High-sensitivity optical fiber irradiation monitoring device and method

Abstract

A high-sensitivity optical fiber irradiation monitoring device and method, comprising: first measuring the i The initial mode instability threshold P of the fiber laser oscillator in a non-irradiated environment before the first operation 1,i According to the i The irradiation environment corresponding to the first work is set according to the response requirements of the total irradiation dose. i The working power P of the fiber laser oscillator under the irradiation environment corresponding to the second work 2,i , P 2,i <P 1,i , working power P 2,i and the initial mode instability threshold P 1,i The closer the fiber laser oscillator is, the more sensitive it is to the total irradiation dose. i The present invention operates under the irradiation environment corresponding to the second operation, and monitors in real time whether the fiber laser oscillator has reached the mode instability threshold under the current irradiation environment. By monitoring whether the fiber oscillator has mode instability, the present invention can determine whether the fiber laser oscillator has reached a certain total irradiation dose under the current irradiation environment, with a highly sensitive monitoring effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear radiation monitoring, and more specifically, relates to a high-sensitivity optical fiber irradiation monitoring device and method. Background Art

[0002] In modern science and industry, highly sensitive fiber laser detectors have attracted significant attention due to their unique detection capabilities. Using optical fiber as a sensing medium, these detectors are capable of precisely measuring physical quantities such as temperature, pressure, strain, and radiation. Currently, fiber optic detectors are widely used in environmental monitoring, medical diagnostics, aerospace, and the nuclear industry.

[0003] Despite their numerous advantages, such as strong resistance to electromagnetic interference, compact size, light weight, and remote sensing capabilities, fiber optic detectors still face several challenges in practical application. First, the stability and reliability of existing fiber optic detectors in high-radiation or extreme environments need to be improved. Second, the sensitivity and resolution of these detectors have not yet met expectations in certain application scenarios, limiting their use in high-precision measurement applications.

[0004] With the continuous advancement of technology and the growing demand for applications, the development of fiber laser detectors with higher sensitivity, better stability, and stronger environmental adaptability has become increasingly important. This is especially true in critical areas such as nuclear energy monitoring, environmental safety, and medical imaging, which place even higher demands on detector performance. Therefore, the research and development of a new generation of high-sensitivity fiber laser detectors is crucial to meeting these demands.

[0005] The development of highly sensitive fiber laser detectors not only improves the performance of existing detection technologies but also opens up new applications. For example, in the nuclear industry, highly sensitive detectors can improve the accuracy of radiation monitoring and safeguard facility safety. In the medical field, high-resolution detectors enable more detailed imaging, thereby improving the accuracy of disease diagnosis. Furthermore, the research results of highly sensitive detectors can promote technological advancement in related fields and drive the development of the entire industry chain.

[0006] Currently, patent application publication number CN 112684485 B discloses a fiber irradiation monitoring device and method. This proposal mentions that multimode optical fibers, exposed to high-energy radiation, generate color centers. This generation of color centers causes a change in the fiber's refractive index and enhances Rayleigh scattering, leading to leakage of the signal laser light transmitted in the fiber core into the quartz cladding. This cladding light, when passing through a cladding light filter, is filtered out by the filter and then transferred to the metal encapsulation layer, causing the metal encapsulation layer to heat up. By monitoring the temperature rise and rate of the metal encapsulation layer using a temperature sensor and a temperature data processor, the total dose and dose rate of the radiation field can be calculated. Patent application publication number CN 107631796 B proposes a method for measuring the total dose and dose rate of an irradiated optical fiber by analyzing the spectral pattern and intensity changes before and after irradiation. Furthermore, a bleaching laser light source is used to bleach the irradiated optical fiber after irradiation, thereby increasing the service life of the irradiated optical fiber. However, these methods are not very sensitive to irradiation. Patent application publication number CN 112684485 B discloses a fiber optic irradiation monitoring device and method that uses temperature changes for indirect measurement, suitable for long-term monitoring. Patent application publication number CN107631796 B proposes a method for directly measuring spectral loss by analyzing spectral patterns and intensity changes before and after irradiation. However, due to large spectral measurement errors, measurement accuracy is also limited. Summary of the Invention

