High-power high-order transverse mode supercontinuum laser source

Abstract

The present invention provides a high-power high-order transverse mode supercontinuum laser light source, including a high-order transverse mode pulse fiber laser, which is used to generate a high-order transverse mode seed pulse laser with time domain stability and high mode purity as a pulse laser seed source; a fiber laser amplifier, which is used to amplify the average power and peak power of the target order high-order transverse mode seed pulse laser, and output a high-power target order high-order transverse mode pump laser as a laser pump source; and a few-mode photonic crystal fiber, which is used as a laser nonlinear transmission medium, to convert the high-power target order high-order transverse mode pump laser into a supercontinuum through nonlinear effects and dispersion effects, while maintaining the mode characteristics of the output laser, and outputting a high-power target order high-order transverse mode supercontinuum laser. The method can increase the upper limit of the output power of the supercontinuum generated by the photonic crystal fiber and increase the proportion of the visible light spectrum.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber lasers, and in particular relates to a high-power high-order transverse mode supercontinuum laser light source. Background Art

[0002] Supercontinuum laser is a light source with an extremely wide spectrum, which can cover the visible light to near infrared and even mid-infrared bands. The current scheme for generating supercontinuum mainly uses fundamental mode pulse laser with high peak power to pump photonic crystal fiber or passive energy transfer fiber, which produces spectrum broadening under the action of dispersion and nonlinear effects. Compared with passive energy transfer fiber, photonic crystal fiber has a higher nonlinear coefficient and a flexible and adjustable dispersion curve, so it is more conducive to the generation of supercontinuum with wide spectral range and good spectral flatness, and is an ideal medium for obtaining supercontinuum. However, there is a problem of low output power in the process of photonic crystal fiber generating supercontinuum.

[0003] In the design process of photonic crystal fiber, reducing the core diameter can reduce the zero dispersion wavelength. In order to effectively broaden the spectrum, the zero dispersion wavelength of the photonic crystal needs to match the wavelength of the pump laser. The zero dispersion wavelength close to 1 μm determines that the photonic crystal fiber must have a smaller core diameter. At the same time, in order to increase the peak power of the pump laser, a large core diameter gain fiber is required for power amplification to obtain a high peak power pulse laser pump source. Usually, there is a large mode field mismatch between the output fiber of the pump laser and the photonic crystal fiber, so it is difficult to withstand higher power, which limits the power increase. Although multi-core photonic crystal fiber, cascaded photonic crystal fiber and long tapered photonic crystal fiber have been proposed to increase the output power of the supercontinuum, the processing technology of photonic crystal fiber is very complicated and is not conducive to promotion. Another way to increase the power of the supercontinuum is to use multi-channel incoherent synthesis, but the beam quality will be greatly reduced compared to before the beam is combined, which is not conducive to the long-distance transmission of the supercontinuum. For a fundamental mode photonic crystal fiber and a high-order mode photonic crystal fiber having the same zero-dispersion wavelength, the latter can have a larger core diameter, and thus is more conducive to increasing the output power.

[0004] In addition, in terms of increasing the proportion of short-wave spectrum, quartz fiber has a large loss for lasers above 2.4 μm. According to the phase matching relationship between long-wave and short-wave of dispersion wave, the generation of spectrum components above 2.4 μm is not conducive to short-wave expansion, which is not conducive to increasing the proportion of short-wave spectrum. For the fundamental mode, the short-wave phase matching wavelength of 2.4 μm in photonic crystal fiber is difficult to match to below 0.4 μm, and the fundamental mode supercontinuum has limitations in enhancing the short-wave spectrum component; while for the higher-order mode, the dispersion matching wavelength of photonic crystal fiber at 2.4 μm can reach below 0.4 μm, so it is more conducive to enhancing the short-wave spectrum component of the supercontinuum.

