Pulse laser amplification module, pulse laser

Abstract

The application discloses a pulse laser amplification module for amplifying a pulse laser beam, comprising a rod-shaped crystal fiber, the outer periphery of the rod-shaped crystal fiber being coated with a gold film; one end of the rod-shaped crystal fiber is provided with an input coupling lens, one end of the input coupling lens being used for inputting the pulse laser beam and pump light, the pulse laser beam and the pump light being capable of passing through the end face center of the one end of the rod-shaped crystal fiber and being focused into the rod-shaped crystal fiber; the other end of the rod-shaped crystal fiber is provided with an output collimating lens, which is used for converting the pulse laser beam output from the rod-shaped crystal fiber into a collimated light beam; the pump light enters the rod-shaped crystal fiber through the end face center of the rod-shaped crystal fiber and propagates in the rod-shaped crystal fiber, and total reflection is generated at the inner surface of the rod-shaped crystal fiber, and the pump light is converged on the center line of the rod-shaped crystal fiber, so that the light intensity of the pump light in the rod-shaped crystal fiber is maximum, the maximum gain particle inversion number is obtained, and the wide-spectrum self-waveguide amplification of the pulse laser beam is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of laser amplification, and in particular to a pulse laser amplification module and a pulse laser. Background Art

[0002] High-energy femtosecond lasers have important applications in high-field physics research, atomic and molecular dynamics, and spectral detection, and are of great scientific value. In recent years, with the study of the interaction mechanism between lasers and materials, high-energy ultrafast lasers have demonstrated their non-contact, cold-processing, and high-precision properties. Their applications in additive and subtractive manufacturing have gradually expanded, making them a new type of processing tool.

[0003] Currently, high-energy femtosecond lasers are generated primarily using chirped pulse amplification, split pulse amplification, and regenerative amplification technologies. Chirped pulse amplification uses a dispersion device to first stretch the picosecond or femtosecond seed pulse to the nanosecond level before amplifying it, and then compressing the pulse to hundreds of femtoseconds using a dispersion compensation device. Split pulse amplification involves first splitting the seed pulse into multiple sub-pulse trains, amplifying them within the amplifier, and then combining them into a single pulse with higher energy. Both chirped pulse amplification and split pulse amplification effectively avoid the optical wave splitting effect and pulse amplification suppression effect caused by high peak energy during the pulse amplification process. Regenerative amplification significantly increases pulse energy by amplifying the pulse multiple times in a regenerative cavity.

[0004] All three of the aforementioned pulse amplification technologies are inevitably affected by the gain-narrowing effect of the gain medium during the laser pulse energy amplification process, which limits the frequency domain width of the output spectrum, further restricting pulse compression and pulse energy enhancement. Furthermore, for regenerative amplification, as the number of intracavity pulse amplification cycles increases during the pulse cyclic amplification process, the high pulse energy poses a serious risk of damage to components such as the Pockels cell and amplifying crystal.

[0005] Therefore, improvements need to be made based on the above-mentioned technical problems to solve the technical problem in the prior art that, during the laser pulse energy amplification process, the gain medium gain narrowing effect is inevitably affected, so as to obtain pulses with high energy, narrow pulse width, wide spectrum and high beam quality. Summary of the Invention

[0006] The present invention aims to provide a pulse laser amplification module and a pulse laser to solve the technical problem in the prior art that, during the laser pulse energy amplification process, gain narrowing effect of the gain medium is unavoidable.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention discloses a pulse laser amplification module for amplifying a pulse laser beam, comprising a rod-shaped crystal fiber, wherein the outer periphery of the rod-shaped crystal fiber is coated with a gold film; an input coupling lens is provided at one end of the rod-shaped crystal fiber, and one end of the input coupling lens is used to input a pulse laser beam and a pump light, and the input coupling lens can make the pulse laser beam and the pump light pass through the end face center of one end of the rod-shaped crystal fiber and focus inside the rod-shaped crystal fiber, that is, the focused light spot is incident into the rod-shaped crystal fiber through the end face center of the rod-shaped crystal fiber, and the focus of the focused light beam is inside the fiber; the rod-shaped crystal fiber An output collimating lens is provided at the other end of the optical fiber, which is used to convert the pulsed laser beam output from the rod-shaped crystal fiber into a collimated beam; the pump light enters the rod-shaped crystal fiber through the center of the end face of the rod-shaped crystal fiber and propagates, and generates total reflection at the inner surface of the rod-shaped crystal fiber and converges on the center line of the rod-shaped crystal fiber, so as to maximize the light intensity of the pump light in the rod-shaped crystal fiber and obtain the maximum gain particle inversion number. The beam self-focusing effect of the Kerr effect and thermal lens effect generated by the strong pump light and the spectrum broadening mode field self-defocusing effect during the laser beam gain amplification process are clamped with each other, thereby realizing wide-spectrum self-waveguide amplification of the pulsed laser beam.

[0009] This scheme utilizes the fact that the center of a rod-shaped crystal fiber has the strongest pump light intensity and the largest gain particle inversion number. During the amplification process, the pulsed laser beam will produce a thermal lensing effect related to the pump light intensity and a Kerr effect related to gain amplification, causing the beam to self-focus during energy amplification. Simultaneously, the energy boost of the laser pulse during gain amplification produces nonlinear amplification, enabling self-phase modulation spectrum broadening. Because pulsed laser beam spectrum broadening introduces an increase in the beam mode field and produces a divergent effect, the pulsed laser beam will also self-defocus during the amplification process. During the amplification process, the self-waveguided beam eliminates spectral components at the edge of the light spot mode field through mode field self-balancing, suppressing mode field distortion. This self-cleaning characteristic achieves high beam quality output.

[0010] Preferably, under the condition that the doping concentration of the rod-shaped crystal fiber remains unchanged, the amplified light beam can be regulated from the waveguide aperture by adjusting the pump spot size and the amplified light beam diameter.

[0011] By adjusting the larger signal beam diameter and pump beam diameter, large-aperture beam self-waveguide amplification can be achieved. While reducing the beam energy density, the pulse compression and pulse energy of the pulsed laser beam can be further improved, avoiding the damage of high-energy pulses to the rod-shaped crystal fiber, and being more conducive to obtaining pulses with high energy, narrow pulse width, wide spectrum, and high beam quality, which has the advantage of generating high-energy laser pulse amplification.

[0012] Specifically, as a preferred embodiment, the ratio of the diameter of the pump spot to the diameter of the amplified light beam is 3:2, and the diameter of the amplified light beam from the waveguide is 2 / 3 to 1 of the diameter of the pump spot.

[0013] Preferably, the end faces at both ends of the rod-shaped crystal fiber and the outer surfaces of the input coupling lens and the output collimating lens are respectively coated with anti-reflection films, and the wavelength of the anti-reflection films matches the wavelength of the input light to increase transmittance.

[0014] Preferably, the rod-shaped crystal optical fiber is embedded in a copper block heat sink by welding. The gold film coated on the cylindrical surface of the rod-shaped crystal fiber not only reflects signal light and pump light, but also serves as a heat transfer medium between the rod-shaped crystal fiber and the copper heat sink. The gold film has excellent thermal conductivity, which allows for excellent heat dissipation of the rod-shaped crystal fiber, preventing damage to the gain medium due to overheating, allowing for higher laser output power, and thus improving laser output power. It also avoids uneven heating of the gain medium, helping to maintain pulse shape and timing characteristics, thereby improving beam quality. It can reduce changes in laser parameters or physical dimensions of optical components due to temperature fluctuations, which can affect beam focusing and directivity. Good heat dissipation can reduce this thermal drift and improve the stability of the entire laser system. It avoids damage to optical components such as lenses and reflectors, reduces thermal stress and thermal damage, and reduces failure rate, thereby extending the service life of the laser and its components and improving system reliability. It prevents changes in the refractive index of the gain medium caused by high temperature, which can lead to laser mode degradation, and helps maintain mode stability. It also reduces the loss of pump light and laser signal light due to thermal effects, thereby improving laser conversion efficiency.

[0015] Preferably, the pulse laser amplification module is a single-channel amplification module, and the input pulse laser beam and pump light can be amplified once in the pulse laser amplification module.

[0016] Preferably, the pulse laser amplification module is a multi-channel amplification module for amplifying the pulse laser multiple times.

[0017] As one of the implementation methods of the multi-channel amplification module, the pulse laser amplification module also includes a first half-wave plate, one side of the first half-wave plate is used to set the pulse seed source, the other side of the first half-wave plate is provided with a first polarization beam splitter, the side of the first polarization beam splitter away from the first half-wave plate is provided with an input coupling lens, a rod-shaped crystal fiber and an output collimating lens in sequence, and the side of the output collimating lens away from the rod-shaped crystal fiber is provided with a first Faraday rotator and a first end face zero-degree reflector in sequence; thus, a two-channel pulse laser amplification module is constituted, which can realize secondary amplification of the pulsed laser.

[0018] The amplification principle of the two-channel pulse laser amplification module is as follows: after the first half-wave plate receives the pulse laser output by the pulse seed source and changes the polarization direction of the pulse laser, the pulse laser is transmitted to the first polarization beam splitter. After the beam splitting effect of the first polarization beam splitter, the pulse laser is further transmitted to the input coupling lens, and then passes through the rod-shaped crystal fiber for the first amplification. The pulse laser is then transmitted to the output collimating lens and the first Faraday rotator in sequence, and then transmitted to the first end face zero-degree reflector for reflection;

[0019] The pulsed laser after the first amplification is reflected by the first end face zero-degree reflector and returns to the first Faraday rotator. It passes through the output collimating lens, rod-shaped crystal fiber, input coupling lens, and first polarization beam splitter in sequence, and then undergoes the beam splitting effect of the first polarization beam splitter to output the pulsed laser after the second amplification.

