Ultra-fast laser generating device

Abstract

The invention discloses an ultrafast laser generating device. The device comprises an ytterbium-doped femtosecond laser light source, a first focusing lens, a first optical window, a first-stage energy transfer device, a first-stage hollow-core capillary optical fiber, a second optical window, a concave reflecting mirror, a half-wave plate, a wire grid polarizing film, a second focusing lens, a third optical window, a first air chamber, a second-stage hollow-core anti-resonance optical fiber, a second air chamber and a fourth optical window. The invention discloses a 90-degree off-axis parabolic mirror and a frequency resolution optical switch pulse measuring device. The incident pulse spectrum is broadened by utilizing a self-phase modulation effect by changing the type and the air pressure of inert gas in the first-stage hollow-core capillary optical fiber; and then the second-stage hollow-core anti-resonance optical fiber is filled with inert gas to generate an air pressure gradient, and sub-20fs-order ultrafast laser flexible transmission is finally realized by utilizing a soliton self-compression effect.

Description

Technical Field

[0001] The invention relates to the technical field of ultrafast lasers, and mainly to a device for generating ultrafast lasers. Background Art

[0002] In today's era of rapid development of science and technology, ultrafast laser technology has become an indispensable and important means in many fields such as physics, chemistry, biology, materials, and medicine. At present, ultrafast lasers are mainly generated by mode locking technology, but the peak power of femtosecond lasers directly output from this is low and cannot meet the needs of various practical applications. Chirped pulse amplification technology can obtain ultrashort pulses of the millijoule level by broadening, amplifying, and then compressing the time-domain pulse, but due to the unavoidable gain bandwidth limitation and dispersion mismatch problems of the gain fiber, the pulse width is usually above 200fs. On January 14, 2015, the patent application with publication number CN104283097A combined the use of chirped pulse amplification technology and separated pulse amplification technology to achieve a pulse width of sub-hundred femtoseconds. Nonlinear amplification technology uses nonlinear effects such as self-phase modulation to amplify the pulse energy while broadening the spectrum, which can effectively obtain sub-hundred-femtosecond microjoule pulses at the 100-watt level. On February 13, 2024, the patent application with publication number CN117559204A enabled the generation, amplification, gain management, nonlinear evolution and compression of pulses to be completed entirely in the optical fiber. The final output laser pulse width was about 50 fs, and the peak power of the laser could reach the megawatt level. However, it was still impossible to achieve ultrafast laser output with a pulse width of sub-twenty femtoseconds.

[0003] At the same time, how to perfectly transmit laser is also an important research topic. Flexible transmission of lasers can get rid of the limitation of spatial optical path, making laser transmission more flexible and convenient, which is in great demand in the fields of precision machining, laser medical treatment, etc.

[0004] Nowadays, a new type of microstructured optical fiber - antiresonant hollow-core optical fiber uses the coherent reflection of light back and forth between the tubular glass films inside the optical fiber to confine the light near the air core and transmit it along the axis. Compared with traditional optical fibers and other microstructured optical fibers, it has the advantages of large mode field area, high damage threshold, low nonlinearity, adjustable dispersion, and free control of the type and composition of the core gas. It is very suitable as a carrier for ultrafast laser transmission, and its unique properties provide new possibilities for the transmission of ultrafast lasers.

[0005] The present invention is based on nonlinear pulse compression technology and two-stage hollow-core optical fiber to generate and transmit ultrafast lasers. It is intended to solve the defects of traditional pulse compression technology, such as the compressed pulse width is not narrow enough and the device is complicated. It ensures the output of ultrafast laser with ultrashort pulse width while taking into account high stability and compactness, and has broad application prospects. Summary of the invention

[0006] The present invention provides an ultrafast laser generating device, which generates and transmits ultrafast laser with a sub-twenty femtosecond pulse width with high repetition rate, high energy and high peak power, solves the defects of the prior art that the device is complex and the pulse width compression is not narrow enough, and has the advantages of high stability, compactness and flexible transmission, and does not need to use a chirped mirror to compensate for dispersion.