[0005] In summary, in the existing schemes for generating fundamental mode supercontinuum based on photonic crystal fibers, there are problems of limited output power and visible light ratio, which restricts the application of supercontinuum. Summary of the invention

[0006] In view of the defects and shortcomings in the prior art, in order to solve the problem of limited output power and visible light ratio when photonic crystal fiber generates fundamental mode supercontinuum, the present invention discloses a high-power high-order transverse mode supercontinuum laser light source, which can achieve high power, high visible light ratio and high mode purity output.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0008] High-power high-order transverse mode supercontinuum laser source, including:

[0009] High-order transverse mode pulse fiber laser, used to generate target-order high-order transverse mode seed pulse laser with time-domain stability and high mode purity, as a pulse laser seed source;

[0010] Fiber laser amplifier, used to amplify the average power and peak power of target-order high-order transverse mode seed pulse laser, output high-power target-order high-order transverse mode pump laser, as a laser pump source;

[0011] Few-mode photonic crystal fiber, as a laser nonlinear transmission medium, is used to convert high-power target-order high-order transverse mode pump laser into a supercontinuum through nonlinear effects and dispersion effects, while maintaining the mode characteristics of the output laser and outputting high-power target-order high-order transverse mode supercontinuum laser.

[0012] Few-mode photonic crystal fiber only supports fundamental mode and transverse mode modes not higher than the target order in the visible light and near-infrared bands. In the process of coupling high-power target-order high-order transverse mode pump laser into the few-mode photonic crystal fiber, the high-order transverse mode pump laser is converted into the target-order high-order transverse mode pulse laser of the same order in the few-mode photonic crystal fiber by means of high-order mode excitation. In addition, the target-order high-order transverse mode pulse laser undergoes spectral broadening under the action of nonlinear effects and dispersion during transmission, thereby generating and outputting high-power target-order high-order transverse mode supercontinuum laser.

[0013] Furthermore, the few-mode photonic crystal fiber has a larger core diameter while making the target mode zero dispersion point close to the central wavelength of the high-power target order high-order transverse mode pump laser, wherein the core diameter of the few-mode photonic crystal fiber is greater than 6μm, thereby increasing the output power upper limit and visible light spectrum proportion of the target order high-order transverse mode supercontinuum laser.

[0014] Furthermore, the target-order high-order transverse mode refers to a specific high-order transverse mode in the optical fiber, which can be designed according to actual application requirements. model, mode or higher order mode.

[0015] Furthermore, the spectral range of the high-power target-order high-order transverse mode supercontinuum laser includes visible light, near-infrared and mid-infrared bands.

[0016] Furthermore, the nonlinear coefficient and dispersion parameter of the few-mode photonic crystal fiber are optimized by optimizing the size and arrangement of its air holes.

[0017] Preferably, the target-order high-order transverse mode is a cylindrical vector beam with a donut-shaped energy distribution and a centrally symmetric polarization state.

[0018] Preferably, the few-mode photonic crystal fiber supports fundamental mode and target high-order transverse mode transmission in the wavelength range of 0.4 ~ 2.4 μm, and the zero dispersion wavelength range of the target high-order transverse mode is 1.04 μm ~ 1.08 μm, while the dispersion matching wavelength of the 2.4 μm wavelength is less than 0.4 μm, and can generate high-power target-order high-order transverse mode supercontinuum laser with a mode purity greater than 70% under high-power target-order high-order transverse mode pump laser pumping.

[0019] Preferably, the central wavelength of the high-order transverse mode pulse fiber laser is 1.06 μm, the mode purity is greater than 90%, the pulse width is 10 ps~1 ns, the output average power is ~10 mW, and the repetition frequency is 1 MHz~30 MHz. Preferably, the fiber laser amplifier is used to amplify the average power of the 1.06 μm target order high-order transverse mode seed pulse laser to more than 100 W and the peak power to more than 5 kW.

[0020] Preferably, the pulse generation method of the high-order transverse mode pulse fiber laser can adopt mode locking, and the mode locking method can adopt electro-optic modulator, semiconductor saturable absorber, carbon nanotube, nonlinear polarization rotation or nonlinear multi-mode interference, etc.

