A semiconductor laser

Abstract

The application discloses a semiconductor laser, which comprises a light-emitting assembly, a beam combining and focusing assembly, a coupling optical fiber and a plurality of reflection and deflection assemblies, wherein the light-emitting assembly comprises a light-emitting unit for emitting pump light perpendicular to a horizontal plane; each reflection and deflection assembly is arranged one-to-one with each light-emitting unit to transmit collimated pump light along a first direction and deflect pump light with the maximum optical path to the center, deflect pump light with the minimum optical path and pump light with the intermediate optical path to the edge; the beam combining and focusing assembly is arranged at the output end of the collimated pump light reflected and deflected by the reflection and deflection assembly to focus the collimated pump light; and the coupling optical fiber is used for coupling the collimated pump light beam focused by the beam combining and focusing assembly. The application adjusts the height of the reflection and deflection assembly to correct the spot shape of the collimated pump light focused by the beam combining and focusing of the plurality of collimated pump light, reduces the duty cycle of the semiconductor laser in the fiber coupling process and reduces the dead zone.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and more particularly to a semiconductor laser. Background Technology

[0002] Fiber optic semiconductor lasers play an important role in fields such as industrial cutting, medicine, beauty, military, and lidar due to their highly stable beam output, good beam quality, and high electro-optic efficiency.

[0003] Semiconductor lasers typically use circular optical fibers, while the laser spot of most semiconductor lasers is trapezoidal before entering the fiber. This results in a "dead zone" (also known as "duty cycle") during fiber coupling, meaning the size of the focused laser spot entering the fiber does not perfectly match the fiber shape (e.g., ...). Figure 1 This problem leads to a decrease in the fiber coupling efficiency of semiconductor lasers, an increase in cladding light, and significant energy loss. For ultra-high power (kilowatts, megawatts) lasers, the lost energy is converted into heat, further increasing manufacturing costs and creating additional heat dissipation pressure on semiconductor lasers. Therefore, reducing the "dead zone" (lowering the "duty cycle") and improving the laser coupling efficiency is essential. Summary of the Invention

[0004] This invention provides a semiconductor laser that modifies the spot shape of the collimated pump light after beam combining and focusing by adjusting the position and height of the reflection and deflection components in the semiconductor laser, thereby reducing the duty cycle of the semiconductor laser during fiber coupling and achieving the purpose of reducing the "dead zone".

[0005] This application provides a semiconductor laser, including a light-emitting assembly, which includes a plurality of light-emitting units arranged sequentially along a first direction, each light-emitting unit being used to emit collimated pump light perpendicular to the horizontal plane;

[0006] Multiple reflection and deflection components are provided, each corresponding to a light-emitting unit, to reflect the collimated pump light to propagate along a first direction and deflect the collimated pump light with the longest optical path to the center, and the collimated pump light with the shortest optical path and the optical path in the middle to the edge; a beam combining and focusing component is provided at the output end of the collimated pump light after reflection and deflection by the reflection and deflection components, to combine and focus the collimated pump light; and a coupling fiber is provided at the output end of the beam combining and focusing component to couple the combined and focused collimated pump beam.

[0007] Optionally, along the first direction, the height of the center position of the multiple reflective deflection components first increases and then decreases.

[0008] Optionally, multiple reflective deflection components are distributed along a first direction in a first region and a second region.

[0009] The height of the reflective deflector in the first region gradually increases along the first direction, while the height of the reflective deflector in the second region gradually decreases along the first direction, and the height of the reflective deflector in the first region is higher than that of the reflective deflector in the second region.

[0010] Optionally, each reflection and deflection component includes a second and a third reflecting mirror arranged sequentially along the output optical path of the collimating pump light.

[0011] In the multiple reflective deflection components, multiple second reflectors are arranged sequentially and parallel to each other along the first direction, and the height of the center position of the multiple second reflectors first increases and then decreases; multiple third reflectors are arranged sequentially and parallel to each other along the first direction, and the height of the center position of the multiple third reflectors first increases and then decreases.

[0012] Optionally, it also includes a housing substrate, with the third reflector disposed perpendicular to the housing substrate, and the top edge of the third reflector being lower than the bottom edge of the second reflector.