[0007] The technical solution of the present invention is as follows: an ultrafast laser generating device, which comprises, in sequence, an ytterbium-doped femtosecond laser light source, a first focusing lens, a pulse spectrum broadening unit, a concave reflector, a half-wave plate, a wire grid polarizer, a second focusing lens, a dispersion compensation and pulse transmission unit, a 90° off-axis parabolic reflector, and a frequency-resolving optical switch pulse measuring device;

[0008] The pulse spectrum broadening unit is used to achieve spectrum broadening, and includes a first-stage energy transmission device sealed by a first optical window and a second optical window, and a first-stage hollow-core capillary optical fiber placed in the first-stage energy transmission device;

[0009] The dispersion compensation and pulse transmission unit is used to achieve compressed pulse width and transmitted pulse energy, including a first air chamber and a second air chamber respectively connected to a third optical window and a fourth optical window on the front side, and having a sub-micrometer through hole on the back side, and a second-stage hollow-core anti-resonant optical fiber with two ends passing through the through holes and fixed to the first air chamber and the second air chamber.

[0010] The working process is as follows: the initial laser pulse emitted by the ytterbium-doped femtosecond laser light source is focused and coupled into the first-stage hollow-core capillary optical fiber placed in the first-stage energy transmission device through the first focusing lens and the first optical window, and is output through the second optical window to achieve spectrum broadening; the broadened laser pulse is collimated by a concave reflector and then the optical path is changed, the energy is adjusted by a half-wave plate and a wire grid polarizer, and then it is focused and coupled into the second-stage hollow-core anti-resonance optical fiber placed in the first air chamber and the second air chamber through the second focusing lens and the third optical window. In the second-stage hollow-core anti-resonance optical fiber, the first air chamber at the incident end is evacuated and the second air chamber at the output end is filled with inert gas to form a pressure gradient. Due to the soliton self-compression effect, ultrafast laser flexible transmission of sub-20fs level is achieved, and it is output through the fourth optical window, and then collimated by a 90° off-axis parabolic reflector and the optical path is turned to enter the frequency-resolving optical switch pulse measurement device to measure the pulse width.

[0011] The first-stage energy transmission device includes: a sealing glass plate, a first gas control valve, an optical fiber fixing seat, and a cylindrical cavity. The sealing glass plate is arranged outside the cylindrical cavity and is used to observe the end face position of the first-stage hollow capillary optical fiber to facilitate coupling adjustment; the first gas control valve is arranged outside the cylindrical cavity and is connected to the gas bottle and the vacuum pump through an air pipe; the optical fiber fixing seat is fixed in the cylindrical cavity, and the material is a metal with good thermal conductivity and is provided with a V-shaped groove; the cylindrical cavity is placed on two two-dimensional translation stages; the first-stage hollow capillary is fixed in the V-shaped groove in the optical fiber fixing seat, and the optical fiber fixing seat is fixed in the cylindrical cavity. The sealing glass plate, the first optical window, the second optical window and the first gas control valve form a sealed space, and an inert gas is filled through the first gas control valve to achieve initial laser pulse spectrum broadening.

[0012] The initial laser pulse emitted by the Yb-doped femtosecond laser source is focused and coupled by the first focusing lens, and the coupled beam focal spot is 1 / e 2 The diameter at the first hollow capillary fiber is 0.5 to 0.8 times the inner diameter of the first stage; the broadened laser pulse is focused and coupled by the second focusing lens, and the coupled beam focal spot is 1 / e 2 The diameter at is 0.5 to 0.8 times the inner diameter of the second-stage hollow-core antiresonant optical fiber;

[0013] Preferably, the first focusing lens couples the beam focal spot 1 / e 2 The diameter at the first stage hollow core capillary fiber is 0.64 times the inner diameter of the first stage; the focal spot of the second focusing lens coupling beam is 1 / e 2 The diameter at is 0.64 times the inner diameter of the second-stage hollow-core antiresonant fiber.

[0014] The first gas control valve is used for charging and discharging of inert gas and regulating and controlling the gas pressure. The inert gas is helium, neon, argon, krypton, or xenon monatomic gas.

