Pulsed Fiber Gas Laser

Abstract

The present invention provides a fiber gas laser with pulse output, comprising a pump source, a pump coupling optical unit, an input coupling mirror, a sealed cavity, a hollow core optical fiber, a chopper and an output coupling mirror. The pump source is a tunable, narrow-linewidth continuous laser light source, and the output waveform of the pump source corresponds to the absorption peak of the gain gas used. A continuous laser light source is used as a pump source, and an active Q-switching scheme is adopted to achieve pulse output. On the one hand, the dependence on the performance of the pump source is reduced, and on the other hand, the cost is greatly reduced because the cost of the continuous laser light source is much lower than that of the pulse laser light source. The chopper is an active Q-switching device, which can freely adjust the pulse width, repetition rate and other parameters of the output pulse. The present invention can obtain a low-cost fiber gas laser with flexible pulse output and high peak power output.

Description

Technical Field

[0001] The invention mainly relates to the technical field of optical fiber lasers, in particular to an optical fiber gas laser with pulse output. Background Art

[0002] As an important means of outputting portable, stable and efficient lasers, fiber lasers have good beam quality and compact structure, and have great development prospects in the field of lasers. In particular, in the fields of medical treatment, material processing and sensing, the number of applications of lasers requiring high average power, compact portable size, high reliability and long-distance beam propagation capabilities is increasing rapidly.

[0003] The hollow-core fiber-based gas laser is a new type of laser light source developed with the emergence of hollow-core fiber. It combines many advantages of traditional gas lasers and fiber lasers and has received widespread attention in recent years. Fiber gas lasers use hollow-core fiber as the transmission carrier of the laser and gas molecules as the gain medium. They combine the advantages of fiber lasers and gas lasers, and have a long action distance, good beam quality, good heat dissipation characteristics, and a high damage threshold. At the same time, different types of gain gases (such as CO2, CO, HF, etc.) can be replaced to output lasers of different wavelengths.

[0004] As for pulsed fiber lasers, they have the characteristics of high peak power and have specific application scenarios in the fields of material processing, medical surgical tissue cutting, optoelectronic countermeasures, etc. However, the means for fiber gas lasers to achieve pulse output are currently very limited, and they mainly rely on pulsed lasers as pump sources to achieve pulse output. This technical means is completely dependent on the performance of the pump source (depending on the performance of the pump source and cannot be adjusted unless the pump source is replaced). The cost of the pulse pump source is higher than that of the continuous light source, and the output repetition rate and pulse width cannot be flexibly adjusted. At the same time, it is also difficult to obtain high peak power pulse output, and the peak power of the pulse output finally obtained cannot exceed the peak power of the pump source. Summary of the invention

[0005] Aiming at the problem that the fiber gas laser in the prior art completely relies on the performance of the pump source, cannot flexibly adjust the output repetition rate and pulse width, and the peak power of the pulse output finally obtained cannot exceed the peak power of the pump source, the present invention proposes a fiber gas laser with pulse output, which can achieve higher pulse energy output and higher peak power pulse output.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A fiber gas laser with pulse output, including a pump source, a pump coupling optical unit, an input coupling mirror, a sealed cavity, a hollow core fiber, a chopper, an output coupling mirror, a beam splitter, a photodetector and a computer control system;

[0008] The pump source outputs pump laser of required power under the control of the computer control system;

[0009] The pump coupling optical unit is used to couple the pump laser into the core of the hollow core optical fiber;

[0010] The input coupling mirror is a coupling mirror located at the pump end of the fiber gas laser, and serves as an end face feedback mirror of the laser in the resonant cavity;

[0011] The sealed cavity comprises an input sealed cavity and an output sealed cavity, the input sealed cavity and the output sealed cavity are respectively located at two ends of the hollow core optical fiber, and are used to seal the gain gas in the hollow core optical fiber; at least one of the input sealed cavity and the output sealed cavity is connected to a vacuum pumping and gas filling system, the vacuum pumping and gas filling system is connected to a computer control system, and the sealed cavity is vacuumed or gas filled under the control of the computer control system, thereby controlling the pressure of the gain gas in the hollow core optical fiber;

[0012] The hollow core optical fiber confines the pump laser in the fiber core, providing an effective interaction distance between the pump laser and the gain gas;

[0013] The chopper is an active Q-switching device, which is arranged in front of the output coupling mirror. The chopper is connected to a computer control system, and the computer control system adjusts the repetition frequency and pulse width of the output pulse laser by controlling the duty cycle and rotation frequency of the chopper.

