Linearly polarized uniform light output semiconductor laser

Abstract

This invention relates to the field of semiconductor laser technology, and more particularly to a semiconductor laser with linearly polarized uniform output. The laser comprises a semiconductor laser module, a polarizing beam splitter, a first focusing lens, a homogenizing rod, a collimating lens, and a second focusing lens arranged coaxially in sequence. The semiconductor laser module outputs linearly polarized laser containing P-polarized and S-polarized states. After polarization state selection by the polarizing beam splitter, one polarized state laser is transmitted, while the other is reflected. The transmitted polarized state laser is focused and coupled by the first focusing lens and then homogenized and shaped by the homogenizing rod. The homogenized laser is collimated by the collimating lens and then focused and output by the second focusing lens. This invention homogenizes and shapes the selected single-polarized state laser using the homogenizing rod, achieving a highly uniform output spot while maintaining high polarization, thus realizing stable output of high-power, single-polarized, and uniformly intensity-distributed linearly polarized laser.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor laser technology, and particularly relates to a semiconductor laser with linearly polarized uniform light output. Background Technology

[0002] High-power semiconductor lasers, with their advantages of high electro-optical conversion efficiency, compact size, lightweight construction, long lifespan, and direct modulation capability, have found wide application in scientific research, medical treatment, industrial processing, and military fields. However, achieving kilowatt-level or higher power output from a single laser unit presents a technical bottleneck, necessitating the use of semiconductor laser beam combining technology. This technology enhances laser power through the synergistic effects of beam collimation, shaping, and beam combining. Semiconductor laser fiber coupling technology couples the beam to an optical fiber output, and a fiber combiner integrates multiple laser units, ultimately achieving high-power laser output. Simultaneously, the uniformity of the beam spot can be optimized after exiting through the fiber.

[0003] The linear polarization characteristics of high-power semiconductor lasers are a core technical parameter, and high-power, high-polarization lasers have crucial application value in many fields. Although individual semiconductor laser chips possess excellent linear polarization characteristics, the degree of linear polarization for a single type (either P-polarization or S-polarization) is typically on the order of 95%. More importantly, when the combined beam is coupled to a traditional circular optical fiber for transmission, the beam's linear polarization characteristics are further compromised due to factors such as internal stress and birefringence during fiber transmission, thus affecting the laser's actual performance. Therefore, maintaining the polarization degree of the beam in a high-power laser combining structure has become a critical technical challenge that urgently needs to be overcome.

[0004] Limited by the inherent properties of semiconductor laser chip materials, structural design, thermal effects, and process errors, it is impossible to completely suppress the s-polarization state in semiconductor laser chips, which are dominated by the p-polarization state. Furthermore, during the homogenization transmission of the combined high-power semiconductor laser beam into a traditional circular optical fiber, complex polarization state changes occur due to the inhomogeneity of the fiber material, its geometric circular symmetry, and internal stress introduced during manufacturing. These factors exacerbate birefringence in the fiber, causing random or periodic changes in the beam's polarization state, thus degrading the initial linear polarization characteristics. Therefore, the degradation of polarization characteristics caused by fiber transmission is a technical problem that needs to be addressed and suppressed for high-power semiconductor laser systems to achieve high-quality applications. Summary of the Invention

[0005] In view of this, the present invention aims to provide a semiconductor laser with linearly polarized uniform light output to solve the problems of maintaining the polarization degree of laser and uniform light output under high power conditions, thereby realizing high power and high polarization uniform light beam output.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A semiconductor laser with linearly polarized uniform beam output includes: a semiconductor laser module, a polarizing beam splitter, a first focusing lens, a uniform beam, a collimating lens, and a second focusing lens arranged coaxially in sequence; wherein, Semiconductor laser modules are used to output linearly polarized lasers, which include P-polarized lasers and S-polarized lasers. A polarization beam splitter is used to filter the polarization state of incident linearly polarized laser light, so that one polarization state of the linearly polarized laser light is transmitted and the other polarization state of the laser light is reflected. The first focusing lens is used to focus and couple the polarized laser transmitted from the polarization beam splitter into the uniform beam. A homogenizing rod is used to homogenize and shape incident polarized laser light, turning it into homogenized light. Collimating lenses are used to collimate homogenized light, converting it into collimated light. The second focusing lens is used to converge the straight light, ultimately outputting a linearly polarized laser with a single polarization state and uniform intensity distribution.

[0007] Furthermore, the light-diffusing rod is made of quartz material, has a cuboid structure, and the area of ​​the light-incident end face of the light-diffusing rod is larger than the area of ​​the laser spot that is focused onto the light-incident end face of the light-diffusing rod by the first focusing lens.

[0008] Furthermore, an antireflection film matching the working wavelength of the laser is deposited on both the light-incident end face and the light-exit end face of the light-monitoring rod, and the transmittance of the antireflection film to the laser is not less than 99.5%.

[0009] Furthermore, the semiconductor laser module is a single semiconductor laser or is composed of at least two semiconductor lasers integrated in a beam-combining manner.