[0015] The first gas chamber and the second gas chamber are respectively equipped with a second gas control valve and a third gas control valve. The second gas control valve is used for vacuuming, and the third gas control valve is used for filling and discharging inert gas and regulating and controlling the air pressure. The inert gas is helium, neon, argon, krypton, or xenon monatomic gas.

[0016] The first-stage energy transmission device and the second air chamber are filled with inert gas; the inert gas includes helium, neon, argon, krypton, and xenon monatomic gas; the first-stage energy transmission device and the second air chamber are respectively equipped with a first gas control valve and a third gas control valve for filling and discharging the inert gas and regulating and controlling the air pressure; the first air chamber is equipped with a second gas control valve, and the second gas control valve is used for vacuuming.

[0017] The concave reflector and the 90° off-axis parabolic reflector collimate the pulses emitted from the first-stage hollow-core capillary and the second-stage hollow-core antiresonant optical fiber and simultaneously deflect the optical path. Compared with a lens, the light beam passing through the concave reflector and the 90° off-axis parabolic reflector will not introduce dispersion and absorption loss, and will not generate spherical aberration and chromatic aberration.

[0018] The first-stage energy transmission device can transmit 400μJ, 29W high-repetition-rate, high-energy ultrafast laser, and has good functions of fixing optical fiber, sealing, heat dissipation, and regulating gas type and air pressure. It also has the characteristics of simple structure, uniform heat dissipation, and strong practicality.

[0019] The first-stage hollow-core capillary optical fiber is no longer than 1 meter.

[0020] The second-stage hollow-core anti-resonance optical fiber is no longer than 2.5 meters.

[0021] The ytterbium-doped femtosecond laser light source is a laser light source with a central wavelength of 1030nm, and the pulse energy is 0μJ-400μJ and the repetition rate is 0kHz-72.4kHz and is adjustable.

[0022] Beneficial technical effects of the present invention:

[0023] An ultrafast laser generating device proposed in the present invention can output femtosecond laser pulses with adjustable energy, good coherence and stable output power; by adjusting the incident pulse energy, gas type and gas pressure, high-energy, high-repetition-rate, sub-20fs ultrafast laser pulse generation and transmission can be achieved; the present invention uses spectrum broadening and pulse compression to achieve the generation and transmission of broadband femtosecond laser light sources for the initial laser pulses; the first-stage energy transmission device of the present invention has uniform heat dissipation, good stability and airtightness, and low processing difficulty, and can accurately control the gas pressure and withstand femtosecond laser transmission with higher power and energy; the present invention takes into account both scientific research and exploration and practical application needs, the experimental device is scientific and reasonable, the cost is controllable and the maintenance is simple, and the device has the advantages of flexible transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the experimental optical path of an ultrafast laser generating device in an embodiment of the present invention.

[0025] Figure 2 The figure is a schematic structural diagram of a first-stage energy transmission device of an ultrafast laser generating device in an embodiment of the present invention.

[0026] Figure 3 : This is a frequency domain and time domain measurement diagram of a high-energy, high-repetition-rate sub-20fs pulse transmitted in an embodiment of the present invention, wherein Figure 3 (a) is the measured FROG trace; Figure 3 (b) is the FROG trace image restored by the algorithm; Figure 3 (c) is the pulse time domain and phase distribution diagram restored by the algorithm; Figure 3 (d) is the measured and recovered pulse frequency domain and phase distribution diagram.

[0027] Reference numerals:

[0028] Ytterbium-doped femtosecond laser light source-1; first focusing lens-2; first optical window-3; first-stage energy transmission device-4; first-stage hollow-core capillary fiber-5; second optical window-6; concave reflector-7; first reflector-8; half-wave plate-9; wire-grid polarizer-10; second reflector-11; third reflector-12; second focusing lens-13; third optical window-14; first gas chamber-15; second gas control valve-151; second-stage hollow-core anti-resonance fiber-16; second gas chamber-17; third gas control valve-171; fourth optical window-18; 90° off-axis parabolic reflector-19; fourth reflector-20; frequency-resolved optical switch pulse measurement device-21.

[0029] Sealing glass plate-41; first gas control valve-42; optical fiber fixing seat-43; cylindrical cavity-44. DETAILED DESCRIPTION

[0030] The present invention is further described below by way of examples and drawings, but the protection scope of the present invention shall not be limited thereto.