[0007] In response to the above defects or improvement needs of the prior art, the present invention provides a high-sensitivity optical fiber irradiation monitoring device and method.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0009] In one aspect, the present invention provides a high-sensitivity optical fiber irradiation monitoring method, comprising the following steps:

[0010] (1) Determine the i Mode instability threshold P of a fiber laser oscillator working in a non-irradiated environment 1,i ;

[0011] (2) Determine the i The irradiation environment corresponding to the next work, start the fiber laser oscillator in the current irradiation environment, and set the working power P of the fiber oscillator in the current irradiation environment to 2,i Set at less than P 1,i The output power of the fiber laser oscillator is continuously collected and recorded, and the output laser time domain characteristics are measured at the output end of the fiber laser oscillator using a high-performance oscilloscope. Based on the output laser time domain characteristics of the fiber laser oscillator under the current irradiation environment, it is determined whether the fiber laser oscillator has reached the mode instability threshold under the current irradiation environment;

[0012] (3) When the fiber laser oscillator reaches the mode instability threshold under the current irradiation environment and the mode instability threshold under the current irradiation environment is P 2,i , then the fiber laser oscillator is turned off, indicating that the fiber oscillator has been exposed to a certain total dose of radiation;

[0013] (4) According to δP i =P 1,i -P 2,i Determine the total radiation dose δP received by the fiber oscillator i The larger the i The greater the total radiation dose to which the fiber oscillator is subjected in the irradiation environment corresponding to the second work;

[0014] (5) Order i=i +1, repeat steps (1) to (4), the fiber laser oscillator performs the i +1 work, and monitor the total irradiation dose of the fiber laser oscillator in each work.

[0015] Furthermore, it also includes setting a threshold value of the number of operations N , when the fiber laser oscillator works N Afterwards, photobleaching or thermal bleaching is used to restore the loss of the fiber laser oscillator caused by irradiation to a certain extent, thereby extending the service life of the fiber laser oscillator.

[0016] Furthermore, the present invention provides an optical fiber irradiation monitoring device for use in the optical fiber irradiation monitoring method, comprising an optical fiber laser oscillator, a detection laser light source, a laser receiving device, a power measuring device, and a power measuring device, wherein the output end of the optical fiber laser oscillator is provided with a laser receiving device, and laser information output by the optical fiber laser oscillator is measured by the power measuring device and the power measuring device after passing through the laser receiving device;

[0017] The detection laser light source is a visible light semiconductor laser, which is used to detect whether the fiber laser is transmitting light and to correct the optical path between the laser output system and the test system. The detection laser light source is injected into the fiber laser oscillator from the other end of the fiber laser oscillator away from the output end of the fiber laser oscillator.

[0018] In the present invention, the type of the fiber laser oscillator is not limited, and can be a forward pumping structure, a backward pumping structure, or a bidirectional pumping structure.

[0019] The present invention is based on the fact that the threshold value of the mode instability effect in a fiber oscillator is sensitive to irradiation. Therefore, the threshold value of the mode instability effect can be used as a judgment basis for fiber irradiation monitoring. Compared with the existing technology, the above technical solution conceived by the present invention can achieve the following beneficial effects:

[0020] The present invention first measures the i The initial mode instability threshold P of the fiber laser oscillator in a non-irradiated environment before the first operation 1,i ; Then according to i The irradiation environment corresponding to the first work is set according to the response requirements of the total irradiation dose. i The working power P of the fiber laser oscillator under the irradiation environment corresponding to the second work 2,i , P 2,i <P 1,i , working power P 2,i and the initial mode instability threshold P 1,i The closer the fiber laser oscillator is, the more sensitive it is to the total irradiation dose. i The present invention utilizes the principle that the mode instability threshold of a fiber laser oscillator is extremely sensitive to irradiation to monitor the total irradiation dose. This method achieves highly sensitive monitoring, and can further enhance sensitivity by increasing the length of the gain fiber or using a gain fiber with a larger absorption coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0022] Figure 1 A schematic structural diagram of the optical fiber irradiation monitoring device provided in Example 1;