[0020] Specifically, a half-wave plate changes the polarization state of polarized light by introducing phase retardation. When linearly polarized light passes through a half-wave plate, its polarization direction rotates according to the optical axis of the wave plate.

[0021] As one implementation of the multi-channel amplification module, the pulse laser amplification module further includes a first half-wave plate, one side of the first half-wave plate is used to set a pulse seed source, the other side of the first half-wave plate is provided with a first polarization beam splitter, and the side of the first polarization beam splitter away from the first half-wave plate is sequentially provided with a second Faraday rotator and a second half-wave plate.

[0022] A second polarization beam splitter is provided on a side of the second half-wave plate away from the second Faraday rotator, an input coupling lens, a rod-shaped crystal fiber, and an output collimating lens are sequentially provided on a side of a first output end of the second polarization beam splitter, and a first Faraday rotator and a first end face zero-degree reflector are sequentially provided on a side of the output collimating lens away from the rod-shaped crystal fiber;

[0023] A second end-face zero-degree reflector is provided at one side of the second output end of the second polarization beam splitter, for reflecting the light split by the second polarization beam splitter;

[0024] Thus, a four-channel pulse laser amplification module is formed, which can achieve four times amplification of the pulse laser.

[0025] The amplification principle of the four-channel pulse laser amplification module is as follows: after the first half-wave plate receives the pulse laser output by the pulse seed source and changes the polarization direction of the pulse laser, the pulse laser is transmitted to the first polarization beam splitter. After the beam splitting effect of the first polarization beam splitter, the pulse laser is further transmitted and sequentially passes through the second Faraday rotator, the second half-wave plate and the second polarization beam splitter. After the beam splitting effect of the second polarization beam splitter, the pulse laser is further transmitted to the input coupling lens, and sequentially passes through the rod-shaped crystal fiber to perform the first amplification of the pulse laser. Then, it is sequentially transmitted to the output collimating lens and the first Faraday rotator, and then transmitted to the first end face zero-degree reflector for reflection;

[0026] The pulsed laser after the first amplification is reflected by the first end face zero-degree reflector and returns to the first Faraday rotator. It then passes through the output collimating lens, the rod-shaped crystal fiber, and the input coupling lens in sequence to output the pulsed laser after the second amplification.

[0027] When the pulsed laser light after the second amplification is transmitted to the second polarization beam splitter, it is transmitted to the second end face zero-degree reflector for reflection. After the reflection, the pulsed laser light after the second amplification is transmitted to the input coupling lens again, and then passes through the rod-shaped crystal fiber to amplify the pulsed laser light for the third time. Then, it is transmitted to the output collimating lens and the first Faraday rotator in sequence, and then transmitted to the first end face zero-degree reflector for reflection.

[0028] After the third amplification, the pulse laser is reflected by the first end face zero-degree reflector and returns to the first Faraday rotator. It then passes through the output collimating lens, the rod-shaped crystal fiber, and the input coupling lens in sequence for the fourth amplification of the pulse laser.

[0029] Then, the second Faraday rotator and the second half-wave plate are adjusted, and the polarization state of the pulsed laser that has been amplified for the fourth time is adjusted, so that the pulsed laser that has been amplified for the fourth time passes through the second polarization beam splitter, and is transmitted to the first polarization beam splitter through the second half-wave plate and the second Faraday rotator in sequence, and then undergoes the beam splitting effect of the first polarization beam splitter to output the pulsed laser that has been amplified for the fourth time.

[0030] In a second aspect, the present invention further discloses a pulse laser, comprising any one of the pulse laser amplification modules described above.

[0031] In summary, the present invention has the following beneficial effects:

[0032] 1. In the pulse laser amplification module and pulse laser of the present invention, the signal light beam is self-waveguided in the rod-shaped crystal to achieve amplification, which has the advantage of self-cleaning of the spot mode and can realize high-beam-quality laser amplification. Specifically, the signal light beam is self-waveguided in the rod-shaped crystal fiber to achieve amplification; during the laser pulse amplification process, the signal light beam achieves dynamic balance of the light beam mode field through the self-focusing process of the Kerr effect and the thermal lens effect and the self-defocusing process of the nonlinear amplification spectrum broadening spot mode field, forming a self-waveguide of the light beam in the rod-shaped crystal. During the amplification process, the self-waveguide light beam eliminates the spectral components at the edge of the spot mode field through mode field self-balancing, suppresses mode field distortion, has the characteristics of mode self-cleaning, and realizes high-beam-quality output. This technology provides a brand-new solution for the generation of ultrashort pulse lasers with high beam quality, high energy, high power, and narrow pulse width.

[0033] 2. In the pulse laser amplification module and pulse laser of the present invention, the amplification module is based on a rod-shaped crystal structure, which can improve the gain amplification pump conversion efficiency, produce high pump conversion efficiency, and achieve high-power laser generation. Specifically, it is embodied in: a rod-shaped crystal structure based on a small core diameter side gold film and the use of end-face pumping. The pump light enters from the end face of the rod-shaped crystal fiber, produces total reflection on the cylindrical surface, and converges the transmission to the center of the rod-shaped crystal fiber. This process enables the center of the rod-shaped crystal fiber to produce the strongest pump light intensity and the largest gain particle inversion number, which is beneficial to the efficient absorption of pump energy by the signal beam, while making the thermal lens self-focusing effect more likely to occur, which is more conducive to the formation of a beam amplification self-waveguide.

[0034] 3. In the pulse laser amplification module and pulse laser of the present invention, the self-waveguide amplification process achieves nonlinear spectrum broadening, thereby suppressing the gain narrowing effect and achieving broadband laser amplification, with the advantages of outputting high-peak energy, narrow pulse lasers. Specifically, the signal beam undergoes self-waveguide amplification in a rod-shaped crystal fiber, generating a nonlinear self-phase modulation effect through the amplified pulse, thereby achieving pulse spectrum broadening. This effectively overcomes the gain narrowing effect of the rod-shaped crystal fiber and ensures broadband pulse spectrum amplification. Simultaneously, the spectrum broadening and mode field divergence of the amplification process are balanced with the Kerr effect and thermal lens self-focusing, forming a self-waveguided amplified beam. Therefore, the self-waveguide spectrum broadening and amplification of the pulse facilitates pulse width compression, enabling the generation of sub-hundredths of a femtosecond, high-peak energy lasers.

[0035] 4. In the pulse laser amplification module and pulse laser of the present invention, the pump spot and mode field aperture can be flexibly controlled during the self-waveguide amplification process, thereby achieving the advantages of high-power and high-energy amplification and reducing the risk of damage to the device. Specifically, the signal beam undergoes self-waveguide amplification in the rod-shaped crystal fiber, and the self-waveguide aperture can be flexibly controlled by the signal beam diameter, the pump beam diameter, and the gain medium doping concentration. By adjusting the larger signal beam diameter and the pump beam diameter, large-aperture beam self-waveguide amplification can be achieved, which reduces the beam energy density while avoiding damage to the rod-shaped crystal fiber caused by high-energy pulses, thus having the advantage of generating high-energy laser pulse amplification.

[0036] 5. The pulsed laser amplification module and pulsed laser of the present invention utilize self-waveguide amplification of a beam with dynamic spot mode field balance to suppress spot mode degradation, and the beam exhibits a self-cleaning effect during amplification. Furthermore, the spectral broadening of the beam during high-energy nonlinear amplification in the self-waveguide effectively suppresses the gain narrowing effect of rod-shaped crystal fibers, facilitating pulse width compression to sub-hundredths of a femtosecond, achieving extremely high peak energy output. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the purpose, technical solutions and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0038] Figure 1 This is a schematic diagram of the self-waveguide amplification of the pulsed laser beam generated by the rod-shaped crystal fiber of the present invention.

[0039] Figure 2 Schematic diagram of a pulse laser device using a single-channel amplification module in Example 1 of the present invention.

[0040] Figure 3 Schematic diagram of a pulse laser device using a two-channel amplification module in the second embodiment of the present invention.

[0041] Figure 4 Schematic diagram of a pulse laser device using a four-channel amplification module in embodiment 3 of the present invention.

[0042] Figure 5 This is a schematic diagram of the pulsed laser spectrum emitted by the pulse seed source when the rod-shaped crystal fiber of the present invention generates a pulsed laser beam from the waveguide for amplification.

[0043] Figure 6 This is a schematic diagram of the self-phase modulation broadening spectrum when the rod-shaped crystal fiber generates a pulsed laser beam and amplifies it from the waveguide.

[0044] Figure 7 This is a schematic diagram of the amplified laser spectrum when the pulsed laser beam generated by the rod-shaped crystal fiber of the present invention is amplified by the waveguide.

[0045] Explanation of the reference numerals: 100, pulse seed source; 101, pulse laser beam; 200, pump coupling module; 201, pump source; 202, pump collimating lens; 203, dichroic mirror; 204, pump light; 300, pulse laser amplification module; 301, input coupling lens; 302, rod-shaped crystal fiber; 303, output collimating lens; 304, first half-wave plate; 305, first polarization beam splitter; 306, first Faraday rotator; 307, first end face zero-degree mirror; 308, second Faraday rotator; 309, second half-wave plate; 310, second polarization beam splitter; 311, second end face zero-degree mirror; 312, gold film; 400, pulse compression module; 401, mirror; 402, right-angle mirror; 403, first diffraction grating; 404, second diffraction grating; 405, downward-pressed roof mirror. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0047] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not require further definition or explanation in subsequent figures. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the figures, or the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and are not to be construed as indicating or implying relative importance. Furthermore, terms such as "horizontal" and "vertical" do not imply that a component must be absolutely horizontal or overhanging, but rather may be slightly tilted. For example, "horizontal" simply refers to a direction that is more horizontal than "vertical," and does not imply that the structure must be completely horizontal, but rather may be slightly tilted. In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense, including, for example, fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0048] The present invention can be applied to the technical field of laser amplification, specifically to the field of high-energy ultrashort pulse laser amplification and strong-field nonlinear optics, and solves the technical problem in the prior art that, during the laser pulse energy amplification process, the gain narrowing effect of the gain medium is inevitably suffered.

