A multi-infrared laser chip frequency-doubled laser

Abstract

The utility model belongs to the technical field of laser, especially a kind of multiple infrared laser chip frequency doubling laser, including pedestal, six infrared laser chips are installed on pedestal, six near-infrared laser chips are arranged in ladder form, fast axis collimating mirror, slow axis collimating mirror and reflector are equipped on near-infrared laser chip, half-wave plate, polarization beam combiner, reflection type volume bragg grating, LBO frequency doubling crystal, beam splitter, focusing mirror are equipped on pedestal.The utility model is based on the optical fiber coupling output infrared light LD module of polarization beam combining technology in space, and through reflection type volume bragg grating, LBO crystal and beam splitter, finally realize the blue light laser output of high brightness, high power, narrow linewidth.

Description

Technical Field

[0001] This utility model relates to the field of laser technology, and in particular to a multi-infrared laser chip frequency doubling laser. Background Technology

[0002] In recent years, with the increasing demand for marine resource development and ecological environment monitoring, high-precision, high-resolution profiling of marine water optical parameters has become a key focus of marine optical research. Accurate measurement of marine water optical parameters is directly related to multiple fields such as marine ecosystem health assessment, marine dynamics research, and marine resource development. However, traditional marine detection methods have many shortcomings in nearshore, highly turbid waters. Optical sensors are limited by light source intensity and spectral characteristics, making deep-water detection difficult; while acoustic detection methods are limited by sound wave attenuation and resolution bottlenecks, making it difficult to meet the requirements for high-precision profiling.

[0003] LiDAR technology, with its active emission, high spatial resolution, and cross-media detection capabilities, has become an ideal means of detecting the optical properties of ocean water. Among these, the choice of operating wavelength is crucial. Current technologies mostly use 450nm blue light, but this band only has effective penetration capability in extremely clear waters. In most of the world's nearshore turbid waters, the 488nm wavelength, being closer to the peak value of the seawater optical transmission window, possesses stronger penetration depth and detection matching characteristics.

[0004] In the field of laser processing, narrow-linewidth infrared frequency-doubled lasers can generate high-brightness, high-power narrow-linewidth blue light, improve frequency doubling conversion efficiency, enhance the power and brightness of the output blue light, meet the demand for high-intensity light, and improve system stability and reliability by optimizing crystal materials and improving optical path design, reducing nonlinear effects and crystal damage risks, ensuring long-term performance and lifespan. They are suitable for high-precision and high-intensity laser cutting, welding and other processing needs, and promote the innovative development of laser processing technology.

[0005] In response to the urgent need for high-power, narrow-linewidth blue lasers in fields such as marine water optical property detection and laser processing, current technology still faces many challenges and has not yet provided a mature solution that balances power, linewidth, system size, and stability.

[0006] On the one hand, traditional blue lasers mainly use blue semiconductor laser chips, but due to material and process limitations, the output power of a single tube is difficult to increase, and multi-tube spatial beam combining schemes result in large system size and soaring power consumption. Furthermore, the beam quality of blue laser chips is poor, making it difficult to meet the requirements of high-precision detection. Even with phase-shifting grating structures, the measured beam width of a single-frequency blue laser remains in the 3 GHz range, and the coherence length is less than 100 meters, which is insufficient for ocean water detection needs.

[0007] On the other hand, while infrared laser chip frequency doubling technology has improved power to some extent, it still faces many challenges in practical applications. Regarding beam quality optimization, when multiple chips are combined, the divergence angle and spot uniformity of the beam are difficult to control, leading to a decrease in beam quality. Simultaneously, beam combining technology is prone to thermal effects under high-power operation, affecting the long-term stability of the laser. Furthermore, thermal management of the frequency doubling crystal is also a critical issue; increased crystal temperature during high-power operation can lead to a decrease in frequency doubling efficiency or even damage the crystal. Moreover, existing frequency doubling lasers still have shortcomings in spectral linewidth control, making it difficult to meet the narrow linewidth requirements of oceanographic detection.

