Process for solving heating problem of recoating area of high-power fiber bragg grating

Abstract

The invention discloses a process for solving heating of a high-power fiber bragg grating recoating area. The process is reasonable in design, convenient to operate and high in working efficiency, and can be applied to high-power fiber bragg gratings manufactured by various different types of optical fibers. The problem that a windowing area generates heat due to recoating due to a necessary process (windowing a coating layer) for inscribing the fiber bragg grating is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of high-power fiber laser resonant cavity preparation, and in particular to a process for solving the heating problem of a high-power fiber grating heavy coating area. Background Art

[0002] High-power fiber lasers are composed of several core components such as pumps, beam combiners, resonant cavities, gain fibers, cladding mode power strippers, and fiber output devices. The resonant cavity is made of a high-reflection double-clad fiber Bragg grating and a low-reflection double-clad fiber Bragg grating. Since the mainstream high-power fiber Bragg grating manufacturing process in the industry is mostly made by ultraviolet exposure in conjunction with a phase mask. Therefore, it is necessary to strip the coating before writing the fiber Bragg grating, which is commonly known as windowing the optical fiber in our industry. From the analysis of defective products produced in industrial production, when the high-power fiber Bragg grating works for a long time, the area where the fiber Bragg grating is burned is not the grating area written by ultraviolet light, but the re-coating incision position. Therefore, the re-coating process of the fiber Bragg grating can directly affect the power tolerance upper limit of the high-power fiber Bragg grating and the upper limit of the time for long-term stable operation.

[0003] The double-clad optical fiber commonly used in our industry has doped quartz as the core, pure quartz as the inner cladding, a low-refractive index coating as the outer cladding (@23℃ refractive index is about 1.373), and a high-refractive index coating glue as the coating layer (@23℃ refractive index is about 1.5).

[0004] In addition, the fine coating fragments and other impurities (high-fold glue solidification) generated by the window opening adhere to the inner cladding, forming a high-fold point. The high-fold point will lead out the pump light in the cladding and the small amount of signal light escaping from the core to the inner cladding, resulting in excessive single-point heat accumulation and burning of the optical fiber. Summary of the invention

[0005] The object of the present invention is to provide a process for solving the heating problem of the re-coating area of ​​a high-power optical fiber grating.

[0006] To achieve the above object, the present invention adopts the following contents: A process for solving the heating of the heavy coating area of ​​a high-power fiber Bragg grating comprises: S1, firstly using a fiber cladding non-damaging stripping machine to strip the coating layer of a double-clad optical fiber to be inscribed, and during the stripping process, selecting a method of opening windows from both sides to the middle; S2. Use a high-pressure air blowing gun to blow air into the window area of ​​the double-clad optical fiber to be inscribed; S3, using blades to strip the coating layer on both sides of the double-clad optical fiber to be inscribed, and using a large-core optical fiber cutter to cut the optical fiber end; S4, connecting the cut optical fiber end to the optical fiber adapter, and using the optical fiber adapter to connect to the multimode optical fiber coupled semiconductor red laser output by FC / PC; S5, turn on the multimode fiber-coupled semiconductor red laser output by FC / PC, and observe the bright spots or blocks in the window area of ​​the double-clad optical fiber to be inscribed; S6. Dip the dust-free paper used for wiping optical fibers into electronically pure anhydrous ethanol and wipe the bright spots or lumps in the window opening area in a single direction until the electronically pure anhydrous ethanol evaporates completely and there are no bright spots or lumps. S7, performing fiber Bragg grating writing; S8. After the writing is completed, the double-clad optical fiber is connected to the multimode optical fiber coupled semiconductor red laser output by FC / PC again to observe whether there are bright spots or lumps. If there are, repeat the above cleaning steps; S9. After cleaning, the window area is subjected to high temperature treatment to accelerate the volatilization of hydrogen and destroy free hydroxide; S10, after high temperature treatment, connect to the red laser again for observation and detection; S11, if there is red light leakage or bright spot, repeat the above cleaning steps; if there is no red light leakage or bright spot, load the optical fiber into the optical fiber coating machine; S12. Before coating, adjust the position of the coating machine fixture so that the optical fiber is in the middle of the coating tank, and give the optical fiber a certain tension so that the optical fiber is in a tight state; S13, cover the coating module, and inject low-fold glue into the coating module. The slower the injection speed, the better. S14, observe the position and flow rate of the glue through the visual window on the module, use the multimode fiber-coupled semiconductor red laser output by FC / PC to observe the light emission at the incision, and turn on the UV lamp of the coating machine for curing; S15. After the double-clad optical fiber is re-coated, the optical fiber is taken out from the coating machine and placed in an oven. The oven temperature is set to 100° C. for dehydrogenation treatment.