[0031] Figure 1 , an ultrafast laser generating device comprises in sequence: 1. an ytterbium-doped femtosecond laser light source; 2. a first focusing lens; 3. a first optical window; 4. a first-stage energy transmission device; 5. a first-stage hollow-core capillary fiber; 6. a second optical window; 7. a concave reflector; 8. a first reflector; 9. a half-wave plate; 10. a wire-grid polarizer; 11. a second reflector; 12. a third reflector; 13. a second focusing lens; 14. a third optical window; 15. a first gas chamber; 151. a second gas control valve; 16. a second-stage hollow-core anti-resonant fiber; 17. a second gas chamber; 171. a third gas control valve; 18. a fourth optical window; 19. a 90° off-axis parabolic reflector; 20. a fourth reflector; 21. a frequency-resolved optical switch pulse measuring device.

[0032] The ytterbium-doped femtosecond laser light source 1 generates an initial laser pulse, and the laser light source parameters are: 1030nm central wavelength, about 190fs pulse width, and 1kHz repetition frequency.

[0033] The half-wave plate 9 and the wire grid polarizer 10 form a pulse energy and polarization adjustment unit. The half-wave plate can change the polarization of light, and the wire grid polarizer transmits specific linear polarized light by fixing the polarization direction. The combination of the two can achieve continuous adjustment of pulse energy.

[0034] The focal lengths of the first and second focusing lenses depend on the focal spot size of the laser pulse after focusing and the inner diameter of the hollow core waveguide. 2 When the diameter at is about 0.64 times the inner diameter of the hollow-core capillary fiber, the theoretical coupling efficiency of the fundamental mode is about 0.98.

[0035] The first-stage energy transmission device 4 is supported and fixed by two two-dimensional translation stages, and the first air chamber 15 and the second air chamber 17 are supported and fixed by two three-dimensional translation stages, ensuring that the laser pulse passes through the first-stage energy transmission device and the first and second air chambers via the axis. The first-stage hollow-core capillary fiber is fixed as a whole in the fiber fixing seat in the first-stage energy transmission device 4, and the two ends of the second-stage hollow-core anti-resonance fiber are fixed in the V-grooves in the first and second air chambers, so that the axis of the first-stage hollow-core capillary fiber coincides with the axis of the first-stage energy transmission device and the axis of the second-stage hollow-core anti-resonance fiber coincides with the axis of the first-stage energy transmission device. The first-stage energy transmission device 4 is sealed by the first optical window 3 and the second optical window 6 at the front and back, and the first gas control valve 42 is used to fill or discharge the inert gas and control the gas pressure. Good air tightness must be ensured when connecting the optical windows. The first air chamber 15 and the second air chamber 17 are rectangular cavities, connected to the third optical window 14 and the fourth optical window 18 on the front, respectively, and have sub-millimeter through holes on the back; the two ends of the second-stage hollow-core anti-resonance optical fiber are inserted and fixed through the through holes, and the through holes are sealed with UV glue; the first air chamber is equipped with a second gas control valve 151 for vacuuming; the second air chamber is equipped with a third gas control valve 171 for filling or discharging inert gas and controlling gas pressure, and good air tightness must be ensured when connecting the optical windows and sealing with UV glue. The first optical window 3, the first-stage energy transmission device 4, the first-stage hollow-core capillary optical fiber 5 and the second optical window 6 constitute a pulse spectrum broadening unit; the third optical window 14, the first air chamber 15, the second-stage hollow-core anti-resonance optical fiber 16, the second air chamber 17 and the fourth optical window 18 constitute a dispersion compensation and pulse transmission unit.

[0036] The first optical window, the second optical window, the third optical window and the fourth optical window are made of fused quartz.