[0049] The present invention forms a dynamic balance between the self-focusing process of the Kerr effect and the thermal lens effect and the self-defocusing process of the light spot mode field; and utilizes the dynamically balanced light beam self-waveguiding effect, the light spot mode self-cleaning phenomenon, and the self-phase modulation spectrum broadening effect to generate high-energy, narrow pulse width, wide spectrum, and high beam quality laser pulses.

[0050] See also Figure 1 Based on the technical problems solved above, the present invention discloses a pulse laser amplification module 300 for amplifying a pulse laser beam 101, comprising a rod-shaped crystal fiber 302, the outer periphery of which is coated with a gold film 312; an input coupling lens 301 is provided at one end of the rod-shaped crystal fiber 302, and one end of the input coupling lens 301 is used to input the pulse laser beam 101 and the pump light 204, and the input coupling lens 301 can make the pulse laser beam 101 and the pump light 204 pass through the end face center of one end of the rod-shaped crystal fiber 302 and focus inside the rod-shaped crystal fiber 302, that is, the focused light spot is formed by the rod-shaped crystal fiber 302. The center of the end face of the rod-shaped crystal fiber 302 is incident into the rod-shaped crystal fiber 302, and the focus of the focused light beam is inside the fiber; the other end of the rod-shaped crystal fiber 302 is provided with an output collimating lens 303, which is used to convert the pulsed laser beam 101 output from the rod-shaped crystal fiber 302 into a collimated light beam; the pump light 204 enters the rod-shaped crystal fiber 302 through the center of the end face of the rod-shaped crystal fiber 302 and propagates, and generates total reflection at the inner surface of the rod-shaped crystal fiber 302, and converges on the center line of the rod-shaped crystal fiber 302, so that the light intensity of the pump light 204 in the rod-shaped crystal fiber 302 is maximized, so as to obtain the maximum gain particle inversion number, thereby realizing broadband self-waveguide amplification of the pulsed laser beam 101.

[0051] See also Figure 1 、 Figures 5 to 7, respectively, show schematic diagrams of the pulsed laser spectrum emitted by the pulse seed source during self-waveguide amplification of a pulsed laser beam generated by a rod-shaped crystal fiber, the self-phase modulation broadening spectrum, and the amplified laser spectrum. As can be seen from the figures, this scheme utilizes the strongest pump light intensity and the largest gain particle inversion number at the center of the rod-shaped crystal fiber. During the amplification process, the pulsed laser beam generates a thermal lensing effect related to the pump light intensity and a Kerr effect related to gain amplification, causing the beam to self-focus during energy amplification. Simultaneously, the energy boost of the laser pulse during the gain amplification process generates nonlinear amplification, achieving self-phase modulation spectrum broadening. Because the pulsed laser beam spectrum broadening introduces an increase in the beam mode field, resulting in a divergent effect, the pulsed laser beam simultaneously experiences self-defocusing during the amplification process. During the amplification process, the self-waveguided beam eliminates spectral components at the edge of the mode field through mode field self-balancing, suppressing mode field distortion and exhibiting mode self-cleaning characteristics, achieving high beam quality output.

[0052] This approach achieves a dynamic balance between the self-focusing processes of the Kerr effect and thermal lensing, and the self-defocusing process of the light spot mode field. Based on the amplification of a pulsed laser beam in a rod-shaped crystal fiber, it utilizes the beam self-focusing and self-defocusing phenomena related to pump light intensity, laser gain amplification, and nonlinear amplification. The self-waveguiding process induced by the dynamic equilibrium of the light spot mode field, the wide-spectrum characteristics of self-phase modulation, the mode self-cleaning advantages of the self-waveguiding process, and the amplification properties of the gain medium to achieve dynamic beam balance and wide-spectrum self-waveguiding amplification.

[0053] This solution can utilize the self-defocusing effect of the pulsed laser beam spectrum broadening mode field and the self-focusing effect of the Kerr effect and thermal lens effect during the gain amplification process to clamp each other, forming a self-waveguide with dynamic balance of the beam mode field, thereby suppressing the degradation of the spot mode and making the beam have a self-cleaning effect during the amplification process.

[0054] This scheme can avoid the gain narrowing effect of the gain medium, has the wide spectrum characteristics of self-phase modulation, and combines the mode self-cleaning advantages of the self-waveguiding process and the amplification characteristics of the gain medium to broaden the frequency domain width of the output spectrum, further improving the pulse compression and pulse energy of the pulsed laser beam, and ultimately forming a hundred-femtosecond pulse laser with a wide spectral range of 800~1100nm, mode self-cleaning, and a high energy gain output of tens of millijoules, becoming a way to obtain pulses with high energy, narrow pulse width, wide spectrum, and high beam quality.

[0055] Specifically, the pulse laser beam is output through a pulse seed source device, and the pump light is output through a pump source device.

[0056] Specifically, the input coupling lens of this solution can focus the input pulsed laser beam through the input coupling lens to the center of the rod-shaped crystal fiber, enabling more efficient energy conversion and amplification of the beam in the gain medium within the fiber. Furthermore, the input coupling lens helps match the mode of the pulsed laser beam with the mode field distribution of the fiber, ensuring efficient coupling of laser energy into the fiber and reducing losses caused by mode mismatch.

[0057] Preferably, when the rod-shaped crystal fiber is used as the gain medium, the doping concentration of the rod-shaped crystal fiber is 0.5% to 10%.

[0058] Under the condition that the doping concentration of the rod-shaped crystal fiber remains unchanged, the self-waveguide aperture of the amplified beam can be controlled by adjusting the pump spot size and the amplified beam diameter. By adjusting the larger signal beam diameter and pump beam diameter, large-aperture self-waveguide amplification of the beam can be achieved. While reducing the beam energy density, it can further improve the pulse compression and pulse energy of the pulsed laser beam, avoiding damage to the rod-shaped crystal fiber caused by high-energy pulses. This is more conducive to obtaining high-energy, narrow pulse width, wide spectrum, and high beam quality pulses, and has the advantage of generating high-energy laser pulse amplification. Specifically, the ratio of the pump spot diameter to the amplified beam diameter is 3:2, the self-waveguide aperture of the amplified beam is between 2 / 3 and 1 / 3 of the pump spot diameter, and the self-waveguide aperture of the amplified beam is controllable. In addition, the self-waveguide aperture can be controlled by selecting different gain medium doping concentrations. In specific applications, when a rod-shaped crystal fiber is used as the gain medium, the doping concentration of the rod-shaped crystal fiber can be selected to be between 0.5% and 10%.

[0059] In a specific implementation, the rod-shaped crystal fiber adopts a yttrium aluminum garnet (YAG) laser crystal doped with rare earth elements; or, the rod-shaped crystal fiber adopts a yttrium aluminum garnet (YAG) laser crystal doped with ytterbium (Yb) particles.

[0060] As one of the application sizes of the rod-shaped crystal fiber, its length is 30 mm and its diameter is 2 mm.

[0061] Preferably, the end faces at both ends of the rod-shaped crystal optical fiber are respectively coated with anti-reflection films, and the wavelength of the anti-reflection films matches the wavelength of the input light to increase the transmittance.

[0062] Preferably, outer surfaces of the input coupling lens and the output collimating lens are respectively coated with anti-reflection films to increase transmittance.

[0063] In specific implementations, pulse seed source 100 utilizes a broadband ultrashort pulse laser. This can emit broadband ultrashort pulses with a defined spectral width and output repetition rates ranging from low to ultra-high (Hz to THz) picosecond or femtosecond ultrafast lasers. When the signal light emitted by this broadband ultrashort pulse seed source is amplified in a rod-shaped crystal fiber, its polarization state can be arbitrary and unrestricted, including horizontal, vertical, or circular polarization.

[0064] In specific implementation, the pulse seed source 100 can generate pulsed laser seed signal light, with an emission center wavelength of 800 nm, 1030 nm, 1064 nm and 1560 nm, etc., a spectral width greater than 10 nm, and can be an ultrafast seed source with adjustable repetition rate from 1 Hz to MHz or a high repetition rate of GHz or THz, with a pulse width of several picoseconds or hundreds of femtoseconds.

[0065] Preferably, the rod-shaped crystal optical fiber is embedded in a copper block heat sink by welding. The gold film coated on the cylindrical surface of the rod-shaped crystal fiber not only reflects signal light and pump light, but also serves as a heat transfer medium between the rod-shaped crystal fiber and the copper heat sink. The gold film has excellent thermal conductivity, which allows for excellent heat dissipation of the rod-shaped crystal fiber, preventing damage to the gain medium due to overheating, allowing for higher laser output power, and thus improving laser output power. It also avoids uneven heating of the gain medium, helping to maintain pulse shape and timing characteristics, thereby improving beam quality. It can also reduce changes in laser parameters or physical dimensions of optical components due to temperature fluctuations, which can affect beam focusing and directivity. Good heat dissipation can reduce this thermal drift and improve the stability of the entire laser system. It avoids damage to optical components such as lenses and reflectors, reduces thermal stress and thermal damage, and reduces failure rate, thereby extending the service life of the laser and its components and improving system reliability. It prevents changes in the refractive index of the gain medium caused by high temperature, which can lead to laser mode degradation, and helps maintain mode stability. It also reduces the loss of pump light and laser signal light due to thermal effects, thereby improving laser conversion efficiency.