[0007] Preferably, the optical fiber cladding non-damaging stripping machine is Fujikura PCS-100; the optical fiber coating machine is Fujikura FSR-05; and the large core diameter optical fiber cutting knife is Fujikura CT-104+.

[0008] Preferably, the wavelength of the multimode fiber-coupled semiconductor red laser is 650 NM and the power is 100 MW.

[0009] Preferably, the refractive index of the optical fiber low-refractive coating glue is @23°C≤1.3773.

[0010] Preferably, the purity of the electronically pure grade anhydrous ethanol is 99.9%.

[0011] This process operation flow can be applied to double-clad fiber Bragg gratings of different specifications and models, and effectively solves the heating problem of the re-coating area caused by three major factors such as window opening, writing, and re-coating; the window opening structure is optimized by the cladding lossless stripping machine, and the window opening area is effectively cleaned with the cooperation of the semiconductor red laser. In addition, the correct selection of low-folding coating glue and the optimization of the coating process enable the low-folding coating glue to adhere well to the inner cladding of the optical fiber, which can effectively solve the problem of heat generated by the pump light and signal light in the cladding light escaping from the cladding when the fiber Bragg grating resonant cavity is constructed.

[0012] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0014] Figure 1 The present invention is a schematic diagram of a process flow for solving the heating problem in the re-coating area of ​​a high-power fiber grating.

[0015] Figure 2 It is a schematic diagram of the optical fiber cladding non-damaging stripping machine of the present invention.

[0016] Figure 3 The present invention uses a non-damaging optical fiber cladding stripping machine to calibrate the area where the coating layer of the double-clad optical fiber to be inscribed is to be stripped.

[0017] Figure 4 It is a schematic diagram of the target effect after the coating layer of the double-clad optical fiber to be inscribed is stripped by using the optical fiber cladding lossless stripping machine of the present invention.

[0018] Figure 5 The present invention uses a high-pressure air blowing gun, which is externally connected to high-purity nitrogen to blow and clean the window opening part.

[0019] Figure 6 It is a schematic diagram of the connection structure of the double-clad optical fiber after windowing of the present invention, using an optical fiber adapter to access the multi-mode optical fiber coupled semiconductor red light laser output by FC / PC to detect coating attachments and other impurities in the windowing area.

[0020] Figure 7 It is a connection schematic diagram of the present invention using a coating machine in cooperation with a multimode fiber coupled semiconductor red light laser output by FC / PC to re-coat the window area.

[0021] Figure 8 It is a schematic diagram of observing various progress of the window opening area through the visible area of ​​the coating module of the coating machine of the present invention.

[0022] Fig. 9 It is the refractive index of the optical fiber inner cladding (synthetic fused silica) at different wavelengths mentioned in the present invention.

[0023] Fig.10 It is a performance diagram of various low-fold glues preliminarily selected in the present invention.

[0024] Fig.11 It is a performance comparison chart of the high-performance low-fold coating glue selected in the present invention.

[0025] Fig.12 It is a multimode fiber-coupled semiconductor red laser output by FC / PC in the present invention.