[0013] Optionally, each light-emitting unit includes those arranged sequentially along the second direction:

[0014] The chip is used to emit pump light along the second direction, and the light-emitting centers of multiple chips are all on the same horizontal plane;

[0015] Fast-axis collimating lens, slow-axis collimating lens; the collimated pump light is formed by the pump light passing through the fast-axis collimating lens and the slow-axis collimating lens; and

[0016] The first reflecting mirror has a preset angle with the horizontal plane. The collimated pump light enters the first reflecting mirror along the second direction and then exits perpendicular to the horizontal plane.

[0017] Optionally, in a single light-emitting unit and its corresponding reflection and deflection assembly, the first and second reflectors are parallel to each other, and the third reflector is perpendicular to the second reflector.

[0018] Optionally, the chip can be packaged as a bar package or a single tube package.

[0019] Optionally, in the reflective deflection assembly located in the first or second zone, the absolute value range of the center height difference between two adjacent reflective deflection assemblies and two adjacent third mirrors is 0.25mm to 0.35mm.

[0020] Optionally, the beam combining and focusing assembly includes a polarization beam combiner and a focusing module arranged sequentially.

[0021] In summary, the semiconductor laser provided in this application, by setting different heights of the reflection and deflection components used to receive collimated pump light, changes the output position of multiple collimated pump light beams after beam combining, and controls the positional arrangement of each collimated pump light spot. This causes the spot with a longer optical path and narrower beam to move to the center of the collimated pump light spot after beam combining and focusing, while the spot with the shortest optical path and narrowest beam is deflected to the edge of the collimated pump light spot after beam combining and focusing. This corrects the spot shape of the collimated pump light after beam combining and focusing, reduces the duty cycle of the semiconductor laser during fiber coupling, and thus reduces the "dead zone". Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the spot end face of a collimated pump beam from a semiconductor laser in the prior art, after beam combining and focusing.

[0023] Figure 2 This is a schematic diagram of the semiconductor laser provided in this application;

[0024] Figure 3 This is a side view of the semiconductor laser provided in this application;

[0025] Figure 4 This is a schematic diagram of the spot end face of the collimated pump beam of the semiconductor laser provided in this application after beam combining and focusing;

[0026] Figure 5 This is a spot pattern of the collimated pump light output by the reflective deflection component provided in this application;

[0027] Figure 6 This is a beam pattern of the collimated pump light after beam focusing provided in this application;

[0028] Figure 7 This is a schematic diagram of the optical path of the collimated pump light provided in this application after passing through the reflection and deflection assembly;

[0029] Figure 8 This is a schematic diagram of the optical path structure of the chip and the reflective deflection component provided in this application;

[0030] Figure 9 yes Figure 8 A schematic diagram of the collimated pump light path in the N region. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the invention and not all structures. Various modifications and variations can be made to the present invention without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, the present invention is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the embodiments provided in the present invention can be combined with each other without contradiction.

[0032] For fiber coupling, the beam parameter product (BPP) is one of the conditions that determines the coupling capability of the fiber: the laser can only couple into the fiber if the laser beam parameter product is less than the fiber beam parameter product. Here, BPP is a constant, equal to the product of the beam waist radius and the far-field half-divergence angle. The fiber beam parameter product is related to the fiber's geometry and numerical aperture.

[0033] In semiconductor lasers, the laser emitted from the chip exhibits varying propagation speeds in different directions. The beam diverges faster in the direction perpendicular to propagation, resulting in a near-Gaussian spot distribution, known as the fast axis. Conversely, the beam diverges slower in the direction parallel to propagation, exhibiting a near-flat-top spot distribution, known as the slow axis. The product of the beam parameters of the fast and slow axes differs, with the product of the slow axis beam parameters being significantly lower than that of the fast axis. Due to this difference in beam parameter products between the slow and slow axes, the optical path structure of semiconductor lasers typically employs spatial stacking along the fast axis to reduce the difference in beam parameter products between the fast and slow axes. However, in this process, the stacking of the fast axis is achieved by sequentially placing the light-emitting components on steps of gradually increasing height. This structure results in each collimated pump light having a different optical path length when reaching the fiber. Figure 1 The diagram shown is a schematic of the laser spot at the end face of a semiconductor laser in the prior art. The shape of the laser spot at the end face of the fiber is often rectangular, trapezoidal, inverted trapezoidal or irregular, and does not completely match the common circular fiber. As a result, the laser output coupling efficiency is low.