[0021] Preferably, the high-order mode selection and excitation method of the high-order transverse mode pulse fiber laser can adopt few-mode Bragg fiber grating, staggered fusion, long-period fiber grating, mode selective coupler, S wave plate, photon lantern, etc.

[0022] The above-mentioned high-power high-order transverse mode supercontinuum laser light source, the present application is beneficial to improving the output power by power amplifying the high-order transverse mode pulse laser with a larger mode field area than the fundamental mode, and at the same time, by designing a few-mode photonic crystal fiber that can match the dispersion of the high-order transverse mode pump laser, it is beneficial to increase the core diameter of the photonic crystal fiber, reduce the fusion loss, optimize the dispersion curve, and solve the problem of the smaller core diameter on the output power in the process of generating supercontinuum in the photonic crystal fiber, so that it can have a zero dispersion point close to the pump laser wavelength while having a larger core diameter, thereby improving the output power upper limit and visible light proportion of the supercontinuum, and solving the problems of low output power and limited visible light proportion of the spectrum generated in the fundamental mode supercontinuum in the photonic crystal fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 Schematic diagram of the structure of a high-power high-order transverse mode supercontinuum laser light source in one embodiment;

[0025] Figure 2 Schematic diagram of the structure of a high-order transverse mode pulse fiber laser in one embodiment;

[0026] Figure 3 A schematic diagram of the structure of a fiber laser amplifier in one embodiment;

[0027] Figure 4 is a schematic cross-sectional view of a few-mode photonic crystal fiber in one embodiment;

[0028] Figure 5 is a dispersion curve of a few-mode photonic crystal fiber in an embodiment;

[0029] Numbers in the figure:

[0030] 1. High-order transverse mode pulsed fiber laser; 2. Fiber laser amplifier; 3. Few-mode photonic crystal fiber;

[0031] 101. Highly reflective Bragg fiber grating; 102. Saturable absorber; 103. First single-mode pump source; 104. First wavelength division multiplexer; 105. First single-clad ytterbium-doped fiber; 106. Long-period fiber grating; 107. Few-mode Bragg fiber grating;

[0032] 201. A second single-mode pump source; 202. A second wavelength division multiplexer; 203. A second single-clad ytterbium-doped optical fiber; 204. A multi-mode pump source; 205. A pump combiner; 206. A double-clad ytterbium-doped optical fiber; 207. An energy transfer optical fiber. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Reference Figure 1 One embodiment provides a high-power high-order transverse mode supercontinuum laser light source, comprising:

[0035] A high-order transverse mode pulse fiber laser 1 is used to generate a target-order high-order transverse mode seed pulse laser with time-domain stability and high mode purity as a pulse laser seed source, wherein the high-order transverse mode is a cylindrical vector beam with a donut-shaped energy distribution and a centrally symmetric polarization state;

[0036] The fiber laser amplifier 2 is used to amplify the average power and peak power of the target-order high-order transverse mode seed pulse laser and output high-power target-order high-order transverse mode pump laser as a laser pump source;

[0037] The few-mode photonic crystal fiber 3, as a laser nonlinear transmission medium, is used to convert high-power target-order high-order transverse mode pump laser into a supercontinuum through nonlinear effects and dispersion effects, while maintaining the mode characteristics of the output laser, and outputting high-power target-order high-order transverse mode supercontinuum laser.

[0038] The high-order transverse mode supercontinuum laser light source provided by the present invention can achieve high-power, high visible light ratio, and high mode purity output. Figure 1 The output end of the medium- and high-order transverse mode pulse fiber laser 1 is connected to the input end of the fiber laser amplifier 2 , and the output end of the fiber laser amplifier 2 is connected to the input end of the few-mode photonic crystal fiber 3 .