[0026] In the figure, each reference numeral is: 1- window area, 2- optical fiber coating, 3- inner cladding, 4- fiber core, 5- double-clad optical fiber, 6- optical fiber clamp, 7- optical fiber coating machine, 8- coating module and visual window of coating machine, 9- optical fiber adapter, 10- multimode optical fiber coupled semiconductor red light laser, 11- coating groove, 12- relative position where the low-fold coating glue needs to flow to the original double-clad optical fiber, 13- visual window of coating machine module, 14- high-pressure air blow gun, 15- air blow gun hose, 16- optical fiber cladding non-damage stripping machine. Implementation

[0027] The technical solution of the present invention will be described clearly and completely below 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] like Figures 1 to 12 As shown, a process for solving the heating of the heavy coating area of ​​a high-power fiber Bragg grating includes: S1, first using a fiber cladding non-damaging stripping machine to strip the coating layer of the double-clad optical fiber to be inscribed, and during the stripping process, the two sides are respectively opened to the middle in a window manner; S2. Use a high-pressure air blowing gun to blow air into the window area of ​​the double-clad optical fiber to be inscribed; S3, using blades to strip the coating layer on both sides of the double-clad optical fiber to be inscribed, and using a large-core optical fiber cutter to cut the optical fiber end; S4, connecting the cut optical fiber end to the optical fiber adapter, and using the optical fiber adapter to connect to the multimode optical fiber coupled semiconductor red laser output by FC / PC; S5, turn on the multimode fiber-coupled semiconductor red laser output by FC / PC, and observe the bright spots or blocks in the window area of ​​the double-clad optical fiber to be inscribed; S6. Dip the dust-free paper used for wiping optical fibers into electronically pure anhydrous ethanol and wipe the bright spots or lumps in the window opening area in a single direction until the electronically pure anhydrous ethanol evaporates completely and there are no bright spots or lumps. S7, performing fiber Bragg grating writing; S8. After the writing is completed, the double-clad optical fiber is connected to the multimode optical fiber coupled semiconductor red laser output by FC / PC again to observe whether there are bright spots or lumps. If there are, repeat the above cleaning steps; S9. After cleaning, the window area is subjected to high temperature treatment to accelerate the volatilization of hydrogen and destroy free hydroxide; S10, after high temperature treatment, connect to the red laser again for observation and detection; S11, if there is red light leakage or bright spot, repeat the above cleaning steps; if there is no red light leakage or bright spot, load the optical fiber into the optical fiber coating machine; S12. Before coating, adjust the position of the coating machine fixture so that the optical fiber is in the middle of the coating tank, and give the optical fiber a certain tension so that the optical fiber is in a tight state; S13, cover the coating module, and inject low-fold glue into the coating module. The slower the injection speed, the better. S14, observe the position and flow rate of the glue through the visual window on the module, use the multimode fiber-coupled semiconductor red laser output by FC / PC to observe the light emission at the incision, and turn on the UV lamp of the coating machine for curing; S15. After the double-clad optical fiber is re-coated, the optical fiber is taken out from the coating machine and placed in an oven. The oven temperature is set to 100° C. for dehydrogenation treatment.

[0032] Furthermore, the optical fiber cladding non-damaging stripping machine is Fujikura PCS-100; the optical fiber coating machine is Fujikura FSR-05; and the large core diameter optical fiber cutting knife is Fujikura CT-104+.

[0033] Furthermore, the wavelength of the multimode fiber-coupled semiconductor red laser is 650NM and the power is 100MW.

[0034] Furthermore, the refractive index of the optical fiber low-refractive coating glue is @23°C≤1.3773.

[0035] Furthermore, the purity of the electronically pure grade anhydrous ethanol is 99.9%.

[0036] Furthermore, the dust-free paper uses Kimwipes Delicate Task Wipers.

[0037] The working principle of the device is as follows: the optical fiber cladding non-damage stripping machine 16 performs a mid-section windowing on the double-clad optical fiber 5. The optical fiber cladding non-damage stripping machine 16 selects a corresponding stripping mode according to the geometric dimensions of the double-clad optical fiber. The cladding diameters of the commonly used high-power double-clad optical fibers on the market are 125um, 130um, 250um, and 400um, respectively. In the optical fiber cladding non-damage stripping machine, the corresponding program can be selected according to the coating diameter and cladding diameter of the double-clad optical fiber 5. If there is no corresponding program for the cladding diameter and the coating diameter, a new program can be set by manual editing. However, we need to select different "shaving numbers" under the program according to different cladding diameters. For cladding diameters of 125um and 130um, we select "24", that is, unidirectional stripping of 24 knives; for cladding diameters of 250um and 400um, we select "64", that is, unidirectional stripping of 64 knives. In this way, the taper and roundness of the coating stripping opening can be guaranteed to the greatest extent. Determine the window opening length based on demand. Assuming that a 40mm window is required, select "stripping length" of 22mm in the program to perform one-way window opening. After the one-way window opening is completed, change the direction of the optical fiber so that the distance between the ring cut at the lower cutting position and the ring cut that has been opened is about 40mm. Perform a second window opening with an overlap of 4mm. During this process, do not use any marker to mark the lower cutting position of the optical fiber cladding non-damaging stripping machine 16, because the marker ink is high-fold and cannot be completely wiped off with alcohol. It is easy to adhere to the inner cladding 3 of the optical fiber, forming a high fold point and causing heat. The effect after the window opening is completed is as follows Figure 4 shown.