[0037] The specific embodiment of the present invention is as follows: the ytterbium-doped femtosecond laser light source 1 outputs an initial laser pulse with a central wavelength of 1030nm, a pulse width of about 190fs, and a repetition frequency of 1kHz, which passes through the first focusing lens 2 to reach the first optical window 3 and the first-stage energy transmission device 4, and is coupled into the first-stage hollow-core capillary fiber 5. The first focusing lens 2 is used to focus the laser pulse, and the selection of its focal length is determined by the numerical relationship between the inner diameter of the first-stage hollow-core capillary fiber 5 and the size of the light spot at the focus. Specifically, a CCD camera is used to detect the size of the light spot at the focus, and lenses with different focal lengths are selected to make the focal spot 1 / e 2 The diameter is close to or equal to 0.64 of the inner diameter of the first-stage hollow-core capillary fiber 5, and the focal length of the lens is optimal at this time. In this embodiment, the focal length of the first focusing lens 2 is 501.8mm. By repeatedly adjusting the two two-dimensional translation stages, the spatial position of the pulse spectrum broadening unit changes, and its axis coincides with the axis of the initial laser pulse. Therefore, the laser pulse is efficiently coupled into the first-stage hollow-core capillary fiber 5 with a length of 80cm and a core diameter of 250μm after being focused by the first focusing lens 2, and at the same time, the energy of the output pulse is the highest and the spot mode is the fundamental mode. The laser pulse output from the pulse spectrum broadening unit is collimated by a concave reflector 7 with a focal length of 500mm, and after the light path is deflected by the first reflector 8, it passes through the energy and polarization adjustment unit to achieve the purpose of continuously adjusting the pulse energy, and continues to deflect the light path through the second reflector 11 and the third reflector 12 to reach the second focusing lens 13 with a focal length of 60mm for focusing. The selection of the focal length is the same as that of the first focusing lens 2. Then, the three-dimensional displacement stage at the incident end is adjusted so that the laser pulse is efficiently coupled into the second-stage hollow-core anti-resonance optical fiber 16 with vacuum at the emission end and inert gas at the output end, and the output pulse energy is the highest, and the spot mode is the fundamental mode. The laser pulse is compressed in the second-stage hollow-core anti-resonance optical fiber 16 by using the negative dispersion of the hollow-core waveguide and the nonlinear effect provided by the inert gas. The chirp amount of the laser pulse output by the pulse spectrum broadening unit is calculated, and the second-stage hollow-core anti-resonance optical fiber 16 of suitable length is selected to optimize the dispersion compensation and realize the sub-20fs laser pulse output. By adjusting the half-wave plate to change the laser pulse energy incident to the second focusing lens, the gas type and pressure in the second air chamber, high-energy, high-repetition-rate, sub-20fs ultrafast laser pulse generation and transmission can be realized. The pulse at the output end of the second-stage hollow-core anti-resonance optical fiber 16 is collimated by the 90° off-axis parabolic reflector 19, and then the optical path is turned by the fourth reflector 20 to enter the frequency-resolving optical switch pulse measurement device 21 for pulse measurement.

[0038] Figure 2 , a structure of a first-stage energy transmission device based on an ultrafast laser generating device, including: a sealing glass plate 41, a first gas control valve 42, an optical fiber fixing seat 43, and a cylindrical cavity 44.

[0039] The sealing glass plate 41 and the cylindrical cavity 44 are tightly connected with screws, which can be used to observe the position of the optical fiber end face and facilitate coupling adjustment. When connecting, the screws need to be tightened to ensure good airtightness and avoid thread slippage.

[0040] Among them, the first gas control valve 42 is connected to the gas bottle and the vacuum pump through the gas pipe, and is used to control the gas in the first-stage energy transmission device 4. Good airtightness must also be ensured during the connection.

[0041] The cylindrical cavity 44 is cylindrical so as to be easily clamped and fixed by the two-dimensional translation stage.

