Green light laser

Abstract

The utility model relates to a kind of green laser, comprising: resonant cavity, for generating non-polarization base frequency light;Frequency doubling unit, for the non-polarization base frequency light is output green laser after frequency doubling. Resonant cavity is provided with: narrowband high reflection fiber grating, second end is connected with the signal fiber of first pump combiner;First pump source, tail fiber is connected with the pump fiber of first pump combiner;First pump combiner, forward use;Multi-clad fiber, first end is connected with the output fiber of first pump combiner, second end is connected with the input fiber of second pump combiner;Second pump combiner, reverse use;Second pump source, tail fiber is connected with the pump fiber of second pump combiner;Narrowband low reflection uniform fiber grating, first end is connected with the output fiber of second pump source;Optical power stripper, input end is connected with the second end of narrowband low reflection uniform fiber grating;High-power output head. The utility model can output green laser, simple structure, low in cost.

Description

Technical Field

[0001] This utility model relates to the field of optics, and in particular to a green laser. Background Technology

[0002] In the industrial sector, green lasers demonstrate significant advantages due to their unique spectral characteristics and efficient energy conversion mechanism. Their wavelength of 500-570nm falls in the mid-range of visible light, exhibiting higher absorption rates for highly reflective materials (such as metals like copper and aluminum) and non-metallic materials (such as plastics, rubber, and wood) compared to infrared lasers. This enables high-precision cutting and welding, significantly reducing the heat-affected zone and improving the smoothness and precision of processed edges, making them particularly suitable for precision applications such as PCB micromachining and lithium battery tab welding. Furthermore, in the field of laser marking, green lasers can create clear and durable marks on material surfaces, meeting the stringent requirements of product traceability and anti-counterfeiting in industries such as electronics and automotive.

[0003] In the existing technology, there are several main solutions for realizing continuous green lasers: one is a semiconductor-pumped all-solid-state green laser, but it has thermal effects, and the system structure is relatively complex, high power output is difficult, and the cost is high; the other is a semiconductor green laser, which has poor wavelength stability, is greatly affected by factors such as temperature and current, and has a complex structure and high cost.

[0004] It is evident that existing green lasers have complex structures and high costs. Utility Model Content

[0005] To solve the above-mentioned technical problems, or at least partially solve them, this utility model provides a green laser that can output green light and has a simple structure and low cost.

[0006] On one hand, a green laser is provided, the green laser comprising:

[0007] A resonant cavity is used to generate non-polarity-maintaining fundamental frequency light;

[0008] A frequency doubling unit is used to double the frequency of the non-polarity-maintaining fundamental frequency light to output laser light, and the output laser light is green light;

[0009] The resonant cavity is provided with:

[0010] The narrowband high-reflectivity fiber grating has a beveled end face at the first end and a second end connected to the signal fiber of the first pump combiner.

[0011] The first pump source has its pigtail connected to the pump fiber of the first pump combiner.

[0012] The first pump combiner is used in the forward direction.

[0013] The multi-clad optical fiber has its first end connected to the output fiber of the first pump combiner, and its second end connected to the input fiber of the second pump combiner.

[0014] The second pump combiner is used in reverse.

[0015] The second pump source has its pigtail connected to the pump fiber of the second pump combiner.

[0016] A narrowband, low-reflection, uniform fiber grating, with its first end connected to the output fiber of the second pump source.

[0017] The optical power stripper has its input end connected to the second end of the narrowband low-reflection uniform fiber Bragg grating.

[0018] The high-power output head has its input end connected to the second end of the optical power stripper and its output end connected to the frequency doubling unit.

[0019] Optionally, the multi-clad optical fiber is a ytterbium-doped double-clad optical fiber.

[0020] Optionally, a nonlinear effect suppressor is also provided in the resonant cavity to suppress nonlinear effects of a specific wavelength in the resonant cavity.

[0021] Optionally, the nonlinear effect suppressor is disposed between the second pump source and the narrowband low-reflection uniform fiber grating, or

[0022] The nonlinear effect suppressor is disposed between the optical power stripper and the high-power output head.

[0023] Optionally, the nonlinear effect suppressor is a chirped tilted fiber grating or a long-period fiber grating.

[0024] Optionally, the frequency multiplier unit includes:

[0025] The polarization beam splitter, with its input end connected to the output end of the high-power output head, is used to split the non-polarization-maintaining fundamental frequency light into P-polarized light and S-polarized light.

