Fiber Bragg Grating Optical Annealing System and Method

Abstract

The fiber grating optical annealing system and method provided by the present invention include: preparing a fiber grating to be annealed, confirming the actual annealing requirements and carrier fiber parameters of the fiber grating to be annealed; determining the annealing laser wavelength, annealing laser initial power and annealing time during the initial annealing operation; performing the first annealing operation; i annealing operation; measure the i The grating power temperature rise coefficient of the fiber Bragg grating after the first annealing operation; i After the first annealing operation, the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating or reaches the annealing limit; if not, according to the first i The power temperature rise coefficient of the fiber Bragg grating after the first annealing operation and the i The spectrum information of the fiber Bragg grating reflected signal light after the first annealing operation is updated. i +1 annealing operation corresponding to the annealing laser wavelength, annealing laser power and annealing time, i = i +1 and proceed to i +1 annealing operation. The present invention reduces the fiber grating power temperature rise coefficient.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber grating technology, and in particular to an optical fiber grating optical annealing system and method. Background Art

[0002] Fiber Bragg grating is a passive device formed by modulating the refractive index of the fiber core. It has the advantages of small size, light weight, good pump light coupling, and low loss. It can be used as the resonant cavity mirror of the fiber oscillator, making the fiber oscillator enter the era of all-fiber. At present, femtosecond laser has become the main tool for preparing fiber Bragg grating. Femtosecond laser has extremely short pulse width and extremely high peak power. When the femtosecond laser is focused on the fiber core, it can cause permanent changes in the refractive index of the core area. The application of femtosecond laser can realize the writing of grating through the fiber coating, so it will not reduce the mechanical stability of the fiber itself. At present, the fiber Bragg grating used in the cavity mirror of high-power laser oscillator inevitably has to consider the heating problem of the grating during the operation of the laser. This is because in the process of femtosecond laser writing fiber Bragg grating, the femtosecond laser will induce chromaticity defects in the writing area of ​​the fiber, thereby producing strong absorption of the signal light. This absorption can be reduced through thermal annealing technology. However, thermal annealing often requires a relatively high annealing temperature, and the commonly used coating materials will melt and be damaged at high temperatures. Therefore, thermal annealing technology is difficult to apply to fiber gratings written through the coating.

[0003] Studies have shown that irradiation with a light source of a specific wavelength and power can reduce the absorption of signal light intensity caused by color center defects to a certain extent. This technology is called optical annealing. This technology is currently used to solve problems such as performance degradation of fiber lasers in radiation environments. Fiber gratings prepared by femtosecond lasers also have color center defects caused by ionizing radiation. Therefore, optical annealing technology can also be applied to the annealing of fiber gratings, namely, fiber grating optical annealing. The concept of laser annealing was also introduced in patent applications with publication numbers CN114518620A and CN116583488A, but the method used is to uniformly heat the grating area with a laser. Its essence is still thermal annealing, which requires the removal of the optical fiber coating. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a fiber grating optical annealing system and method.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] In one aspect, the present invention provides a method for optical annealing of a fiber grating, characterized in that it comprises the following steps:

[0007] S1, prepare the fiber Bragg grating to be annealed, confirm the actual annealing requirements of the fiber Bragg grating to be annealed and the carrier fiber parameters, the carrier fiber parameters include the fiber doping ion type, doping ion concentration, carrier fiber structure size;

[0008] S2. Determine the annealing laser wavelength during the initial annealing operation λ 1. Annealing laser initial power P 1 and annealing time t 1;

[0009] S3. i Second annealing operation: introducing the first i The corresponding wavelength for the second annealing operation λ i ,power P i The annealing laser is used to detect the changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light in real time during the current annealing operation. The annealing laser power is adjusted during the current annealing operation according to the changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light in real time to prevent the annealing operation from erasing the fiber Bragg grating itself until the current annealing operation is completed. The annealing time of the current annealing operation is t i , record i spectral information of the fiber Bragg grating reflected signal light after the second annealing operation, wherein the spectral information of the fiber Bragg grating reflected signal light includes spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light;

