High-power fiber laser capable of inhibiting unstable effect of space radiation mode

Abstract

The invention relates to a high-power fiber laser capable of inhibiting an unstable effect of a space radiation mode. Comprising a seed source, an amplification stage pumping source, a forward beam combiner, a gain fiber, a reverse beam combiner composed of a beam combining area and a tail fiber, a cladding light stripper, a collimation output system, a temperature monitoring module located in the beam combining area of the reverse beam combiner, a leakage light power detection module located in a tail fiber of a pumping arm of the reverse beam combiner, and a near-infrared photoelectric probe. A time domain / frequency domain analysis module, a spatial radiation mode instability effect identification module and an optical fiber laser electric control module; the laser provided by the invention can be used for efficiently inhibiting the unstable effect of the radiation-induced mode, can fill the blank in the related fields of a high-power optical fiber laser for space for effectively inhibiting the unstable effect of the radiation-induced mode, and provides a powerful guarantee for executing a space task.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and demonstrates a high-power fiber laser for space use that can effectively suppress radiation-induced mode instability effects. The invention can effectively suppress radiation-induced mode instability effects caused by space radiation, and can fill the gap in the related field of high-power fiber lasers for space use that are highly stable and have a long lifespan. Background Art

[0002] High-power fiber lasers have the advantages of good beam quality, high conversion efficiency, compact structure, and convenient thermal management. They have important application value in both civilian and military fields. Fiber lasers have a mode instability effect. When the laser power exceeds the mode instability threshold, the laser will experience drastic fluctuations in output power and degradation of the laser mode, which seriously affects the output performance of the laser and the safety of the device. When a high-power fiber laser works in an irradiated environment, the irradiation loss causes the mode instability threshold of the laser to drop, which is the radiation-induced mode instability effect.

[0003] When the radiation-induced mode instability effect occurs, the fundamental mode and high-order mode components of the laser are periodically coupled, causing the high-order mode power to increase rapidly and be filtered out by the cladding light stripper, resulting in violent fluctuations and a sharp drop in the fundamental mode power, which ultimately causes the thermal load of the laser to increase rapidly and even cause a risk of burning. Therefore, it is very important and urgent to accurately judge the radiation-induced mode instability effect of the fiber laser in order to limit the pump light power in time and prevent further increase in the thermal load of the laser. At present, the research work on the radiation-induced mode instability effect of high-power fiber lasers for space applications has not been published publicly, and the present invention can fill the gap in this field.

[0004] The present invention has carried out the following innovative optimizations: comprehensive judgment is made from multiple aspects such as the temperature of the reverse beam combining area, the leakage light power, and the laser time domain / frequency domain characteristic signals, so as to accurately identify the radiation-induced mode instability effect; based on the degree of the radiation-induced mode instability effect of the current fiber laser, the pump current of the laser is feedback-regulated, which, on the one hand, protects the safety of the fiber laser device, and on the other hand, suppresses the radiation-induced mode instability effect through light / thermal bleaching; the present invention is based on modular design, which is convenient for system debugging and maintenance. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a high-power fiber laser that can suppress the radiation-induced mode instability effect in space, which can efficiently suppress the radiation-induced mode instability effect, fill the gap in the related field of high-power fiber lasers for space use that effectively suppress the radiation-induced mode instability effect, and provide strong guarantee for the execution of space missions.

[0006] The technical solution of the present invention is: a high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects, comprising a seed source, an amplifier-stage pump source, a forward beam combiner, a gain fiber, a reverse beam combiner consisting of a beam combining region and a pigtail, a cladding light stripper, a collimation output system, a temperature monitoring module located in the beam combining region of the reverse beam combiner, a leakage optical power detection module located in the pigtail of the pump arm of the reverse beam combiner, a near-infrared photoelectric probe, a time domain / frequency domain analysis module, a spatial radiation-induced mode instability effect identification module, and a fiber laser electrical control module;

[0007] The seed light emitted by the seed source and the pump light emitted by the pump source are combined by the forward combiner and injected into the gain fiber to realize laser amplification. The amplified laser passes through the reverse combiner, the cladding light stripper and the collimated output system in sequence, and finally outputs the collimated laser. The pump arm pigtail of the reverse combiner is used to monitor the leakage optical power, and the cladding light stripper is used to strip the cladding light in the output laser. The temperature monitoring module is used to monitor the temperature of the combining area of ​​the reverse combiner. The optical power detection module is used to monitor the leakage of the pump arm pigtail of the reverse combiner. The near-infrared photoelectric probe is installed on the collimated output system to convert the scattered light signal of the collimated laser into an electrical signal; the time domain / frequency domain analysis module receives the electrical signal output by the near-infrared photoelectric probe, parses the time domain / frequency domain characteristic signal of the collimated laser and sends it to the identification module; the identification module determines whether the laser has a radiation-induced mode instability effect based on the received time domain / frequency domain characteristic signal, and outputs a locking pump signal when it occurs; the optical fiber laser electrical control module is used to control the power and power supply timing of the seed source and the amplifier stage pump source.