[0023] Figure 2 This is a schematic diagram of the structure of Example 1 applied to gamma ray irradiation;

[0024] Figure 3 A schematic structural diagram of the optical fiber irradiation monitoring device provided in Example 2;

[0025] Figure 4 A schematic structural diagram of the optical fiber irradiation monitoring device provided in Example 3;

[0026] Figure 5 1 is a diagram of output power and time domain information measured by an optical fiber irradiation monitoring device during irradiation in one embodiment;

[0027] Figure annotation:

[0028] 1. Detection laser source; 2. Forward pump combiner; 3. Fiber-coupled semiconductor laser; 4. High-reflectivity fiber Bragg grating (FBG); 5. Gain fiber; 6. Low-reflectivity fiber Bragg grating (FBG); 7. Cladding filter; 8. Fiber output end; 9. Laser receiving device; 10. Power measurement device; 11. Power measurement device; 12. γ-ray irradiation field; 13. Backward pump combiner. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] In one embodiment, a high-sensitivity optical fiber irradiation monitoring method is provided, comprising the following steps:

[0031] (1) Determine the i Mode instability threshold P of a fiber laser oscillator working in a non-irradiated environment 1,i ;

[0032] (2) Determine the i The irradiation environment corresponding to the next work, start the fiber laser oscillator in the current irradiation environment, and set the working power P of the fiber oscillator in the current irradiation environment to 2,i Set at less than P 1,i The output power of the fiber laser oscillator is continuously collected and recorded, and the output laser time domain characteristics are measured at the output end of the fiber laser oscillator using a high-performance oscilloscope. Based on the output laser time domain characteristics of the fiber laser oscillator under the current irradiation environment, it is determined whether the fiber laser oscillator has reached the mode instability threshold under the current irradiation environment;

[0033] (3) When the fiber laser oscillator reaches the mode instability threshold under the current irradiation environment and the mode instability threshold under the current irradiation environment is P 2,i , then the fiber laser oscillator is turned off, indicating that the fiber oscillator has been exposed to a certain total dose of radiation;

[0034] (4) According to δ P i =P 1,i -P 2,i Determine the total radiation dose that the fiber oscillator receives. δ P i The larger the iThe greater the total radiation dose to which the fiber oscillator is subjected in the irradiation environment corresponding to the second work;

[0035] (5) Order i=i +1, repeat steps (1) to (4), the fiber laser oscillator performs the i +1 work, and monitor the total irradiation dose of the fiber laser oscillator in each work.

[0036] Since the mode instability effect in the fiber laser oscillator is very sensitive to loss, the mode instability threshold of the fiber laser oscillator is Total radiation dose D The relationship can be expressed as: ,in a It is a parameter related to the structure and material properties of the fiber laser oscillator. d is a parameter related to the quantum defect of the fiber laser oscillator. D is the total irradiation dose. At the same time, the irradiation sensitivity of the fiber laser oscillator can be adjusted by parameter design, such as increasing the gain fiber length in the fiber laser oscillator (changing the parameter a ), which is more sensitive to radiation, and this principle can be used to test the total radiation dose.

[0037] Determine the mode instability threshold of fiber laser oscillators under different irradiation environments Total radiation dose D Measure the mode instability threshold at least twice under different total irradiation doses D The existing mode instability threshold measurement method and irradiation total dose test equipment (such as Fluke 451B) are used to measure the total irradiation dose. In this way, the mode instability threshold of the fiber laser oscillator under different irradiation total doses D is measured. , based on two measurements and the mode instability threshold of the fiber laser oscillator Total radiation dose D The relationship , the parameters can be calculated a and d The value is completed a and d The calibration can be done conveniently to measure the total irradiation dose of the fiber laser oscillator in the irradiation environment.