[0010] S4. Measure i The grating power temperature rise coefficient of the fiber Bragg grating after the first annealing operation;

[0011] S5. Determine i After the first annealing operation, whether the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating or reaches the annealing limit, if so, the fiber Bragg grating after annealing is obtained, if not, go to step S6;

[0012] S6. According to i The power temperature rise coefficient of the fiber Bragg grating after the first annealing operation and the i The spectrum information of the fiber Bragg grating reflected signal light after the first annealing operation is updated. i +1 annealing operation corresponding to the annealing laser wavelength λ i+1 , annealing laser power P i+1 and annealing time t i+1 , i = i +1, return to step S3.

[0013] Furthermore, during the annealing operation, the annealing laser wavelength is determined according to the following method:

[0014] Determine the dopant ion type in the fiber grating carrier fiber;

[0015] Obtaining the radiation-induced absorption spectrum corresponding to the doped ions;

[0016] The annealing laser wavelength is selected within the wavelength range where the radiation induced absorption spectrum forms a peak.

[0017] Further, in step S3, adjusting the annealing laser power during the current annealing operation according to the real-time detection of changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light includes:

[0018] (i) detecting the change in the spectral bandwidth of the fiber Bragg grating reflected light, the change in the reflectivity of the fiber Bragg grating reflected light, and the change in the central wavelength of the fiber Bragg grating reflected light between the current sampling time and the previous sampling time according to the set sampling interval;

[0019] (ii) determining whether the change value of the spectral bandwidth of the fiber Bragg grating reflected light, the change value of the reflectivity of the fiber Bragg grating reflected light, and the change value of the central wavelength of the fiber Bragg grating reflected light meet the corresponding set requirements; if all meet the corresponding set requirements, continue to anneal at the current annealing power; if there is at least one change value that does not meet the corresponding set requirements, reduce the current annealing power according to the set power step, and return to step (i) until the current annealing operation is completed.

[0020] Further, in step S5, the determination i Whether the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating or reaches the annealing limit after the first annealing operation includes:

[0021] Judgement i whether the grating power temperature rise coefficient of the fiber Bragg grating after the first annealing operation reaches a first set threshold and whether the spectrum information of the fiber Bragg grating reflected signal light is lower than a second set threshold;

[0022] Jordi i After the first annealing operation, the grating power temperature rise coefficient reaches the first set threshold and the spectrum information of the grating reflected signal light is not lower than the second set threshold, then it is considered that the first i After the first annealing operation, the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating;

[0023] Jordi i After the first annealing operation, the grating power temperature rise coefficient does not reach the first set threshold and the spectrum information of the grating reflected signal light is not lower than the second set threshold, then it is considered that the first iAfter the first annealing operation, the fiber Bragg grating does not meet the actual annealing requirements of the fiber Bragg grating and does not reach the annealing limit;

[0024] Jordi i When the spectrum information of the fiber Bragg grating reflected signal light after the first annealing operation is lower than the second set threshold, it is considered that the first i After the first annealing operation, the fiber Bragg grating reaches the annealing limit.

[0025] On the other hand, the present invention provides a fiber Bragg grating optical annealing system for implementing the above-mentioned fiber Bragg grating optical annealing method, comprising a broadband light source, a pump laser, a pump power combiner, and a fiber Bragg grating to be annealed, wherein the input end of the pump power combiner has a plurality of pump arms and a signal arm, wherein the signal arm is connected to the broadband light source, each pump arm is correspondingly connected to a pump laser, and the output end of the pump power combiner is connected to the input end of the fiber Bragg grating to be annealed;

[0026] The pump laser is used to output pump laser; the broadband light source is a wide-spectrum laser with adjustable output wavelength, which outputs signal light of required wavelength according to needs;

[0027] The output end of the pump power combiner transmits the annealing laser of the signal light wavelength to the fiber grating to be annealed to perform the annealing operation.

