semiconductor lasers, and are coated with anti-reflection films for the emission wavelength of quantum cascade semiconductor lasers on both sides.

[0030] The spatial beam combining crystal 7, such as Figure 3 As shown, a material with high transmittance corresponding to the emission wavelength of the quantum cascade semiconductor laser is used, and the incident surface 8 and the exit surface 9 of the longitudinal quantum cascade semiconductor laser collimated beam on the spatial beam combining crystal are coated with an anti-reflection film corresponding to the emission wavelength of the quantum cascade semiconductor laser, and the reflection surfaces 10-15 with an angle greater than 45° of the transverse quantum cascade semiconductor laser collimated beam on the spatial beam combining crystal are coated with a total reflection film layer corresponding to the emission wavelength of the quantum cascade semiconductor laser.

[0031] When the device is working, the divergent light beam emitted by the longitudinal quantum cascade semiconductor laser 1 becomes a collimated light beam after passing through the longitudinal collimating lens 2, then passes through the longitudinal focusing lens 3, passes through the incident surface 8 on the spatial beam combining crystal 7, enters the spatial beam combining crystal, and finally focuses on the rear end design position of the exit surface 9 on the spatial beam combining crystal.

[0032] The distribution and arrangement effect of the quantum cascade semiconductor laser beam when it passes through the spatial beam combining crystal before focusing is as follows Figure 4 shown.

[0033] The divergent beam of the transverse quantum cascade semiconductor laser 4 is transformed into a collimated beam after passing through the transverse collimating lens 5, and then passes through the longitudinal focusing lens 6 and is reflected by the reflecting surfaces 10-15 on the spatial beam combining crystal 7. Figure 5 As shown, the beam is focused at the same position where the longitudinally focused beam is focused.

[0034] It can be seen from the above technical solution that the present invention has the following significant features:

[0035] 1. The spatial beam combining method of the present invention can ensure that the focused light beams after spatial beam combining of the quantum cascade semiconductor lasers are compactly arranged together, and the focused light spot size is small.

[0036] 2. The compact arrangement of the peripheral collimated light beams around the central collimated light beam adopted in the present invention allows emission focusing to obtain a single focused light spot.

[0037] 3. The dispersed arrangement of the quantum cascade semiconductor lasers in the spatial beam combining method adopted by the present invention is beneficial to its heat dissipation design.

[0038] 4. The spatial beam combining method adopted by the present invention is also applicable to general semiconductor lasers.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A quantum cascade semiconductor laser single spot focusing spatial beam combining system, characterized in that: include: A spatial beam combining crystal (7), a longitudinal beam unit, and a multi-path transverse beam unit; the spatial beam combining crystal (7) is in the shape of a multi-prism, the lower bottom surface of the spatial beam combining crystal (7) serves as an incident surface (8), the upper bottom surface serves as an exit surface (9), and the side surfaces serve as reflection surfaces; the longitudinal beam unit is coaxially arranged on one side of the incident surface (8), and the multi-path transverse beam units are arranged one-to-one on one side of the reflection surface; the mid-infrared laser beam emitted by the longitudinal beam unit passes through the beam combining crystal (7), is emitted from the exit surface (9), and is focused behind the beam combining crystal (7); the mid-infrared laser beam emitted by the multi-path transverse beam unit is reflected by the reflection surface, changes its transmission direction, and is focused on the same position where the longitudinal laser beam is focused.

2. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 1, characterized in that: The longitudinal beam unit comprises a longitudinal quantum cascade semiconductor laser (1), a longitudinal collimating lens (2), and a longitudinal focusing lens (3). A mid-infrared divergent laser beam emitted by the longitudinal quantum cascade semiconductor laser (1) is converted into a collimated beam after passing through the longitudinal collimating lens (2), and is incident on an incident surface (8) of a spatial beam combining crystal (7) after passing through the longitudinal focusing lens (3).

3. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 2, characterized in that: Each transverse beam unit comprises a transverse quantum cascade semiconductor laser (4), a transverse collimating lens (5), and a transverse focusing lens (6). A mid-infrared divergent laser beam emitted by the transverse quantum cascade semiconductor laser (4) is converted into a collimated beam after passing through the transverse collimating lens (5), and is incident on a reflection surface of a spatial beam combining crystal (7) after passing through the transverse focusing lens (6).

4. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 3, characterized in that: The incident surface (8) and the exit surface (9) of the longitudinal collimating lens (2), the longitudinal focusing lens (3), the transverse collimating lens (5), the transverse focusing lens (6), and the spatial beam combining crystal (7) are all coated with an anti-reflection film for the emission wavelength of the quantum cascade semiconductor laser.

5. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 4, characterized in that: The reflection surface of the spatial beam combining crystal (7) is plated with a total reflection film layer for the emission wavelength of the quantum cascade semiconductor laser.

6. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 5, characterized in that: The spatial beam combining crystal (7) is configured as a hexagonal pyramid and has six reflection surfaces.

7. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 6, characterized in that: The spatial beam combining crystal (7) is configured as a regular hexagonal pyramid.

8. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 7, characterized in that: The inclination angle of the reflecting surface and the incident angle of the laser beam of the transverse beam unit relative to the reflecting surface are set to ensure that the reflected beam and the longitudinal laser beam are focused at the same position.

9. The quantum cascade semiconductor laser single spot focusing spatial beam combining system according to claim 8, characterized in that: The incident angle of the laser beam of the transverse beam unit relative to the reflective surface is greater than 45°.

10. Application of the quantum cascade semiconductor laser single spot focusing spatial beam combining system according to any one of claims 1 to 9 in the field of quantum cascade semiconductor laser technology.

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