[0026] The first optical path is used to double the frequency of the P-polarized light;

[0027] The second optical path is used to double the frequency of the S-polarized light;

[0028] A polarization beam combiner is used to combine the frequency-doubled P-polarized light and the frequency-doubled S-polarized light into a combined laser beam;

[0029] The collimation unit is used to collimate the combined laser beam before outputting it.

[0030] Optionally, the polarization beam splitter is suitable for the 1.0 μm band, and the polarization beam splitter is coated with a 1.0 μm band antireflection coating;

[0031] The polarization combiner is suitable for the 0.5μm band and is coated with an antireflective coating for the 0.5μm band.

[0032] Optionally, the first optical path includes:

[0033] The first half-wave plate, with its incident surface used to receive the P-polarized light from one side of the polarization beam splitter,

[0034] The first focusing lens has its incident surface connected to the optical path of its exit surface of the first half-wave plate.

[0035] The first LBO frequency doubling crystal has its incident surface aligned with the exit surface of the first focusing lens.

[0036] The first beam splitter is connected to the output surface optical path of the first LBO frequency doubling crystal, and the output surface is connected to the optical path of the polarization combiner.

[0037] The second optical path includes:

[0038] The second half-wave plate, with its incident surface used to receive the S-polarized light from one side of the polarization beam splitter,

[0039] The second focusing lens has its incident surface aligned with the optical path of the exit surface of the second half-wave plate.

[0040] The second LBO frequency doubling crystal has its incident surface aligned with the exit surface of the second focusing lens.

[0041] The second beam splitter is connected to the output surface optical path of the second LBO frequency doubling crystal.

[0042] The third half-wave plate has its incident surface connected to the exit surface of the second beam splitter, and its exit surface is connected to the optical path of the polarization combiner.

[0043] Optionally, the first half-wave plate, the first focusing lens, the second focusing lens, and the second half-wave plate are coated with an anti-reflection coating in the 1.0 μm band;

[0044] The third half-wave plate is coated with an antireflective film in the 0.5μm band;

[0045] The incident and exit surfaces of the first LBO frequency doubling crystal are simultaneously coated with antireflective films in the 1.0 μm and 0.5 μm bands, respectively.

[0046] The incident and output surfaces of the second LBO frequency doubling crystal are simultaneously coated with antireflective coatings in the 1.0μm and 0.5μm bands, respectively.

[0047] Optionally, the lengths of the first LBO frequency doubling crystal and the second LBO frequency doubling crystal are any one of 25mm, 40mm, and 60mm;

[0048] The focal lengths of the first focusing lens and the second focusing lens are any one of 60mm, 100mm, 125mm, and 150mm;

[0049] The lens spacing in the collimation unit is any one of 25mm, 30mm, 45mm, or 60mm.

[0050] This invention provides a green laser, which includes: a resonant cavity for generating non-polarization-maintaining fundamental frequency light; and a frequency doubling unit for doubling the non-polarization-maintaining fundamental frequency light to output laser light, wherein the output laser light is green light. The resonant cavity is equipped with: a narrowband high-reflectivity fiber grating, with a first end having a beveled end face and a second end connected to the signal fiber of a first pump combiner; a first pump source, with its pigtail connected to the pump fiber of the first pump combiner; the first pump combiner being used in the forward direction; a multi-clad fiber, with its first end connected to the output fiber of the first pump combiner and its second end connected to the input fiber of a second pump combiner; the second pump combiner being used in the reverse direction; a second pump source, with its pigtail connected to the pump fiber of the second pump combiner; a narrowband low-reflectivity uniform fiber grating, with its first end connected to the output fiber of the second pump source; an optical power stripper, with its input end connected to the second end of the narrowband low-reflectivity uniform fiber grating; and a high-power output head, with its input end connected to the second end of the optical power stripper and its output end connected to the frequency doubling unit. This invention utilizes a resonant cavity structure composed of a pair of narrowband high-reflectivity fiber gratings 1, a narrowband low-reflectivity uniform fiber grating, and multi-clad optical fibers. Pumped by a first and second pump source via a combiner, it achieves narrow-linewidth, high-power fundamental frequency light output. Frequency doubling of the fundamental frequency light improves the frequency doubling efficiency and increases the output power of the green light. Furthermore, because this invention's green laser uses a non-polarity-maintaining resonant cavity direct output structure and employs lower-cost components, the overall cost of the green laser can be reduced. Attached Figure Description

[0051] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0052] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 The diagram shown is a structural schematic of the green laser according to an embodiment of the present invention.