[0066] Preferably, the pulse laser amplification module is a single-channel amplification module, and the input pulse laser beam and pump light can be amplified once in the pulse laser amplification module.

[0067] As one implementation of a single-channel amplification module, the present invention discloses embodiment 1.

[0068] Example 1

[0069] It should be noted that, in this embodiment, the pulse laser amplification module is suitable for amplifying various seed source laser wavelengths. In this embodiment, only the seed source pulse laser with a wavelength of 1030nm is used as an example for illustration, and its use is not limited. The pump light in this embodiment uses 969nm.

[0070] See also Figure 1 and Figure 2 The pulse laser amplification module includes a rod-shaped crystal fiber, the outer periphery of which is coated with a gold film; the rod-shaped crystal fiber has a cylindrical shape.

[0071] The rod-shaped crystal fiber 302 is a YAG laser crystal doped with Yb particles, with a length of 30 mm and a diameter of 2 mm, and the end faces are coated with 969 nm and 1030 nm anti-reflection coatings; it is used to amplify the signal light output by the broadband ultrashort pulse seed source.

[0072] An input coupling lens 301 is provided at one end of the rod-shaped crystal fiber 302. One end of the input coupling lens 301 is used to input the pulsed laser beam 101 and the pump light 204. The pulsed laser beam 101 and the pump light 204 can be focused by the input coupling lens 301 to the center of the end face of one end of the rod-shaped crystal fiber 302.

[0073] In this embodiment, the input coupling lens 301 is a fused silica plano-convex lens with a focal length of 400 mm and coated with a 700-1100 nm anti-reflection coating. It is used to couple 969 nm pump light into the rod-shaped crystal fiber 302 and simultaneously focus 1030 nm signal light into the rod-shaped crystal fiber 302 for self-waveguide amplification.

[0074] The other end of the rod-shaped crystal fiber 302 is provided with an output collimating lens 303 for converting the pulsed laser beam 101 output from the rod-shaped crystal fiber 302 into a collimated beam;

[0075] In this embodiment, the output collimating lens 301 can be a fused silica plano-convex lens with a focal length of 400 mm and coated with a 700-1100 nm anti-reflection coating; it is used to collimate the 1030 nm amplified self-waveguide beam output by the Yb / YAG rod-shaped crystal fiber 302 .

[0076] The pump light 204 enters the rod-shaped crystal fiber 302 through the center of the end face of the rod-shaped crystal fiber 302 and propagates therein, and generates total reflection at the inner surface of the rod-shaped crystal fiber 302 and converges on the center line of the rod-shaped crystal fiber 302, so as to maximize the light intensity of the pump light 204 in the rod-shaped crystal fiber 302, thereby obtaining the maximum gain particle inversion number, thereby realizing broadband self-waveguide amplification of the pulsed laser beam 101.

[0077] The pulsed laser amplification module of this embodiment utilizes the strongest pump light intensity and the largest gain particle inversion number at the center of the rod-shaped crystal fiber. During the amplification process, the pulsed laser beam generates a thermal lensing effect related to the pump light intensity and a Kerr effect related to gain amplification, causing the beam to self-focus during energy amplification. Simultaneously, the energy boost of the laser pulse during gain amplification generates nonlinear amplification, achieving self-phase modulation spectrum broadening. Because the pulsed laser beam spectrum broadening introduces an increase in the beam mode field, resulting in a divergent effect, the pulsed laser beam simultaneously experiences self-defocusing during the amplification process.

[0078] The pulse laser amplification module of this embodiment can utilize the self-defocusing effect of the pulse laser beam spectrum broadening mode field and the self-focusing effect of the Kerr effect and the thermal lens effect during the gain amplification process to clamp each other, forming a self-waveguide with dynamic balance of the beam mode field, thereby suppressing the degradation of the spot mode and making the beam have a self-cleaning effect during the amplification process.

[0079] This embodiment also discloses a pulse laser including the above-mentioned pulse amplifier, wherein the pulse laser includes a pulse seed source 100, a pump coupling module 200, a pulse laser amplification module 300 and a pulse compression module 400;

[0080] See also Figure 1 , which is a schematic diagram of the self-waveguide amplification process and effects of the pulse laser amplification module. The laser pulse achieves self-cleaning high-energy amplification in a wide spectrum mode, and its main process occurs in the pulse laser amplification module 300.

[0081] The pump coupling module 200 includes a pump source 201, a pump collimating lens 202, and a dichroic mirror 203 connected in series. The pump source 201 is used to emit pump light. The light output end of the pump source 201 is connected to the pump collimating lens 202. After the pump light is collimated by the pump collimating lens 202, the pump light is emitted to the dichroic mirror 203 and is collinear with the pulse laser emitted by the pulse seed source at the reflecting end of the dichroic mirror 203.

[0082] The pulse emission end of the pulse seed source 100 is connected to the light input end of the dichroic mirror 203 , and is emitted from the light projection end of the dichroic mirror 203 and is collinear with the pump light.

[0083] Specifically, the pulse seed source 100 adopts a broadband ultrashort pulse seed source.

[0084] Specifically, the pulse seed source 100 of this embodiment can generate pulsed laser seed signal light, with an emission center wavelength of 800 nm, 1030 nm, 1064 nm and 1560 nm, etc., a spectral width greater than 10 nm, and can be an ultrafast seed source with an adjustable repetition rate from 1 Hz to MHz or a high repetition rate of GHz or THz, with a pulse width of several picoseconds or hundreds of femtoseconds.

[0085] Specifically, the pump source 201 of this embodiment adopts a semiconductor diode pump with an emission wavelength of 969 nm and an output power of 400 W, which is used to pump the rod-shaped crystal fiber 302 .

[0086] Specifically, the pump collimating lens 202 of this embodiment is a plano-convex lens made of fused quartz, with a focal length of 40 mm and coated with a 969 nm anti-reflection film, and is used to collimate the pump light.

[0087] Specifically, the dichroic mirror 203 of this embodiment is a 1000nm long-pass dichroic mirror, which has a reflective effect on light less than 1000nm incident at a 45-degree angle; it has a transmissive effect on light greater than 1000nm incident at a 45-degree angle; and is used to reflect the 969nm pump light and transmit the 1030nm seed signal light and then transmit them collinearly to the pulse laser amplification module 300.

[0088] The pulse compression module 400 includes a reflector 401, a right-angle reflector 402, a first diffraction grating 403, a second diffraction grating 404 and a downward-pressing roof mirror 405; the pulse compression module 400 is used to compress the amplified laser output by the Yb / YAG rod-shaped crystal fiber 302 and compress the pulse width to the level of hundreds of femtoseconds.

[0089] Specifically, the reflector 401 of this embodiment uses a 1-inch diameter dielectric film reflector with a reflectivity greater than 99.5% for a 1000-1100 nm 45-degree incident light beam; it is used to deflect the amplified laser output by the Yb / YAG rod-shaped crystal fiber amplifier 302 and guide it into the pulse compression module 400.

[0090] Specifically, the right-angle reflector 402 of this embodiment adopts a 45-degree dielectric film reflector with a right-angle side length of 10 mm, which is placed at the incident light path end of the pulse compression module 400. Its center height is lower than the incident light beam height, and the height difference is 10 mm; it is used to reflect the compressed pulse of the pulse compression module 400 to export the laser.

[0091] Specifically, the first diffraction grating 403 and the second diffraction grating 404 of this embodiment are 1000-line transmission gratings or reflection gratings, which are placed in parallel in the pulse compression module 400 and operate at the Littow angle to compensate for the dispersion of the amplified pulse and compress the pulse width.

[0092] The Littrow angle refers to the condition where the diffraction angle of the diffraction grating is equal to the incident angle, that is, the angle when the first-order diffracted beam is parallel to the incident beam. In laser systems, the Littrow configuration can be used for pulse compression, where the diffraction grating is used to compensate for the temporal broadening of the laser pulse. The relationship between the Littrow angle and the incident angle is expressed as:

[0093] sin( θ L ) = mλ / d ;

[0094] Where, θ L for Littrow angle, m is the diffraction order (usually taken as 1 for a Littrow configuration), λ is the wavelength of the incident light, d is the grating constant of the diffraction grating, that is, the distance between adjacent grating lines.

[0095] Specifically, the downward-pressing roof mirror 405 of this embodiment includes two cemented reflecting prisms coated with a 700-1100nm dielectric film; it is used to lower the height of the light beam passing through the first diffraction grating 403 and the second diffraction grating 404 in the forward direction, and reverse the transmission direction of the diffracted light beam after passing through the first diffraction grating 403 and the second diffraction grating 404 in the forward direction. The height of the light beam is lowered by 10mm.

[0096] The pulse laser of this embodiment operates as follows: the signal light emitted by the pulse seed source is transmitted to the right, becomes collinear with the pump light emitted by the pump coupling module 200 at the dichroic mirror 203, and then enters the pulse laser amplification module 300. After amplification by the pulse laser amplification module 300, it is transmitted to the pulse compression module 400 for pulse compression. After the pulse compression module 400 completes the pulse width compression, the transmission height will drop by 10 mm and the transmission direction will be reversed. After being transmitted to the right-angle reflector 402, it is reflected by the reflector 402 and output as a pulse laser. At this point, the signal light emitted by the ultrashort pulse seed source has undergone the above-mentioned transmission, self-waveguide amplification, and pulse compression process to achieve high-energy, narrow-pulse-width laser generation.