[0038] First, use an ultrasonic cleaner to perform deep cleaning on the high-pressure air gun 14 and the air gun hose 15 to ensure that no impurities and particles are ejected during the blowing process to avoid secondary contamination of the optical fiber cladding and damage to the cladding. After the ultrasonic cleaning is completed, blow with external nitrogen for 3-5 minutes to allow the alcohol in the tube and the gun to evaporate quickly and take away some of the residual impurities inside. Use the high-pressure air gun 14 to blow air in a single direction on the window area and the annular cut to achieve preliminary cleaning and minimize the adhesion of coating debris and other impurities to the cladding.

[0039] Therefore, cleaning the window area is an inevitable process, and it is necessary to cooperate with the multimode fiber-coupled semiconductor red laser (wavelength 650NM, power 100MW) output by FC / PC to simulate the transmission of pump light in the cladding. Because high-power fiber lasers are all made of double-clad optical fibers, and such high-power lasers all use cladding pump structures, that is, pump light is transmitted in the cladding. Since the commonly used pump light is 915nm or 976nm, both of which are invisible light, visible red light close to them is selected as detection.

[0040] The preliminarily processed window area is suspended in the air, and the two ends of the optical fiber are de-coated with a blade, and the two ends are cut with a large core diameter optical fiber cutter (Fujikura CT-104+). The cut optical fiber at one end is connected to the optical fiber adapter 9 of the corresponding size, and the optical fiber adapter 9 is connected to the multi-mode fiber-coupled semiconductor red laser 10 output by FC / PC.

[0041] Turn on the multimode fiber-coupled semiconductor red laser 10 and observe the bright spots or impurities in the window area 1. Since the red light is transmitted in the inner cladding of the optical fiber, when there are no other high-folding objects or attachments on the surface of the inner cladding, the red light cannot leak out of the inner cladding. On the contrary, when a red bright spot is seen, it means that there are high-folding attachments or impurities stuck to the cladding. Use high-purity electronic-grade anhydrous ethanol with dust-free paper, wipe from one side to the other, wipe in one direction, and do not wipe back and forth to avoid secondary contamination of the optical fiber. And when wiping, wipe one ring cut in one direction to another ring cut. In this process, no force should be applied to the ring cut to avoid damaging the shape of the cut. When wiping the cladding, you need to press the dust-free paper with your fingers, wrap the cladding with force and wipe it. When you are about to reach the next ring cut, relax your fingers so that the dust-free paper gently passes over the next ring cut. During the wiping process, follow the principle of: from light to heavy, and then to light. After wiping is completed, use a high-pressure nitrogen blow gun 14 to blow air to the window area to accelerate the volatilization of alcohol, and observe whether red light still leaks from the cladding. If red light still leaks, repeat the above process and continue to clean and wipe the window area. However, the number of wiping times for each window area shall not exceed 3 times, otherwise the optical fiber will be damaged, and after a single wipe, the dust-free paper shall be scrapped and shall not be reused to avoid grease contamination of the cladding.

[0042] For fiber Bragg grating writing, the specific writing system and process flow can refer to the patent "A toe-cut writing system for writing large mode field chirped fiber Bragg grating" (publication number: CN114325927A).