[0010] Furthermore, the light-incident and light-outcrystal surfaces of the first focusing lens, collimating lens, and second focusing lens are all coated with anti-reflection films that match the laser operating wavelength, and the transmittance of the anti-reflection films to the laser is not less than 99.5%.

[0011] Furthermore, an antireflection coating matching the working wavelength of the laser is deposited on the incident light end face of the polarizing beam splitter, and the transmittance of the antireflection coating to the laser is not less than 99.5%; a polarizing beam splitting film for polarizing beam splitting is deposited on the beam splitting working surface of the polarizing beam splitter.

[0012] Furthermore, the shape of the laser spot output by the second focusing lens matches the shape of the light-emitting end face of the homogenizing rod.

[0013] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The present invention uses polarization separation technology to screen the polarization state of the output laser of the semiconductor laser module, and couples the single polarization state laser retained after screening to the homogenizing rod for light intensity homogenization and shaping. On the basis of ensuring high polarization degree of laser, the output spot with excellent uniformity is obtained by beam shaping, so as to realize the stable output of high power, single polarization state and uniform light intensity distribution of linearly polarized laser.

[0014] (2) The linearly polarized uniform light output semiconductor laser created by the present invention can flexibly configure the shape structure of the light output end face of the uniform light rod according to the shape requirements of the output light spot in industrial application scenarios, and has good scalability and engineering applicability. Attached Figure Description

[0015] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of a semiconductor laser with linearly polarized uniform light output as described in an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures: 1. Semiconductor laser module; 2. Polarizing beam splitter; 3. First focusing lens; 4. Beam homogenizer; 5. Collimating lens; 6. Second focusing lens. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, an embodiment of the present invention provides a semiconductor laser with linearly polarized uniform light output, comprising: a semiconductor laser module 1, a polarizing beam splitter 2, a first focusing lens 3, a uniform light rod 4, a collimating lens 5, and a second focusing lens 6 arranged coaxially in sequence; wherein, the semiconductor laser module 1 is used to output linearly polarized laser, which includes P-polarized laser and S-polarized laser; the polarizing beam splitter 2 is used to screen the polarization state of the incident linearly polarized laser, so that one polarization state of the linearly polarized laser is transmitted and the other polarization state is reflected; the first focusing lens 3 is used to focus and couple the polarized laser transmitted from the polarizing beam splitter 2 into the uniform light rod 4; the uniform light rod 4 is used to homogenize and shape the incident polarized laser, turning it into homogenized light; the collimating lens 5 is used to collimate the homogenized light, turning it into collimated light; the second focusing lens 6 is used to converge the collimated light, ultimately outputting a linearly polarized laser with a single polarization state and uniform intensity distribution.

[0023] Semiconductor laser module 1 is a single semiconductor laser or is composed of at least two semiconductor lasers integrated by beam combining.

[0024] An antireflection coating matching the working wavelength of the laser is deposited on the incident light end face of the polarization beam splitter 2, and the transmittance of the antireflection coating to the laser is not less than 99.5%; a polarization beam splitting film for polarization beam splitting is deposited on the beam splitting working surface of the polarization beam splitter 2.

[0025] The homogenizing rod 4 is made of quartz and has a cuboid structure. The area of ​​the incident light end face of the homogenizing rod 4 is larger than the area of ​​the laser spot that is focused onto the incident light end face of the homogenizing rod 4 by the first focusing lens 3. Both the incident light end face and the exit light end face of the homogenizing rod 4 are coated with antireflection films that match the working wavelength of the laser. The transmittance of the antireflection films to the laser is not less than 99.5%.

[0026] The light-incident end face and the light-outcident end face of the first focusing lens 3, the collimating lens 5 and the second focusing lens 6 are all coated with anti-reflection films that match the working wavelength of the laser. The transmittance of the anti-reflection film to the laser is not less than 99.5%.

[0027] The shape of the laser spot output by the second focusing lens 6 matches the shape of the light-emitting end face of the light-diffusing rod 4. In industrial applications, the shape of the light-emitting end face of the light-diffusing rod 4 is set according to the preset laser spot shape.

[0028] Semiconductor laser module 1 is a high-power laser capable of outputting linearly polarized laser light, including P-polarized and S-polarized light. The polarization degree of the P-polarized light is approximately 95%, and the polarization degree of the S-polarized light is approximately 5%. In free-running mode, the center wavelength of its linearly polarized laser is 1064 nm ± 3 nm, and the spectral linewidth is approximately 3 nm.

[0029] The linearly polarized laser output from semiconductor laser module 1 undergoes polarization state screening through polarization beam splitter 2. An antireflection coating with a wavelength of 1064nm±50nm is deposited on the incident end face of polarization beam splitter 2, and the transmittance of this antireflection coating is not less than 99.5%. A polarization beam splitting film for polarization beam splitting is deposited on the beam splitting working surface of polarization beam splitter 2, so that the P-polarized light in the linearly polarized laser is transmitted and output, while the S-polarized light is reflected.