[0054] Figure 2 The diagram shown is a schematic representation of the chirped tilted fiber optic grating according to an embodiment of the present invention.

[0055] Among them, 110 is the resonant cavity; 120 is the frequency doubling unit; 1 is the narrowband high-reflection fiber grating; 2 is the first pump source; 3 is the first pump combiner; 4 is the multi-clad fiber; 5 is the second pump combiner; 6 is the second pump source; 7 is the nonlinear effect suppressor; 8 is the narrowband low-reflection uniform fiber grating; 9 is the optical power stripper; 10 is the high-power output head; 11 is the polarization beam splitter; 12 is the polarization combiner; 13 is the collimation unit; 21 is the first half-wave plate; 22 is the first focusing lens; 23 is the first LBO frequency doubling crystal; 24 is the first beam splitter; 31 is the second half-wave plate; 32 is the second focusing lens; 33 is the second LBO frequency doubling crystal; 34 is the second beam splitter; and 35 is the third half-wave plate. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0057] Figure 1 The diagram shown is a structural schematic of the green laser according to an embodiment of the present invention. Figure 1 As shown, the green laser includes:

[0058] The resonant cavity 110 is used to generate non-polarization-maintaining fundamental frequency light;

[0059] The frequency doubling unit 120 is used to double the frequency of the non-polarity-maintaining fundamental frequency light and output laser light, wherein the output laser light is green light;

[0060] The resonant cavity 110 is provided with:

[0061] The narrowband high-reflectivity fiber grating 1 has a beveled end face at its first end and its second end connected to the signal fiber of the first pump combiner 3.

[0062] The first pump source 2 has its pigtail connected to the pump fiber of the first pump combiner 3.

[0063] The first pump combiner 3 is used in the forward direction.

[0064] The multi-clad optical fiber 4 has its first end connected to the output fiber of the first pump combiner 3, and its second end connected to the input fiber of the second pump combiner 5.

[0065] The second pump combiner 5 is used in reverse.

[0066] The second pump source 6 has its pigtail connected to the pump fiber of the second pump combiner 5.

[0067] The narrowband low-reflection uniform fiber grating 8 has its first end connected to the output fiber of the second pump source 6.

[0068] The input end of the optical power stripper 9 is connected to the second end of the narrowband low-reflection uniform fiber grating 8.

[0069] The high-power output head 10 has its input end connected to the second end of the optical power stripper 9 and its output end connected to the frequency multiplier unit 120.

[0070] The narrowband high-reflectivity fiber grating 1 has an end face that has been beveled, which can be cut at an 8° angle.

[0071] Narrowband high-reflection fiber grating 1 and narrowband low-reflection uniform fiber grating 8 are used to form laser resonant cavity 110, which can input high-power laser. The high-power laser output in this invention is a laser with a wavelength of 1.0 μm.

[0072] The narrowband high-reflectivity fiber grating 1 is etched with a center wavelength in the 1.0μm band, a 3dB bandwidth of 0.5~0.3nm, and a reflectivity greater than 99.9%; the narrowband low-reflectivity uniform fiber grating 8 is etched with a center wavelength in the 1.0μm band, a 3dB bandwidth of 0.08~0.05nm, and a reflectivity of 10%~20%. Both the narrowband high-reflectivity fiber grating 1 and the narrowband low-reflectivity uniform fiber grating 8 can withstand kilowatt-level high power.

[0073] In this embodiment of the invention, the narrowband high-reflectivity fiber grating 1 can be etched either onto the signal fiber of the first combiner or onto the signal fiber fused to the non-polarization-maintaining fiber of the first combiner. Since the fundamental frequency optical system of the green laser in this embodiment is a non-polarization-maintaining system, no orthogonal splicing is required. One side of the pigtail of the narrowband high-reflectivity fiber grating 1 is beveled at an 8-degree angle to prevent cross-sectional feedback and parasitic oscillations, thus stabilizing the laser output.

