A casing process method for solving bright spots in the cladding of rare earth-doped optical fibers

Abstract

The present invention relates to a casing process method for solving the bright spots of rare earth-doped optical fiber cladding, and belongs to the field of optical fiber manufacturing technology. It includes the following steps: wiping the surface of the casing to be cleaned with alcohol; placing the casing to be cleaned into a casing cleaning device, and first pickling and washing the inside of the casing; introducing gas into the casing to purge the inside of the casing; fixing the core rod handle to one end of the core rod, and clamping the core rod handle on a chuck of a casing lathe, and straightening and polishing the core rod; fixing the casing handle at one end of the removed casing, and clamping the casing handle on another chuck of the casing lathe, and introducing gas into the casing to straighten the casing; moving the casing so that the core rod is sleeved inside the casing; and then fusing one end of the casing with the core rod through a flame main lamp. There are no bubbles or impurities at the interface between the core rod and the casing of the present application, which reduces the defect points in the cladding and improves the service life of the laser.

Description

Technical Field

[0001] The invention relates to a casing process method for solving bright spots in cladding of rare earth-doped optical fiber, belonging to the technical field of optical fiber manufacturing. Background Art

[0002] Fiber lasers are a new generation of lasers after chemical lasers, gas lasers and solid-state lasers. In recent years, fiber lasers, especially high-power fiber lasers, have attracted more and more attention and have been widely used in medical treatment, industrial cutting and welding, scientific research, national defense and other fields.

[0003] As fiber lasers are widely used in different fields, new requirements are put forward for their optical performance. For high-power fiber lasers, in order to increase the output power while controlling the beam quality, the rare-earth-doped gain fiber used is required to have low loss, high pump light absorption efficiency, high longitudinal and radial uniformity, single mode and large mode field. In order to meet these requirements, it is necessary to further improve the existing fiber preform preparation technology.

[0004] In the process of preparing rare earth doped optical fiber rods, the casing process is inevitable, but the traditional casing process has defects in the interface between the core rod and the casing, which are specifically manifested as bright spots caused by bubbles or impurities. After drawing, these bright spots will be in the cladding.

[0005] During use, the pump light passes through the high-reflection and low-reflection in the rare-earth doped optical fiber, and is reflected between the cladding and the core layer by the low-refractive coating and the optical fiber interface. The core is stimulated to produce lasers of the required wavelength due to the presence of rare earth elements. If there are defects in the cladding, a bright spot will be generated when the pump light passes through the defect, and the optical fiber will heat up and burn, affecting the life of the laser. In addition, the return light generated by the bright spot will damage the laser peripheral equipment, such as the high-reflection and low-reflection. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a casing process method for solving the bright spots in the cladding of rare earth-doped optical fibers in accordance with the above-mentioned prior art, thereby avoiding the presence of bubbles or impurities at the interface between the core rod and the casing, reducing the defects in the cladding, avoiding the heating and burning of the optical fiber, and prolonging the service life of the laser.

[0007] The technical solution adopted by the present invention to solve the above-mentioned problem is: a casing process method for solving the bright spots of the cladding of rare earth-doped optical fibers, the casing process method comprising the following steps:

[0008] Step 1: Wipe the surface of the sleeve to be cleaned with alcohol;

[0009] Step 2: Put the cleaned casing into the casing cleaning device, and pickle the inside of the casing. The inner diameter of the casing after pickling meets the following requirements: D酸洗后 -D 酸洗前 =0.1-0.2mm, then washed with water;

[0010] Step 3: introducing gas into the casing to purge the inside of the casing, and then taking it out from the casing cleaning device;

[0011] Step 4: Fix the mandrel handle to one end of the mandrel, and clamp the mandrel handle on a chuck of the casing lathe to straighten and polish the mandrel;

[0012] Step 5: Fix a casing handle at one end of the casing taken out from the casing cleaning device, and clamp the casing handle on another chuck of the casing lathe, and arrange the casing and the core rod opposite to each other; introduce gas into the casing to straighten the casing;

[0013] Step 6: Move the sleeve so that the core rod is placed inside the sleeve; then fuse one end of the sleeve with the core rod through the flame main lamp;

[0014] Step 7: Turn off the gas and evacuate the inside of the casing. The flame main lamp moves toward the casing side and the mandrel completes the casing process.