[0097] This embodiment achieves a dynamic balance between the self-focusing process of the Kerr effect and thermal lensing effect, and the self-defocusing process of the light spot mode field, in a pulsed laser amplification module. Based on the amplification of a pulsed laser beam in a rod-shaped crystal fiber, the self-focusing and self-defocusing phenomena associated with pump light intensity, laser gain amplification, and nonlinear amplification are utilized. The self-waveguiding process induced by the dynamic balancing of the light spot mode field, the wide-spectrum characteristics of self-phase modulation, the mode self-cleaning advantages of the self-waveguiding process, and the amplification characteristics of the gain medium are combined to achieve a dynamic balanced wide-spectrum self-waveguiding amplification of the beam.

[0098] As one of the implementations of a multi-channel amplifier, the present invention discloses a second embodiment.

[0099] Example 2

[0100] Preferably, the pulse laser amplification module is a multi-channel amplification module for amplifying the pulse laser multiple times.

[0101] See also Figure 3 As one of the implementations of the multi-channel amplification module, the pulse laser amplification module 300 is a two-channel pulse laser amplification module 300, which can achieve secondary amplification of the pulse laser. Figure 3 As shown, the dual-channel pulsed laser amplification module 300 of this embodiment is based on the single-channel amplification module and further includes a first half-wave plate 304. One side of the first half-wave plate 304 is used to set the pulse seed source 100. The other side of the first half-wave plate 304 is provided with a first polarization beam splitter 305. The side of the first polarization beam splitter 305 away from the first half-wave plate 304 is provided with an input coupling lens 301, a rod-shaped crystal fiber 302, and an output collimating lens 303. The side of the output collimating lens 303 away from the rod-shaped crystal fiber 302 is provided with a first Faraday rotator 306 and a first end-face zero-degree reflector 307. Thus, a dual-channel pulsed laser amplification module is formed. The first half-wave plate 304, the polarization beam splitter, the first Faraday rotator 306, and the first end-face zero-degree reflector 307 are optical devices used to change the polarization state and transmission direction of the light beam.

[0102] The amplification principle of the two-channel pulse laser amplification module 300 of this embodiment is:

[0103] After receiving the pulsed laser output by the pulse seed source 100 and changing the polarization direction of the pulsed laser, the first half-wave plate 304 transmits the pulsed laser to the first polarization beam splitter 305. After the beam splitting effect of the first polarization beam splitter 305, the pulsed laser is further transmitted to the input coupling lens 301, and then passes through the rod-shaped crystal fiber 302 for the first amplification of the pulsed laser. The pulsed laser is then transmitted to the output collimating lens 303 and the first Faraday rotator 306 in sequence, and then transmitted to the first end face zero-degree reflector 307 for reflection.

[0104] The pulsed laser that has undergone the first amplification is reflected by the first end face zero-degree reflector 307 and returns to the first Faraday rotator 306. It then passes through the output collimating lens 303, the rod-shaped crystal fiber 302, the input coupling lens 301, and the first polarization beam splitter 305 in sequence, and then undergoes the beam splitting effect of the first polarization beam splitter 305 to output the pulsed laser that has undergone the second amplification.

[0105] Specifically, a half-wave plate changes the polarization state of polarized light by introducing phase retardation. When linearly polarized light passes through a half-wave plate, its polarization direction rotates according to the optical axis of the wave plate.

[0106] It should be noted that, in this embodiment, the pulse laser amplification module is suitable for amplifying various seed source laser wavelengths. In this embodiment, only the seed source pulse laser with a wavelength of 1030nm is used as an example for illustration, and its use is not limited. The pump light in this embodiment uses 969nm.

[0107] Specifically, the rod-shaped crystal fiber 302 of this embodiment is a YAG laser crystal doped with Yb particles, with a length of 30 mm and a diameter of 2 mm, and end faces coated with 969 nm and 1030 nm antireflection coatings; it is used to amplify the signal light output by the broadband ultrashort pulse seed source.

[0108] An input coupling lens 301 is provided at one end of the rod-shaped crystal fiber 302. One end of the input coupling lens 301 is used to input the pulsed laser beam 101 and the pump light 204. The pulsed laser beam 101 and the pump light 204 can be focused by the input coupling lens 301 to the center of the end face of one end of the rod-shaped crystal fiber 302.

[0109] In this embodiment, the input coupling lens 301 is a fused silica plano-convex lens with a focal length of 400 mm and coated with a 700-1100 nm anti-reflection coating. It is used to couple 969 nm pump light into the rod-shaped crystal fiber 302 and simultaneously focus 1030 nm signal light into the rod-shaped crystal fiber 302 for self-waveguide amplification.

[0110] The other end of the rod-shaped crystal fiber 302 is provided with an output collimating lens 303 for converting the pulsed laser beam 101 output from the rod-shaped crystal fiber 302 into a collimated beam;

[0111] In this embodiment, the output collimating lens 301 can be a fused silica plano-convex lens with a focal length of 400 mm and coated with a 700-1100 nm anti-reflection coating; it is used to collimate the 1030 nm amplified self-waveguide beam output by the Yb / YAG rod-shaped crystal fiber 302 .

[0112] The pump light enters the rod-shaped crystal fiber through the center of the end face of the rod-shaped crystal fiber and propagates into the rod-shaped crystal fiber, and generates total reflection at the inner surface of the rod-shaped crystal fiber and converges on the center line of the rod-shaped crystal fiber, so that the light intensity of the pump light in the rod-shaped crystal fiber is maximized, thereby obtaining the maximum gain particle inversion number, thereby realizing wide-spectrum self-waveguide amplification of the pulsed laser beam.

[0113] Specifically, the wavelength of the first half-wave plate of this embodiment is 1030 nm, and a 0.5-inch true zero-order air-gap fused quartz half-wave plate coated with a 1030 nm anti-reflection film is used; it is used to rotate the polarization state of the 1030 nm signal light so that the 1030 nm signal light is fully transmitted through the first polarization beam splitter 305 in a horizontal polarization state.

[0114] Specifically, the first polarization beam splitter 305 of this embodiment adopts a beam splitter cube with a side length of 10 mm and coated with a polarization beam splitting film, which has the function of fully transmitting horizontally polarized light and fully reflecting vertically polarized light.

[0115] Specifically, the first Faraday rotator 306 of this embodiment is composed of a strong magnet and an optically active crystal. The first Faraday rotator 306 performs a 45-degree counterclockwise polarization rotation on the forward and reverse light beams, and produces a 90-degree polarization rotation on the same light beam that passes through the first Faraday rotator 306 twice.

[0116] Specifically, the first end face zero-degree reflector 307 of this embodiment is coated with a 1030nm 0-degree high reflective film and has a size of 1 inch.

[0117] The pulsed laser amplification module of this embodiment utilizes the strongest pump light intensity and the largest gain particle inversion number at the center of the rod-shaped crystal fiber. During the amplification process, the pulsed laser beam generates a thermal lensing effect related to the pump light intensity and a Kerr effect related to gain amplification, causing the beam to self-focus during energy amplification. Simultaneously, the energy boost of the laser pulse during gain amplification generates nonlinear amplification, achieving self-phase modulation spectrum broadening. Because the pulsed laser beam spectrum broadening introduces an increase in the beam mode field, resulting in a divergent effect, the pulsed laser beam simultaneously experiences self-defocusing during the amplification process.

[0118] The pulse laser amplification module of this embodiment can utilize the self-defocusing effect of the pulse laser beam spectrum broadening mode field and the self-focusing effect of the Kerr effect and the thermal lens effect during the gain amplification process to clamp each other, forming a self-waveguide with dynamic balance of the beam mode field, thereby suppressing the degradation of the spot mode and making the beam have a self-cleaning effect during the amplification process.

[0119] like Figure 3 As shown, this embodiment also discloses a pulse laser including the above-mentioned pulse amplifier, wherein the pulse laser includes a pulse seed source 100, a pump coupling module 200, a pulse laser amplification module 300 and a pulse compression module 400;

[0120] The pump coupling module 200 includes a pump source 201, a pump collimating lens 202, and a dichroic mirror 203 connected in series. The dichroic mirror 203 is disposed between the first polarization beam splitter 305 and the input coupling lens 301.

[0121] The pump source 201 is used to emit pump light. The light output end of the pump source 201 is connected to the pump collimating lens 202. After the pump light is collimated by the pump collimating lens 202, the pump light is emitted to the dichroic mirror 203 and is collinear with the pulsed laser output by the first polarization beam splitter 305 at the reflecting end of the dichroic mirror 203.

[0122] The pulse emission end of the pulse seed source 100 is connected to the light input end of the first half-wave plate 304, and is emitted from the light projection end of the first half-wave plate 304 to the first polarization beam splitter 305. Then, the pulse laser passes through the beam splitting effect of the first polarization beam splitter 305 and becomes collinear with the pump light.

[0123] Specifically, the pulse seed source 100 adopts a broadband ultrashort pulse seed source.

[0124] Specifically, the pulse seed source 100 of this embodiment can generate pulsed laser seed signal light, with an emission center wavelength of 800 nm, 1030 nm, 1064 nm and 1560 nm, etc., a spectral width greater than 10 nm, and can be an ultrafast seed source with an adjustable repetition rate from 1 Hz to MHz or a high repetition rate of GHz or THz, with a pulse width of several picoseconds or hundreds of femtoseconds.

[0125] Specifically, the pump source 201 of this embodiment adopts a semiconductor diode pump with an emission wavelength of 969 nm and an output power of 400 W, which is used to pump the rod-shaped crystal fiber 302 .

[0126] Specifically, the pump collimating lens 202 of this embodiment is a plano-convex lens made of fused quartz, with a focal length of 40 mm and coated with a 969 nm anti-reflection film, and is used to collimate the pump light.