[0014] The output coupling mirror is a coupling mirror located at the output end of the fiber gas laser, and serves as an end face feedback mirror of the laser in the resonant cavity;

[0015] The beam splitter is a beam splitter device for outputting pulsed lasers, and is arranged behind the output coupling mirror. A very small portion of the output pulsed laser is transmitted through the beam splitter for subsequent photoelectric detection, and the remaining majority of the pulsed laser is reflected by the beam splitter and output as laser.

[0016] The photoelectric detector is a detection device that outputs pulsed lasers and is arranged on the transmission light path of the spectroscope to detect the pulsed laser information transmitted through the spectroscope and convert the detected optical signal into an electrical signal for transmission to the computer control system;

[0017] The computer control system collects the electrical signal output by the photodetector and controls the pump source, the vacuum pumping and gas filling system, and the chopper, including: generating control signals for the pump source, the vacuum pumping and gas filling system, and the chopper, controlling the output power of the pump source, controlling the gas pressure in the hollow-core optical fiber, and controlling the repetition frequency and pulse width of the output pulse laser to achieve a pulse laser output with a stable pulse sequence and an ideal pulse waveform.

[0018] Through the above technical solution, the present invention adopts an active Q-switching solution to achieve pulse output, which reduces the dependence on the performance of the pump source compared to the prior art.

[0019] The pump source of the present invention is a tunable, narrow-linewidth continuous laser light source, and the output wavelength of the pump source corresponds to the absorption peak of the gain gas used. A continuous laser light source is used as a pump source, and an active Q-switching scheme is adopted to achieve pulse output. On the one hand, it reduces the dependence on the performance of the pump source. On the other hand, since the cost of the continuous laser light source is much lower than that of the pulse laser light source, the cost is greatly reduced. The chopper is an active Q-switching device, and the pulse width, repetition rate and other parameters of the output pulse can be freely adjusted. The present invention obtains a low-cost fiber gas laser with flexible pulse output. At the same time, compared with the existing scheme using a pulse light source, the present invention can achieve high peak power output. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] Figure 1 is a schematic structural diagram of a pulsed output fiber gas laser in one embodiment;

[0022] Figure 2 is a control flow chart of an embodiment;

[0023] Figure 3 is a schematic diagram of a stable pulse sequence detected by a photodetector in one embodiment;

[0024] Figure 4 is a schematic diagram of an unstable pulse sequence detected by a photoelectric detector in one embodiment;

[0025] Numbers in the figure:

[0026] 1. Pump source; 2. Pump beam expander lens; 3. First high reflective mirror; 4. Second high reflective mirror; 5. Input coupling mirror; 6. Coupling lens; 7. Input window; 8. Input sealed cavity; 9. Vacuuming and inflation system; 10. Hollow core optical fiber; 11. Output sealed cavity; 12. Output window; 13. Laser beam expander; 14. Chopper; 15. Output coupling mirror; 16. Spectrometer; 17. Photodetector; 18. Computer control system. DETAILED DESCRIPTION

[0027] 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.

[0028] In one embodiment, referring to Figure 1 , providing a pulsed output fiber gas laser, comprising a pump source 1, a pump coupling optical unit, an input coupling mirror 5, a sealed cavity, a hollow core fiber 10, a chopper 14, an output coupling mirror 15, a beam splitter 16, a photodetector 17 and a computer control system 18;

[0029] The pump source 1 outputs a pump laser of required power under the control of a computer control system 18;

[0030] The pump coupling optical unit is used to couple the pump laser into the core of the hollow core optical fiber 10;

[0031] The input coupling mirror 5 is a coupling mirror located at the pump end of the fiber gas laser, and serves as an end face feedback mirror of the laser in the resonant cavity;

[0032] The sealed cavity comprises an input sealed cavity 8 and an output sealed cavity 11, wherein the input sealed cavity 8 and the output sealed cavity 11 are respectively located at two ends of the hollow core optical fiber 10, and are used to seal the gain gas in the hollow core optical fiber 10; at least one of the input sealed cavity 8 and the output sealed cavity 11 is connected to a vacuum pumping and inflation system 9, and the vacuum pumping and inflation system 9 is connected to a computer control system 18, and the sealed cavity is vacuumed or inflated under the control of the computer control system 18, thereby controlling the pressure of the gain gas in the hollow core optical fiber 10;

[0033] The hollow core optical fiber 10 confines the pump laser in the fiber core, providing an effective interaction distance between the pump laser and the gain gas;

[0034] The chopper 14 is an active Q-switching device, which is arranged in front of the output coupling mirror 15. The chopper 14 is connected to a computer control system 18, which adjusts the repetition frequency and pulse width of the output pulse laser by controlling the duty cycle and rotation frequency of the chopper 14.