[0039] Few-mode photonic crystal fiber only supports fundamental mode and transverse mode modes not higher than the target order in the visible light and near-infrared bands. In the process of coupling high-power target-order high-order transverse mode pump laser into the few-mode photonic crystal fiber, the high-order transverse mode pump laser is converted into the target-order high-order transverse mode pulse laser of the same order in the few-mode photonic crystal fiber by means of high-order mode excitation. In addition, the target-order high-order transverse mode pulse laser undergoes spectral broadening under the action of nonlinear effects and dispersion during the transmission process, thereby generating and outputting high-power target-order high-order transverse mode supercontinuum laser.

[0040] In the above embodiment, the high-order transverse mode pulse fiber laser 1 and the fiber laser amplifier 2 are used as high-order transverse mode pump laser pulse generation modules, wherein the high-order transverse mode pulse fiber laser 1 is used to generate a target-order high-order transverse mode seed pulse laser with time-domain stability and high mode purity, and the fiber laser amplifier 2 is used to amplify the average power and peak power of the pulse laser while maintaining good mode characteristics to obtain a target-order high-order transverse mode pulse laser with high peak power, high average power and high mode purity.

[0041] Furthermore, by rationally designing the geometric structure of the few-mode photonic crystal fiber, the few-mode photonic crystal fiber has a larger core diameter and the target mode zero dispersion point is close to the central wavelength of the high-power target order high-order transverse mode pump laser. The core diameter of the few-mode photonic crystal fiber is greater than 6 μm, thereby increasing the output power upper limit and visible light spectrum proportion of the target order high-order transverse mode supercontinuum laser.

[0042] The high-order transverse modes in the present invention include model, mode or higher order mode.

[0043] The spectral range of high-power target-order high-order transverse mode supercontinuum laser includes visible light, near-infrared band and mid-infrared band.

[0044] The high-order transverse mode pulse fiber laser 1 of the present invention can generate a target-order high-order transverse mode pulse laser with stable output and high mode purity, which is used as a seed source for a fiber laser amplifier. In a specific embodiment, the central wavelength of the high-order transverse mode pulse fiber laser 1 is 1.06 μm, the mode purity is greater than 90%, the pulse width is 10 ps~1 ns, the output average power is ~10 mW, and the repetition frequency is 1 MHz~30 MHz. The high-order mode pulse laser with the above parameters is used as a seed source for a fiber laser amplifier, which can obtain a good power amplification effect and generate a high-order mode pulse laser with high average power and high peak power.

[0045] The structure of the high-order transverse mode pulse fiber laser in one embodiment is as follows: Figure 2As shown, it is composed of a high-reflection fiber Bragg grating 101, a saturable absorber 102, a first single-mode pump source 103, a first wavelength division multiplexer 104, a first single-clad ytterbium-doped fiber 105, a long-period fiber grating 106, and a few-mode Bragg fiber grating 107. The high-reflection fiber Bragg grating 101 is connected to the saturable absorber 102, the saturable absorber 102 and the first single-mode pump source 103 are connected to the first wavelength division multiplexer 104, the first wavelength division multiplexer 104 is connected to one end of the first single-clad ytterbium-doped fiber 105, the other end of the first single-clad ytterbium-doped fiber 105 is connected to the long-period fiber grating 106, and the long-period fiber grating 106 is connected to the few-mode Bragg fiber grating 107. The high-reflection Bragg fiber grating 101 and the few-mode Bragg fiber grating 107 form a resonant cavity, and the saturable absorber 102 modulates the continuously running laser in the resonant cavity to obtain a stable output pulse laser; the first single-mode pump source 103 is a single-mode laser diode, which is coupled into the first single-clad ytterbium-doped fiber 105 through the first wavelength division multiplexer 104; the long-period fiber grating 106 has a period that satisfies the phase matching condition between the fundamental mode and the target-order high-order mode in the optical fiber, thereby converting the fundamental mode pulse laser into the target-order high-order transverse mode pulse laser; the few-mode Bragg fiber grating 107 has different central reflection wavelengths at the fundamental mode and the target-order high-order mode. By selecting a specific laser resonant wavelength through the high-reflection Bragg fiber grating 101 and the few-mode Bragg fiber grating 107, high-efficiency reflection of the fundamental mode laser in the resonant cavity can be achieved, and the target-order high-order transverse mode pulse laser is output at the same time, and the target-order high-order transverse mode seed pulse laser with a mode purity greater than 90% is obtained.