[0015] The casing cleaning device in step 2 comprises a cabinet, wherein an openable and closable cover is provided on the cabinet, a pad is provided in the cabinet, the casing is placed on the pad, and sealing members are provided at both ends of the casing to seal the inside of the casing; an acid storage box is provided under the cabinet, one end of the casing is connected to the acid storage box through a first connecting pipe, and the other end of the casing is connected to the acid storage box through a second connecting pipe, and the acid in the acid storage box enters the casing through the first connecting pipe to pickle it, and then flows back to the acid storage box through the second connecting pipe.

[0016] The first connecting pipe is provided with a first pneumatic valve group, and the first pneumatic valve group is provided with a first air inlet and a first water inlet; the second connecting pipe is provided with a second pneumatic valve group, and the second pneumatic valve group is provided with a second air outlet and a second water outlet; water flows into the casing through the first water inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second water outlet to wash the inside of the casing; and then gas flows into the casing through the first air inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second air outlet to purge the casing.

[0017] The acid solution is a mixture of 40%-50% HF and 60%-65% HNO3, the ratio of HNO3 to HF is 1:10-1:15, and the pickling time is 20-60 minutes.

[0018] The water washing time in step 2 is 2-5 minutes; the gas purging time in step 3 is 10-30 minutes.

[0019] In the step 4, the core rod polishing flow rate is 100-120 L / min.

[0020] In the step five, an adapter block is provided at the end of the sleeve handle, and the adapter block is connected to a third connecting pipe so that the air pipe is connected to the inner cavity of the sleeve; the air pipe is provided with a third pneumatic valve group, and the third pneumatic valve group is provided with a vacuum port and a gas inlet.

[0021] The flow rate of the gas introduced in step 5 is 50ML-100ML.

[0022] Compared with the prior art, the advantages of the present invention are: in a casing process method for solving bright spots in the cladding of rare earth-doped optical fibers,

[0023] 1. The casing cleaning device is a horizontal fully enclosed structure. The acid liquid circulates in a closed manner and does not come into contact with the outside air, effectively avoiding HF volatilization. The concentration of HF remains basically unchanged during use, thereby ensuring the casing cleaning effect and greatly reducing pollution.

[0024] 2. One end of the casing handle is connected to the third connecting tube. Before the casing and the core rod are sealed, a certain flow of high-purity O2 or high-purity N2 is introduced to isolate the inner wall of the casing and the surface of the core rod from the outside air.

[0025] There are no bubbles or impurities at the interface between the core rod and the sleeve of the present application, which reduces the defects in the cladding. After drawing and loading into the laser, there is no fiber burning or laser burning, which increases the service life of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a casing cleaning device in a casing process method for solving bright spots on the cladding of a rare-earth-doped optical fiber according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the installation of a sleeve and a core rod in a sleeve process method for solving bright spots in the cladding of a rare-earth-doped optical fiber according to an embodiment of the present invention;

[0028] In the figure, 1 is a cabinet, 2 is a cover plate, 3 is a pad, 4 is a sleeve, 5 is a seal, 6 is a first connecting pipe, 7 is a first pneumatic valve group, 8 is a second connecting pipe, 9 is a second pneumatic valve group, 10 is an acid storage box, 11 is a core rod, 12 is a core rod handle, 13 is a sleeve handle, 14 is a transfer block, 15 is a third connecting pipe, 16 is a third pneumatic valve group, and 17 is a flame main lamp. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the accompanying drawings.

[0030] In this embodiment, a casing process method for solving bright spots in the cladding of rare earth-doped optical fibers is provided. The casing process method comprises the following steps:

[0031] Step 1: Wipe the surface of the sleeve 4 to be cleaned with alcohol.

