Zoom coupler of laser before entering fiber

Abstract

The utility model relates to a fiber-in front laser zoom coupler, which belongs to the technical field of optical shaping, and is characterized in that an integral light path comprises a light emitting unit, a wave locking unit, a shaping unit, a beam combining unit and a zoom coupling unit which are sequentially arranged along a light beam propagation direction, the light emitting unit comprises a plurality of groups of laser chips, the wave locking unit comprises a Bragg grating, the shaping unit comprises but is not limited to a fast axis collimating lens, a slow axis collimating lens and a fast axis compression lens, the beam combining unit comprises but is not limited to a small reflector, a large reflector and a polarization splitting prism, and the zoom coupling unit comprises but is not limited to spherical mirror groups with different focal lengths. By adjusting the overall focal length of the zoom coupler, the requirements of various light spot sizes before fiber entrance can be met, the design cost of model selection of various coupling lenses is reduced, and the aberration and spherical aberration of the system are reduced to a certain extent by introducing the lens group zoom coupling unit. Meanwhile, the mode of replacing a traditional coupling lens with the plugging structure also meets the requirements of practicability and convenience of an existing laser.

Description

Technical Field

[0001] The utility model relates to a pre-fiber laser zoom coupler, belonging to the technical field of optical shaping. Background Art

[0002] Since the advent of the laser, laser technology has developed rapidly. Semiconductor lasers, due to their advantages such as small size, light weight, long life, stable operation, low cost, and suitability for fiber-optic transmission, are widely used in fields such as detection, medicine, lighting, materials processing, and fiber / solid-state laser pump sources. Whether used as fiber / solid-state laser pump sources or in detection applications, the need to match the spot size requirements after exiting the fiber has led to increasingly diverse requirements for the spot size and NA (numerical aperture) before coupling into the fiber.

[0003] Existing semiconductor lasers usually adjust the spot size by two means: before entering the fiber and after exiting the fiber. Traditional pre-fiber coupling usually focuses the light beam into the optical fiber through a single coupling lens or a fast-slow axis coupling lens group after beam shaping. However, this method cannot meet the shaping requirements of various spot sizes and NAs before entering the fiber. It is necessary to design coupling lenses with different focal lengths before entering the fiber to match different application scenarios. This means that for the same laser module, it is necessary to add coupling lenses with different focal lengths to meet the requirements of different spot sizes. For post-fiber spot shaping, as recorded in document CN113253468A, a lens group is usually assembled after the fiber is exited to expand or contract the fast-slow axis spot after the fiber is exited, so as to achieve the goal of outputting spots of different sizes.

[0004] Although existing semiconductor laser beam shaping solutions are relatively complete, the following issues still exist: Size adjustment solutions before fiber entry are relatively simple, and beam adjustment solutions after fiber exit use costly solutions such as microlens arrays. Both pre-fiber entry and post-fiber exit spot size control solutions increase the selection or number of lenses, which increases R&D and production costs and reduces the versatility of beam shaping lens sets. However, the current semiconductor laser field prefers fewer optical components and more versatile optical component selection in module packaging to achieve the goals of reducing aberrations and lowering costs. Therefore, there is still room for improvement in the current semiconductor laser pre-fiber beam shaping solutions. Summary of the Invention

[0005] In response to the limitations of existing technologies, the present invention provides a pre-fiber laser beam zoom coupler structure that can solve the technical problem of the existing pre-fiber laser spot zoom solution requiring additional coupling lens selection. The plug-in zoom coupler, composed of lens groups, can be directly assembled on the target laser. By manually adjusting the spacing between the lens groups in the zoom coupler and mechanically fixing the lens position, a universal zoom coupler can be used to meet the requirements of a larger beam zoom range before fiber entry. At the same time, the optical design of the pre-fiber lens group shaping instead of a single coupling lens or a fast-slow axis coupling lens can reduce aberrations and spherical aberrations to a certain extent, further meeting the needs of high-precision fields for different zoom solutions.