[0034] Based on this, the present invention provides a semiconductor laser in view of one or more of the above-mentioned problems existing in the prior art. Figure 2 This is a schematic diagram of the semiconductor laser provided in this application. Figure 3 This is a side view of the semiconductor laser provided in this application. Figure 4 This is a schematic diagram of the beam end face of the collimated pump light of the semiconductor laser provided in this application after beam combining and focusing. Figure 5This is a pattern of the collimated pump light output by the reflection and deflection assembly provided in this application. Figure 6 This is a beam pattern of the collimated pump light after focusing, provided in this application.

[0035] Definition: The semiconductor laser described in this application... Figure 2 The state defined in the text refers to the vertical and horizontal relationships between various components.

[0036] In this application, the arrangement direction of chip 111 is defined as the first direction X, the light emission direction of chip 111 is defined as the second direction Y, and the direction perpendicular to the horizontal plane is defined as the third direction Z to describe this application.

[0037] Please refer to Figure 2 The semiconductor laser provided in this embodiment of the invention includes a light-emitting component, multiple reflection and deflection components 12, a beam-combining and focusing component 13, and a coupling fiber 14. The light-emitting component 12 includes multiple components along a first direction (i.e., Figure 2 The semiconductor laser comprises a series of output units 11 arranged sequentially along the positive X-axis. Each output unit 11 emits collimated pump light perpendicular to the horizontal plane. Each reflection and deflection assembly 12 corresponds to each output unit 11, reflecting the collimated pump light to propagate along the first direction and deflecting the collimated pump light with the longest optical path to the center, and the collimated pump light with the shortest optical path and the intermediate optical path to the edge. A beam combining and focusing assembly 13 is disposed at the output end of the collimated pump light after reflection and deflection by the reflection and deflection assembly 12, for beam combining and focusing the collimated pump light. A coupling fiber 14 is disposed at the output end of the beam combining and focusing assembly 13 to couple the beam combining and focused collimated pump light. The semiconductor laser also includes some fixing members 31 for fixing the reflection and deflection assembly 12. It should be noted that the fixing members 31 have no effect on the transmission of the collimated pump light. In one embodiment, a schematic diagram of the beam end face of the collimated pump beam focused by the semiconductor laser provided in this application is shown below. Figure 4 As shown, this beam reshaping of the collimated pump beam through beam combining and focusing changes its shape from an inverted trapezoid to a more symmetrical, closer-to-circular hexagon. This shape effectively reduces the duty cycle (i.e., dead zone) of the coupling fiber 14, decreases energy loss of the collimated pump light at the coupling fiber 14, alleviates the heat dissipation pressure on the coupling fiber 14, and thus improves the coupling efficiency of the coupling fiber 14.

[0038] In this application, along the first direction, the height of the center position of the plurality of reflective deflection components 12 first increases and then decreases. For example... Figure 3As shown, in one embodiment of this application, by adjusting the position and height of the reflection and deflection component 12 that receives the collimated pump light, the emission position of the collimated pump light emitted from multiple light-emitting units 11 after beam combining is changed, thereby controlling the position arrangement of the collimated pump light emitted from each light-emitting unit 11 in the beam spot of the beam combined and focused collimated pump light. This moves the beam spot with a longer optical path and a narrower beam to the middle of the beam spot of the beam combined and focused collimated pump light, which can also be understood as the center of the coupling fiber 14; at the same time, the beam spot with the shortest optical path and a shorter beam is deflected to the edge of the beam spot of the beam combined and focused collimated pump light, which can also be understood as the edge of the coupling fiber 14.