[0046] In one embodiment, the pulse generation method of the high-order transverse mode pulse fiber laser 1 can adopt mode locking, and the mode locking method can adopt an electro-optic modulator, a semiconductor saturable absorber, a carbon nanotube, nonlinear polarization rotation or nonlinear multi-mode interference, etc.

[0047] In a specific embodiment, the mode locking may adopt an active mode locking structure using an electro-optic modulator as a main component, or may adopt a passive mode locking structure using a semiconductor saturable absorption mirror as a main component.

[0048] In one embodiment, the high-order mode selection and excitation method of the high-order transverse mode pulse fiber laser 1 can adopt few-mode Bragg fiber grating, staggered fusion, long-period fiber grating, mode selective coupler, S wave plate, photon lantern, etc.

[0049] In a specific embodiment, a target-order high-order mode is selected by a few-mode Bragg fiber grating, and a target-order high-order mode is excited by a long-period fiber grating.

[0050] In one embodiment, the fiber laser amplifier 2 adopts a master oscillator power amplification structure to amplify the average power of the low-power target-order high-order transverse mode seed pulse laser to more than 100 W and the peak power to more than 5 kW.

[0051] In a specific embodiment, the fiber laser amplifier 2 is used to amplify the average power and peak power of the 1.06 μm target order high-order transverse mode seed pulse laser. The structure of the fiber laser amplifier 2 is as follows: Figure 3 As shown, the fiber laser amplifier 2 adopts a master oscillator power amplification structure, including a two-stage power amplification structure, including a second single-mode pump source 201, a second wavelength division multiplexer 202, a second single-clad ytterbium-doped fiber 203, a multimode pump source 204, a pump combiner 205, a double-clad ytterbium-doped fiber 206, and an energy transfer fiber 207. Among them, the first stage pre-amplification is composed of the second single-mode pump source 201, the second wavelength division multiplexer 202, and the second single-clad ytterbium-doped fiber 203. The target order high-order transverse mode seed pulse laser output by the high-order transverse mode pulse fiber laser 1 and the pump light output by the second single-mode pump source 201 are coupled to the second single-clad ytterbium-doped fiber 203 through the second wavelength division multiplexer 202, and the average power of the target order high-order transverse mode seed pulse laser is amplified to 1 W~5 W.

[0052] The second-stage main amplifier is composed of a multimode pump source 204, a pump combiner 205, and a double-clad ytterbium-doped fiber 206. The laser output by the second single-clad ytterbium-doped fiber 203 and the multimode pump source 204 are coupled to the double-clad ytterbium-doped fiber 206 via the pump combiner 205, and the average power of the target-order high-order transverse mode pulse laser is amplified to more than 100 W, and the peak power is amplified to more than 5 kW, which is used as the pump laser of the few-mode photonic crystal fiber and outputted via the energy transfer fiber 207.

[0053] In one of the embodiments, the gain fibers used for pre-amplification and main amplification of the fiber laser amplifier 2 are both few-mode fibers, which support transmission and power amplification of fundamental mode and target-order high-order transverse modes, but do not support transmission and power amplification of transverse modes higher than the target transverse mode order. By optimizing parameters such as gain fiber length, core diameter, doping concentration, and doping method, the purity of the laser mode output by the fiber laser amplifier is maintained above 80%.