[0035] The output coupling mirror 15 is a coupling mirror located at the output end of the fiber gas laser, and serves as an end face feedback mirror of the laser in the resonant cavity;

[0036] The beam splitter 16 is a beam splitter device for outputting pulsed lasers, and is arranged behind the output coupling mirror 15. A very small portion of the output pulsed laser is transmitted through the beam splitter for subsequent photoelectric detection, and the remaining majority of the pulsed laser is reflected by the beam splitter and output as laser.

[0037] The photodetector 17 is a detection device for outputting pulsed laser, and is arranged on the transmission light path of the spectroscope 16, and is used to detect the pulsed laser information transmitted through the spectroscope 16, and convert the detected optical signal into an electrical signal and transmit it to the computer control system 18;

[0038] The computer control system 18 collects the electrical signal output by the photodetector 17, and controls the pump source 1, the vacuum and gas filling system 9, and the chopper 14. Specifically, it generates control signals for the pump source 1, the vacuum and gas filling system 9, and the chopper 14, controls the output power of the pump source 1, controls the gas pressure in the hollow-core optical fiber 10, controls the repetition frequency and pulse width of the output pulse laser, and realizes a pulse laser output with a stable pulse sequence and an ideal pulse waveform.

[0039] The pump source 1 described in the present invention is a tunable, narrow-linewidth continuous laser light source, which outputs a pump laser of required power under the control of a computer control system 18, and the output wavelength of the pump source 1 corresponds to the absorption peak of the gain gas used;

[0040] The beam splitter 16 is coated with a high reflective film with high reflectivity to the output pulse laser band (such as a reflectivity of more than 99% to the pulse laser band, including but not limited to 99.9%), and is used for splitting the output laser.

[0041] The detection band of the photodetector 17 should match the emission spectrum of the gain gas used, and the rising edge time of the photodetector 17 should not be greater than 1 nanosecond, which is used to collect the output laser pulse waveform and pulse sequence.

[0042] The computer control system 18 can collect signals collected by the photodetector, control the output power of the pump source and the repetition frequency of the chopper, and control the operation of the vacuum pumping and gas filling system 9 to control the gas pressure in the hollow core optical fiber 10 .

[0043] In one embodiment, the pump coupling optical unit includes a pump beam expander lens 2, a first high reflective mirror 3, a second high reflective mirror 4 and a coupling lens 6, and the input coupling mirror 5 is arranged between the second high reflective mirror 4 and the coupling lens 6. The pump beam expander lens 2 expands the pump laser into parallel light; the first high reflective mirror 3 and the second high reflective mirror 4 realize the optical path collimation of the pump laser and change the optical path direction; the coupling lens 6 realizes the mode matching of the pump laser and the core of the hollow core fiber, and efficiently couples the pump laser into the core of the hollow core fiber 10. The pump laser generated by the pump source 1 is expanded by the pump beam expander lens 2, and the optical path is collimated by the first high reflective mirror 3 and the second high reflective mirror 4. The collimated pump laser passes through the input coupling lens 5 and is then focused by the coupling lens 6 to realize the mode matching of the pump laser and the core of the hollow core fiber. The input coupling mirror 5 has high transmittance to the pump light band and high reflectivity to the output laser band.

[0044] In one embodiment, the sealed cavity includes an input sealed cavity 8 and an output sealed cavity 11, and the input sealed cavity 8 and the output sealed cavity 11 are respectively located at the two ends of the hollow core optical fiber 10, and are used to seal the gain gas in the hollow core optical fiber 10. In this embodiment, the input sealed cavity 8 is connected to a vacuum pumping and inflation system 9, and the vacuum pumping and inflation system 9 evacuates the hollow core optical fiber 10 through the input sealed cavity 8, and then fills the hollow core optical fiber 10 with gain gas of appropriate air pressure.