[0039] Please continue to refer to Figure 2 Multiple reflective deflection components 12 are distributed along a first direction in a first region 12a and a second region 12b. The height of the reflective deflection components 12 in the first region 12a gradually increases along the first direction, and the height of the reflective deflection components 12 in the second region 12b gradually decreases along the first direction. In one embodiment of this application, the height of the reflective deflection components 12 is divided into two parts. The division of the height of the first region 12a and the second region 12b is related to the number of reflective deflection components 12. For example, if the number of reflective deflection components 12 is N, for ease of description, the reflective deflection components 12 can be numbered starting from 1 along the first direction. When N is an even number, the height of the reflective deflection components 12 along the first direction is... In one direction, the position between the reflection deflection assembly 12 numbered N / 2-1 and N / 2 is taken as the boundary point between the first region 12a and the second region 12b; or, the position between the reflection deflection assembly 12 numbered N / 2+1 and N / 2 is taken as the boundary point between the first region 12a and the second region 12b. When N is odd, the position between the reflection deflection assembly 12 numbered (N+1) / 2 and (N-1) / 2 is taken as the boundary point between the first region 12a and the second region 12b. The position height of the reflection deflection assembly in the first region 12a is higher than the position height of the reflection deflection assembly in the second region 12b.

[0040] In one embodiment, each reflection deflection assembly 12 includes a second reflector 121 and a third reflector 122 sequentially arranged along the output optical path of the collimating pump light. Among the plurality of reflection deflection assemblies 12, the plurality of second reflectors 121 are arranged sequentially and parallel to each other along a first direction, and the height of the center position of the plurality of second reflectors 121 first increases and then decreases; the plurality of third reflectors 122 are arranged sequentially and parallel to each other along the first direction, and the height of the center position of the plurality of third reflectors 122 first increases and then decreases. (Reference) Figure 2 and Figure 3Taking the collimated pump light optical path including a first reflector 114 and a reflection deflection assembly 12 including a second reflector 121 and a third reflector 122 as an example. Along the first direction, in the first region 12a, the height and relative position of the reflection deflection assembly 12 corresponding to each light-emitting unit 11 need to be adjusted according to the optical path length of each light-emitting unit 11. As the optical path length gradually increases, the height of the reflection deflection assembly 12 is gradually increased in a stepwise manner. Along the first direction, in the second region 12b, as the optical path length gradually decreases, the height of the third reflector 122 is gradually decreased in a stepwise manner, thereby reducing or even eliminating the light-blocking effect of the third reflector 122. At the same time, care should be taken to avoid the third reflector 122 in the second region 12b blocking the collimated pump light deflected by the third reflector 122 in the first region 12a. Finally, all collimated pump lights are deflected by the third reflector 122 and then... Figure 2 The light spots converge in the first direction, resulting in a spatially stacked light spot along the fast axis, such as... Figure 4 As shown.

[0041] Based on the above embodiments, refer to Figure 2 and Figure 3 The semiconductor laser also includes a housing substrate 30. The top edge of the third reflector 122 is lower than the bottom edge of the second reflector 121 to ensure that the third reflector 122 can receive the collimated pump light during normal use. The third reflector 122 is arranged perpendicular to the housing substrate to ensure that the collimated pump light, after beam combining and focusing, can be emitted horizontally during normal use. A fixing member 31 is fixed to the housing substrate 30 to fix the reflection and deflection assembly 12. The fixing member 31 has no effect on the transmission of the collimated pump light.

[0042] Optionally, in one embodiment, such as Figure 2 As shown, each light-emitting unit includes light-emitting units along the second direction ( Figure 2 The chip 111, fast-axis collimating lens 112, slow-axis collimating lens 113, and first reflecting mirror 114 are arranged sequentially in the positive Y-axis direction.

[0043] Chip 111 emits pump light along the second direction, and the light-emitting centers of multiple chips are all located on the same horizontal plane. Since the divergence angle of the collimated pump light emitted from chip 111 is relatively large, a fast-axis collimating lens 112 and a slow-axis collimating lens 113 are also used to collimate the pump light. The fast-axis collimating lens 112 can be used to collimate the pump light along the fast axis, and the slow-axis collimating lens 113 can be used to collimate the pump light along the slow axis. After passing through the fast-axis collimating lens 112 and the slow-axis collimating lens 113, the pump light is collimated. The first reflecting mirror 114 has a preset angle with the horizontal plane, and the collimated pump light enters the first reflecting mirror 114 along the second direction and exits perpendicular to the horizontal plane.