[0006] The technical solution of the utility model is as follows:

[0007] A pre-fiber laser zoom coupler comprises a light-emitting unit, a wave-locking unit, a shaping unit, a beam-combining unit, and a zoom coupling unit, which are sequentially arranged along the beam propagation direction. The light-emitting unit comprises two rows of multiple laser chips, with the upper and lower rows of laser chips staggered and opposite each other. The wave-locking unit comprises a volume Bragg grating, the shaping unit comprises a fast-axis collimating lens, a slow-axis collimating lens, a small reflector, and a large reflector. The beam-combining unit comprises a polarization beam splitter prism and a fast-axis compression lens.

[0008] The optical path of the upper row of laser chips is equipped with a fast axis collimating lens, a volume Bragg grating, a slow axis collimating lens, and a small reflector in sequence. All the light from the upper row of laser chips is collected on the large reflector and reflected to the polarization beam splitter prism.

[0009] The optical path of the lower row of laser chips is sequentially provided with a fast-axis collimating lens, a volume Bragg grating, a slow-axis collimating lens, and a small reflector. The light from all the lower row laser chips is collected into a polarization beam splitter prism, which combines the optical paths of the upper and lower rows. A fast-axis compression lens and a zoom coupling unit are sequentially provided on the optical path after the polarization beam splitter prism.

[0010] The zoom coupling unit includes an outer shell and three spherical mirror lenses with a threaded structure. The outer shell is a cylindrical shell with a guide groove provided along the axial direction. The threaded structure includes a screw and a nut. The spherical mirror lens is fixed on the screw. One side of the screw is connected to the nut, and the other side is fixed to the outer shell by dispensing glue. When in use, the screw with the lens is inserted into the outer shell through the guide groove so that the lens is located on the optical path inside the outer shell. The spacing between the three lenses is adjusted left and right along the guide groove, and fixed to the outer wall of the outer shell by the nut. After the position is fixed, glue is dispensed on the other side of the spherical mirror to further reinforce the lens. The zoom coupling unit is assembled between the laser light outlet and the optical fiber through a plug-in structure.

[0011] Preferably, a scale is provided on the outside of the guide groove to facilitate fixing the position.

[0012] Preferably, the three spherical mirror lenses are one mirror, two mirrors, and three mirrors respectively. The system zoom is achieved by adjusting the interval between the lenses. The focal lengths of the one mirror, the two mirrors, and the three mirrors are f1, f2, and f3 respectively. The focal length f of the zoom coupling unit as a whole needs to meet Wherein d1 is the interval between the first and second spherical mirrors, and d2 is the interval between the second and third mirrors. By changing d1 and d2 individually or simultaneously, the overall zoom of the zoom coupling system can be achieved.

[0013] Further preferably, the convex surface of the first and third mirrors faces the incident direction of the light path, and the convex surface of the second mirror faces the emitting direction of the light path.

[0014] For example, by adjusting the front-to-back position of one mirror in the optical path, the optical spot entering the fiber can be zoomed 7-12mm. By adjusting the front-to-back position of three mirrors in the optical path, the optical spot entering the fiber can be zoomed 6-11mm. By adjusting the front-to-back position of one and two mirrors in the optical path, the optical spot entering the fiber can be zoomed 6.5-12mm.

[0015] The beneficial effects of the present invention are:

[0016] The zoom method of the coupling zoomer before fiber entry provided by the utility model is simple. The overall zoom of the coupling zoomer is achieved by adjusting the interval between one lens or multiple lenses in the zoom coupler, providing a larger zoom range. By replacing the traditional single coupling lens or fast-slow axis coupling lens group with the zoom coupler, it can match various spot size requirements before fiber entry, and can flexibly adjust the zoom range while reducing the selection of traditional coupling lenses, which can reduce the design cost of laser coupling lenses. At the same time, adding lens groups can also reduce the spherical aberration and aberration caused by the lens.