[0045] The input sealed cavity 8 includes an input window plate 7, through which the pump laser is coupled to the core of the hollow core optical fiber 10, and the output sealed cavity 11 includes an output window plate 12, through which the laser emitted from the output end of the hollow core optical fiber 10 is output. The input window plate 7 has high transmittance to the pump light band and the output laser band; the output window plate 12 has high transmittance to the output laser band. The hollow core optical fiber 10 has low transmission loss for the lasers in the pump laser band and the output laser band.

[0046] The input coupling mirror 5, coupling lens 6, input window 7, hollow core fiber 10, output window 12, laser beam expander 13 and output coupling mirror 15 form a resonant cavity structure. The laser emitted from the input end of the hollow core fiber 10 passes through the input window 7 and is expanded by the coupling lens 6; further, the laser beam expanded by the coupling lens 6 is incident on the input coupling mirror 5 and is reflected by the original path, and the reflected laser beam is focused by the coupling lens 6 and coupled to the core of the hollow core fiber 10 again through the input window 7. The laser beam emitted from the output end of the hollow core fiber 10 passes through the output window 12 and is expanded by the laser beam expander 13. After the expanded laser beam is incident on the output coupling mirror 15, part of the laser beam passes through the output coupling mirror 15 and becomes the final output laser beam, and the other part of the laser beam is reflected by the original path, and the laser beam reflected by the original path is focused by the laser beam expander 13 and coupled to the core of the hollow core fiber 10 again through the output window 12. The chopper 14 is placed between the laser beam expander 13 and the output coupling mirror 15. The Q value of the resonant cavity is adjusted by the rapid rotation of the chopper to finally achieve pulse output. The output coupling mirror 15 is a plane mirror, which is partially transparent to the output laser band. The above embodiment adopts an oscillator structure and uses the chopper as an active Q-switching device to obtain pulse output by adjusting the Q value of the resonant cavity. The above embodiment can obtain pulse output without a pulse pump source, which reduces the cost of the system. The Q-switching technology used is not affected by the output wavelength, is available in the entire band, and has a wider applicability.

[0047] The output pulse laser is divided into two beams after passing through the beam splitter 16 coated with a high reflective film, wherein the transmitted light is incident on the photodetector 17, and the reflected light is used as the final output laser after reflection. The pulse signal collected by the photodetector 17 is transmitted to the computer control system 18. The computer control system 18 controls the pump source 1, the vacuum and gas filling system 9, and the chopper 14 according to the collected pulse waveform and pulse sequence information.

[0048] In one embodiment, referring to Figure 2 The computer control system 18 collects the electrical signal output by the photodetector 17, controls the pump source 1, the vacuum pumping and gas charging system 9, and the chopper 14, and the control process includes:

[0049] (1) Initialization: the initial pump power of the pump source is 10% of its maximum output power, the chopper repetition frequency should be no less than 1 MHz; the gas pressure in the hollow-core optical fiber should not be higher than 0.1 mbar;

[0050] (2) Determine whether the pump power of the current pump source can be increased. If the pump power of the current pump source has reached the maximum value, that is, it cannot be increased, go to step (10); if the pump power of the current pump source can be increased, go to step (3);

[0051] (3) Controlling the pump source to increase the pump power with a set pump power increase step size;

[0052] (4) Based on the electrical signal output by the photodetector, obtain the pulse sequence of the currently output pulse laser, calculate the repetition frequency of the pulses in the pulse sequence whose intensity is higher than the set intensity value; perform root mean square calculation on the peak-to-peak value change of the pulses in the pulse sequence whose intensity is higher than the set intensity value, where the number of single pulses contained in the pulse sequence should not be less than 10;

[0053] (5) Based on the calculated RMS value, determine whether the pulse sequence is stable. If the pulse repetition frequency is equal to the first set value (for example, the first set value is set to 1 MHz, then the pulse repetition frequency corresponding to the output pulse laser should be 1 MHz. If it does not meet the requirements, the pulse sequence is determined to be unstable. It should be noted that the first set value is set according to the actual situation and is not limited to 1 MHz) and the RMS value is less than the second set value (the second set value is set according to the actual situation. As an example, the second set value is set to 3%), then the pulse sequence is determined to be stable, and the process goes to step (6). If the pulse repetition frequency is not equal to the first set value or the RMS value is greater than or equal to the second set value, then the pulse sequence is determined to be unstable, and the speed of the chopper is reduced to reduce the repetition frequency by the set step size, and the process goes to step (4).