[0028] Furthermore, the fiber grating optical annealing system also includes a reflection spectrum real-time monitoring device;

[0029] The reflective spectrum real-time monitoring device includes an optical fiber circulator and a spectrum analyzer;

[0030] The optical fiber circulator is arranged between the broadband light source and the pump signal combiner;

[0031] The broadband light source is connected to the input end of the fiber circulator, and the first output end of the fiber circulator is connected to the signal arm of the pump power combiner, which is used to transfer the signal light output by the broadband light source to the pump power combiner; the second output end of the fiber circulator is connected to the spectrum analyzer, which is used to input the received fiber grating reflected signal light into the spectrum analyzer;

[0032] The spectrum analyzer is used to obtain spectrum information of the signal light reflected by the fiber grating according to the signal light reflected by the fiber grating.

[0033] Furthermore, the fiber Bragg grating optical annealing system also includes a fiber clamping device for fixing and straightening the fiber Bragg grating to be annealed.

[0034] Furthermore, the optical spectrum analyzer is connected to the output end of the fiber grating.

[0035] Furthermore, an isolator is integrated inside the broadband light source.

[0036] Furthermore, the pump laser output includes pump lasers of different wavelengths.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The fiber Bragg grating optical annealing system and method provided by the present invention applies optical annealing technology to fiber Bragg grating annealing, and causes a photobleaching effect by irradiating a low-power laser of a specific wavelength, so that the fiber Bragg grating can be annealed through the coating layer without stripping the coating layer of the optical fiber, thereby improving the stability of the fiber Bragg grating. Compared with thermal annealing, the present invention reduces the fiber Bragg grating power temperature rise coefficient while avoiding the damage to the optical fiber structure caused by stripping the coating layer during thermal annealing.

[0039] The fiber Bragg grating optical annealing system of the present invention also has a reflection spectrum real-time monitoring device, which can monitor the spectrum information of the fiber Bragg grating reflected signal light in real time during the annealing process, and control the annealing wavelength, annealing power and annealing time based on this, and further optimize the annealing parameters to obtain a fiber Bragg grating that meets the annealing requirements, while also ensuring that the fiber Bragg grating itself will not be erased during the annealing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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.

[0041] Figure 1 A flow chart of a fiber Bragg grating optical annealing method provided by an embodiment;

[0042] Figure 2 A schematic diagram of a fiber Bragg grating optical annealing system provided in an embodiment.

[0043] Figure annotation:

[0044] 1. Broadband light source; 2. Fiber circulator; 3. Pump laser; 4. Pump power combiner; 5. Fiber Bragg grating; 6. Spectrum analyzer; 7. Fiber clamping device. DETAILED DESCRIPTION

[0045] 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.

[0046] Reference Figure 1 In one embodiment, a fiber grating optical annealing method is provided, comprising the following steps:

[0047] S1, prepare the fiber Bragg grating to be annealed, confirm the actual annealing requirements of the fiber Bragg grating to be annealed and the carrier fiber parameters, the carrier fiber parameters include the fiber doping ion type, doping ion concentration, carrier fiber structure size;

[0048] S2. Determine the annealing laser wavelength during the initial annealing operation λ 1. Annealing laser initial power P 1 and annealing time t 1;

[0049] S3. i Second annealing operation: introducing the first i The corresponding wavelength for the second annealing operation λ i ,power P i The annealing laser is used to detect the changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light in real time during the current annealing operation. The annealing laser power is adjusted during the current annealing operation according to the changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light in real time to prevent the annealing operation from erasing the fiber Bragg grating itself until the current annealing operation is completed. The annealing time of the current annealing operation is t i , record i spectral information of the fiber Bragg grating reflected signal light after the second annealing operation, wherein the spectral information of the fiber Bragg grating reflected signal light includes spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light;

[0050] S4. Measure i The grating power temperature rise coefficient of the fiber Bragg grating after the first annealing operation;

[0051] S5. Determine i After the first annealing operation, whether the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating or reaches the annealing limit, if so, the fiber Bragg grating after annealing is obtained, if not, go to step S6;

[0052] S6. According to iThe power temperature rise coefficient of the fiber Bragg grating after the first annealing operation and the i The spectrum information of the fiber Bragg grating reflected signal light after the first annealing operation is updated. i +1 annealing operation corresponding to the annealing laser wavelength λ i+1 , annealing laser power P i+1 and annealing time t i+1 , i = i +1, return to step S3.