[0008] The radiation-induced mode instability effects include:

[0009] The temperature of the beam combining area of ​​the reverse beam combiner rises by 10°C within 10s;

[0010] The optical power leakage from the pump arm pigtail increases by 75W within 10s;

[0011] The collimated laser produces repetitive pulses on the millisecond scale in the time domain;

[0012] In the frequency domain, an envelope peak appears on the kilohertz scale;

[0013] When the above four situations occur simultaneously, the identification module determines that the laser has experienced radiation-induced mode instability effect, and then outputs a locking pump signal.

[0014] The central wavelength of the seed source output light is between 1030nm and 1100nm, and the seed light power is adjustable.

[0015] The pump wavelength of the amplifying stage pump source is 915±10nm or 976±10nm, and it is cascaded by multiple laser diodes, and its total pump power is adjustable.

[0016] The temperature monitoring module is used to monitor the temperature of the combining area of ​​the reverse combiner. The monitoring temperature range covers 0 to 90°C. The triggering and clearing alarm conditions are adjustable. The conditions are as follows: when the temperature rises by 10°C within 10s, the temperature alarm signal is triggered. When the temperature drops to a stable value, that is, the change rate is less than 2% within 15 minutes, the temperature alarm signal is cleared.

[0017] The optical power detection module is used to monitor the leakage optical power of the reverse combiner pump arm. The monitoring power range is greater than 600W@1030nm~1100nm. The triggering and clearing alarm conditions are adjustable. The conditions are as follows: when the leakage optical power rises by 75W within 10s, the power alarm signal is triggered. When the leakage optical power drops to a stable value, that is, the change rate is less than 1.5% within 15 minutes, the power alarm signal is cleared.

[0018] The time domain / frequency domain analysis module is used to analyze the time / frequency domain characteristics of the laser electrical signal. The triggering and releasing alarm conditions are adjustable, and the conditions are as follows: when a repetitive pulse on the millisecond scale appears in the time domain and an envelope peak on the kilohertz scale appears in the frequency domain, the time / frequency domain alarm signal is triggered; when the above characteristic signals disappear, the time / frequency domain alarm signal is released.

[0019] The identification module is used to accurately determine whether the radiation-induced mode instability effect occurs. When the temperature monitoring module, the leakage optical power detection module, and the time domain / frequency domain analysis module trigger the alarm signal at the same time, it is determined that the laser has experienced radiation-induced mode instability at this time, and a pump current locking instruction is immediately issued; when the temperature monitoring module, the leakage optical power detection module, and the time domain / frequency domain analysis module all release the alarm signal, it is determined that the radiation-induced mode instability effect of the laser has been effectively suppressed, and a pump current unlocking instruction is immediately issued.

[0020] The near-infrared photoelectric probe is installed on the collimated output system, used to collect the scattered light of the collimated laser and convert the scattered light signal into an electrical signal. The detection rate is not less than 100M / s and the bandwidth is not less than 100MHz.

[0021] The electronic control module is used to control the power supply timing and power supply current of the laser seed source and pump source. When the electronic control module receives the pump current lock instruction issued by the identification module, the pump current is not allowed to continue to increase, which is used to protect the laser module; when the pump current unlock instruction is received, the pump current is allowed to continue to increase, which can improve the output power of the laser.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention can accurately determine the radiation-induced mode instability effect of the optical fiber laser. Through experimental research, after the radiation-induced mode instability effect occurs in the optical fiber laser, the temperature of the reverse beam combining area rises rapidly, the leakage light power of the reverse beam combiner pump arm increases rapidly, and the laser time domain / frequency domain characteristic signal is obvious; with long-term light output, based on the combined effect of photobleaching / thermal bleaching, the radiation-induced loss in the laser gradually decreases, accompanied by the effective suppression of the radiation-induced mode instability effect, and finally the temperature fluctuation of the reverse beam combining area drops to a stable value, the leakage light power fluctuation drops to a stable value, and the time domain / frequency domain characteristic signal disappears. The present invention combines three aspects of characteristic signals and can accurately determine whether the current optical fiber laser has experienced the radiation-induced mode instability effect.