[0074] Green laser is a light source with a wavelength between 532nm and 556nm, and the wavelength of the laser output by this invention is within the range of green laser.

[0075] In this embodiment of the present invention, the multi-clad optical fiber 4 is a ytterbium-doped double-clad optical fiber.

[0076] The multi-clad fiber 4 can be a large-mode-field ytterbium-doped double-clad fiber, and the fiber type can be 14 / 250μm, 20 / 400μm, 25 / 400μm, 34 / 460 / 530μm, etc., capable of handling kilowatt-level high power; where 14, 20, 25, etc., represent the core diameter; and 250, 400, etc., represent the cladding diameter. In this invention, it is used as a gain fiber, and the ytterbium doping concentration of the multi-clad fiber 4 achieves a gain coefficient of not less than 1.5dB / m. A shorter gain fiber length can reduce the accumulation of nonlinear effects.

[0077] In one embodiment of this invention, the large-mode-field ytterbium-doped multi-clad fiber 4 is a 20 / 400μm large-core diameter non-polarization-maintaining fiber. Its cladding pump absorption at 976nm reaches 1.44~1.92dB / m, and its numerical aperture (NA) is 0.065.

[0078] In this invention, multi-clad optical fibers with different core and cladding sizes 4 exhibit different performance characteristics, such as 14 / 250μm, 25 / 400μm, 30 / 400μm, and 34 / 460 / 530μm (triple-clad fiber, where 34 represents the core diameter, 460 represents the inner cladding diameter, and 530 represents the outer cladding diameter). For the same numerical aperture, using fibers with smaller cores (limits the distribution of optical modes, reduces multimode interference, improves beam quality, and also offers better bending performance, making it suitable for complex spatial layouts; however, it increases the power density per unit area, making it prone to nonlinear effects). Using fibers with larger cores can transmit greater laser energy; the larger mode field area effectively reduces the power density per unit area and increases the nonlinear effect threshold; however, it makes higher-order modes easier to excite, leading to mode instability, power instability, and deteriorated beam quality. Combining the advantages of different fibers, different fibers can be used to construct the laser.

[0079] In this invention, the narrowband high-reflection fiber grating 1 and the narrowband low-reflection uniform fiber grating 8 are also inscribed on the same type of fiber as the multi-clad fiber 4.

[0080] In this invention, the first pump combiner 3 and the second pump combiner 5 can be forward pumping, backward pumping, or dual-end pumping combiners. The first pump combiner 3 is used in reverse, while the second pump combiner 5 is used in forward.

[0081] In this invention, the signal pigtails of the first pump combiner 3 and the second pump combiner 5 should be cut at an 8° angle and fixed with adhesive. The type of high-power pump combiner can be any one of (2+1)×1, (4+1)×1, or (6+1)×1.

[0082] In one embodiment of this utility model, the first pump combiner 3 is a (6+1)×1 type combiner with a pump fiber of 135 / 155μm, which is suitable for a 260W output 976nm wavelength-locked semiconductor laser, or a 140W output 976nm wavelength-locked semiconductor laser, in which case the pump fiber is replaced with 105 / 125μm.

[0083] The first pump source 2 and the second pump source 6 use multiple pump sources combined (e.g. Figure 1 The combination of two primary pump sources (2) and two secondary pump sources (6) offers advantages over a single high-power pump source in terms of reduced heat dissipation and heat distribution. Furthermore, wavelength-locked output ensures power stability during the final fundamental frequency output. Using a 976nm semiconductor laser for pumping results in an absorption coefficient 3-4 times higher than that of a 915nm laser, significantly reducing the length of the gain fiber, mitigating nonlinear effects, and improving frequency doubling efficiency.

[0084] The second pump combiner 5 is a (6+1)×1 type combiner, and its input and output pigtails are both 20 / 400μm non-polarization-maintaining passive optical fibers.

[0085] In this invention, the first pump source 2 and the second pump source 6 are semiconductor lasers, which are single-mode or multi-mode output lasers. Their output is continuous, the pump wavelength is 915 or 976 nm, and the pump power is greater than 140 W.

[0086] In this invention, the optical power stripper 9 is used to strip away unwanted residual light from the cladding.

[0087] In this invention, the optical power stripper 9 is made based on the etching and texturing method and is used to remove cladding light, including excess pump light and Raman light generated by nonlinear effects.