[0053] During the annealing operation, the annealing laser wavelength is determined according to the following method:

[0054] Determine the dopant ion type in the fiber grating carrier fiber;

[0055] Obtaining the radiation-induced absorption spectrum corresponding to the doped ions;

[0056] The annealing laser wavelength is selected within the wavelength range where the radiation induced absorption spectrum forms a peak.

[0057] By selecting the annealing laser wavelength within the wavelength range where the radiation induced absorption spectrum forms a spectral peak, the laser in this wavelength band causes a photobleaching effect, thereby weakening the signal light intensity absorption caused by the color center defect, solving the problem of heating of the fiber grating during use caused by the signal light intensity absorption caused by the color center defect induced in the process of writing the fiber grating, and reducing the grating power temperature rise coefficient of the fiber grating to a set threshold value; if the annealing laser wavelength is not within the wavelength range where the radiation induced absorption spectrum forms a spectral peak, the grating power temperature rise coefficient of the fiber grating cannot be reduced to the set threshold value.

[0058] In one embodiment, the carrier fiber is an ytterbium-doped fiber, and according to the wavelength range of the spectrum peak formed by the radiation-induced absorption spectrum of the ytterbium ions, the 350nm-450nm band is selected as the selection range of the annealing laser wavelength. In another embodiment, the carrier fiber is a germanium-doped fiber, and according to the wavelength range of the spectrum peak formed by the radiation-induced absorption spectrum of the germanium ions, the 400nm-500nm band is selected as the selection range of the annealing laser wavelength.

[0059] In step S3, adjusting the annealing laser power during the current annealing operation according to the real-time detection of changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light comprises:

[0060] (i) detecting the change in the spectral bandwidth of the fiber Bragg grating reflected light, the change in the reflectivity of the fiber Bragg grating reflected light, and the change in the central wavelength of the fiber Bragg grating reflected light between the current sampling time and the previous sampling time according to the set sampling interval;

[0061] (ii) determining whether the change value of the spectral bandwidth of the fiber Bragg grating reflected light, the change value of the reflectivity of the fiber Bragg grating reflected light, and the change value of the central wavelength of the fiber Bragg grating reflected light meet the corresponding set requirements; if all meet the corresponding set requirements, continue to anneal at the current annealing power; if there is at least one change value that does not meet the corresponding set requirements, reduce the current annealing power according to the set power step, and return to step (i) until the current annealing operation is completed.

[0062] By real-time detection of the change value of the spectral bandwidth of the fiber Bragg grating reflected light, the change value of the reflectivity of the fiber Bragg grating reflected light, and the change value of the central wavelength of the fiber Bragg grating reflected light at each sampling moment, it is judged whether the change value meets the corresponding set requirements, thereby controlling the change speed of each sampling, preventing the annealing operation from erasing the fiber Bragg grating itself due to the change value not meeting the corresponding set requirements, and then realizing precise control of the annealing operation, ensuring that the actual annealing requirements of the fiber Bragg grating can be met after the annealing operation.

[0063] In step S5, the determination i Whether the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating or reaches the annealing limit after the first annealing operation includes:

[0064] Judgement i whether the grating power temperature rise coefficient of the fiber Bragg grating after the first annealing operation reaches a first set threshold and whether the spectrum information of the fiber Bragg grating reflected signal light is lower than a second set threshold;

[0065] Jordi i After the first annealing operation, the grating power temperature rise coefficient reaches the first set threshold and the spectrum information of the grating reflected signal light is not lower than the second set threshold, then it is considered that the first i After the first annealing operation, the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating;

[0066] Jordi i After the first annealing operation, the grating power temperature rise coefficient does not reach the first set threshold and the spectrum information of the grating reflected signal light is not lower than the second set threshold, then it is considered that the first i After the first annealing operation, the fiber Bragg grating does not meet the actual annealing requirements of the fiber Bragg grating and does not reach the annealing limit;

[0067] Jordi i When the spectrum information of the fiber Bragg grating reflected signal light after the first annealing operation is lower than the second set threshold, it is considered that the first i After the first annealing operation, the fiber Bragg grating reaches the annealing limit.