[0032] Step 2: Place the casing 4 to be cleaned into the casing cleaning device. The casing cleaning device first pickles the inner wall of the casing 4. The acid is pumped into the casing cleaning device through the acid storage tank 10 to pickle the inside of the casing 4. The inner hole diameter of the casing 4 after pickling satisfies: D 酸洗后- D 酸洗前 =0.1-0.2mm; then rinse the inner wall of the sleeve 4 with pure water for 2-5min.

[0033] like Figure 1 As shown, the sleeve cleaning device includes a cabinet 1, and a cover plate 2 that can be opened and closed is provided on the cabinet 1 to achieve sealing or opening of the cabinet 1. A pad 3 is provided in the cabinet 1, and the sleeve 4 is placed on the pad 3. Seals 5 are provided at both ends of the sleeve 4 to seal the inside of the sleeve 4. An acid storage tank 10 is provided below the cabinet 1, and the inlet end of the sleeve is connected to the acid storage tank 10 through a first connecting pipe 6, and the outlet end of the sleeve 4 is connected to the acid storage tank 10 through a second connecting pipe 8. The acid in the acid storage tank 10 is pumped into the first connecting pipe 6 by an acid pump, and then flows into the sleeve 4 to pickle it, and then flows back to the acid storage tank 10 through the second connecting pipe 8. The acid solution in the acid storage box 10 is a mixture of 40%-50% HF and 60%-65% HNO3, with HNO3:HF being 1:10-1:15. The pickling time is determined according to the HF concentration. When 40% HF is used, the pickling time is controlled within 30-60 minutes, and when 50% HF is used, the pickling time is controlled within 20-30 minutes. The acid solution is introduced into the sleeve 4 through two connecting pipes and is not exposed to the air throughout the process, thereby avoiding HF from being diffused into the air during the pickling process and greatly reducing pollution.

[0034] Among them, a first pneumatic valve assembly 7 is provided on the first connecting pipe 6, and a first air inlet and a first water inlet are provided on the first pneumatic valve assembly 7. A second pneumatic valve assembly 9 is provided on the second connecting pipe 8, and a second air outlet and a second water outlet are provided on the second pneumatic valve assembly 9. Water flows into the casing 4 through the first water inlet and the first connecting pipe 6, and then flows out through the second connecting pipe 8 and the second water outlet, and the water flushes the inside of the casing 4.

[0035] After sealing members 5 are arranged at both ends of the sleeve 4, water pressure is used to detect leakage to ensure that the sealed sleeve does not leak.

[0036] Step 3: After flushing with pure water, N2 at a temperature of 60-70°C is introduced into the casing 4 to purge the inside of the casing for 10-30 minutes, and then the casing is taken out of the casing cleaning device. N2 flows into the casing through the first air inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second air outlet to purge the casing.

[0037] Step 4: If Figure 2 As shown, the mandrel handle 12 is welded to one end of the mandrel 11, and the mandrel handle 12 is clamped in the chuck of the casing lathe, and the mandrel 11 is straightened and polished, and the polishing flow rate is 100-150L / min.

[0038] Step 5: The sleeve 4 taken out from the sleeve cleaning device is welded to the sleeve handle 13 at one end, and the sleeve handle 13 is clamped on another chuck of the sleeve lathe so that the sleeve 4 and the core rod 11 are arranged relative to each other. An adapter block 14 is set at the end of the sleeve handle 13, and the adapter block 14 is connected to the third connecting pipe 15, so that the third connecting pipe 15 is connected to the inner cavity of the sleeve 4. The third connecting pipe 15 is provided with a third pneumatic valve group 16, and the third pneumatic valve group 16 is provided with a vacuum port and a gas inlet, and the vacuum port is connected to the vacuum pump. High-purity O2 or N2 is introduced into the third connecting pipe 15 through the gas inlet, and then flows into the inner cavity of the sleeve. The gas flow rate is 50-100ML to straighten the sleeve.

[0039] Step 6: Move the machine base with the sleeve handle, and move the sleeve toward the core rod so that the core rod is inserted into the sleeve. Use the lathe H2O2 flame main lamp 17 to fuse one end of the sleeve with the core rod. The H2:O2 ratio is 2:1, and the H2 flow rate is 100-200L / Min.