[0008] Furthermore, infrared laser chip frequency doubling technology also has significant shortcomings in beam shaping and beam combining techniques. Design and assembly errors of the fast and slow axis collimators affect the beam divergence angle and spot quality, thereby reducing fiber coupling efficiency and spatial beam combining efficiency. Existing beam combining schemes mostly employ simple spatial or polarization beam combining techniques, which are insufficient for achieving high-brightness, high-power laser output, and also suffer from deficiencies in beam polarization purity and long-term stability. These problems make infrared laser chip frequency doubling technology unable to meet the demands of fields such as marine water detection and laser processing for high-power, narrow-linewidth, and high-beam-quality lasers. Utility Model Content

[0009] The purpose of this invention is to address the shortcomings of the prior art by proposing a multi-infrared laser chip frequency doubling laser.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A multi-infrared laser chip frequency doubling laser includes a base on which six infrared laser chips are mounted. The six near-infrared laser chips are arranged in a stepped manner. Each near-infrared laser chip is equipped with a fast-axis collimating mirror, a slow-axis collimating mirror, and a reflector. The base is equipped with a half-wave plate, a polarization beam combiner, a reflective volume Bragg grating, an LBO frequency doubling crystal, a beam splitter, and a focusing mirror.

[0012] Preferably, the wavelength of the six infrared laser chips is 976nm and the step height is 0.4mm.

[0013] Preferably, the fast-axis collimating lens is an aspherical cylindrical lens with a focal length of 1.11 mm.

[0014] Preferably, the slow-axis collimating lens is a cylindrical lens with a focal length of 10.23 mm.

[0015] Preferably, the diffraction wavelength of the reflective volume Bragg grating is 976nm±0.1nm, and the diffraction efficiency is 34%±3%.

[0016] Compared with the prior art, the advantages of this utility model are:

[0017] This invention relates to an infrared laser LD module based on spatial and polarization beam combining technology, which ultimately achieves high-brightness, high-power, and narrow-linewidth blue laser output through a reflective volume Bragg grating, an LBO crystal, and a beam splitter.

[0018] 1. The structure of this patented laser combines spatial beam combining technology and polarization beam combining technology. By designing and optimizing the beam combining scheme, two parallel beams are used on the basis of a stepped arrangement structure to achieve efficient spatial convergence of multiple laser beams. This ensures that the combined beam has good polarization characteristics and beam quality, meeting the needs of fields such as marine water body detection and laser processing for high-brightness, high-power, and high-beam-quality lasers.

[0019] 2. In the internal structure of the laser, a scheme using reflective body Bragg grating external cavity feedback and LBO crystal frequency doubling technology is adopted to achieve narrow linewidth and high power laser output. By utilizing the output spectral characteristics of LBO crystal and combining it with reflective body Bragg grating to lock the laser beam wavelength and narrow the linewidth, the output spectral characteristics are improved and the power consumption of the laser is reduced.

[0020] 3. In the selection of laser chips, a 976nm near-infrared laser chip was adopted, breaking through the bottleneck of low laser power of single blue light chips. At the same time, combined with frequency doubling technology, 488nm blue light laser output was achieved, which can be applied to the detection of the euphotic layer in most sea areas and near-shore turbid waters, as well as the field of laser processing of precious metals. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a multi-infrared laser chip frequency doubling laser proposed in this utility model;

[0022] Figure 2 This is a top view schematic diagram of a multi-infrared laser chip frequency doubling laser proposed in this utility model.

[0023] In the diagram: 1. Infrared laser chip; 2. Fast-axis collimating lens; 3. Slow-axis collimating lens; 4. Reflector; 5. Half-wave plate; 6. Polarization combiner; 7. Reflective volume Bragg grating; 8. LBO frequency doubling crystal; 9. Beam splitter; 10. Focusing lens. Detailed Implementation

[0024] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this embodiment, and not all embodiments.