[0068] By judging whether the spectrum information of the signal light reflected by the fiber grating and the temperature rise coefficient of the grating power have reached the corresponding set threshold, the annealing operation is controlled to be stopped or not; on the one hand, when the spectrum information of the signal light reflected by the fiber grating is not lower than the second set threshold, it is judged whether the temperature rise coefficient of the grating power has reached the corresponding set threshold to determine whether the desired fiber grating after annealing is obtained. If the actual annealing requirements are not met, the annealing laser wavelength, annealing laser power and annealing time of the next annealing operation are adjusted, and the desired fiber grating after annealing is obtained by iterative processing; on the other hand, when the spectrum information of the signal light reflected by the fiber grating is lower than the second set threshold, it means that the annealing limit has been reached, and the annealing operation is stopped at this time, avoiding the erasure of the fiber grating itself by continuing the annealing process after reaching the annealing limit, causing the performance of the fiber grating to be damaged. The fiber grating prepared by the present invention is tested after each annealing, so that the fiber grating has a grating power temperature rise coefficient of the set threshold. Furthermore, the present invention utilizes optical characteristics for annealing, so there is no need to remove the coating layer of the optical fiber during the annealing operation; and since the annealing utilizing optical characteristics does not use very high temperatures, it will not cause damage to the optical fiber grating structure.

[0069] Reference Figure 2 In one embodiment, a fiber Bragg grating optical annealing system is provided, comprising a broadband light source 1, a pump laser 3, a pump power combiner 4, and a fiber Bragg grating 5 to be annealed, wherein the input end of the pump power combiner 4 has a plurality of pump arms and a signal arm, wherein the signal arm is connected to the broadband light source 1, each pump arm is correspondingly connected to a pump laser 3, and the output end of the pump power combiner 4 is connected to the input end of the fiber Bragg grating 5 to be annealed;

[0070] The pump laser 3 is used to output pump laser; the broadband light source 1 is a wide-spectrum laser with adjustable output wavelength, which outputs signal light of required wavelength according to needs;

[0071] The output end of the pump power combiner 4 transmits the annealing laser of the signal light wavelength to the fiber grating 5 to be annealed to perform the annealing operation.

[0072] The fiber grating optical annealing system also includes a reflection spectrum real-time monitoring device;

[0073] The reflective spectrum real-time monitoring device comprises an optical fiber circulator 2 and a spectrum analyzer 6;

[0074] The optical fiber circulator 2 is arranged between the broadband light source 1 and the pump signal combiner 4;

[0075] The broadband light source 1 is connected to the input end of the fiber circulator 2, and the first output end of the fiber circulator 2 is connected to the signal arm of the pump power combiner 4, which is used to transfer the signal light output by the broadband light source 1 to the pump power combiner 4; the second output end of the fiber circulator 2 is connected to the spectrum analyzer 6, which is used to input the received fiber grating reflected signal light into the spectrum analyzer 6;

[0076] The spectrum analyzer 6 is used to obtain spectrum information of the signal light reflected by the fiber Bragg grating 5 according to the signal light reflected by the fiber Bragg grating 5 .

[0077] An isolator is integrated inside the broadband light source 1, and the isolator is used to prevent the reflected light from damaging the broadband light source.

[0078] By setting up a real-time monitoring device for the reflection spectrum, the spectrum information of the fiber Bragg grating reflected signal light can be monitored in real time during the annealing process, and based on this, the annealing wavelength, annealing power and annealing time during the annealing operation can be controlled to further optimize the annealing parameters, thereby obtaining a fiber Bragg grating that meets the annealing requirements, while also ensuring that the fiber Bragg grating itself will not be erased during the annealing process.