[0054] (6) Based on the electrical signal output by the photodetector, the pulse waveform of the currently output pulsed laser is obtained;

[0055] (7) Determine whether there is a tail pulse based on the pulse waveform. If there is no extra pulse between two adjacent main pulses whose pulse repetition frequency is equal to the first set value, it indicates that there is no tail pulse, and go to step (8); if there is an extra pulse between two adjacent main pulses whose pulse repetition frequency is equal to the first set value, it indicates that there is a tail pulse, and control the vacuum pumping and gas filling system to operate, control the vacuum pumping and gas filling system to operate, so that the air pressure in the hollow core optical fiber is increased by a set air pressure step (the specific air pressure step is set according to the actual situation, such as 0.05 mbar), and go to step (6);

[0056] (8) Based on the electrical signal output by the photodetector, obtain the pulse sequence of the currently output pulse laser, calculate the repetition frequency of the pulses in the pulse sequence whose intensity is higher than the set intensity value; perform root mean square calculation on the peak-to-peak value change of the pulses in the pulse sequence whose intensity is higher than the set intensity value, wherein the number of single pulses contained in the pulse sequence should not be less than 10, and go to step (9);

[0057] (9) judging whether the pulse sequence is stable based on the calculated RMS value; if the pulse repetition frequency is equal to the first set value and the RMS value is less than the second set value, the pulse sequence is judged to be stable, and the process goes to step (2); if the pulse repetition frequency is not equal to the first set value or the RMS value is greater than or equal to the second set value, the pulse sequence is judged to be unstable, and the speed of the chopper is reduced to reduce the repetition frequency by a set step (the specific set step is set according to the actual situation, such as reducing the repetition frequency by 0.1 kHz), and the process goes to step (4);

[0058] (10) End.

[0059] Wherein, based on the electrical signal output by the photodetector, a pulse sequence of the currently output pulsed laser is obtained, wherein the number of single pulses contained in the pulse sequence should not be less than 10.

[0060] In the process of judging whether the pulse sequence is stable based on the calculated RMS value, the set value can be determined according to the actual situation. In one embodiment, judging whether the pulse sequence is stable based on the calculated RMS value, if the RMS value is less than 3%, the pulse sequence is judged to be stable, and if the RMS value is greater than or equal to 3%, the pulse sequence is judged to be unstable.

[0061] Reference Figure 3 and Figure 4 , Figure 3 This is a schematic diagram of a stable pulse sequence detected by a photodetector in an embodiment; the repetition frequency of the pulses in the pulse sequence whose intensity is higher than the set intensity value (set to 0.2) is calculated. After calculation, the repetition frequency of the pulse sequence is 1MHz, which meets the first set value of 1 MHz, and the peak-to-peak value change root mean square is 1%, which is less than the second set value of 3%, indicating that the pulse sequence is a stable pulse sequence. Figure 3 The small pulse in the dotted line of the middle circle is the tail pulse. The intensity value is set to eliminate the interference of the tail pulse when judging the repetition frequency of the pulse sequence. Figure 4 It is a schematic diagram of an unstable pulse sequence detected by a photodetector in one embodiment. The repetition frequency of the pulses in the pulse sequence whose intensity is higher than the set intensity value (set to 0.2) is calculated. After calculation, the repetition frequency of the pulse sequence is 3 MHz, which does not meet the first set value of 1 MHz, and the peak-to-peak value change root mean square is 17%, which is greater than the second set value of 3%, indicating that the pulse sequence is an unstable pulse sequence.

[0062] The present invention uses a computer control system to control the pump source, vacuum and gas filling system, and chopper according to the collected pulse waveform and pulse sequence information. Under different pump powers, different hollow-core fiber parameters, and different gain gas / gas pressure conditions, the control method provided by the above embodiment of the present invention can achieve pulse laser output with stable pulse sequence and ideal pulse waveform.