[0024] (2) The optical path structure of the present invention is simple and easy to implement, which effectively solves the problem of radiation-induced mode instability faced by space high-power fiber lasers.

[0025] (3) The present invention is based on modular design. The fiber laser module adopts a mature optical path structure. The monitoring module, identification module, and electronic control module all adopt mature modules, which are easy to test and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects provided by the present invention;

[0027] Figure 2 This is a schematic diagram of the changes in laser power, leakage light power, and temperature in the reverse beam combining area with the opening time after radiation-induced mode instability occurs. DETAILED DESCRIPTION

[0028] The present invention discloses a high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects, comprising a seed source 101, an amplifier-stage pump source 102, a forward beam combiner 103, a gain fiber 104, a reverse beam combiner 105 consisting of a beam combining region and a pigtail, a cladding light stripper 106, a collimation output system 107, a temperature monitoring module 108 located in the beam combining region of the reverse beam combiner 105, a leakage optical power detection module 109 located in the pigtail of the pump arm of the reverse beam combiner 105, a near-infrared photoelectric probe 110, a time domain / frequency domain analysis module 111, a spatial radiation-induced mode instability effect identification module 112, and a fiber laser electrical control module 113;

[0029] The seed light emitted by the seed source 101 and the pump light emitted by the pump source 102 are combined by the forward combiner 103 and injected into the gain fiber 104 to realize laser amplification. The amplified laser passes through the reverse combiner 105, the cladding light stripper 106 and the collimated output system 107 in sequence, and finally outputs the collimated laser. The pump arm pigtail of the reverse combiner 105 is used to monitor the leakage light power, and the cladding light stripper 106 is used to strip the cladding light in the output laser. The temperature monitoring module 108 is used to monitor the temperature of the combining area of ​​the reverse combiner 105. The optical power detection module 109 is used to monitor the pump arm of the reverse combiner 105. The leakage light power of the pigtail of the arm; the near-infrared photoelectric probe 110 is installed on the collimation output system 107, and is used to convert the scattered light signal of the collimated laser into an electrical signal; the time domain / frequency domain analysis module 111 receives the electrical signal output by the near-infrared photoelectric probe 110, parses the time domain / frequency domain characteristic signal of the collimated laser and sends it to the identification module 112; the identification module 112 determines whether the laser has a radiation-induced mode instability effect based on the received time domain / frequency domain characteristic signal, and outputs a locking pump signal when it occurs; the optical fiber laser electrical control module 113 is used to control the power and power supply timing of the seed source 101 and the amplifier stage pump source 102.

[0030] After the fiber laser operates at the current locked pump power for a period of time, due to the combined effects of photobleaching and thermal bleaching, the radiation-induced loss in the laser gradually decreases, and the radiation-induced mode instability threshold gradually increases. At the same time, the output power of the fiber laser rises to a stable value and changes at a rate of less than 1.5% within 15 minutes, the temperature in the reverse beam combining region drops to a stable value and changes at a rate of less than 2% within 15 minutes, the leakage light power drops to a stable value and changes at a rate of less than 1.5% within 15 minutes, the millisecond-scale repetitive pulses in the time domain disappear, and the kilohertz-scale envelope peak in the frequency domain disappears; the identification module 112 determines that the radiation-induced mode instability effect of the laser has been effectively suppressed, and at the same time, the pump source current is unlocked by the electronic control module 113.

[0031] The radiation-induced mode instability effects include:

[0032] The temperature of the beam combining area of ​​the reverse beam combiner 105 rises by 10°C within 10s;

[0033] The optical power leakage from the pump arm pigtail increases by 75W within 10s;

[0034] The collimated laser produces repetitive pulses on the millisecond scale in the time domain;

[0035] In the frequency domain, an envelope peak appears on the kilohertz scale;

[0036] When the above four situations occur simultaneously, the identification module 112 determines that the laser has experienced radiation-induced mode instability, and then outputs a locking pump signal.

[0037] The central wavelength of the output light of the seed source 101 is between 1030 nm and 1100 nm, and the seed light power is adjustable.