[0042] Among them, the optical fiber holder 43 is placed and fixed in the cylindrical cavity 44 through the card slot. The material is a metal with good thermal conductivity and is provided with a V-shaped groove. In this embodiment, the preferred material is copper. The use of copper tape to cover the entire section or multiple sections of the hollow capillary optical fiber can achieve the effect of good optical fiber fixation. Copper has excellent thermal conductivity. The hollow capillary optical fiber is in close contact with the optical fiber holder and the copper tape, which can quickly dissipate the heat generated by the high-energy, high-repetition-rate ultrafast laser transmitted in the hollow capillary, so that the optical fiber is not easily burned. Since the hollow capillary optical fiber, the optical fiber holder and the cylindrical cavity are well fixed, when the displacement stage is used to adjust the spatial position of the hollow capillary optical fiber, the first-level energy transmission device can ensure the stability of the laser pulse transmission. The specific operation is as follows: First, the hollow capillary optical fiber is placed on the optical fiber holder, the optical fiber is glued with copper tape, and then the optical fiber holder is inserted through one end of the cylindrical cavity until the card slot position, and finally the cylindrical cavity is firmly fixed on the two two-dimensional displacement stages at the head and tail. Through the sealing glass plate, observe and adjust the displacement stage so that the hollow capillary fiber port is located at the focus, and finally connect the sealing glass plate, the first gas control valve, the gas bottle and the vacuum pump, and seal the two ends of the cylindrical cavity with the first optical window and the second optical window to ensure that there is no air leakage and thus accurately control the type and pressure of the gas in the cavity. In this embodiment, the first-stage energy transmission device can transmit 400μJ, 29W high-repetition-rate, high-energy ultrafast laser, which is only one of the cases and should not be used to limit the scope of protection of the present invention.

[0043] Figure 3, the frequency domain and time domain measurement diagram of the high-energy, high-repetition-rate, sub-20fs ultrafast laser pulses generated. By adjusting the laser pulse energy output by the pulse spectrum broadening unit, the gas type and pressure in the second gas chamber, the generation and transmission of high-energy, high-repetition-rate, sub-20fs ultrafast laser pulses can be achieved. Among them, in this embodiment, in the first-stage energy transmission device, the optimal setting for the initial laser pulse spectrum broadening is: the inert gas is argon; the optimal setting value of the gas pressure is 1200mbar; the optimal setting of the drive pulse energy is 400μJ. The optimal settings of the gas type and gas pressure in the first-stage energy transmission device need to be determined according to the length of the second-stage antiresonant hollow-core optical fiber. In the second gas chamber of this embodiment, the optimal settings for the generation and transmission of sub-20fs ultrafast lasers are: the inert gas is neon; the gas pressure range is 3200mbar to 3900mbar; the driving pulse energy range matched by the gas pressure is 11μJ to 13μJ. Typically, in this embodiment, the optimal settings for generating and transmitting an ultrafast laser with a pulse width of 17.3 fs are: the inert gas is neon; the gas pressure is 3260 mbar; the driving pulse energy matching the gas pressure is 12.48 μJ. The specific parameters such as the type of gas used in the second gas chamber, the gas pressure and the driving pulse energy should be determined according to the actual situation.

Claims

1. An ultrafast laser generating device, characterized in that: Including in order: Ytterbium-doped femtosecond laser light source (1), a first focusing lens (2), a pulse spectrum broadening unit, a concave reflector (7), a half-wave plate (9), a wire grid polarizer (10), a second focusing lens (13), a dispersion compensation and pulse transmission unit, a 90° off-axis parabolic reflector (19), and a frequency-resolving optical switch pulse measurement device (21); The pulse spectrum broadening unit is used to achieve spectrum broadening, and comprises a first-stage energy transmission device (4) sealed by a first optical window (3) and a second optical window (6), and a first-stage hollow-core capillary optical fiber (5) placed in the first-stage energy transmission device; The dispersion compensation and pulse transmission unit is used to compress pulse width and transmit pulse energy, and comprises a first air chamber (15) and a second air chamber (17) respectively connected to a third optical window (14) and a fourth optical window (18) on the front side, and having a sub-millimeter through hole on the back side, and a second-stage hollow-core anti-resonance optical fiber (18) with two ends passing through the through holes and fixed to the first air chamber and the second air chamber; The initial laser pulse emitted by the ytterbium-doped femtosecond laser light source is focused and coupled into a first-stage hollow-core capillary optical fiber disposed in a first-stage energy transmission device through a first focusing lens via a first optical window, and is outputted through a second optical window to achieve spectrum broadening; the broadened laser pulse is collimated by a concave reflector and then changes the optical path, and the energy is adjusted through a half-wave plate and a wire grid polarizer, and then is focused and coupled into a second-stage hollow-core anti-resonant optical fiber disposed in a first air chamber and a second air chamber through a second focusing lens via a third optical window; in the second-stage hollow-core anti-resonant optical fiber, the first air chamber at the incident end is evacuated and the second air chamber at the output end is filled with an inert gas to form an air pressure gradient; due to the soliton self-compression effect, ultrafast laser flexible transmission of sub-20 fs order is achieved, and the pulse is outputted through a fourth optical window, and then collimated by a 90° off-axis parabolic reflector and the optical path is turned to enter a frequency-resolving optical switch pulse measuring device to measure the pulse width.