[0038] Furthermore, in step (3), according to The current total radiation dose can be calculated, where Indicates the first i The total radiation dose that the fiber oscillator receives during this operation is: aIt is a parameter related to the structure and material properties of the fiber laser oscillator. d is a parameter related to the quantum defect of the fiber laser oscillator. a and d Obtained through calibration.

[0039] Furthermore, the present invention also includes setting a threshold value of the number of operations N , when the fiber laser oscillator works N After the irradiation, photobleaching or thermal bleaching is used to restore some of the fiber laser oscillator's wear caused by irradiation, thereby extending the life of the fiber laser oscillator. In the scheme of using photobleaching to restore some of the fiber laser oscillator's wear caused by irradiation, a 405nm or 455nm fiber-coupled semiconductor laser is preferably used as the bleaching light source, and the bleaching light source output power is greater than 20mW.

[0040] In one embodiment, a fiber irradiation monitoring device is provided, comprising a fiber laser oscillator, a detection laser light source 1, a laser receiving device 9, a power measuring device 10, and a power measuring device 11. The output end of the fiber laser oscillator is provided with a laser receiving device 9. The laser information output by the fiber laser oscillator passes through the laser receiving device 9 and is measured by the power measuring device 10 and the power measuring device 11.

[0041] The detection laser source 1 is a visible light semiconductor laser used to detect whether the fiber laser is transmitting light and to correct the optical path between the laser output system and the test system. The detection laser source 1 is injected into the fiber laser oscillator from the other end of the fiber laser oscillator, away from the output end of the fiber laser oscillator.

[0042] The type of the fiber laser oscillator is not limited, and can be a forward pumping structure, a backward pumping structure, or a bidirectional pumping structure.

[0043] The detection laser light source 1 is a visible light semiconductor laser with a central wavelength of 400nm-700nm.

[0044] Through the design of the fiber laser oscillator, it can be made to operate near the mode instability threshold. The detection laser light source is used to detect whether the fiber laser is passing light. In the entire fiber laser oscillator structure, only the gain fiber is sensitive to the total irradiation dose. By measuring the output laser time domain characteristics at the output end of the fiber laser oscillator, if mode instability occurs, it means that the gain fiber has experienced a certain total dose of irradiation. The present invention utilizes the mode instability effect of the fiber oscillator to perform loss detection, improves the sensitivity of fiber irradiation monitoring, and can achieve high-sensitivity monitoring of weak irradiation environments. The sensitivity of the total irradiation dose can be controlled by the working power P2 of the fiber laser. At the same time, the sensitivity can be further improved by increasing the length of the gain fiber, using a gain fiber with a larger absorption coefficient, and so on.

[0045] Reference Figure 1 , Figure 1 The schematic diagram of the structure of the optical fiber irradiation monitoring device provided in Example 1 includes a fiber laser oscillator, a detection laser light source 1, a laser receiving device 9, a power measuring device 10, and a power measuring device 11. The fiber laser oscillator is a forward pumping structure, including a forward pumping combiner 2, a fiber-coupled semiconductor laser 3, a high-reflectivity fiber Bragg grating 4, a gain fiber 5, a low-reflectivity fiber Bragg grating 6, a cladding filter 7, and an optical fiber output end 8. The output fiber of the detection laser light source 1 is connected to the signal arm of the forward pumping combiner 2. The output fibers of the plurality of fiber-coupled semiconductor lasers 3 are respectively connected to the pump arms of the forward pumping combiner 2. The combining end of the forward pumping combiner 2 is connected to the first end of the high-reflectivity fiber Bragg grating 4. The two ends of the gain fiber 5 are fused to the second end of the high-reflectivity fiber Bragg grating 4 and the first end of the low-reflectivity fiber Bragg grating 6, respectively. The two ends of the cladding filter 7 are respectively connected to the second end of the low-reflectivity fiber Bragg grating 6 and the optical fiber output end 8. The laser information outputted from the optical fiber output end 8 passes through the laser receiving device 9 and is measured by the power measuring device 10 and the power measuring device 11 .

[0046] The detection laser light source 1 is a semiconductor laser with a central wavelength of 633 nm, which is used to detect whether the optical fiber laser is transmitting light and to correct the optical path between the laser output system and the test system.