[0044] Specifically, the angle between the first reflector 120 and the horizontal plane is 45 degrees, so that the collimated pump light is emitted from the first reflector 114 perpendicular to the horizontal plane.

[0045] Please refer to Figure 7 In this application, in a single light-emitting unit 11 and its corresponding reflection and deflection assembly 12, the first reflector 114 and the second reflector 121 are parallel to each other to ensure that during normal use, the collimated pump light can be emitted horizontally to the third reflector 122; the third reflector 122 is perpendicular to the second reflector 121.

[0046] Optionally, the chip can be packaged as a bar package or a single-tube package. When the chip is packaged as a single-tube package, the reliability of the chip during use can be guaranteed; when the chip 111 is packaged as a bar package, the light-emitting centers located on the same horizontal plane are located in the same bar, which helps to reduce the chip packaging cost and the difficulty of adjusting the optical path.

[0047] Optionally, in the reflective deflection assembly located in the first or second zone, the absolute value range of the center height difference between two adjacent reflective deflection assemblies and two adjacent third mirrors is 0.25 mm to 0.35 mm. For example, in the reflective deflection assembly 12 located in the first zone 12a, the center height difference between two adjacent reflective deflection assemblies can be 0.3 mm, and in the reflective deflection assembly 12 located in the second zone 12b, the center height difference between two adjacent reflective deflection assemblies can also be 0.3 mm.

[0048] It should be noted that in this embodiment, the plane on which the housing substrate 30 is located is used as the horizontal plane for height description reference. The height of the light-emitting center of the light-emitting unit 11 is the height of the light-emitting center on the plane on which the housing substrate 30 is located, and the height of the reflection deflection component 12 is the height of the reflection center of the reflection deflection component 12 on the plane on which the housing substrate 30 is located.

[0049] Figure 8 This is a schematic diagram of the optical path structure of the light-emitting unit 11 and the reflection and deflection assembly 12 provided in this application. Figure 9 yes Figure 8 A schematic diagram of the optical path of the light-emitting unit 11 in the N region. In one embodiment of this application, the light is emitted from the unit 11. Figure 8 The reflection deflection component 12 located at the center of the area within the dashed box N serves as the central reflection deflection component 12. The height of its center position is used as a reference to adjust the positions and heights of other reflection deflection components 12. The collimated pump light emitted from this light-emitting unit 11 illuminates the bottom edge of its corresponding reflection deflection component 12, such as... Figure 9 As shown, it is then reflected to subsequent optical elements ( Figure 9(Not shown in the image). The remaining reflective deflection components 12 are identical to the central reflective deflection component 12, receiving and reflecting the corresponding pump light. Taking the center position height of the central reflective deflection component 12 as a reference, along the first direction, the center position height of the reflective deflection component 12 corresponding to the last light-emitting unit 11 in the first region 12a is d+0.3, d+0.6, d+0.9, d+1.2, and d+1.5 respectively, with the unit being mm:millimeters; along the first direction, the position height of the reflective deflection component 12 in the second region 12b is d, d-0.3, d-0.6, d-0.9, and d-1.2 respectively, with the unit being mm:millimeters. This configuration allows the collimated pump light with the longest optical path to be deflected to the center of the collimated pump light after beam combining and focusing, and the collimated pump light with the shortest optical path and the middle optical path to be deflected to the edge of the collimated pump light after beam combining and focusing. The shape of the collimated pump light spot after beam combining and focusing is changed from the original "inverted trapezoid" to a "hexagon" that is more symmetrical and closer to a circle, and finally coupled into the coupling fiber 14.

[0050] Where d is the position height of the intermediate reflective deflection component 12, and (d-0.3) is the distance along the axis. Figure 8 The position and height of the first reflective deflection component 12 in the first direction, and so on, will be explained one by one.