[0063] Fiber gas lasers have the characteristic of flexible output wavelength. In combination with this characteristic, the present invention proposes a pulse laser acquisition scheme applicable to all bands. The gain gas described in the above embodiments of the present invention includes but is not limited to CO, CO2, HBr, C2H2, H2 and other gases. The chopper should have different duty cycles and rotation frequencies, and the operating frequency and duty cycle of the laser can be adjusted by controlling the duty cycle and rotation frequency of the chopper. The present invention uses a chopper to achieve active Q-switching, which is a mechanical Q-switching scheme. It can also be replaced with other devices to achieve mechanical Q-switching (such as a galvanometer). The active Q-switching technology can flexibly adjust the frequency and duty cycle, thereby achieving flexible adjustment of the repetition frequency and pulse width of the pulsed laser.

[0064] Matters not covered by the present invention are known technologies.

[0065] 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.

[0066] 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.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pulsed fiber gas laser, characterized in that: It includes a pump source, a pump coupling optical unit, an input coupling mirror, a sealed cavity, a hollow core optical fiber, a chopper, an output coupling mirror, a spectroscope, a photodetector and a computer control system; The pump source is a continuous laser light source, which outputs pump laser of required power under the control of a computer control system; The pump coupling optical unit is used to couple the pump laser into the core of the hollow core optical fiber; The input coupling mirror is a coupling mirror located at the pump end of the fiber gas laser, and serves as an end face feedback mirror of the laser in the resonant cavity; The sealed cavity comprises an input sealed cavity and an output sealed cavity, the input sealed cavity and the output sealed cavity are respectively located at two ends of the hollow core optical fiber, and are used to seal the gain gas in the hollow core optical fiber; at least one of the input sealed cavity and the output sealed cavity is connected to a vacuum pumping and gas filling system, the vacuum pumping and gas filling system is connected to a computer control system, and the sealed cavity is vacuumed or gas filled under the control of the computer control system, thereby controlling the pressure of the gain gas in the hollow core optical fiber; The hollow core optical fiber confines the pump laser in the fiber core, providing an effective interaction distance between the pump laser and the gain gas; The chopper is an active Q-switching device, which is arranged in front of the output coupling mirror. The chopper is connected to a computer control system, and the computer control system adjusts the repetition frequency and pulse width of the output pulse laser by controlling the duty cycle and rotation frequency of the chopper. The output coupling mirror is a coupling mirror located at the output end of the fiber gas laser, and serves as an end face feedback mirror of the laser in the resonant cavity; The beam splitter is a beam splitter device for outputting pulsed lasers, and is arranged behind the output coupling mirror. A very small portion of the output pulsed laser is transmitted through the beam splitter for subsequent photoelectric detection, and the remaining majority of the pulsed laser is reflected by the beam splitter and output as laser. The photoelectric detector is a detection device that outputs pulsed lasers and is arranged on the transmission light path of the spectroscope to detect the pulsed laser information transmitted through the spectroscope and convert the detected optical signal into an electrical signal for transmission to the computer control system; The computer control system collects the electrical signal output by the photodetector and controls the pump source, the vacuum pumping and gas filling system, and the chopper, including: generating control signals for the pump source, the vacuum pumping and gas filling system, and the chopper, controlling the output power of the pump source, controlling the gas pressure in the hollow-core optical fiber, and controlling the repetition frequency and pulse width of the output pulse laser to achieve a pulse laser output with a stable pulse sequence and an ideal pulse waveform.

2. The pulsed output fiber gas laser according to claim 1, characterized in that: The pump source is a tunable, narrow-linewidth continuous laser light source, and the output wavelength of the pump source corresponds to the absorption peak of the gain gas used.

3. The pulsed output fiber gas laser according to claim 2, characterized in that: The pump coupling optical unit comprises a pump beam expander lens, a first high-reflection mirror, a second high-reflection mirror, and a coupling lens; the pump beam expander lens expands the pump laser into parallel light; the first high-reflection mirror and the second high-reflection mirror realize the optical path collimation of the pump laser and change the direction of the optical path; the coupling lens realizes the mode matching of the pump laser and the core of the hollow-core optical fiber, and efficiently couples the pump laser into the core of the hollow-core optical fiber.

4. The pulsed-output fiber gas laser according to claim 3, characterized in that: After the pump beam expander lens expands the beam, the pump laser after the optical path is collimated by the first high-reflection mirror and the second high-reflection mirror passes through the input coupling lens and is focused by the coupling lens to achieve mode matching between the pump laser and the core of the hollow-core optical fiber.