[0047] The forward pump combiner 2 is specifically (N+1) 1 forward pump combiner, 2≤N≤18, with N pump arms, one signal arm and one combiner end.

[0048] The fiber-coupled semiconductor laser 3 is the excitation source for the gain fiber 5 to generate upper-level particles. It includes semiconductor lasers of various wavelength bands that match the absorption peak of the gain fiber 5. The semiconductor lasers of various wavelength bands include a combination of one or more wavelength bands of 808 nanometers, 915 nanometers, 940 nanometers, 976 nanometers, and 1550 nanometers.

[0049] The gain fiber 5 is a gain fiber doped with rare earth ions (such as ytterbium) and is used for laser generation and transmission. The cross-sectional structure of the fiber is selected from double cladding, wherein the core diameter is in the range of 25 to 40 μm to obtain a suitable mode instability threshold; the inner cladding diameter is in the range of 125 to 600 μm.

[0050] The high-reflectivity fiber Bragg grating 4 is a high-reflectivity device of the laser resonant cavity in the fiber laser oscillator, and its reflectivity is greater than 90%. The reflection center wavelength matches the center wavelength of the low-reflectivity fiber Bragg grating 6. The fiber core diameter of the high-reflectivity fiber Bragg grating 4 matches the diameter of the signal energy transmission fiber, and is used to reflect most of the signal laser back into the resonant cavity.

[0051] The reflectivity of the low-reflectivity fiber Bragg grating 6 is in the range of 4% to 50%, and its core diameter matches the diameter of the signal transmission fiber. It is the low-reflection and output end of the laser resonant cavity, used to reflect part of the signal into the resonant cavity and output most of the laser outside the resonant cavity.

[0052] Figure 1 The optical fiber irradiation monitoring method of the optical fiber irradiation monitoring device shown includes the following steps:

[0053] (1) Determine the i Mode instability threshold P of a fiber laser oscillator working in a non-irradiated environment 1,i ;

[0054] (2) Determine the i The irradiation environment corresponding to the next work, start the fiber laser oscillator in the current irradiation environment, and set the working power of the fiber oscillator P 2,i Set at less than P 1,i The output power of the fiber laser oscillator is continuously collected and recorded, and the output laser time domain characteristics are measured at the output end of the fiber laser oscillator using a high-performance oscilloscope. Based on the output laser time domain characteristics of the fiber laser oscillator under the current irradiation environment, it is determined whether the fiber laser oscillator has reached the mode instability threshold under the current irradiation environment;

[0055] (3) When the fiber laser oscillator reaches the mode instability threshold P under the current irradiation environment 2,i , then the fiber laser oscillator is turned off, indicating that the fiber oscillator has been exposed to a certain total dose of radiation;

[0056] (4) According to δP i =P 1,i -P 2,i Determine the total radiation dose δP received by the fiber oscillator i The larger the i The greater the total radiation dose to which the fiber oscillator is subjected in the irradiation environment corresponding to the second work;

[0057] (5) Order i=i +1, repeat steps (1) to (4), the fiber laser oscillator performs the i +1 work, and monitor the total irradiation dose of the fiber laser oscillator in each work.

[0058] After the fiber laser oscillator has worked for many times, the loss of the fiber laser oscillator caused by irradiation can be restored to a certain extent by using photobleaching or thermal bleaching. The restored fiber laser oscillator can work again, thus extending the service life of the fiber laser oscillator.

[0059] Reference Figure 2 , is a schematic structural diagram of Example 1 applied to gamma-ray irradiation. When the optical fiber irradiation monitoring device is applied to gamma-ray irradiation for monitoring, the gain fiber 5 in the optical fiber laser oscillator is placed in the gamma-ray irradiation field 12 (i.e., the gamma-ray irradiation environment), while the other components of the optical fiber irradiation monitoring device (detection laser light source 1, forward pump combiner 2, fiber-coupled semiconductor laser 3, high-reflectivity fiber Bragg grating 4, low-reflectivity fiber Bragg grating 6, cladding filter 7, optical fiber output end 8, laser receiving device 9, power measurement device 10, and power measurement device 11) are arranged away from the gamma-ray irradiation field 12.