[0030] P-polarized light passing through polarizing beam splitter 2 is converged and coupled into uniform light rod 4 by first focusing lens 3 with a focal length of 100mm. Anti-reflection coatings with a wavelength of 1064nm±50nm are deposited on both the light-incident and light-out surfaces of the first focusing lens 3. The transmittance of this anti-reflection coating to the laser is not less than 99.5%.

[0031] The light-diffusing rod 4 has a rectangular structure with a 2mm×2mm square light-incident end face and a length of 150mm. Both the light-incident end face and the light-outcrystal end face are coated with an anti-reflection film in the 1064nm±50nm wavelength band. The transmittance of this anti-reflection film to the laser is not less than 99.5%.

[0032] It should be noted that this embodiment only uses one specification of the homogenizing rod 4 as an example for illustration. In some embodiments, the homogenizing rod 4 has a cuboid structure, and its light-incident end face and light-outcident end face can also be a rectangle of 2mm×3mm; this is something that traditional circular optical fibers cannot achieve. The homogenizing rod 4 has polarization-maintaining characteristics that traditional circular optical fibers do not have, mainly due to the symmetrical geometric structure, uniform material properties and uniformly distributed internal stress of the homogenizing rod 4, so that the light beam can maintain its initial polarization state well during transmission.

[0033] After being homogenized and shaped, the P-polarized laser beam is emitted from the homogenizing rod 4 in a divergent state. It is then collimated by a collimating lens 5 with a focal length of 100 mm, and then converged by a second focusing lens 6 with a focal length of 150 mm. Finally, a high-power, single-polarization linearly polarized laser beam with uniform intensity distribution is output. Anti-reflection coatings with a wavelength range of 1064 nm ± 50 nm are deposited on both the incident and emitting surfaces of the collimating lens 5 and the second focusing lens 6. These anti-reflection coatings have a transmittance of not less than 99.5% for the laser beam.

[0034] It should be noted that the focal lengths of the collimating lens 5 and the second focusing lens 6 can be designed and adjusted according to the focal spot parameters of the final output laser. Secondly, the shape of the laser spot output by the second focusing lens 6 matches the geometric shape of the light-emitting end face of the light-diffusing rod 4. In industrial applications, the shape of the light-emitting end face of the light-diffusing rod 4 can be set according to the preset laser spot shape, which has good scalability and engineering applicability.

[0035] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0036] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A linearly polarized uniform output semiconductor laser, characterized by, include: The semiconductor laser module, polarizing beam splitter, first focusing lens, beam homogenizer, collimating lens, and second focusing lens are arranged coaxially in sequence; among them... The semiconductor laser module is used to output linearly polarized laser, which includes P-polarized laser and S-polarized laser; The polarization beam splitter is used to filter the polarization state of the incident linearly polarized laser, so that one polarization state of the linearly polarized laser is transmitted and the other polarization state of the laser is reflected. The first focusing lens is used to focus and couple the polarized laser transmitted by the polarizing beam splitter into the homogenizing rod; The homogenizing rod is used to homogenize and shape the incident polarized laser light, turning it into homogenized light. The collimating lens is used to collimate the homogenized light, converting it into collimated light. The second focusing lens is used to converge the collimated light, and finally output a linearly polarized laser with a single polarization state and uniform intensity distribution.

2. The linearly polarized uniform output power semiconductor laser of claim 1, wherein, The light-diffusing rod is made of quartz material and has a cuboid structure. The area of ​​the light-incident end face of the light-diffusing rod is larger than the area of ​​the laser spot that is focused on the light-incident end face of the light-diffusing rod by the first focusing lens.

3. A linearly polarized uniform output semiconductor laser according to claim 1 or 2, characterized in that An antireflection film matching the working wavelength of the laser is deposited on both the light-incident end face and the light-exit end face of the light-monitoring rod, and the transmittance of the antireflection film to the laser is not less than 99.5%.

4. The linearly polarized uniform output power semiconductor laser of claim 1, wherein, The semiconductor laser module is a single semiconductor laser or is composed of at least two semiconductor lasers integrated by a beam combining method.

5. The linearly polarized uniform output power semiconductor laser of claim 1, wherein, An antireflection coating matching the laser operating wavelength is deposited on both the light-incident end face and the light-outcident end face of the first focusing lens, the collimating lens, and the laser transmittance of the antireflection coating is not less than 99.5%.

6. The linearly polarized uniform output power semiconductor laser of claim 1, wherein, An antireflection coating matching the working wavelength of the laser is deposited on the incident light end face of the polarizing beam splitter, and the transmittance of the antireflection coating to the laser is not less than 99.5%; a polarizing beam splitting film for polarization beam splitting is deposited on the beam splitting working surface of the polarizing beam splitter.

7. The linearly polarized uniform output power semiconductor laser of claim 1, wherein, The shape of the laser spot output by the second focusing lens matches the shape of the light-emitting end face of the light-diffusing rod.

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