[0025] Reference Figures 1-2A multi-infrared laser chip frequency-doubled laser includes a base on which six infrared laser chips 1 are mounted. The six near-infrared laser chips 1 are arranged in a stepped configuration. Each near-infrared laser chip 1 has a fast-axis collimating mirror 2, a slow-axis collimating mirror 3, and a reflector 4. The base also includes a half-wave plate 5, a polarization combiner 6, a reflective volume Bragg grating 7, an LBO frequency-doubled crystal 8, a beam splitter 9, and a focusing mirror 10. The beam splitter 9 has a transmission wavelength of 488 nm and a reflection wavelength of 976 nm. Multiple high-power infrared laser chips 1 are selected as the fundamental frequency source. The output 976 nm fundamental frequency light is first collimated by the fast-axis collimating mirror 2 and the slow-axis collimating mirror 3 to reduce beam divergence and improve beam quality. Subsequently, the beam is spatially combined by the reflector 4, and then polarized by the polarization combiner 6. Finally, the reflective volume Bragg grating 7 achieves wavelength locking and linewidth narrowing, ensuring the narrow linewidth characteristics of the output beam. Next, the beam is frequency-doubled by an LBO frequency-doubling crystal 8, converting the 976nm infrared light into 488nm blue light. The frequency-doubled blue light is then separated by a beam splitter 9 to ensure the purity of the output light and avoid interference from stray light on the detection results. Finally, the output light is focused by a focusing mirror 10 to reduce damage to the device from reflected light and improve the stability and reliability of the system. By combining spatial beam combining technology and polarization beam combining technology, and optimizing the beam combining scheme, efficient focusing of multiple laser beams in space is achieved, ensuring that the combined beam has good polarization characteristics and beam quality, meeting the needs of fields such as marine water body detection and laser processing for high-brightness, high-power, and high-beam-quality lasers.

[0026] Featuring a compact structure, high-quality output spectrum, high power, and high stability, this laser can be applied to marine lidar for detecting the optical characteristics of ocean waters, particularly suitable for high-precision detection in turbid nearshore waters. Simultaneously, this laser is also suitable for high-precision, high-intensity laser processing, driving innovation in related technologies. Through innovative optical structure design and frequency doubling technology, it solves problems such as power bottlenecks, poor beam quality, and insufficient stability in existing technologies, achieving high brightness, high power, narrow linewidth, and high beam quality.

[0027] In this embodiment, the wavelength of the six infrared laser chips 1 is 976nm and the step height is 0.4mm.

[0028] In this embodiment, the fast-axis collimating lens 2 is an aspherical cylindrical lens with a focal length of 1.11 mm.

[0029] In this embodiment, the slow-axis collimating lens 3 is a cylindrical lens with a focal length of 10.23 mm.

[0030] In this embodiment, the diffraction wavelength of the reflective volume Bragg grating 7 is 976nm±0.1nm, and the diffraction efficiency is 34%±3%.

[0031] In this embodiment, in order to improve the output power of the laser, multiple single infrared laser chips 1 with a front-end surface reflectivity of 0.02% are used. Spatial beam combining technology and polarization beam combining technology are combined. By optimizing the beam combining scheme, multiple laser beams are efficiently converged in space, ensuring that the combined beam has good polarization characteristics and beam quality, which meets the needs of high brightness, high power and high beam quality lasers in fields such as marine water body detection and laser processing.

[0032] To enhance laser output power, a stepped spatial arrangement structure is adopted in the spatial beam combining technology, placing six infrared laser chips 1 with a wavelength of 976nm. The step height is 0.4mm, which ensures that the laser beams do not interfere with each other and further compresses the beam dead zone. The infrared laser chips 1 are integrated on the secondary heat sink substrate, ensuring the advantages of high power stability, long life and good reliability of the infrared light LD.