[0038] The pump wavelength of the amplifier stage pump source 102 is 915±10 nm or 976±10 nm, and it is composed of a plurality of laser diodes cascaded, and its total pump power is adjustable.

[0039] The temperature monitoring module 108 is used to monitor the temperature of the combining area of ​​the reverse combiner. The monitoring temperature range covers 0 to 90°C. The triggering and clearing alarm conditions are adjustable. The conditions are as follows: when the temperature rises by 10°C within 10s, the temperature alarm signal is triggered. When the temperature drops to a stable value, that is, the rate of change is less than 2% within 15 minutes, the temperature alarm signal is cleared.

[0040] The optical power detection module 109 is used to monitor the leakage optical power of the reverse combiner pump arm. The monitoring power range is greater than 600W@1030nm~1100nm. The triggering and clearing alarm conditions are adjustable. The conditions are as follows: when the leakage optical power rises by 75W within 10s, the power alarm signal is triggered. When the leakage optical power drops to a stable value, that is, the change rate is less than 1.5% within 15 minutes, the power alarm signal is cleared.

[0041] The time domain / frequency domain analysis module 111 is used to analyze the time / frequency domain characteristics of the laser electrical signal. The triggering and releasing alarm conditions are adjustable, and the conditions are as follows: when repetitive pulses on the millisecond scale appear in the time domain and envelope peaks on the kilohertz scale appear in the frequency domain, the time / frequency domain alarm signal is triggered; when the above characteristic signals disappear, the time / frequency domain alarm signal is released.

[0042] The identification module 112 is used to accurately determine whether the radiation-induced mode instability effect occurs. When the temperature monitoring module 108, the leakage light power detection module 109, and the time domain / frequency domain analysis module 111 trigger the alarm signal at the same time, it is determined that the laser has experienced the radiation-induced mode instability effect, and a pump current locking instruction is immediately issued; when the temperature monitoring module 108, the leakage light power detection module 109, and the time domain / frequency domain analysis module 111 all release the alarm signal, it is determined that the radiation-induced mode instability effect of the laser has been effectively suppressed, and a pump current unlocking instruction is immediately issued.

[0043] The near-infrared photoelectric probe 110 is installed on the collimated output system 107, and is used to collect the scattered light of the collimated laser and convert the scattered light signal into an electrical signal. The detection rate is not less than 100M / s, and the bandwidth is not less than 100MHz.

[0044] The electric control module 113 is used to control the power supply timing and power supply current of the laser seed source 101 and the pump source 102. When the electric control module 113 receives the pump current lock instruction issued by the identification module 112, the pump current is not allowed to continue to increase, which is used to protect the laser module; when the pump current unlock instruction is received, the pump current is allowed to continue to increase, which can improve the output power of the laser.

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following Figure 1 It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] Please refer to Figure 1 The high-power fiber laser module is responsible for outputting high-power laser. In the embodiment, ytterbium-doped fiber is used as the gain fiber, the core / package size is 20 / 400μm, the laser output power is about 2000W, the slope efficiency is about 80%, the laser center wavelength is 1064nm, and the mode instability threshold is about 2200W. The laser is affected by space irradiation, and radiation-induced loss occurs in the ytterbium-doped fiber, and the radiation-induced loss heat load reduces the threshold of the mode instability effect, causing the threshold to drop to 1000W. When the laser is pumped at a power of 1200W, the output laser power is 1000W before irradiation, but after irradiation, the laser exhibits a radiation-induced mode instability effect.

[0047] See also Figure 2 , after the radiation-induced mode instability occurs, the laser power, leakage light power, and temperature of the reverse beam combining area change with the opening time:

[0048] T1 is the first stage after the laser power exceeds the radiation-induced mode instability threshold. It is mainly manifested in that the output power drops rapidly and then recovers slightly, the leakage light power rises rapidly and then drops slightly, and the temperature in the reverse beam combining area rises rapidly. The typical output power drops by about 200W in 10s, the leakage light power increases by about 75W in 10s, and the temperature rises by about 10°C in 10s.

[0049] T2 is the second stage after the radiation-induced mode instability effect occurs. The laser power is relatively stable but still lower than the original value, the leakage light power is relatively stable, and the temperature in the reverse beam combining area rises slightly.

[0050] T3 is the third stage after the radiation-induced mode instability effect occurs. The laser power decreases again significantly and then gradually stabilizes, the leakage light power increases again significantly and then gradually stabilizes, and the temperature in the reverse beam combining area increases slowly.