[0127] Specifically, the dichroic mirror 203 of this embodiment is a 1000nm long-pass dichroic mirror, which has a reflective effect on light less than 1000nm incident at a 45-degree angle; it has a transmissive effect on light greater than 1000nm incident at a 45-degree angle; and is used to reflect the 969nm pump light and transmit the 1030nm seed signal light and then transmit them collinearly to the pulse laser amplification module 300.

[0128] The pulse compression module 400 includes a right-angle mirror 402, a first diffraction grating 403, a second diffraction grating 404 and a downward-pressing roof mirror 405; the pulse compression module 400 is used to compress the amplified laser output by the Yb / YAG rod-shaped crystal fiber 302 and compress the pulse width to the level of hundreds of femtoseconds.

[0129] Specifically, the right-angle reflector 402 of this embodiment adopts a 45-degree dielectric film reflector with a right-angle side length of 10 mm, which is placed at the incident light path end of the pulse compression module 400 and is used to receive the incident light from the first polarization beam splitter 305. The center height is lower than the incident light beam height, and the height difference is 10 mm; it is used to reflect the compressed pulse of the pulse compression module 400 out of the laser.

[0130] Specifically, the first diffraction grating 403 and the second diffraction grating 404 of this embodiment are 1000-line transmission gratings or reflection gratings, which are placed in parallel in the pulse compression module 400 and operate at the Littow angle to compensate for the dispersion of the amplified pulse and compress the pulse width.

[0131] Specifically, the downward-pressing roof mirror 405 of this embodiment includes two cemented reflecting prisms coated with a 700-1100nm dielectric film; it is used to lower the height of the light beam passing through the first diffraction grating 403 and the second diffraction grating 404 in the forward direction, and reverse the transmission direction of the diffracted light beam after passing through the first diffraction grating 403 and the second diffraction grating 404 in the forward direction. The height of the light beam is lowered by 10mm.

[0132] The working process of the pulse laser in this embodiment: Figure 3 First, a pulsed laser is generated by a pulse seed source, transmitted through the first half-wave plate 304, and becomes a horizontal polarization state under the polarization rotation of the first half-wave plate 304; then it is transmitted through the first polarization beam splitter (PBS) 305 and transmitted to the dichroic mirror 203, and after transmitting through the dichroic mirror 203, it is transmitted collinearly with the 969nm pump light, and after being focused by the input coupling lens 301, it enters the Yb / YAG rod-shaped crystal fiber 302 and undergoes broadband self-waveguide amplification; then the pulsed laser forms an amplified laser after the first self-waveguide amplification, continues to transmit and is collimated by the output collimating lens 303, and then After reaching the first Faraday rotator 306, the amplified laser light passes through the first Faraday rotator 306, and its polarization direction is rotated 45 degrees counterclockwise. The amplified laser light then passes through the first end face zero-degree reflector 307, where it is reflected at 0 degrees. After the propagation direction is reversed, it begins to propagate in the opposite direction. After passing through the first Faraday rotator 306 for the second time, the polarization direction is rotated 45 degrees counterclockwise again, becoming a vertical polarization state. The amplified laser light then passes through the output coupling lens 303 again, and after being focused, it enters the Yb / YAG rod-shaped crystal fiber 302, where it undergoes a second self-waveguide amplification in a vertical polarization state.

[0133] After the second self-waveguide amplification, the amplified beam is collimated by the input coupling lens 301, transmitted through the dichroic mirror 203, and then reaches the first polarization beam splitter 305. The amplified beam in the vertical polarization state is reflected by the first polarization beam splitter 305 and enters the pulse compression module 400. After pulse width compression is completed in the pulse compression module 400, a high-energy, narrow-pulse-width compressed laser output is generated. The above process completes the two-pass beam wide-spectrum self-waveguide amplification laser output.

[0134] As one of the implementations of a multi-channel amplifier, the present invention discloses a third embodiment.

[0135] Example 3

[0136] See also Figure 4 As one of the implementations of the multi-channel amplification module, the pulse laser amplification module 300 is a four-channel pulse laser amplification module 300, which can achieve four times amplification of the pulse laser. Figure 4 As shown, the four-channel pulse laser amplification module 300 of this embodiment is based on the single-channel amplification module and further includes a first half-wave plate 304. One side of the first half-wave plate 304 is used to set the pulse seed source 100. The other side of the first half-wave plate 304 is provided with a first polarization beam splitter 305. The side of the first polarization beam splitter 305 away from the first half-wave plate 304 is sequentially provided with a second Faraday rotator 308 and a second half-wave plate 309.

[0137] A second polarization beam splitter 310 is provided on a side of the second half-wave plate 309 away from the second Faraday rotator 308. An input coupling lens 301, a rod-shaped crystal fiber 302, and an output collimating lens 303 are sequentially provided on one side of a first output end of the second polarization beam splitter 310. A first Faraday rotator 306 and a first end face zero-degree reflector 307 are sequentially provided on the side of the output collimating lens 303 away from the rod-shaped crystal fiber 302.

[0138] A second end face zero-degree reflector 311 is provided at one side of the second output end of the second polarization beam splitter 310, for reflecting the light split by the second polarization beam splitter 310;

[0139] Thus, a four-channel pulse laser amplification module is formed.

[0140] The amplification principle of the four-channel pulse laser amplification module 300 is as follows: after the first half-wave plate 304 receives the pulse laser output by the pulse seed source 100 and changes the polarization direction of the pulse laser, the pulse laser is transmitted to the first polarization beam splitter 305. After the beam splitting effect of the first polarization beam splitter 305, the pulse laser is further transmitted and passes through the second Faraday rotator 308, the second half-wave plate 309 and the second polarization beam splitter 310 in sequence. After the beam splitting effect of the second polarization beam splitter 310, the pulse laser is further transmitted to the input coupling lens 301, and passes through the rod-shaped crystal fiber 302 in sequence to amplify the pulse laser for the first time. Then, it is transmitted to the output collimating lens 303 and the first Faraday rotator 306 in sequence, and then transmitted to the first end face zero-degree reflector 307 for reflection;

[0141] The pulsed laser light after the first amplification is reflected by the first end face zero-degree reflector 307 and returns to the first Faraday rotator 306. It then passes through the output collimating lens 303, the rod-shaped crystal fiber 302, and the input coupling lens 301 in sequence, and outputs the pulsed laser light after the second amplification.

[0142] When the twice-amplified pulse laser is transmitted to the second polarization beam splitter 310, it is transferred to the second end face zero-degree reflector 311 for reflection. The reflected twice-amplified pulse laser is again transmitted to the input coupling lens 301, and then passes through the rod-shaped crystal fiber 302 for a third amplification. It is then transmitted to the output collimating lens 303 and the first Faraday rotator 306 in sequence, and then transmitted to the first end face zero-degree reflector 307 for reflection.

[0143] After the third amplification, the pulsed laser is reflected by the first end face zero-degree reflector 307 and returns to the first Faraday rotator 306. It then passes through the output collimating lens 303, the rod-shaped crystal fiber 302, and the input coupling lens 301 in sequence for the fourth amplification.

[0144] The second Faraday rotator 308 and the second half-wave plate 309 are then adjusted to adjust the polarization state of the fourth-amplified pulsed laser light. The fourth-amplified pulsed laser light passes through the second polarization beam splitter 310, and then sequentially through the second half-wave plate 309 and the second Faraday rotator 308 to the first polarization beam splitter 305. After being split by the first polarization beam splitter 305, the fourth-amplified pulsed laser light is output. Each half-wave plate, polarization beam splitter, Faraday rotator, and end-face zero-degree mirror 401 are optical devices used to change the polarization state and transmission direction of a light beam.

[0145] It should be noted that, in this embodiment, the pulse laser amplification module is suitable for amplifying various seed source laser wavelengths. In this embodiment, only the seed source pulse laser with a wavelength of 1030nm is used as an example for illustration, and its use is not limited. The pump light in this embodiment uses 969nm.

[0146] Specifically, the rod-shaped crystal fiber 302 of this embodiment is a YAG laser crystal doped with Yb particles, with a length of 30 mm and a diameter of 2 mm, and end faces coated with 969 nm and 1030 nm antireflection coatings; it is used to amplify the signal light output by the broadband ultrashort pulse seed source.

[0147] An input coupling lens 301 is provided at one end of the rod-shaped crystal fiber 302. One end of the input coupling lens 301 is used to input the pulsed laser beam 101 and the pump light 204. The pulsed laser beam 101 and the pump light 204 can be focused by the input coupling lens 301 to the center of the end face of one end of the rod-shaped crystal fiber 302.

[0148] In this embodiment, the input coupling lens 301 is a fused silica plano-convex lens with a focal length of 400 mm and coated with a 700-1100 nm anti-reflection coating. It is used to couple 969 nm pump light into the rod-shaped crystal fiber 302 and simultaneously focus 1030 nm signal light into the rod-shaped crystal fiber 302 for self-waveguide amplification.

[0149] The other end of the rod-shaped crystal fiber 302 is provided with an output collimating lens 303 for converting the pulsed laser beam 101 output from the rod-shaped crystal fiber 302 into a collimated beam;

[0150] In this embodiment, the output collimating lens 301 can be a fused silica plano-convex lens with a focal length of 400 mm and coated with a 700-1100 nm anti-reflection coating; it is used to collimate the 1030 nm amplified self-waveguide beam output by the Yb / YAG rod-shaped crystal fiber 302 .