5. The pulsed output fiber gas laser according to claim 1, 2, 3 or 4, characterized in that: The input sealed cavity includes an input window plate, and the pump laser is coupled into the core of the hollow core optical fiber through the input window plate. The output sealed cavity includes an output window plate, and the laser emitted from the output end of the hollow core optical fiber is output through the output window plate.

6. The pulsed-output fiber gas laser according to claim 5, characterized in that: The input window has high transmittance to the pump laser band and the output laser band, and the output window has high transmittance to the output laser band.

7. The pulsed-output fiber gas laser according to claim 1 or 2 or 3 or 4 or 6, characterized in that: The vacuuming and filling system includes a vacuum pump, a gas cylinder, a pressure regulating valve, and a barometer, which are used to vacuum the hollow core optical fiber through a sealed cavity and then fill it with gain gas of appropriate pressure, and can realize pressure regulation and monitoring of the gain gas in the hollow core optical fiber.

8. The pulsed-output fiber gas laser according to claim 7, characterized in that: The gain gas is CO, CO2, HBr, C2H2 or H2.

9. The pulsed-output fiber gas laser according to claim 8, characterized in that: The detection band of the photodetector should match the emission spectrum of the gain gas used, and the rising edge time of the photodetector should not be greater than 1 nanosecond, which is used to collect the output laser pulse waveform and pulse sequence.

10. The pulsed-output fiber gas laser according to claim 7 or 8, characterized in that: The computer control system controls the pump source, vacuum pumping and inflation system, and chopper, including: (1) Initialization: the initial pump power of the pump source is 10% of its maximum output power, the chopper repetition frequency should be no less than 1 MHz; the gas pressure in the hollow-core optical fiber should not be higher than 0.1 mbar; (2) Determine whether the pump power of the current pump source can be increased. If the pump power of the current pump source has reached the maximum value, that is, it cannot be increased, go to step (10); if the pump power of the current pump source can be increased, go to step (3); (3) Controlling the pump source to increase the pump power with a set pump power increase step size; (4) Based on the electrical signal output by the photodetector, the pulse sequence of the currently output pulse laser is obtained, and the repetition frequency of the pulses in the pulse sequence whose intensity is higher than the set intensity value is calculated; the root mean square calculation of the peak-to-peak value change of the pulses in the pulse sequence whose intensity is higher than the set intensity value is performed; (5) Determine whether the pulse sequence is stable based on the calculated RMS value. If the pulse repetition frequency is equal to the first set value and the RMS value is less than the second set value, the pulse sequence is determined to be stable, and the process goes to step (6); if the pulse repetition frequency is not equal to the first set value or the RMS value is greater than or equal to the second set value, the pulse sequence is determined to be unstable, and the speed of the chopper is reduced to reduce the repetition frequency by a set step, and the process goes to step (4); (6) Based on the electrical signal output by the photodetector, the pulse waveform of the currently output pulsed laser is obtained; (7) Determine whether there is a tail pulse based on the pulse waveform. If there is no extra pulse between two adjacent main pulses whose pulse repetition frequency is equal to the first set value, it indicates that there is no tail pulse, and go to step (8); if there is an extra pulse between two adjacent main pulses whose pulse repetition frequency is equal to the first set value, it indicates that there is a tail pulse, and control the vacuum pumping and gas filling system to operate, control the vacuum pumping and gas filling system to operate, so that the air pressure in the hollow core optical fiber is increased by the set air pressure step length, and go to step (6); (8) Based on the electrical signal output by the photodetector, the pulse sequence of the currently output pulse laser is obtained, and the repetition frequency of the pulses in the pulse sequence whose intensity is higher than the set intensity value is calculated; the peak-to-peak value change of the pulses in the pulse sequence whose intensity is higher than the set intensity value is calculated by the root mean square, and then the process goes to step (9); (9) judging whether the pulse sequence is stable based on the calculated RMS value; if the pulse repetition frequency is equal to the first set value and the RMS value is less than the second set value, the pulse sequence is judged to be stable, and the process goes to step (2); if the pulse repetition frequency is not equal to the first set value or the RMS value is greater than or equal to the second set value, the pulse sequence is judged to be unstable, and the speed of the chopper is reduced so that the repetition frequency is reduced by a set step, and the process goes to step (4); (10) End.

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