[0033] Furthermore, in order to achieve high-brightness laser output while compressing the laser size, it is proposed to place two parallel beams in a stepped structure. One parallel beam is composed of 6 infrared laser chips 1. Finally, the polarization beams of the two beams are combined using a half-wave plate 5 and a polarization beam combiner 6 (PBS), which further improves the output power without changing the beam quality.

[0034] To ensure that the divergence angle and beam quality of the combined beam are close and to further improve the coupling efficiency between the LD and the optical fiber, an aspherical cylindrical mirror with a focal length of 1.11 mm was designed as the fast-axis collimating mirror 2 and a cylindrical mirror with a focal length of 10.23 mm was designed as the slow-axis collimating mirror 3. The divergence angles of the laser beam in the fast and slow axis directions are compressed respectively, so that the divergence angles of the laser beam in the fast and slow axis directions after optical collimation are significantly reduced, thereby further ensuring the beam transmission quality.

[0035] To meet the detection requirements in nearshore turbid waters, namely high power and narrow linewidth, a reflective volume Bragg grating (RVBG) was selected for external cavity feedback after the collimator to narrow the laser output linewidth. This is because using a volume Bragg grating with narrow bandwidth and good locking quality allows for narrow-bandwidth frequency-doubled light with beam characteristics consistent with the fundamental frequency. Stable output and efficient operation of narrow-bandwidth frequency-doubled light under external cavity locking with the VRBG is achieved. The reflective VRBG has a diffraction wavelength of 976 nm ± 0.1 nm and a diffraction efficiency of 34% ± 3%. The VRBG, as external cavity feedback, can re-feed back light of a specific wavelength to the output region, reducing light loss at that wavelength. This facilitates mode competition with other wavelengths, prioritizing reaching the threshold for laser output, resulting in a single wavelength mode output and achieving external cavity wavelength locking. Simultaneously, the VRBG effectively improves the output spectral quality. Ultimately, the goal of wavelength locking and linewidth narrowing is achieved.

[0036] To obtain a 488nm blue laser output suitable for marine exploration and laser processing, an LBO (lithium triborate) frequency doubling crystal 8 is used after the reflective volume Bragg grating 7 to double the frequency of the input 976nm infrared laser. After passing through a beam splitter, the required 488nm blue laser output can be obtained.

[0037] Since the beam after polarization combining is approximately a rectangular parallel beam, it needs to be focused by a lens before it can be coupled into the optical fiber. Therefore, a focusing lens 10 is added to the output end of the laser to focus the beam, and finally outputs 488nm blue laser light.

[0038] The above description is only a preferred embodiment of this practice, but the scope of protection of this embodiment is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the scope of the technology disclosed in this embodiment, based on the technical solution and the inventive concept of this embodiment, should be covered within the scope of protection of this embodiment.

Claims

1. A frequency-doubled laser with multiple infrared laser chips, characterized in that, The device includes a base on which six infrared laser chips (1) are mounted. The six near-infrared laser chips (1) are arranged in a stepped manner. The near-infrared laser chips (1) are equipped with a fast-axis collimating lens (2), a slow-axis collimating lens (3) and a reflector (4). The base is equipped with a half-wave plate (5), a polarization beam combiner (6), a reflective volume Bragg grating (7), an LBO frequency doubling crystal (8), a beam splitter (9), and a focusing lens (10).

2. The multi-infrared laser chip frequency doubling laser according to claim 1, characterized in that, The six infrared laser chips (1) have a wavelength of 976nm and a step height of 0.4mm.

3. A multi-infrared laser chip frequency doubling laser according to claim 2, characterized in that, The fast-axis collimating lens (2) is an aspherical cylindrical lens with a focal length of 1.11 mm.

4. A multi-infrared laser chip frequency doubling laser according to claim 3, characterized in that, The slow-axis collimating lens (3) is a cylindrical lens with a focal length of 10.23 mm.

5. A multi-infrared laser chip frequency doubling laser according to claim 4, characterized in that, The diffraction wavelength of the reflective volume Bragg grating (7) is 976nm ± 0.1nm, and the diffraction efficiency is 34% ± 3%.

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