2. An ultrafast laser generating device as claimed in claim 1, characterized in that: The first-stage energy transmission device comprises: a sealing glass plate (41), a first gas control valve (42), an optical fiber fixing seat (43), and a cylindrical cavity (44); The sealing glass plate (41) is arranged outside the cylindrical cavity; The first gas control valve (42) is arranged outside the cylindrical cavity and is connected to the gas bottle and the vacuum pump through a gas pipe; The optical fiber fixing seat (43) is fixed in the cylindrical cavity (44); the optical fiber fixing seat (43) is made of metal with good electrical conductivity and is provided with a V-shaped groove; The cylindrical cavity (44) is placed on two two-dimensional translation stages; The first-stage hollow capillary (5) is fixed in a V-shaped groove in an optical fiber fixing seat (43), and the optical fiber fixing seat (43) is fixed in a cylindrical cavity (44). The sealing glass plate (41), the first optical window (3), the second optical window (6) and the first gas control valve (42) form a sealed space, and an inert gas is filled through the first gas control valve to achieve initial laser pulse spectrum broadening.

3. An ultrafast laser generating device as claimed in claim 1 or 2, characterized in that: The initial laser pulse emitted by the ytterbium-doped femtosecond laser light source (1) is focused and coupled by a first focusing lens (2), and the focal spot of the coupled beam is 1 / e 2 The diameter at the point is 0.5 to 0.8 times the inner diameter of the first-stage hollow-core capillary optical fiber (5); the broadened laser pulse is focused and coupled by the second focusing lens (13), and the coupled beam focal spot is 1 / e 2 The diameter at the position is 0.5 to 0.8 times the inner diameter of the second-stage hollow-core anti-resonance optical fiber (16).

4. The ultrafast laser generating device according to claim 3, characterized in that: The first focusing lens (2) couples the beam focal spot 1 / e 2 The diameter at the position is 0.64 times the inner diameter of the first-stage hollow-core capillary optical fiber (5); the focal spot of the coupled light beam of the second focusing lens (13) is 1 / e 2 The diameter at the position is 0.64 times the inner diameter of the second-stage hollow-core anti-resonance optical fiber (16).

5. The ultrafast laser generating device according to claim 2, characterized in that: The first gas control valve is used for charging and discharging of inert gas and regulating and controlling the gas pressure. The inert gas is helium, neon, argon, krypton, or xenon monatomic gas.

6. The ultrafast laser generating device according to claim 1, characterized in that: The first gas chamber (15) and the second gas chamber (17) are respectively provided with a second gas control valve (151) and a third gas control valve (171); the second gas control valve (151) is used for evacuating the air, and the third gas control valve (171) is used for charging and discharging an inert gas and regulating and controlling the gas pressure; the inert gas is helium, neon, argon, krypton, or xenon monatomic gas.

7. The ultrafast laser generating device according to claim 1, characterized in that: The length of the first-stage hollow-core capillary optical fiber (5) is no more than 1 meter.

8. The ultrafast laser generating device according to claim 1, characterized in that: The length of the second-stage hollow-core anti-resonance optical fiber (16) is no more than 2.5 meters.

9. The ultrafast laser generating device according to claim 1, characterized in that: The ytterbium-doped femtosecond laser light source (1) is a laser light source with a central wavelength of 1030 nm, and has an adjustable pulse energy of 0 μJ to 400 μJ and a repetition rate of 0 kHz to 72.4 kHz.

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