[0017] This utility model's assembly structure uses a plug-in mechanism, replacing the traditional single coupling lens or fast-slow axis coupling lens assembly within the laser. This increases the internal optical design space, reduces the laser's size, and facilitates repair of the zoom coupler. By changing the lens position within the zoom coupler, zooming to different input fiber spot sizes can be quickly achieved. After determining the coupling position, the spherical mirror is mechanically fixed using screws and glue on both sides, meeting the practical and convenient requirements of existing laser modification applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Attachment Figure 1 Schematic diagram of the overall optical path structure of a traditional coupling lens;

[0019] Attachment Figure 2 This is a schematic diagram of the overall optical path structure of the utility model;

[0020] Attachment Figure 3 A schematic structural diagram of the fiber-insertion front zoom coupling unit of the plug-in structure of the utility model;

[0021] Attachment Figure 4 A schematic structural diagram of the spherical mirror in the zoom coupling unit of the utility model;

[0022] Attachment Figure 5 Schematic diagram of the position of one mirror in the zoom coupling unit when the overall focal length of the zoom coupler is 7mm;

[0023] Attachment Figure 6 Schematic diagram of the position of one lens in the zoom coupling unit when the overall focal length of the zoom coupler is 12mm;

[0024] Attachment Figure 7 Schematic diagram of the positions of the three mirrors in the zoom coupling unit when the overall focal length of the zoom coupler is 6mm;

[0025] Attachment Figure 8 Schematic diagram of the positions of the three mirrors in the zoom coupling unit when the overall focal length of the zoom coupler is 11mm;

[0026] Attachment Figure 9 Schematic diagram of the positions of the first and second mirrors in the zoom coupling unit when the overall focal length of the zoom coupler is 6.5mm;

[0027] Attachment Figure 10 Schematic diagram of the positions of the first and second mirrors in the zoom coupling unit when the overall focal length of the zoom coupler is 12mm;

[0028] Attachment Figure 11 Schematic diagram of the light spot before fiber entry, where the focal length of the zoom coupler is adjusted to 7mm by changing the position of one mirror;

[0029] Attachment Figure 12 Schematic diagram of the light spot before fiber entry, where the focal length of the zoom coupler is adjusted to 12mm by changing the position of one mirror;

[0030] Attachment Figure 13 Schematic diagram of the light spot before fiber entry by adjusting the focal length of the zoom coupler to 6.5mm by simultaneously changing the positions of the first and second mirrors;

[0031] Attachment Figure 14 Schematic diagram of the light spot before fiber entry by adjusting the focal length of the zoom coupler to 12mm by simultaneously changing the positions of the first and second mirrors;

[0032] Symbols shown in the accompanying drawings:

[0033] 1. Laser chip; 2. Fast-axis collimating lens; 3. Volume Bragg grating; 4. Slow-axis collimating lens; 5. Small reflector; 6. Large reflector; 7. Polarization beam splitter prism; 8. Fast-axis compression lens; 9. First mirror with focal length f1 = 17.5 mm; 10. Second mirror with focal length f2 = 74.5 mm; 11. Third mirror with focal length f3 = 7.4 mm. DETAILED DESCRIPTION

[0034] The present invention will be further described below through embodiments and in conjunction with the accompanying drawings, but is not limited thereto.

[0035] Example 1:

[0036] A pre-fiber laser zoom coupler, referring to Figure 1 and Figure 2 , Figure 1 The optical path structure of the fiber laser is coupled using a conventional coupling lens. Figure 2 The optical path structure of a fiber laser uses a zoom coupling unit instead of different selected coupling lenses to zoom the light spot before entering the fiber. Figure 2 The overall optical path structure includes a light-emitting unit, a wave-locking unit, a shaping unit, a beam-combining unit, and a zoom coupling unit, arranged sequentially along the propagation direction of the light beam. The light-emitting unit includes multiple laser chips 1 arranged in two straight rows, staggered and aligned. The laser chips 1 have similar strip widths, cavity lengths, and fast- and slow-axis divergence angles. Laser light emitted by the light-emitting unit passes through the wave-locking unit, shaping unit, beam-combining unit, and zoom coupling unit before being coupled into the output optical fiber. The light-emitting unit generates the incident laser light source, and the laser chips 1 are arranged sequentially with equal intervals on the same side and staggered with equal intervals on the opposite side. The wave-locking unit includes a volume Bragg grating 3, which locks the fast-axis collimated laser light to a specific wavelength band. The shaping unit includes a fast-axis collimating lens 2, a slow-axis collimating lens 4, a small reflector 5, and a large reflector 6. Specifically, the fast-axis collimating lens 2 and the slow-axis collimating lens 4 collimate the light spot in the fast and slow axis directions, respectively. The small reflector 5 and the large reflector 6 are used to change the direction of the light beams on both sides to facilitate beam combining. The beam combining unit includes a polarization beam splitter prism 7 and a fast-axis compression lens 8. The fast-axis compression lens 8 mainly functions to compress the combined light spot passing through the polarization beam splitter prism 7 in the fast axis direction to achieve the purpose of making the combined light spot size consistent with the slow axis direction. The polarization beam splitter prism 7 is used to combine light beams of different polarization states on both sides.

[0037] The zoom coupling unit comprises a housing and three spherical mirror lenses with threaded structures, Figure 3 、 Figure 4, along the direction of the optical path are mirror 9, mirror 10, and mirror 11 respectively. The outer shell is a cylindrical shell with a guide groove provided along the axial direction. The threaded structure includes a screw and a nut. The spherical mirror lens is fixed on the screw. One side of the screw is connected to the nut, and the other side is fixed to the outer shell by dispensing glue. When in use, the screw with the lens is inserted into the outer shell through the guide groove so that the lens is located on the optical path inside the outer shell. The three lenses can move freely inside the zoom coupler. The spacing between the three lenses is adjusted left and right along the guide groove. After determining the coupling position, the coupling position is mechanically fixed by the nut on one side of the spherical mirror, and fixed to the outer wall of the outer shell by the nut. After fixing the position, glue is dispensed on the other side of the spherical mirror to further strengthen the lens. The zoom coupling unit is assembled between the laser light outlet and the optical fiber through a plug-in structure.

[0038] like Figure 2 As shown, the optical path of the upper row of laser chips is sequentially equipped with a fast-axis collimating lens, a volume Bragg grating, a slow-axis collimating lens, and a small reflector. All light from the upper row of laser chips is collected on the large reflector and reflected to the polarization beam splitter prism. The optical path of the lower row of laser chips is sequentially equipped with a fast-axis collimating lens, a volume Bragg grating, a slow-axis collimating lens, and a small reflector. All light from the lower row of laser chips is collected on the polarization beam splitter prism, which combines the optical paths of the upper and lower rows. A fast-axis compression lens and a zoom coupling unit are sequentially arranged on the optical path after the polarization beam splitter prism.

[0039] In this embodiment, the focal lengths f1, f2, and f3 of the first, second, and third mirrors are 17.5 mm, 74.5 mm, and 7.4 mm, respectively. Figure 5 、 6 , fix the second and third mirrors, adjust the position of the first mirror, and change the interval between the first and second mirrors to achieve an overall zoom of 7-12mm for the zoom coupler. Figure 11 、 12 By adjusting the position of one mirror, the spot sizes at 7mm and 12mm of the overall focal length of the zoom coupler are changed respectively. There are obvious differences in the size of the spots, which shows that this embodiment achieves the control of the spot size before fiber entry by changing the position of a single spherical mirror and adjusting the focal length of the zoom coupler.