[0043] After the double-clad optical fiber completes the fiber grating writing, the optical fiber adapter 9 needs to be connected to the multimode fiber-coupled semiconductor red light laser 10 through the flange. Observe whether the particles suspended in the air are attached to the inner cladding 3 of the optical fiber due to writing. If bright spots or red spots appear, first use a nitrogen high-pressure air blow gun 14 to blow and clean the optical fiber cladding. If the blowing cannot be done, the above cladding cleaning method can only be repeated, wiping 1-2 times in one direction for deep cleaning; if there are no red spots or bright spots, the window area will be treated with high temperature. The main purpose is to quickly and effectively remove the hydrogen in the grating area and destroy the free hydrogen-oxygen bonds to reduce the transmission loss of the optical signal in the fiber core. After high-temperature treatment, it is necessary to connect to the multimode fiber-coupled semiconductor red light laser 10 for secondary verification to see if there is any light leakage or high-refractive index attachments. If bright spots or red spots appear, first use a nitrogen high-pressure air blow gun 14 to blow and clean the optical fiber cladding. If blowing cannot be done, the above-mentioned cladding cleaning method can only be repeated, wiping unidirectionally 1-2 times for deep cleaning. If there are no red spots or bright spots, use the optical fiber coating machine 7 for coating.

[0044] Optical fiber coating machine 7. Selection of low-reflection glue. Optical fiber transmission uses the principle of total reflection of light. Light will be totally reflected at the interface between the fiber core and the cladding, and the light will be locked inside the fiber core and propagate forward. Even if it passes through a curved path, the light will not be emitted from the fiber. Then the refractive index of the fiber core and the inner cladding must meet the following conditions: n 纤芯 >n 内包层 Due to the double-clad fiber structure, the pump light is transmitted in the inner cladding, so the inner cladding and the outer cladding also meet the total reflection condition. Then the refractive index of the outer cladding and the refractive index of the inner cladding meet the following conditions: n 内包层 >n 外包层 , from the above, we can know that n 纤芯 >n 内包层 >n 外包层 .

[0045] The parts we strip off during the windowing process include the high-refractive coating layer and the low-refractive outer cladding. Since we cannot ensure that the optical fiber and the mask stripes are completely perpendicular when writing the fiber grating, we will introduce a tilted fiber grating with a very small tilt angle. During the cavity-building process, the tilted fiber grating will inject part of the signal light in the fiber core into the inner cladding at a specific angle. Due to the special incident angle of the signal light, it may destroy the total reflection structure of the optical fiber and manifest itself in the form of weak heat energy. This is especially obvious at the junction of the outer cladding and the inner cladding (annular incision) of the window. According to Fig. 9 It can be seen that when the wavelength is 852nm, the refractive index of the fiber inner cladding is approximately around 1.4525. The numerical aperture (NA) of the conventional double-clad fiber cladding in the industry is > 0.46. According to the formula >0.46, n 内包层=1.4525, we can get n 外包层 <1.3773, so we choose the principle of low refractive index coating glue <1.3773; Fig.10 As shown in the figure, when the refractive index wavelength is 852nm, the coating glues that meet the conditions are SPC-325, SPC-347, SPC-355, SPC-363, SPC-370, and SPC-373. However, we can see that although the refractive index of these low-refraction glues meets the requirements, the melting point temperature performance is very poor. However, other types of glue can meet this requirement, such as Fig.11 As shown in the figure, HTC-363 low-fold adhesive has excellent performance, and the refractive index calibration under different wavelengths is very close, all 1.363. The performance under high temperature is also very good. Therefore, the low-fold adhesive used for coating is EFIRON's HTC-363.

[0046] According to the geometric dimensions of the double-clad optical fiber 5, select a suitable coating procedure. On the basis of the original procedure, set the amount of glue injection to be 5mm larger than the window area; set the resin injection rate to 0.1mm / s; set the irradiation time to 130-150 seconds, and set the UV lamp power to 5; use dust-free paper with high-purity electronic pure grade anhydrous ethanol to clean the coating slot 11 in the coating machine module; after the alcohol evaporates, place the double-clad window area in the middle of the coating slot 11 in the coating machine module to make it symmetrical on the left and right; cover the optical fiber clamps 6 of the optical fiber coating machine 7 respectively, and observe the flow of low-fold glue and real-time position through the coating module visual window 13 of the coating machine; when the low-fold glue flows through the annular cuts at both ends and completely covers the annular cuts, observe whether the red light leaks at the annular cuts. When the glue stops flowing, do not rush to open the coating machine curing button, but wait until the red light is completely non-luminous at the annular cut before opening the curing button. This is very important. The main purpose is to remove the air from the annular cut so that the low fold glue (HTC-363) fits the inner cladding 3 of the optical fiber and the annular cut completely without leaving any gaps. The main purpose of low curing power and long curing time is to make the low fold glue (HTC-363) cure slowly to prevent curing too quickly, which will cause rapid deformation and shrinkage, resulting in delamination of the cladding, original coating and re-coated areas.