[0054] In a specific embodiment, the fiber laser amplifier 2 selects ytterbium-doped fiber with a core diameter of 15 μm and a numerical aperture of 0.08 as the gain fiber. It only supports the fundamental mode and the first-order high-order transverse mode at 1.06 μm, while ensuring the power amplification of the first-order high-order transverse mode, it avoids the generation of higher-order modes, thereby obtaining a target-order high-power laser pulse with a mode purity greater than 80%.

[0055] In one embodiment, the proposed few-mode photonic crystal fiber 3 supports fundamental mode and target-order high-order transverse mode transmission in the wavelength range of 0.4 to 2.4 μm, and the zero dispersion wavelength range of the target high-order mode is 1.04 μm to 1.08 μm. At the same time, the dispersion matching wavelength of the 2.4 μm wavelength is less than 0.4 μm. When pumped by a high-power target-order high-order transverse mode pump laser, a high-power target-order high-order transverse mode supercontinuum laser with a mode purity greater than 70% can be generated.

[0056] In one embodiment, the core diameter of the few-mode photonic crystal fiber is greater than 6 μm. The larger core diameter can facilitate low-loss fusion with the pump laser output fiber, improve coupling efficiency, and thus obtain higher output power.

[0057] In one embodiment, the nonlinear coefficient and dispersion parameter of the few-mode photonic crystal fiber 3 are optimized by optimizing the size and arrangement of its air holes.

[0058] In a specific embodiment, based on Figure 2 The high-order transverse mode pulsed fiber laser shown in Figure 3 The fiber laser amplifier shown and Figure 4 The few-mode photonic crystal fiber shown is constructed as Figure 1 The high-power high-order transverse mode supercontinuum laser source shown in the figure. The central wavelength of the high-order transverse mode pulse fiber laser is 1.06 μm, the mode purity is greater than 90%, the pulse width is 10ps~1 ns, the output average power is ~10 mW, and the repetition frequency is 1 MHz~30 MHz. The fiber laser amplifier is used to amplify the average power of the 1.06μm high-order transverse mode seed pulse laser to more than 100 W and the peak power to more than 5 kW. The cross-sectional diagram of the few-mode photonic crystal fiber is shown in the figure. Figure 4 As shown, the dispersion curve of few-mode photonic crystal fiber is as follows Figure 5 As shown, the core of the few-mode photonic crystal fiber is located in the center, and an air hole array is arranged in a regular hexagonal array around the core. The air hole array contains multiple layers of regular hexagonal air hole sub-arrays from the inside to the outside, wherein the core diameter is 8.8 μm, the air hole diameter is 4.2 μm, and the air hole period in the air hole array is 6.5 μm; the fundamental mode zero dispersion point of the few-mode photonic crystal fiber is 1.147 nm, which is far away from the 1.06 μm pump wavelength; the zero dispersion point of the target order high-order transverse mode of the few-mode photonic crystal fiber is smaller than the fundamental mode zero dispersion point, which is 1.053 nm, and can match the 1.06 μm pump wavelength; when the 1.06 μm high-power target order high-order transverse mode pump laser is transmitted in the few-mode photonic crystal fiber, it can greatly broaden the spectrum under the action of dispersion waves and nonlinear effects, and obtain a high-power target order high-order transverse mode supercontinuum laser.

[0059] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. High-power high-order transverse mode supercontinuum laser source, characterized in that: include: High-order transverse mode pulse fiber laser, used to generate target-order high-order transverse mode seed pulse laser with time-domain stability and high mode purity, as a pulse laser seed source; Fiber laser amplifier, used to amplify the average power and peak power of target-order high-order transverse mode seed pulse laser, output high-power target-order high-order transverse mode pump laser, as a laser pump source; The few-mode photonic crystal fiber, as a laser nonlinear transmission medium, is used to convert a high-power target order high-order transverse mode pump laser into a supercontinuum through nonlinear effects and dispersion effects, while maintaining the mode characteristics of the output laser, and outputting a high-power target order high-order transverse mode supercontinuum laser. The few-mode photonic crystal fiber supports fundamental mode and target high-order transverse mode transmission in the wavelength range of 0.4 to 2.4 μm, and the zero dispersion wavelength range of the target high-order transverse mode mode is 1.04 μm to 1.08 μm. At the same time, the dispersion matching wavelength of the 2.4 μm wavelength is less than 0.4 μm. Under the pumping of the high-power target order high-order transverse mode pump laser, a high-power target order high-order transverse mode supercontinuum laser with a mode purity greater than 70% can be generated.