[0151] The pump light enters the rod-shaped crystal fiber through the center of the end face of the rod-shaped crystal fiber and propagates into the rod-shaped crystal fiber, and generates total reflection at the inner surface of the rod-shaped crystal fiber and converges on the center line of the rod-shaped crystal fiber, so that the light intensity of the pump light in the rod-shaped crystal fiber is maximized, thereby obtaining the maximum gain particle inversion number, thereby realizing wide-spectrum self-waveguide amplification of the pulsed laser beam.

[0152] Specifically, the wavelength of the first half-wave plate and the second half-wave plate of this embodiment are both 1030nm, and a 0.5-inch true zero-order air-gap fused quartz 1 / 2 wave plate coated with a 1030nm anti-reflection film is used; it is used to rotate the polarization state of the 1030nm signal light so that the 1030nm signal light is fully transmitted through the first polarization beam splitter 305 in a horizontal polarization state.

[0153] Specifically, the first polarization beam splitter 305 and the second polarization beam splitter 310 of this embodiment both use beam splitting cubes with a side length of 10 mm and coated with a polarization beam splitting film, which have the function of fully transmitting horizontally polarized light and fully reflecting vertically polarized light.

[0154] Specifically, the first Faraday rotator 306 and the second Faraday rotator 308 of this embodiment are both composed of a strong magnet and an optically active crystal. The first Faraday rotator 306 performs a 45-degree counterclockwise polarization rotation on the forward and reverse light beams, and produces a 90-degree polarization rotation on the same light beam that passes through the first Faraday rotator 306 twice. Similarly, the second Faraday rotator 308 performs a 45-degree counterclockwise polarization rotation on the forward and reverse light beams, and produces a 90-degree polarization rotation on the same light beam that passes through the second Faraday rotator 308 twice.

[0155] Specifically, the first end face zero-degree reflector 307 of this embodiment is coated with a 1030nm 0-degree high reflective film and has a size of 1 inch.

[0156] The pulsed laser amplification module of this embodiment utilizes the strongest pump light intensity and the largest gain particle inversion number at the center of the rod-shaped crystal fiber. During the amplification process, the pulsed laser beam generates a thermal lensing effect related to the pump light intensity and a Kerr effect related to gain amplification, causing the beam to self-focus during energy amplification. Simultaneously, the energy boost of the laser pulse during gain amplification generates nonlinear amplification, achieving self-phase modulation spectrum broadening. Because the pulsed laser beam spectrum broadening introduces an increase in the beam mode field, resulting in a divergent effect, the pulsed laser beam simultaneously experiences self-defocusing during the amplification process.

[0157] The pulse laser amplification module of this embodiment can utilize the self-defocusing effect of the pulse laser beam spectrum broadening mode field and the self-focusing effect of the Kerr effect and the thermal lens effect during the gain amplification process to clamp each other, forming a self-waveguide with dynamic balance of the beam mode field, thereby suppressing the degradation of the spot mode and making the beam have a self-cleaning effect during the amplification process.

[0158] like Figure 4 As shown, this embodiment also discloses a pulse laser including the above-mentioned pulse amplifier, wherein the pulse laser includes a pulse seed source 100, a pump coupling module 200, a pulse laser amplification module 300 and a pulse compression module 400;

[0159] The pump coupling module 200 includes a pump source 201, a pump collimating lens 202, and a dichroic mirror 203 connected in series. The dichroic mirror 203 is disposed between the second polarization beam splitter 310 and the input coupling lens 301.

[0160] The pump source 201 is used to emit pump light. The light output end of the pump source 201 is connected to the pump collimating lens 202. After the pump light is collimated by the pump collimating lens 202, the pump light is emitted to the dichroic mirror 203 and is collinear with the pulsed laser output by the second polarization beam splitter 310 at the reflecting end of the dichroic mirror 203.

[0161] The pulse emission end of the pulse seed source 100 is connected to the light input end of the first half-wave plate 304, and is emitted from the light projection end of the first half-wave plate 304 to the first polarization beam splitter 305. Then, the pulse laser passes through the second Faraday rotator 308 and the second half-wave plate in sequence, and then passes through the splitting effect of the second polarization beam splitter 310 to be collinear with the pump light.

[0162] Specifically, the pulse seed source 100 adopts a broadband ultrashort pulse seed source.

[0163] Specifically, the pulse seed source 100 of this embodiment can generate pulsed laser seed signal light, with an emission center wavelength of 800 nm, 1030 nm, 1064 nm and 1560 nm, etc., a spectral width greater than 10 nm, and can be an ultrafast seed source with an adjustable repetition rate from 1 Hz to MHz or a high repetition rate of GHz or THz, with a pulse width of several picoseconds or hundreds of femtoseconds.

[0164] Specifically, the pump source 201 of this embodiment adopts a semiconductor diode pump with an emission wavelength of 969 nm and an output power of 400 W, which is used to pump the rod-shaped crystal fiber 302 .

[0165] Specifically, the pump collimating lens 202 of this embodiment is a plano-convex lens made of fused quartz, with a focal length of 40 mm and coated with a 969 nm anti-reflection film, and is used to collimate the pump light.

[0166] Specifically, the dichroic mirror 203 of this embodiment is a 1000nm long-pass dichroic mirror, which has a reflective effect on light less than 1000nm incident at a 45-degree angle; it has a transmissive effect on light greater than 1000nm incident at a 45-degree angle; and is used to reflect the 969nm pump light and transmit the 1030nm seed signal light and then transmit them collinearly to the pulse laser amplification module 300.

[0167] The pulse compression module 400 includes a right-angle mirror 402, a first diffraction grating 403, a second diffraction grating 404 and a downward-pressing roof mirror 405; the pulse compression module 400 is used to compress the amplified laser output by the Yb / YAG rod-shaped crystal fiber 302 and compress the pulse width to the level of hundreds of femtoseconds.

[0168] Specifically, the right-angle reflector 402 of this embodiment adopts a 45-degree dielectric film reflector with a right-angle side length of 10 mm, which is placed at the incident light path end of the pulse compression module 400 and is used to receive the incident light from the first polarization beam splitter 305. The center height is lower than the incident light beam height, and the height difference is 10 mm; it is used to reflect the compressed pulse of the pulse compression module 400 out of the laser.

[0169] Specifically, the first diffraction grating 403 and the second diffraction grating 404 of this embodiment are 1000-line transmission gratings or reflection gratings, which are placed in parallel in the pulse compression module 400 and operate at the Littow angle to compensate for the dispersion of the amplified pulse and compress the pulse width.

[0170] Specifically, the downward-pressing roof mirror 405 of this embodiment includes two cemented reflecting prisms coated with a 700-1100nm dielectric film; it is used to lower the height of the light beam passing through the first diffraction grating 403 and the second diffraction grating 404 in the forward direction, and reverse the transmission direction of the diffracted light beam after passing through the first diffraction grating 403 and the second diffraction grating 404 in the forward direction. The height of the light beam is lowered by 10mm.

[0171] The working process of the pulse laser in this embodiment: Figure 4 First, the pulse seed source generates seed signal light, which is transmitted to the right and first passes through the first half-wave plate 304. It is changed to a horizontal polarization state under the polarization rotation of the first half-wave plate 304; then it is transmitted through the polarization beam splitter 405, the second Faraday rotator 308 and the second half-wave plate 309 in sequence. When passing through the second Faraday rotator 308, its polarization direction will be rotated 45 degrees counterclockwise. After passing through the second half-wave plate 309, the polarization direction is rotated 45 degrees clockwise and turned back to a horizontal polarization state again; then it is transmitted through the second polarization beam splitter 310 and the dichroic mirror 203 in sequence and then co-linearly transmitted with the 969nm pump light; under the focusing of the input coupling lens 301, it enters the Yb / YAG rod crystal fiber 302 for broadband self-waveguide amplification;

[0172] After self-waveguide amplification, the signal light is collimated by the output collimating lens 303 and then enters the first Faraday rotator 306. After passing through the first Faraday rotator 306, the polarization direction of the light beam is rotated 45 degrees counterclockwise. It then propagates to the end face zero-degree reflector 307. After generating a 0-degree reflection, the propagation direction of the light beam is reversed. It then propagates to the left and passes through the first Faraday rotator 306 again. The polarization direction is rotated 45 degrees counterclockwise again and becomes a vertical polarization state. After passing through the output coupling lens 303 again, the light beam is focused into the Yb / YAG rod-shaped crystal fiber 302 and then undergoes a second broadband self-waveguide amplification in a vertical polarization state.

[0173] After the second broadband self-waveguide amplification, the light beam continues to propagate to the left under the collimation of the input coupling lens 301, passes through the dichroic mirror 203, and reaches the second polarization beam splitter 310. Since the polarization state of the amplified light beam is vertically polarized, it will be reflected 90 degrees at the second polarization beam splitter 310, and then propagate downward to the end face zero-degree reflector 311. After the 0-degree reflection, it returns along the original path, passes through the second polarization beam splitter 310 and the dichroic mirror 203 in sequence, and then propagates to the right in a collinear manner with the 969nm pump light. After being focused by the input coupling lens 301, it enters the Yb / YAG rod-shaped crystal fiber 302 to generate the third broadband self-waveguide amplification. After the third broadband self-waveguide amplification, the light beam continues to propagate to the right, is collimated again by the output collimating lens 303, and enters the first Faraday rotator 306.

[0174] After passing through the first Faraday rotator 306, the polarization direction of the beam undergoes another counterclockwise rotation of 45 degrees. It then reaches the end face zero-degree reflector 307, where it undergoes another 0-degree reflection and reverses its direction of propagation. It then propagates leftward through the first Faraday rotator 306, where its polarization direction rotates another 45 degrees counterclockwise to a horizontal polarization state. After passing through the output coupling lens 303 for the fourth time, the collimated beam is focused again into the Yb / YAG rod-shaped crystal fiber 302. It then undergoes a fourth round of broadband self-waveguide amplification in a horizontal polarization state.