[0047] After curing is completed, open the coating module and the visual window of the optical fiber coating machine 7, and then open the optical fiber clamp-6 of the optical fiber coating machine (FSR-05); take out the coated double-clad optical fiber.

[0048] The coated optical fiber is placed in an oven at 100°C for 72 hours to dehydrogenate the pigtail portion of the double-clad optical fiber.

[0049] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0050] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A process for solving the heating of the re-coating area of ​​a high-power fiber grating, comprising: S1. First, use a fiber cladding non-damaging stripping machine to strip the coating layer of the double-clad optical fiber to be inscribed, and during the stripping process, choose to open windows from both sides to the middle; S2. Use a high-pressure air blowing gun to blow air into the window area of ​​the double-clad optical fiber to be inscribed; S3, using blades to strip the coating layer on both sides of the double-clad optical fiber to be inscribed, and using a large-core optical fiber cutter to cut the optical fiber end; S4, connecting the cut optical fiber end to the optical fiber adapter, and using the optical fiber adapter to connect to the multimode optical fiber coupled semiconductor red laser output by FC / PC; S5, turn on the multimode fiber-coupled semiconductor red laser output by FC / PC, and observe the bright spots or blocks in the window area of ​​the double-clad optical fiber to be written; S6. Dip the dust-free paper used for wiping optical fibers into electronically pure anhydrous ethanol and wipe the bright spots or lumps in the window opening area in a single direction until the electronically pure anhydrous ethanol evaporates completely and there are no bright spots or lumps. S7, performing fiber Bragg grating writing; S8. After the writing is completed, the double-clad optical fiber is connected to the multimode optical fiber coupled semiconductor red laser output by FC / PC again to observe whether there are bright spots or lumps. If there are, repeat the above cleaning steps; S9. After cleaning, the window area is subjected to high temperature treatment to accelerate the volatilization of hydrogen and destroy free hydroxide; S10, after high temperature treatment, connect to the red laser again for observation and detection; S11, if there is red light leakage or bright spot, repeat the above cleaning steps; if there is no red light leakage or bright spot, load the optical fiber into the optical fiber coating machine; S12. Before coating, adjust the position of the coating machine fixture so that the optical fiber is in the middle of the coating tank, and give the optical fiber a certain tension so that the optical fiber is in a tight state; S13, cover the coating module, and inject low-fold glue into the coating module. The slower the injection speed, the better. S14, observe the position and flow rate of the glue through the visual window on the module, use the multimode fiber-coupled semiconductor red laser output by FC / PC to observe the light emission at the incision, and turn on the UV lamp of the coating machine for curing; S15. After the double-clad optical fiber is re-coated, the optical fiber is taken out from the coating machine and placed in an oven. The oven temperature is set to 100° C. for dehydrogenation treatment.

2. A process for solving the heating of the re-coating area of ​​high-power fiber Bragg grating according to claim 1, characterized in that: The optical fiber cladding non-damaging stripping machine is Fujikura PCS-100; the optical fiber coating machine is Fujikura FSR-05; and the large core diameter optical fiber cutting knife is Fujikura CT-104+.

3. A process for solving the heating of the re-coating area of ​​high-power fiber Bragg grating according to claim 1, characterized in that: The wavelength of the multimode fiber-coupled semiconductor red laser is 650NM and the power is 100MW.

4. A process for solving the heating of the re-coating area of ​​high-power fiber Bragg grating according to claim 1, characterized in that: The refractive index of the optical fiber low-refractive coating glue is @23°C≤1.3773.

5. A process for solving the heating of the re-coating area of ​​high-power fiber Bragg grating according to claim 1, characterized in that: The purity of the electronically pure grade anhydrous ethanol is 99.9%.

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