[0060] Reference Figure 3 , Figure 3 The schematic diagram of the structure of the optical fiber irradiation monitoring device provided in Example 2 includes a fiber laser oscillator, a detection laser light source 1, a laser receiving device 9, a power measuring device 10, and a power measuring device 11. The difference from Example 1 is that the fiber laser oscillator is a backward pumping structure. The fiber laser oscillator includes a fiber-coupled semiconductor laser 3, a high-reflectivity fiber Bragg grating 4, a gain fiber 5, a low-reflectivity fiber Bragg grating 6, a cladding filter 7, an optical fiber output end 8, and a backward pumping combiner 13. The backward pumping combiner 13 is specifically (N+1) A backward-pumped combiner (1), with 2≤N≤18, has N pump arms, a signal arm, and a combining end. The output fiber of the detection laser source 1 is connected to the first end of the high-reflectivity fiber Bragg grating 4. The two ends of the gain fiber 5 are fused to the second end of the high-reflectivity fiber Bragg grating 4 and the first end of the low-reflectivity fiber Bragg grating 6, respectively. The output fibers of multiple fiber-coupled semiconductor lasers 3 are respectively connected to the pump arms of the backward-pumped combiner 13. The second end of the low-reflectivity fiber Bragg grating 6 is connected to the combining end of the backward-pumped combiner 13. The two ends of the cladding filter 7 are respectively connected to the signal arm of the backward-pumped combiner 13 and the fiber output end 8. The laser information output from the fiber output end 8 is measured by a power measurement device 10 and a power measurement device 11 after passing through a laser receiving device 9.

[0061] Reference Figure 4 , Figure 4The schematic diagram of the structure of the optical fiber irradiation monitoring device provided in Example 3 includes a fiber laser oscillator, a detection laser light source 1, a laser receiving device 9, a power measuring device 10, and a power measuring device 11. The difference from Example 1 is that the fiber laser oscillator is a bidirectional pumping structure. The fiber laser oscillator includes a forward pumping combiner 2, a fiber-coupled semiconductor laser 3, a high-reflectivity fiber Bragg grating 4, a gain fiber 5, a low-reflectivity fiber Bragg grating 6, a backward pumping combiner 13, a cladding filter 7, and an optical fiber output end 8; the forward pumping combiner 2 is specifically (N+1) 1 forward pump combiner, 2≤N≤18, with N pump arms, one signal arm and one combining end. Similarly, the backward pump combiner 13 is specifically (N+1) A backward pumping combiner (2≤N≤18) is provided, having N pump arms, a signal arm, and a combining end. The output fiber of the detection laser light source 1 is connected to the signal arm of the forward pumping combiner 2; the output fibers of multiple fiber-coupled semiconductor lasers 3 are respectively connected to the pump arms of the forward pumping combiner 2; the combining end of the forward pumping combiner 2 is connected to the first end of the high-reflectivity fiber Bragg grating 4; the two ends of the gain fiber 5 are respectively fused to the second end of the high-reflectivity fiber Bragg grating 4 and the first end of the low-reflectivity fiber Bragg grating 6; the output fibers of multiple fiber-coupled semiconductor lasers 3 are respectively connected to the pump arms of the backward pumping combiner 13; the second end of the low-reflectivity fiber Bragg grating 6 is connected to the combining end of the backward pumping combiner 13; and the two ends of the cladding filter 7 are respectively connected to the signal arm of the backward pumping combiner 13 and the fiber output end 8. The laser information outputted from the optical fiber output end 8 passes through the laser receiving device 9 and is measured by the power measuring device 10 and the power measuring device 11 .

[0062] Figure 5 Figure 1 is a diagram of the output power and time domain information measured by the optical fiber irradiation monitoring device during irradiation in one embodiment. The optical fiber laser oscillator operates below the mode instability threshold. As the total irradiation dose increases, the mode instability threshold gradually decreases. Figure 5 When the output power is near the mode instability threshold, the output power becomes extremely sensitive and severe jitter occurs in the time domain. The total irradiation dose of the environment can be obtained by measuring the time domain characteristics of the output laser at the output end.