[0040] Example 2:

[0041] A laser zoom coupler before fiber entry, the structure of which is as described in Example 1, the focal lengths f1, f2, and f3 of the first, second, and third mirrors are 17.5 mm, 74.5 mm, and 7.4 mm respectively. Figure 7 、 8 Similarly, by fixing the first and second mirrors, adjusting the position of the third mirror, and changing the interval between the second and third mirrors, the overall zoom of the zoom coupler can be achieved from 6 to 11 mm. By adjusting the focal length of the zoom coupler, the size of the light spot before entering the fiber can be controlled.

[0042] Example 3:

[0043] A laser zoom coupler before fiber entry, the structure of which is as described in Example 1, the focal lengths f1, f2, and f3 of the first, second, and third mirrors are 17.5 mm, 74.5 mm, and 7.4 mm respectively. Figure 9 、 10 , fix the three mirrors, adjust the position of the first and second mirrors, and change the intervals between the first, second and third mirrors to achieve an overall zoom of 6.5-12mm for the zoom coupler. Figure 13 、 14 By adjusting the positions of the first and second mirrors, respectively, the spot sizes at the overall focal lengths of the zoom coupler at 6.5 mm and 12 mm are changed. There are obvious differences in the sizes of the spots, indicating that this embodiment achieves the control of the spot size before fiber entry by changing the position of the multi-spherical mirror and adjusting the focal length of the zoom coupler.

Claims

1. A pre-fiber laser zoom coupler, characterized in that: The optical fiber optical fiber comprises a light-emitting unit, a wave-locking unit, a shaping unit, a beam-combining unit, and a zoom coupling unit, which are sequentially arranged along the propagation direction of the light beam. The light-emitting unit comprises a double row of multiple groups of laser chips, and the upper and lower rows of laser chips are staggered and arranged opposite to each other. The wave-locking unit comprises a volume Bragg grating, the shaping unit comprises a fast-axis collimating lens, a slow-axis collimating lens, a small reflector, and a large reflector. The beam-combining unit comprises a polarization beam splitter prism and a fast-axis compression lens. The optical path of the upper row of laser chips is equipped with a fast axis collimating lens, a volume Bragg grating, a slow axis collimating lens, and a small reflector in sequence. All the light from the upper row of laser chips is collected on the large reflector and reflected to the polarization beam splitter prism. The optical path of the lower row of laser chips is sequentially provided with a fast-axis collimating lens, a volume Bragg grating, a slow-axis collimating lens, and a small reflector. The light from all the lower row laser chips is collected into a polarization beam splitter prism, which combines the optical paths of the upper and lower rows. A fast-axis compression lens and a zoom coupling unit are sequentially provided on the optical path after the polarization beam splitter prism. The zoom coupling unit includes an outer shell and three spherical mirror lenses with a threaded structure. The outer shell is a cylindrical shell with a guide groove provided along the axial direction. The threaded structure includes a screw and a nut. The spherical mirror lens is fixed on the screw. One side of the screw is connected to the nut, and the other side is fixed to the outer shell by dispensing glue. The zoom coupling unit is assembled between the laser light outlet and the optical fiber through a plug-in structure.

2. The pre-fiber laser zoom coupler according to claim 1, characterized in that: There is a scale on the outside of the guide groove.

3. The pre-fiber laser zoom coupler according to claim 1, characterized in that: The three spherical mirror lenses are mirror one, mirror two, and mirror three. The focal lengths of mirror one, mirror two, and mirror three are f1, f2, and f3 respectively. The focal length f of the zoom coupling unit as a whole is Where d1 is the distance between the first and second spherical mirrors, and d2 is the distance between the second and third spherical mirrors.

4. The pre-fiber laser zoom coupler according to claim 3, characterized in that: The convex surfaces of the first and third mirrors face the incident direction of the light path, and the convex surface of the second mirror faces the outgoing direction of the light path.

5. The pre-fiber laser zoom coupler according to claim 3, characterized in that: The focal length of the first lens is f1 = 17.5mm, the focal length of the second lens is f2 = 74.5mm, and the focal length of the third lens is f3 = 7.4mm.

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