[0088] In this invention, the optical power stripper 9 removes excess optical power transmitted in the cladding and releases it into the external environment. In fiber lasers, especially when the pump structure is a multi-clad fiber 4, the pump light is transmitted through the cladding, while the laser signal mainly propagates in the fiber core. At the fiber end or critical locations in the system, unabsorbed pump light or other unwanted light (such as SRS light coupled into the cladding by the CTFBG) often remains in the cladding. The optical power stripper 9 is designed so that the cladding light leaks into the coating or absorbing material in a specific area as it passes through, is absorbed and converted into heat, and then dissipated through the outer shell.

[0089] In this invention, the high-power output head 10 is used to output 1.0μm laser light. It can be a QCS with collimation output function or other output heads, but an additional collimation lens group is required.

[0090] This invention utilizes a resonant cavity 110 structure composed of a pair of narrowband high-reflectivity fiber gratings 1, a narrowband low-reflectivity uniform fiber grating 8, and a multi-clad fiber 4. Pumped by a first pump source 2 and a second pump source 6 via a pump combiner, it achieves narrow-linewidth, high-power fundamental frequency light output. Frequency doubling of the fundamental frequency light improves the frequency doubling efficiency and increases the power of the green light output. Furthermore, because this invention's green laser uses a non-polarity-maintaining resonant cavity 110 direct output structure and employs lower-cost components, the overall cost of the green laser can be reduced.

[0091] In this embodiment of the present invention, a nonlinear effect suppressor 7 is further provided in the resonant cavity 110 to suppress nonlinear effects of a specific wavelength in the resonant cavity 110.

[0092] In this embodiment of the invention, the nonlinear effect suppressor 7 is disposed between the second pump source 6 and the narrowband low-reflection uniform fiber grating 8, such as... Figure 1 As shown; or

[0093] The nonlinear effect suppressor 7 is disposed between the optical power stripper 9 and the high-power output head 10. Figure 1 (Not shown in the image).

[0094] In this embodiment of the present invention, the nonlinear effect suppressor 7 is a chirped tilted fiber grating or a long-period fiber grating.

[0095] In this embodiment of the invention, the nonlinear effect suppressor 7 is used to suppress the nonlinear effects generated by the laser under high-power operation.

[0096] The nonlinear effect suppressor 7 can be a chirped tilted fiber grating (CTFBG). The CTFBG has an angle between its grating surface and the fiber axis, enabling it to couple forward-propagating core modes to backward-propagating cladding modes, such as... Figure 2 As shown.

[0097] Figure 2 The diagram shows a schematic of the chirped tilted fiber grating (CTFBG) according to an embodiment of this invention. By controlling parameters such as the period, length, and chirp rate of the CTFBG, the loss peak of the CTFBG can be registered with the Stokes light spectrum excited by the SRS effect. This allows the SRS effect to be coupled from the fiber core to the cladding, and the fiber laser's own cladding stripper can then completely remove it from the laser system, while simultaneously optimizing the beam quality.

[0098] In this embodiment of the invention, the chirped tilted fiber grating (CTFBG) can also be replaced by other types of devices that suppress stimulated Raman scattering, such as long-period fiber gratings (LPFG).

[0099] In this embodiment of the invention, the nonlinear effect suppressor 7 is placed inside the resonant cavity 110, which ensures the purity of the fundamental frequency light spectrum and can almost suppress the nonlinear effect, thereby increasing the threshold of transverse mode instability of the fundamental frequency light and optimizing the beam quality.

[0100] In this embodiment of the present invention, the frequency multiplication unit 120 includes:

[0101] The polarization beam splitter 11 has its input end connected to the output end of the high-power output head 10, and is used to split the non-polarization-maintaining fundamental frequency light into P-polarized light and S-polarized light.

[0102] The first optical path is used to double the frequency of the P-polarized light;

[0103] The second optical path is used to double the frequency of the S-polarized light;

[0104] Polarization beam combiner 12 is used to combine the frequency-doubled P-polarized light and the frequency-doubled S-polarized light into a combined laser beam;

[0105] The collimation unit 13 is used to collimate the combined laser beam before outputting it.

[0106] In this embodiment of the present invention, the polarization beam splitter 11 is suitable for the 1.0 μm band, and the polarization beam splitter 11 is coated with a 1.0 μm band antireflection film;

[0107] The polarization combiner 12 is suitable for the 0.5μm band, and the polarization combiner 12 is coated with an anti-reflection coating for the 0.5μm band.