[0063] The present invention proposes a highly sensitive optical fiber radiation monitoring device and method. This solution is sensitive to radiation through a mode instability effect threshold, and can therefore be used to monitor optical fiber radiation loss.

[0064] The technical features of the above embodiments can be combined arbitrarily. In order 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.

[0065] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and such modifications and improvements are intended to fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A high-sensitivity optical fiber irradiation monitoring method, characterized in that: The following steps are involved: (1) Determine the i Mode instability threshold P of a fiber laser oscillator working in a non-irradiated environment 1,i ; (2) Determine the i The irradiation environment corresponding to the next work, start the fiber laser oscillator in the current irradiation environment, and set the working power P of the fiber oscillator in the current irradiation environment to 2,i Set at less than P 1,i The output power of the fiber laser oscillator is continuously collected and recorded, and the output laser time domain characteristics are measured at the output end of the fiber laser oscillator using an oscilloscope with a bandwidth greater than 100 MHz. Based on the output laser time domain characteristics of the fiber laser oscillator under the current irradiation environment, it is determined whether the fiber laser oscillator has reached the mode instability threshold under the current irradiation environment; (3) When the fiber laser oscillator reaches the mode instability threshold under the current irradiation environment and the mode instability threshold under the current irradiation environment is P 2,i , then the fiber laser oscillator is turned off, indicating that the fiber oscillator has been exposed to a certain total dose of radiation; (4) According to δ P i =P 1,i -P 2,i Determine the total radiation dose that the fiber oscillator receives. δ P i The larger the i The greater the total radiation dose to which the fiber oscillator is subjected in the irradiation environment corresponding to the second work; (5) Order i=i +1, repeat steps (1) to (4), the fiber laser oscillator performs the i +1 work, and monitor the total irradiation dose of the fiber laser oscillator in each work.

2. The high-sensitivity optical fiber irradiation monitoring method according to claim 1, characterized in that: Also includes setting the threshold of the number of work times N , when the fiber laser oscillator works N Afterwards, photobleaching or thermal bleaching is used to restore the loss of the fiber laser oscillator caused by irradiation to a certain extent, thereby extending the service life of the fiber laser oscillator.

3. The high-sensitivity optical fiber irradiation monitoring method according to claim 1, characterized in that: In step (3), according to The current total radiation dose can be calculated, where Indicates the first i The total radiation dose that the fiber oscillator receives during this operation is: a It is a parameter related to the structure and material properties of the fiber laser oscillator. d is a parameter related to the quantum defect of the fiber laser oscillator. a and d Obtained through calibration.

4. The optical fiber irradiation monitoring device used in the high-sensitivity optical fiber irradiation monitoring method according to claim 1, characterized in that: The invention comprises a fiber laser oscillator, a detection laser light source (1), a laser receiving device (9), a power measuring device (10) and a power measuring device (11); the output end of the fiber laser oscillator is provided with a laser receiving device (9); laser information output by the fiber laser oscillator passes through the laser receiving device (9) and is measured by the power measuring device (10) and the power measuring device (11); The detection laser light source (1) is a visible light semiconductor laser, which is used to detect whether the optical fiber laser is transmitting light and to correct the optical path between the laser output system and the test system; the detection laser light source (1) is injected into the optical fiber laser oscillator from the other end of the optical fiber laser oscillator away from the output end of the optical fiber laser oscillator.