[0051] T4 is the fourth stage after the radiation-induced mode instability effect occurs. The laser power increases and gradually stabilizes and is higher than the original value, the leakage light power decreases and gradually stabilizes (the rate of change within 15 minutes is less than 1.5%), and the temperature of the reverse beam combining area gradually decreases to a stable value (the rate of change within 15 minutes is less than 2.0%).

[0052] The T` stage is when the laser is exposed for a long time and the radiation-induced loss in the laser gradually decreases due to the combined effects of photobleaching and thermal bleaching. At this time, the radiation-induced mode instability effect is suppressed and the various parameters of the laser return to normal.

[0053] Specifically in this embodiment, the temperature monitoring module monitors that the temperature of the reverse beam combining area rises by 10°C within 10 seconds, the optical power detection module monitors that the leakage optical power of the pump arm of the reverse beam combiner increases by 75W within 10 seconds, and the near-infrared photoelectric sensor and the time domain / frequency domain analysis module monitor that the collimated laser has repeated pulses on the millisecond scale in the time domain and envelope peaks on the kilohertz scale in the frequency domain, and at the same time triggers the temperature alarm, leakage optical power alarm, and time / frequency domain alarm signal; the recognition module determines that the radiation-induced mode instability effect has occurred at this time. In order to protect the safety of the fiber laser, the electronic control The module executed the instruction to limit the pump power. At this time, the pump current value can be reduced but not allowed to continue to increase. After 2 hours of continuous light output, the temperature of the reverse beam combining area has dropped and gradually stabilized (the rate of change is less than 1.5% within 15 minutes), the leakage light power of the pump arm of the reverse beam combiner has dropped and gradually stabilized (the rate of change is less than 2.0% within 15 minutes), and the time / frequency domain characteristic signal of the collimated laser has disappeared. At this time, the radiation-induced mode instability effect of the laser has been effectively suppressed. The identification module makes a judgment, and the pump power limit is released by the electric control module. The pump current value can continue to increase. Affected by the radiation-induced loss, the output power of the laser is stabilized at 900W at this time, which is still lower than the 1000W before irradiation, but the radiation-induced mode instability effect has been effectively suppressed.

[0054] The test results of this embodiment show that the present invention can accurately judge whether the fiber laser has radiation-induced mode instability effect based on multiple characteristic signals and perform corresponding operations, further realizing effective suppression of radiation-induced mode instability effect on the basis of ensuring the safety of the fiber laser. The present invention has the advantages of accurate judgment, simple optical path, modular design, etc., and can fill the gap in the related field of high-power fiber lasers for space use that effectively suppress radiation-induced mode instability effect, and provide strong guarantee for the execution of space missions.

[0055] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects, characterized in that: The invention comprises a seed source (101), an amplifier-stage pump source (102), a forward beam combiner (103), a gain optical fiber (104), a reverse beam combiner (105) composed of a beam combining region and a pigtail, a cladding light stripper (106), a collimation output system (107), a temperature monitoring module (108) located in the beam combining region of the reverse beam combiner (105), a leakage optical power detection module (109) located in the pigtail of the pump arm of the reverse beam combiner (105), a near-infrared photoelectric probe (110), a time domain / frequency domain analysis module (111), a spatial radiation-induced mode instability effect identification module (112), and a fiber laser electrical control module (113); The seed light emitted by the seed source (101) and the pump light emitted by the pump source (102) are combined by the forward combiner (103) and injected into the gain optical fiber (104) to realize laser amplification. The amplified laser passes through the reverse combiner (105), the cladding light stripper (106) and the collimated output system (107) in sequence, and finally outputs collimated laser light. The pump arm pigtail of the reverse combiner (105) is used to monitor the leakage optical power, and the cladding light stripper (106) is used to strip the cladding light in the output laser. The temperature monitoring module (108) is used to monitor the temperature of the combining area of ​​the reverse combiner (105). The optical power detection module (109) is used to monitor the temperature of the reverse combiner (105). 05) the leakage light power of the pigtail of the pump arm; the near-infrared photoelectric probe (110) is installed on the collimated output system (107) and is used to convert the scattered light signal of the collimated laser into an electrical signal; the time domain / frequency domain analysis module (111) receives the electrical signal output by the near-infrared photoelectric probe (110), parses the time domain / frequency domain characteristic signal of the collimated laser and sends it to the identification module (112); the identification module (112) determines whether the laser has a radiation-induced mode instability effect based on the received time domain / frequency domain characteristic signal, and outputs a locking pump signal when it occurs; the optical fiber laser electrical control module (113) is used to control the power and power supply timing of the seed source (101) and the amplifier stage pump source (102).