[0079] The fiber Bragg grating optical annealing system further comprises a fiber clamping device 7 for fixing and straightening the fiber Bragg grating 5 to be annealed. The fiber Bragg grating 5 is fixed and straightened by the fiber clamping device 7 to ensure the stability of the fiber Bragg grating during the annealing process, thereby ensuring the effect of the annealing operation.

[0080] The pump laser output includes pump lasers of different wavelengths. A plurality of lasers 3 can be connected to the pump power combiner 4, and the lasers 3 output pump lasers of different wavelengths or the same wavelength to the pump power combiner 4, and the pump power combiner 4 combines the pump lasers of different wavelengths or the same wavelength for output, thereby improving the efficiency of the annealing process.

[0081] In one embodiment, there are multiple lasers 3 , and different lasers 3 output pump lasers with different wavelengths. The pump power combiner 4 combines the pump lasers output by all lasers 3 with the signal light output by the broadband light source 1 and inputs the combined beams into the fiber grating 5 .

[0082] In one embodiment, the spectrum analyzer 6 is connected to the output end of the fiber grating 5, and the other devices are arranged to remain the same. Figure 2 The spectrum analyzer 6 is connected to the output end of the fiber Bragg grating 5, and can monitor the spectrum information of the transmitted light through the fiber Bragg grating 5 in real time during the annealing process, and adjust the annealing power according to the spectrum information of the transmitted light of the fiber Bragg grating 5 during the annealing process; the spectrum information of the transmitted light of the fiber Bragg grating 5 includes the fiber Bragg grating transmission spectrum contrast.

[0083] In one embodiment, the set threshold value of the fiber Bragg grating transmission spectrum contrast is 20 dB. When the spectrum analyzer detects that the fiber Bragg grating transmission spectrum contrast is lower than 20 dB, it indicates that the annealing limit is reached.

[0084] Matters not covered by the present invention are known technologies.

[0085] 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.

[0086] 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.

[0087] 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 method for optical annealing of a fiber Bragg grating, characterized in that: The following steps are involved: S1, prepare the fiber Bragg grating to be annealed, confirm the actual annealing requirements of the fiber Bragg grating to be annealed and the carrier fiber parameters, the carrier fiber parameters include the fiber doping ion type, doping ion concentration, carrier fiber structure size; S2. Determine the annealing laser wavelength during the initial annealing operation , annealing laser initial power and annealing time ; S3. Second annealing operation: introducing the first The corresponding wavelength for the second annealing operation ,power The annealing laser is used to detect the changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light in real time during the current annealing operation. The annealing laser power is adjusted during the current annealing operation according to the changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light in real time to prevent the annealing operation from erasing the fiber Bragg grating itself until the current annealing operation is completed. The annealing time of the current annealing operation is , record spectral information of the fiber Bragg grating reflected signal light after the second annealing operation, wherein the spectral information of the fiber Bragg grating reflected signal light includes spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light; S4. Measure The grating power temperature rise coefficient of the fiber Bragg grating after the first annealing operation; S5. Determine the After the first annealing operation, whether the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating or reaches the annealing limit, if so, the fiber Bragg grating after annealing is obtained, if not, go to step S6; S6. According to The power temperature rise coefficient of the fiber Bragg grating after the first annealing operation and the The spectrum information of the fiber Bragg grating reflected signal light after the first annealing operation is updated. Annealing laser wavelength corresponding to the second annealing operation , annealing laser power and annealing time , , return to step S3.

2. The optical annealing method of fiber Bragg grating according to claim 1, characterized in that: During the annealing operation, the annealing laser wavelength is determined according to the following method: Determine the dopant ion type in the fiber grating carrier fiber; Obtaining the radiation-induced absorption spectrum corresponding to the doped ions; The annealing laser wavelength is selected within the wavelength range where the radiation induced absorption spectrum forms a peak.