2. The high-power high-order transverse mode supercontinuum laser source according to claim 1, characterized in that: Few-mode photonic crystal fiber only supports fundamental mode and transverse mode modes not higher than the target order in the visible light and near-infrared bands. In the process of coupling high-power target-order high-order transverse mode pump laser into the few-mode photonic crystal fiber, the high-order transverse mode pump laser is converted into the target-order high-order transverse mode pulse laser of the same order in the few-mode photonic crystal fiber by means of high-order mode excitation. In addition, the target-order high-order transverse mode pulse laser undergoes spectral broadening under the action of nonlinear effects and dispersion during transmission, thereby generating and outputting high-power target-order high-order transverse mode supercontinuum laser.

3. The high-power high-order transverse mode supercontinuum laser source according to claim 1, characterized in that: The core diameter of the few-mode photonic crystal fiber is greater than 6 μm, and the zero dispersion point of the target mode is close to the central wavelength of the high-power target-order high-order transverse mode pump laser, thereby increasing the output power upper limit and visible light spectrum proportion of the target-order high-order transverse mode supercontinuum laser.

4. The high-power high-order transverse mode supercontinuum laser source according to claim 1, characterized in that: The target order high-order transverse mode is designed as TM according to actual application requirements. 01 Mode, TE 01 mode or higher order mode.

5. The high-power high-order transverse mode supercontinuum laser source according to claim 1, characterized in that: The spectral range of high-power target-order high-order transverse mode supercontinuum laser includes visible light, near-infrared and mid-infrared bands.

6. The high-power high-order transverse mode supercontinuum laser source according to claim 1, characterized in that: The few-mode photonic crystal fiber optimizes its nonlinear coefficient and dispersion parameter by optimizing the size and arrangement of its air holes.

7. The high-power high-order transverse mode supercontinuum laser source according to any one of claims 1 to 6, characterized in that: The central wavelength of the high-order transverse mode pulse fiber laser is 1.06 μm, the mode purity is greater than 90%, the pulse width is 10 ps~1 ns, the output average power is 10 mW, and the repetition frequency is 1 MHz~30 MHz.

8. The high-power high-order transverse mode supercontinuum laser source according to claim 7, characterized in that: The fiber laser amplifier is used to amplify the average power of the 1.06 μm target-order high-order transverse mode seed pulse laser to more than 100 W and the peak power to more than 5 kW.

9. The high-power high-order transverse mode supercontinuum laser source according to claim 1, characterized in that: The core of the few-mode photonic crystal fiber is located in the center, and an air hole array is arranged in a regular hexagonal array around the core. The air hole array contains multiple layers of regular hexagonal air hole sub-arrays from the inside to the outside, where the core diameter is 8.8 μm, the air hole diameter is 4.2 μm, and the air hole period in the air hole array is 6.5 μm. The fundamental mode zero dispersion point of few-mode photonic crystal fiber is 1.147 nm, far away from the 1.06 μm pump wavelength; The zero dispersion point of the target-order high-order transverse mode of the few-mode photonic crystal fiber is smaller than the zero dispersion point of the fundamental mode, which is 1.053nm, and can match the 1.06 μm pump wavelength; When the 1.06 μm high-power target-order high-order transverse mode pump laser is transmitted in the few-mode photonic crystal fiber, the spectrum can be greatly broadened under the action of dispersive waves and nonlinear effects, and a high-power target-order high-order transverse mode supercontinuum laser can be obtained.

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