2. A high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects according to claim 1, characterized in that: The radiation-induced mode instability effects include: The temperature of the beam combining area of ​​the reverse beam combiner (105) rises by 10°C within 10s; The optical power leakage from the pump arm pigtail increases by 75W within 10s; The collimated laser produces repetitive pulses on the millisecond scale in the time domain; In the frequency domain, an envelope peak appears on the kilohertz scale; When the above four situations occur simultaneously, the identification module (112) determines that the laser has experienced radiation-induced mode instability, and then outputs a locking pump signal.

3. A high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects according to claim 1, characterized in that: The central wavelength of the light output by the seed source (101) is between 1030nm and 1100nm, and the power of the seed light is adjustable.

4. A high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects according to claim 1, characterized in that: The pump wavelength of the amplification stage pump source (102) is 915±10 nm or 976±10 nm, and it is composed of a plurality of laser diodes cascaded, and its total pump power is adjustable.

5. The high-power fiber laser capable of suppressing spatial radiation-induced mode instability effect according to claim 1, characterized in that: The temperature monitoring module (108) is used to monitor the temperature of the beam combining area of ​​the reverse beam combiner. The monitoring temperature range covers 0 to 90° C. The triggering and releasing alarm conditions are adjustable. The conditions are as follows: when the temperature rises by 10° C. within 10 seconds, the temperature alarm signal is triggered. When the temperature drops to a stable value, that is, the rate of change within 15 minutes is less than 2%, the temperature alarm signal is released.

6. A high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects according to claim 1, characterized in that: The optical power detection module (109) is used to monitor the leakage optical power of the reverse beam combiner pump arm, the monitoring power range is greater than 600W@1030nm~1100nm, and the triggering and releasing alarm conditions are adjustable. The conditions are as follows: when the leakage optical power rises by 75W within 10s, the power alarm signal is triggered, and when the leakage optical power drops to a stable value, that is, the change rate within 15 minutes is less than 1.5%, the power alarm signal is released.

7. A high-power fiber laser capable of suppressing spatial radiation-induced mode instability effects according to claim 1, characterized in that: The time domain / frequency domain analysis module (111) is used to analyze the time / frequency domain characteristics of the laser electrical signal. The triggering and releasing alarm conditions are adjustable. The conditions are as follows: when a repetitive pulse on a millisecond scale appears in the time domain and an envelope peak on a kilohertz scale appears in the frequency domain, the time / frequency domain alarm signal is triggered; when the above characteristic signals disappear, the time / frequency domain alarm signal is released.

8. The high-power fiber laser capable of suppressing spatial radiation-induced mode instability effect according to claim 1, characterized in that: The identification module (112) is used to accurately determine whether a radiation-induced mode instability effect occurs. When the temperature monitoring module (108), the leakage light power detection module (109), and the time domain / frequency domain analysis module (111) trigger an alarm signal at the same time, it is determined that the laser has experienced a radiation-induced mode instability effect, and a pump current locking instruction is immediately issued. When the temperature monitoring module (108), the leakage light power detection module (109), and the time domain / frequency domain analysis module (111) all release the alarm signal, it is determined that the radiation-induced mode instability effect of the laser has been effectively suppressed, and a pump current unlocking instruction is immediately issued.

9. The high-power fiber laser capable of suppressing spatial radiation-induced mode instability effect according to claim 1, characterized in that: The near-infrared photoelectric probe (110) is installed on the collimated output system (107) and is used to collect scattered light of the collimated laser and convert the scattered light signal into an electrical signal. The detection rate is not less than 100 M / s and the bandwidth is not less than 100 MHz.

10. The high-power fiber laser capable of suppressing spatial radiation-induced mode instability effect according to claim 1, characterized in that: The electric control module (113) is used to control the power supply timing and power supply current of the laser seed source (101) and the pump source (102). When the electric control module (113) receives a pump current locking instruction issued by the identification module (112), the pump current is not allowed to continue to increase, so as to protect the laser module; when the pump current unlocking instruction is received, the pump current is allowed to continue to increase, so as to improve the output power of the laser.

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