[0108] In this embodiment of the invention, the sum of the powers of the P-polarized light and the S-polarized light should be equal to the power of the fundamental frequency light input to the polarization beam splitter 11.

[0109] In this embodiment of the present invention, the first optical path includes:

[0110] The first half-wave plate 21 has an incident surface for receiving the P-polarized light from one side of the polarization beam splitter 11.

[0111] The first focusing lens 22 has its incident surface connected to the exit surface of the first half-wave plate 21.

[0112] The first LBO (nonlinear optical crystal) frequency doubling crystal 23 has its incident surface aligned with the exit surface of the first focusing lens 22.

[0113] The first beam splitter 24 is connected to the output surface optical path of the first LBO frequency doubling crystal 23, and the output surface is connected to the optical path of the polarization combiner 12.

[0114] The second optical path includes:

[0115] The second half-wave plate 31 has an incident surface for receiving the S-polarized light from one side of the polarization beam splitter 11.

[0116] The second focusing lens 32 has its incident surface connected to the exit surface of the second half-wave plate 31.

[0117] The second LBO frequency doubling crystal 33 has its incident surface aligned with the exit surface of the second focusing lens 32.

[0118] The second beam splitter 34 is connected to the output surface optical path of the second LBO frequency doubling crystal 33.

[0119] The third half-wave plate 35 has its incident surface connected to the exit surface of the second beam splitter 34, and its exit surface is connected to the optical path of the polarization combiner 12.

[0120] In this embodiment of the invention, the first half-wave plate 21 can adjust the polarization direction of the P-polarized light, and the first focusing lens 22 is responsible for precisely focusing the light beam onto the geometric center of the first LBO frequency doubling crystal 23. By optimizing the rotation angle of the half-wave plate and the position of the lens, combined with adjusting the crystal temperature, the frequency doubling efficiency is maximized, generating the first green laser light.

[0121] Compared with the first optical path, the second optical path has an additional third half-wave plate 35, which can control the polarization state of S-polarized light.

[0122] Collimation unit 13 is composed of plano-convex lenses, which will not be described in detail here.

[0123] In this embodiment of the present invention, the first half-wave plate 21, the first focusing lens 22, the second focusing lens 32, and the second half-wave plate 31 are coated with an anti-reflection film in the 1.0 μm band;

[0124] The third half-wave plate 35 is coated with an anti-reflection film in the 0.5μm band;

[0125] The incident and exit surfaces of the first LBO frequency doubling crystal 23 are simultaneously coated with antireflective films in the 1.0 μm and 0.5 μm bands, respectively.

[0126] The incident and output surfaces of the second LBO frequency doubling crystal 33 are simultaneously coated with antireflective coatings in the 1.0μm and 0.5μm bands, respectively.

[0127] In this embodiment of the present invention, the lengths of the first LBO frequency doubling crystal 23 and the second LBO frequency doubling crystal 33 are any one of 25mm, 40mm, and 60mm.

[0128] The focal lengths of the first focusing lens 22 and the second focusing lens 32 are any one of 60mm, 100mm, 125mm, and 150mm;

[0129] The lens spacing in the collimation unit 13 is any one of 25mm, 30mm, 45mm, or 60mm.

[0130] To reduce surface reflection and increase transmitted light energy, this invention employs multiple optical surface coatings, with 0.5μm having a wavelength of 532nm and 1.0μm having a wavelength of 1064nm.

[0131] An antireflection coating is applied for green light at 532nm and fundamental frequency light at 1064nm to increase frequency doubling efficiency and prevent reflection.

[0132] In this invention, a polarization beam splitter 11 is used to separate the fundamental frequency light and increase its polarization degree before frequency doubling, thereby improving the utilization rate of the fundamental frequency light. The two green beams are combined to optimize the frequency doubling efficiency and increase the output power of the green light.