[0175] After the fourth broad spectrum self-waveguide amplification, the light beam is collimated again by the input coupling lens 301, transmitted through the dichroic mirror 203, and then reaches the second polarization beam splitter 310. The amplified light beam in the horizontal polarization state is transmitted through the second polarization beam splitter 310.

[0176] The light then passes through the second half-wave plate 309, where its polarization direction undergoes a counterclockwise rotation of 45 degrees. After passing through the second Faraday rotator 308, the polarization direction undergoes another counterclockwise rotation of 45 degrees, returning to a vertical polarization state. It then passes through the polarization beam splitter 305, where it undergoes a 90-degree reflection. It then enters the pulse compression module 400, where pulse compression is completed to produce a high-energy, narrow-pulse-width laser output. This completes the four-beam, broad-spectrum self-waveguide amplified laser output.

[0177] In summary, the pulse laser amplification module and pulse laser disclosed in the present invention have the following technical effects:

[0178] 1. In the pulse laser amplification module and pulse laser of the present invention, the signal light beam is self-waveguided in the rod-shaped crystal to achieve amplification, which has the advantage of self-cleaning of the spot mode and can realize high-beam-quality laser amplification. Specifically, the signal light beam is self-waveguided in the rod-shaped crystal fiber to achieve amplification; during the laser pulse amplification process, the signal light beam achieves dynamic balance of the light beam mode field through the self-focusing process of the Kerr effect and the thermal lens effect and the self-defocusing process of the nonlinear amplification spectrum broadening spot mode field, forming a self-waveguide of the light beam in the rod-shaped crystal. During the amplification process, the self-waveguide light beam eliminates the spectral components at the edge of the spot mode field through mode field self-balancing, suppresses mode field distortion, has the characteristics of mode self-cleaning, and realizes high-beam-quality output. This technology provides a brand-new solution for the generation of ultrashort pulse lasers with high beam quality, high energy, high power, and narrow pulse width.

[0179] 2. In the pulse laser amplification module and pulse laser of the present invention, the amplification module is based on a rod-shaped crystal structure, which can improve the gain amplification pump conversion efficiency, produce high pump conversion efficiency, and achieve high-power laser generation. Specifically, it is embodied in: a rod-shaped crystal structure based on a small core diameter side gold film and the use of end-face pumping. The pump light enters from the end face of the rod-shaped crystal fiber, produces total reflection on the cylindrical surface, and converges the transmission to the center of the rod-shaped crystal fiber. This process enables the center of the rod-shaped crystal fiber to produce the strongest pump light intensity and the largest gain particle inversion number, which is beneficial to the efficient absorption of pump energy by the signal beam, while making the thermal lens self-focusing effect more likely to occur, which is more conducive to the formation of a beam amplification self-waveguide.

[0180] 3. In the pulse laser amplification module and pulse laser of the present invention, the self-waveguide amplification process achieves nonlinear spectrum broadening, thereby suppressing the gain narrowing effect and achieving broadband laser amplification, with the advantages of outputting high-peak energy, narrow pulse lasers. Specifically, the signal beam undergoes self-waveguide amplification in a rod-shaped crystal fiber, generating a nonlinear self-phase modulation effect through the amplified pulse, thereby achieving pulse spectrum broadening. This effectively overcomes the gain narrowing effect of the rod-shaped crystal fiber and ensures broadband pulse spectrum amplification. Simultaneously, the spectrum broadening and mode field divergence of the amplification process are balanced with the Kerr effect and thermal lens self-focusing, forming a self-waveguided amplified beam. Therefore, the self-waveguide spectrum broadening and amplification of the pulse facilitates pulse width compression, enabling the generation of sub-hundredths of a femtosecond, high-peak energy lasers.

[0181] 4. In the pulse laser amplification module and pulse laser of the present invention, the pump spot and mode field aperture can be flexibly controlled during the self-waveguide amplification process, thereby achieving the advantages of high-power and high-energy amplification and reducing the risk of damage to the device. Specifically, the signal beam undergoes self-waveguide amplification in the rod-shaped crystal fiber, and the self-waveguide aperture can be flexibly controlled by the signal beam diameter, the pump beam diameter, and the gain medium doping concentration. By adjusting the larger signal beam diameter and the pump beam diameter, large-aperture beam self-waveguide amplification can be achieved, which reduces the beam energy density while avoiding damage to the rod-shaped crystal fiber caused by high-energy pulses, thus having the advantage of generating high-energy laser pulse amplification.

[0182] 5. The pulsed laser amplification module and pulsed laser of the present invention utilize self-waveguide amplification of a beam with dynamic spot mode field balance to suppress spot mode degradation, and the beam exhibits a self-cleaning effect during amplification. Furthermore, the spectral broadening of the beam during high-energy nonlinear amplification in the self-waveguide effectively suppresses the gain narrowing effect of rod-shaped crystal fibers, facilitating pulse width compression to sub-hundredths of a femtosecond, achieving extremely high peak energy output.

[0183] It will be understood that the present invention is described through some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Under the guidance of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. The embodiments described in the present invention are some embodiments of the present invention, not all embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

Claims

1. A pulse laser amplification module for amplifying a pulse laser beam, characterized in that: The invention comprises a rod-shaped crystal fiber, the outer periphery of which is coated with a gold film; an input coupling lens is provided at one end of the rod-shaped crystal fiber, and one end of the input coupling lens is used to input a pulsed laser beam and pump light. The input coupling lens can make the pulsed laser beam and pump light pass through the center of the end face of one end of the rod-shaped crystal fiber and focus them inside the rod-shaped crystal fiber; an output collimating lens is provided at the other end of the rod-shaped crystal fiber, and is used to convert the pulsed laser beam output from the rod-shaped crystal fiber into a collimated beam; the pump light enters the rod-shaped crystal fiber through the center of the end face of the rod-shaped crystal fiber, propagates, generates total internal reflection at the inner surface of the rod-shaped crystal fiber, and converges on the center line of the rod-shaped crystal fiber, so that the light intensity of the pump light in the rod-shaped crystal fiber is maximized, thereby obtaining the maximum gain particle inversion number, thereby realizing broadband self-waveguide amplification of the pulsed laser beam; Under the condition that the doping concentration of the rod-shaped crystal fiber remains unchanged, the self-waveguide aperture of the amplified light beam can be controlled by adjusting the size of the pump light spot and the diameter of the amplified light beam; the signal light beam is amplified by self-waveguiding in the rod-shaped crystal fiber; during the laser pulse amplification process, the signal light beam achieves dynamic balance of the light beam mode field through the self-focusing process of the Kerr effect and the thermal lens effect and the self-defocusing process of the nonlinear amplification spectrum broadening light spot mode field, forming a light beam self-waveguide in the rod-shaped crystal; during the amplification process, the self-waveguide light beam achieves mode field self-balancing, discards the spectral components at the edge of the light spot mode field, suppresses mode field distortion, and has the characteristics of mode self-cleaning.

2. The pulse laser amplification module according to claim 1, characterized in that: The ratio of the diameter of the pump spot to the diameter of the amplified beam is 3:2, and the diameter of the amplified beam from the waveguide is 2 / 3 to 1 of the diameter of the pump spot.

3. The pulse laser amplification module according to claim 1, characterized in that: The end faces at both ends of the rod-shaped crystal optical fiber and the outer surfaces of the input coupling lens and the output collimating lens are respectively coated with anti-reflection films, and the wavelength of the anti-reflection films matches the wavelength of the input light.

4. The pulse laser amplification module according to claim 1, characterized in that: The rod-shaped crystal optical fiber is embedded in the copper block heat sink by welding.

5. The pulse laser amplification module according to claim 1, characterized in that: The pulse laser amplification module is a single-channel amplification module, and the input pulse laser beam and pump light can be amplified once in the pulse laser amplification module.

6. The pulse laser amplification module according to claim 1, characterized in that: The pulse laser amplification module is a multi-channel amplification module, which is used to amplify the pulse laser multiple times.

7. The pulse laser amplification module according to claim 1, characterized in that: It also includes a first half-wave plate, one side of the first half-wave plate is used to set a pulse seed source, the other side of the first half-wave plate is provided with a first polarization beam splitter, the side of the first polarization beam splitter away from the first half-wave plate is provided with an input coupling lens, a rod-shaped crystal fiber and an output collimating lens in sequence, and the side of the output collimating lens away from the rod-shaped crystal fiber is provided with a first Faraday rotator and a first end face zero-degree reflector in sequence; thus, a two-channel pulse laser amplification module is formed, which can realize secondary amplification of pulsed laser.

8. The pulse laser amplification module according to claim 1, characterized in that: The system further comprises a first half-wave plate, one side of the first half-wave plate is used to set a pulse seed source, the other side of the first half-wave plate is provided with a first polarization beam splitter, and the side of the first polarization beam splitter away from the first half-wave plate is sequentially provided with a second Faraday rotator and a second half-wave plate; A second polarization beam splitter is provided on a side of the second half-wave plate away from the second Faraday rotator, an input coupling lens, a rod-shaped crystal fiber, and an output collimating lens are sequentially provided on a side of a first output end of the second polarization beam splitter, and a first Faraday rotator and a first end face zero-degree reflector are sequentially provided on a side of the output collimating lens away from the rod-shaped crystal fiber; A second end-face zero-degree reflector is provided at one side of the second output end of the second polarization beam splitter, for reflecting the light split by the second polarization beam splitter; Thus, a four-channel pulse laser amplification module is formed, which can achieve four times amplification of the pulse laser.

9. A pulsed laser, characterized in that The method comprises the pulse laser amplification module according to any one of claims 1 to 8.

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