3. The optical annealing method of fiber Bragg grating according to claim 1, characterized in that: In step S3, adjusting the annealing laser power during the current annealing operation according to the real-time detection of changes in the spectral bandwidth, reflectivity and central wavelength of the fiber Bragg grating reflected light comprises: (i) detecting the change in the spectral bandwidth of the fiber Bragg grating reflected light, the change in the reflectivity of the fiber Bragg grating reflected light, and the change in the central wavelength of the fiber Bragg grating reflected light between the current sampling time and the previous sampling time according to the set sampling interval; (ii) determining whether the change value of the spectral bandwidth of the fiber Bragg grating reflected light, the change value of the reflectivity of the fiber Bragg grating reflected light, and the change value of the central wavelength of the fiber Bragg grating reflected light meet the corresponding set requirements; if all meet the corresponding set requirements, continue to anneal at the current annealing power; if there is at least one change value that does not meet the corresponding set requirements, reduce the current annealing power according to the set power step, and return to step (i) until the current annealing operation is completed.

4. The optical annealing method of fiber Bragg grating according to claim 1, characterized in that: In step S5, the determination Whether the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating or reaches the annealing limit after the first annealing operation includes: Judgement whether the grating power temperature rise coefficient of the fiber Bragg grating after the first annealing operation reaches a first set threshold and whether the spectrum information of the fiber Bragg grating reflected signal light is lower than a second set threshold; Jordi After the first annealing operation, the grating power temperature rise coefficient reaches the first set threshold and the spectrum information of the grating reflected signal light is not lower than the second set threshold, then it is considered that the first After the first annealing operation, the fiber Bragg grating meets the actual annealing requirements of the fiber Bragg grating; Jordi After the first annealing operation, the grating power temperature rise coefficient does not reach the first set threshold and the spectrum information of the grating reflected signal light is not lower than the second set threshold, then it is considered that the first After the first annealing operation, the fiber Bragg grating does not meet the actual annealing requirements of the fiber Bragg grating and does not reach the annealing limit; Jordi When the spectrum information of the fiber Bragg grating reflected signal light after the first annealing operation is lower than the second set threshold, it is considered that the first After the first annealing operation, the fiber Bragg grating reaches the annealing limit.

5. A fiber Bragg grating optical annealing system for implementing the method as claimed in claim 1, characterized in that: It includes a broadband light source, a pump laser, a pump power combiner, and a fiber Bragg grating to be annealed, wherein the input end of the pump power combiner has multiple pump arms and a signal arm, wherein the signal arm is connected to the broadband light source, each pump arm is correspondingly connected to a pump laser, and the output end of the pump power combiner is connected to the input end of the fiber Bragg grating to be annealed; The pump laser is used to output pump laser; the broadband light source is a wide-spectrum laser with adjustable output wavelength, which outputs signal light of required wavelength according to needs; The output end of the pump power combiner transmits the annealing laser of the signal light wavelength to the fiber grating to be annealed to perform the annealing operation.

6. The fiber Bragg grating optical annealing system according to claim 5, characterized in that: Also included is a reflectance spectrum real-time monitoring device; The reflective spectrum real-time monitoring device includes an optical fiber circulator and a spectrum analyzer; The optical fiber circulator is arranged between the broadband light source and the pump signal combiner; The broadband light source is connected to the input end of the fiber circulator, and the first output end of the fiber circulator is connected to the signal arm of the pump power combiner, which is used to transfer the signal light output by the broadband light source to the pump power combiner; the second output end of the fiber circulator is connected to the spectrum analyzer, which is used to input the received fiber grating reflected signal light into the spectrum analyzer; The spectrum analyzer is used to obtain spectrum information of the signal light reflected by the fiber grating according to the signal light reflected by the fiber grating.

7. The fiber Bragg grating optical annealing system according to claim 5, characterized in that: The invention also comprises a fiber clamping device for fixing and straightening the fiber grating to be annealed.

8. The fiber Bragg grating optical annealing system according to claim 6, characterized in that: The spectrum analyzer is connected to the output end of the optical fiber grating.

9. The fiber Bragg grating optical annealing system according to claim 5, characterized in that: An isolator is integrated inside the broadband light source.

10. The fiber Bragg grating optical annealing system according to claim 5, characterized in that: The pump laser output includes pump lasers of different wavelengths.

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