5. The optical fiber irradiation monitoring device according to claim 4, characterized in that: The fiber laser oscillator is a forward pumping structure, comprising a forward pumping combiner (2), a fiber-coupled semiconductor laser (3), a high-reflectivity fiber Bragg grating (4), a gain fiber (5), a low-reflectivity fiber Bragg grating (6), a cladding filter (7), and a fiber output end (8); the output fiber of the detection laser light source (1) is connected to the signal arm of the forward pumping combiner (2); The output optical fibers of the plurality of fiber-coupled semiconductor lasers (3) are respectively connected to the pump arms of the forward pump combiner (2); the combining end of the forward pump combiner (2) is connected to the first end of the high-reflectivity fiber Bragg grating (4); the two ends of the gain optical fiber (5) are respectively fused to the second end of the high-reflectivity fiber Bragg grating (4) and the first end of the low-reflectivity fiber Bragg grating (6); and the two ends of the cladding filter (7) are respectively connected to the second end of the low-reflectivity fiber Bragg grating (6) and the optical fiber output end (8).

6. The optical fiber irradiation monitoring device according to claim 4, characterized in that: The fiber laser oscillator is a backward pumping structure, comprising a fiber-coupled semiconductor laser (3), a high-reflectivity fiber Bragg grating (4), a gain fiber (5), a low-reflectivity fiber Bragg grating (6), a cladding filter (7), a fiber output end (8), and a backward pumping combiner (13); the output fiber of the detection laser light source (1) is connected to the first end of the high-reflectivity fiber Bragg grating (4), and the two ends of the gain fiber (5) are respectively fused to the second end of the high-reflectivity fiber Bragg grating (4) and the first end of the low-reflectivity fiber Bragg grating (6); the output fibers of multiple fiber-coupled semiconductor lasers (3) are respectively connected to the pump arms of the backward pumping combiner (13); the second end of the low-reflectivity fiber Bragg grating (6) is connected to the combining end of the backward pumping combiner (13), and the two ends of the cladding filter (7) are respectively connected to the signal arm of the backward pumping combiner (13) and the fiber output end (8).

7. The optical fiber irradiation monitoring device according to claim 4, characterized in that: The fiber laser oscillator is a bidirectional pumping structure, comprising a forward pumping combiner (2), a fiber-coupled semiconductor laser (3), a high-reflectivity fiber Bragg grating (4), a gain fiber (5), a low-reflectivity fiber Bragg grating (6), a backward pumping combiner (13), a cladding filter (7), and a fiber output end (8); the output fiber of the detection laser light source (1) is connected to the signal arm of the forward pumping combiner (2); The output optical fibers of a plurality of fiber-coupled semiconductor lasers (3) are respectively connected to the pump arms of the forward pump combiner (2); the combining end of the forward pump combiner (2) is connected to the first end of the high-reflectivity fiber Bragg grating (4); the two ends of the gain optical fiber (5) are respectively fused to the second end of the high-reflectivity fiber Bragg grating (4) and the first end of the low-reflectivity fiber Bragg grating (6); the output optical fibers of a plurality of fiber-coupled semiconductor lasers (3) are respectively connected to the pump arms of the backward pump combiner (13); the second end of the low-reflectivity fiber Bragg grating (6) is connected to the combining end of the backward pump combiner (13); and the two ends of the cladding filter (7) are respectively connected to the signal arm of the backward pump combiner (13) and the optical fiber output end (8).

8. The optical fiber irradiation monitoring device according to any one of claims 4 to 7, characterized in that: The detection laser light source (1) is a visible light semiconductor laser with a central wavelength of 400nm-700nm; The fiber-coupled semiconductor laser (3) is an excitation source for the gain fiber (5) to generate upper energy level particles. The fiber-coupled semiconductor laser (3) includes semiconductor lasers of various wavelength bands that match the absorption peak of the gain fiber (5). The semiconductor lasers of various wavelength bands include a combination of one or more wavelength bands of 808 nanometers, 915 nanometers, 940 nanometers, 976 nanometers, and 1550 nanometers.

9. The optical fiber irradiation monitoring device according to claim 5 or 7, characterized in that: The forward pump combiner (2) is (N+1) 1 forward pump combiner, 2≤N≤18, with N pump arms, one signal arm and one combiner end.

10. The optical fiber irradiation monitoring device according to claim 6 or 7, characterized in that: The backward pump combiner (13) is (N+1) 1 Backward pumped combiner, 2≤N≤18, with N pump arms, one signal arm and one combining end.

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