[0051] Optionally, the beam combining and focusing assembly 13 includes a polarization beam combiner and a focusing module arranged sequentially. The beam combining and focusing assembly 13 is located in the optical path of the collimated pump light and is used to combine and focus the collimated pump light, facilitating its coupling into the coupling fiber 14. The polarization beam combiner can be a block-shaped or sheet-shaped polarization beam combiner, which can be used to further combine multiple collimated pump lights. The focusing module can be a combination of one or more focusing mirrors, which can be used to focus multiple collimated pump lights. The collimated pump light, combined by the polarization beam combiner and focused by the focusing assembly, forms a beam-combined and focused collimated pump light, which is coupled into the coupling fiber 14, enabling high-power laser output. Compared with conventional semiconductor lasers with the same optical path pump source, the semiconductor laser provided in this embodiment theoretically improves coupling efficiency by 1-2%.

[0052] It is understood that the semiconductor laser provided in this application also includes an electrical module, which is electrically connected to the light source module. The electrical module includes a control circuit, and multiple chips are electrically connected to the control circuit. The control circuit is configured to control the drive current of the chips to adjust the power value of the collimated pump light and stabilize the laser power of the collimated pump light after beam combining and focusing.

[0053] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A semiconductor laser, characterized by, The application relates to a semiconductor laser device. The light-emitting assembly comprises a plurality of light-emitting units arranged in sequence along a first direction, each of the light-emitting units being used for emitting collimated pumping light perpendicular to a horizontal plane. A plurality of reflection and deflection assemblies are arranged one by one with each of the light-emitting units, used for reflecting the collimated pumping light to be transmitted along the first direction, and deflection of the collimated pumping light with the maximum optical path to the center, and deflection of the collimated pumping light with the minimum and intermediate optical path to the edge. The plurality of reflection and deflection assemblies are distributed in a first area and a second area along the first direction, each of the reflection and deflection assemblies comprises a second mirror and a third mirror arranged in sequence along an output light path of the collimated pumping light, the center height of the second mirror and the center height of the third mirror in the first area gradually increase along the first direction, the center height of the second mirror and the center height of the third mirror in the second area gradually decrease along the first direction, and the center height of the second mirror in the first area is higher than the center height of the second mirror in the second area, and the center height of the third mirror in the first area is higher than the center height of the third mirror in the second area. Each of the light-emitting units comprises, arranged in sequence along a second direction: a chip used for emitting pumping light along the second direction, the light-emitting center of the plurality of chips is in the same horizontal plane; a fast-axis collimating mirror and a slow-axis collimating mirror, the collimated pumping light is formed by the pumping light after the fast-axis collimating mirror and the slow-axis collimating mirror; and a first mirror with a preset included angle between the first mirror and the horizontal plane, the collimated pumping light is emitted perpendicular to the horizontal plane after entering the first mirror along the second direction; a beam combining and focusing assembly arranged at the output end of the collimated pumping light reflected and deflected by the reflection and deflection assembly, used for beam combining and focusing of the collimated pumping light; and a coupling optical fiber arranged at the output end of the beam combining and focusing assembly, used for coupling the beam combining and focusing collimated pumping light.

2. The semiconductor laser device according to claim 1, wherein 3. The semiconductor laser of claim 2, wherein, in the plurality of reflection and deflection assemblies, the plurality of second mirrors are arranged in sequence and parallel to each other along the first direction, and the plurality of third mirrors are arranged in sequence and parallel to each other along the first direction.

4. The semiconductor laser of claim 3, wherein, Further comprising a housing substrate, the third mirror is arranged perpendicular to the housing substrate, and the top edge of the third mirror is lower than the bottom edge of the second mirror.

5. The semiconductor laser of claim 4, wherein, In a single light-emitting unit and its corresponding reflection and deflection assembly, the first mirror and the second mirror are parallel to each other, and the third mirror is perpendicular to the second mirror.

6. The semiconductor laser of claim 2, wherein, The packaging mode of the chip is bar packaging or single tube packaging.

7. The semiconductor laser of claim 1, wherein, In the reflection and deflection assembly located in the first area or the second area, the absolute value range of the center height difference of two adjacent third mirrors is 0.25mm-0.35mm. The beam combining and focusing assembly comprises a polarization beam combiner and a focusing module arranged in sequence.

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