[0133] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0134] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A green laser, characterized in that, The green laser includes: A resonant cavity is used to generate non-polarity-maintaining fundamental frequency light; A frequency doubling unit is used to double the frequency of the non-polarity-maintaining fundamental frequency light to output laser light, and the output laser light is green light; The resonant cavity is provided with: The narrowband high-reflectivity fiber grating has a beveled end face at the first end and a second end connected to the signal fiber of the first pump combiner. The first pump source has its pigtail connected to the pump fiber of the first pump combiner. The first pump combiner is used in the forward direction. The multi-clad optical fiber has its first end connected to the output fiber of the first pump combiner, and its second end connected to the input fiber of the second pump combiner. The second pump combiner is used in reverse. The second pump source has its pigtail connected to the pump fiber of the second pump combiner. A narrowband, low-reflection, uniform fiber grating, with its first end connected to the output fiber of the second pump source. The optical power stripper has its input end connected to the second end of the narrowband low-reflection uniform fiber Bragg grating. The high-power output head has its input end connected to the second end of the optical power stripper and its output end connected to the frequency doubling unit.

2. The green laser according to claim 1, characterized in that, The multi-clad optical fiber is a ytterbium-doped double-clad optical fiber.

3. The green laser according to claim 1, characterized in that, The resonant cavity is also equipped with a nonlinear effect suppressor to suppress nonlinear effects at specific wavelengths within the resonant cavity.

4. The green laser according to claim 3, characterized in that, The nonlinear effect suppressor is disposed between the second pump source and the narrowband low-reflection uniform fiber grating, or The nonlinear effect suppressor is disposed between the optical power stripper and the high-power output head.

5. The green laser according to claim 3, characterized in that, The nonlinear effect suppressor is a chirped tilted fiber grating or a long-period fiber grating.

6. The green laser according to claim 1, characterized in that, The frequency multiplier unit includes: The polarization beam splitter, with its input end connected to the output end of the high-power output head, is used to split the non-polarization-maintaining fundamental frequency light into P-polarized light and S-polarized light. The first optical path is used to double the frequency of the P-polarized light; The second optical path is used to double the frequency of the S-polarized light; A polarization beam combiner is used to combine the frequency-doubled P-polarized light and the frequency-doubled S-polarized light into a combined laser beam; The collimation unit is used to collimate the combined laser beam before outputting it.

7. The green laser according to claim 6, characterized in that, The polarization beam splitter is suitable for the 1.0 μm band, and the polarization beam splitter is coated with a 1.0 μm band antireflection coating; The polarization combiner is suitable for the 0.5μm band and is coated with an antireflective coating for the 0.5μm band.

8. The green laser according to claim 6, characterized in that, The first optical path includes: The first half-wave plate, with its incident surface used to receive the P-polarized light from one side of the polarization beam splitter, The first focusing lens has its incident surface connected to the optical path of its exit surface of the first half-wave plate. The first LBO frequency doubling crystal has its incident surface aligned with the exit surface of the first focusing lens. The first beam splitter is connected to the output surface optical path of the first LBO frequency doubling crystal, and the output surface is connected to the optical path of the polarization combiner. The second optical path includes: The second half-wave plate, with its incident surface used to receive the S-polarized light from one side of the polarization beam splitter, The second focusing lens has its incident surface aligned with the optical path of the exit surface of the second half-wave plate. The second LBO frequency doubling crystal has its incident surface aligned with the exit surface of the second focusing lens. The second beam splitter is connected to the output surface optical path of the second LBO frequency doubling crystal. The third half-wave plate has its incident surface connected to the exit surface of the second beam splitter, and its exit surface is connected to the optical path of the polarization combiner.

9. The green laser according to claim 8, characterized in that, The first half-wave plate, the first focusing lens, the second focusing lens, and the second half-wave plate are coated with an anti-reflection coating in the 1.0 μm band; The third half-wave plate is coated with an antireflective film in the 0.5μm band; The incident and exit surfaces of the first LBO frequency doubling crystal are simultaneously coated with antireflective films in the 1.0 μm and 0.5 μm bands, respectively. The incident and output surfaces of the second LBO frequency doubling crystal are simultaneously coated with antireflective coatings in the 1.0μm and 0.5μm bands, respectively.

10. The green laser according to claim 8, characterized in that, The lengths of the first LBO frequency doubling crystal and the second LBO frequency doubling crystal are any one of 25mm, 40mm, and 60mm; The focal lengths of the first focusing lens and the second focusing lens are any one of 60mm, 100mm, 125mm, and 150mm; The lens spacing in the collimation unit is any one of 25mm, 30mm, 45mm, or 60mm.

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