[0040] Step 7: Close the gas inlet and stop introducing high-purity O2 or N2. Turn on the vacuum pump to evacuate the space between the casing and the core rod, with a vacuum degree of 50-500mbar. Move the main flame lamp of the H2O2 lathe toward the casing to fuse the casing to the core rod, with the H2 flow rate of 100-200L / min and the main flame lamp moving speed of 5-20mm / min. The core rod completes the casing process.

[0041] Embodiment 1

[0042] Step 1: Wipe the surface of the sleeve to be cleaned with alcohol.

[0043] Step 2: Place the casing to be cleaned into the casing cleaning device. The casing cleaning device first pickles the inner wall of the casing. The acid is pumped from the acid storage tank to the casing cleaning device to pickle the inside of the casing. The inner diameter of the casing after pickling meets the following requirements: D 酸洗后- D 酸洗前 =0.15mm; then rinse the inner wall of the casing with pure water for 3 minutes.

[0044] like Figure 1As shown, the casing cleaning device includes a cabinet, and a cover plate that can be opened and closed is provided on the cabinet to realize the closing or opening of the cabinet. A pad is provided in the cabinet, and the casing is placed on the pad. Seals are provided at both ends of the casing to seal the inside of the casing. The acid storage box is arranged below the cabinet, and the inlet end of the casing is connected to the acid storage box through a first connecting pipe, and the first end of the casing is connected to the acid storage box through a second connecting pipe. The acid in the acid storage box is pumped into the first connecting pipe by an acid pump and then flows into the casing for pickling, and then flows back to the acid storage box through the second connecting pipe. The acid in the acid storage box is a mixture of 40% HF and 63% HNO3, with HNO3:HF being 1:10, and the pickling time being 60 minutes. The acid is introduced into the casing through two connecting pipes, and is not exposed to the air throughout the process, which avoids the diffusion of HF into the air during the pickling process, and greatly reduces pollution.

[0045] The first connecting pipe is provided with a first pneumatic valve assembly, and the first pneumatic valve assembly is provided with a first air inlet and a first water inlet. The second connecting pipe is provided with a second pneumatic valve assembly, and the second pneumatic valve assembly is provided with a second air outlet and a second water outlet. Water flows into the casing through the first water inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second water outlet, and the water flushes the inside of the casing.

[0046] Step 3: After being rinsed with pure water, N2 at a temperature of 65°C is introduced into the casing to purge the inside of the casing for 20 minutes, and then the casing is taken out of the casing cleaning device. N2 flows into the casing through the first air inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second air outlet to purge the casing.

[0047] Step 4: Weld the mandrel handle to one end of the mandrel, clamp the mandrel handle to the chuck of the casing lathe, and straighten and polish the mandrel at a polishing flow rate of 110 L / min.

[0048] Step 5: Weld the sleeve handle at one end of the sleeve taken out from the sleeve cleaning device, and clamp the sleeve handle to the other chuck of the sleeve lathe so that the sleeve and the core rod are arranged relative to each other. An adapter block is set at the end of the sleeve handle, and the adapter block is connected to the third connecting pipe, so that the third connecting pipe is connected to the inner cavity of the sleeve. The third connecting pipe is provided with a third pneumatic valve group, and the third pneumatic valve group is provided with a vacuum port and a gas inlet, and the vacuum port is connected to the vacuum pump. High-purity O2 is introduced into the third connecting pipe through the gas inlet, and then flows into the inner cavity of the sleeve. The gas flow rate is 50ML to straighten the sleeve.

[0049] Step 6: Move the machine base that holds the sleeve handle, and move the sleeve toward the core rod so that the core rod is inserted into the sleeve. Use the main flame of the lathe H2O2 to fuse one end of the sleeve with the core rod. The H2:O2 ratio is 2:1, and the H2 flow rate is 125L / Min.

[0050] Step 7: Close the gas inlet and stop introducing high-purity O2. Turn on the vacuum pump to evacuate the space between the sleeve and the core rod to a vacuum degree of 200mbar. Move the main flame lamp of the H2O2 lathe toward the sleeve to fuse the sleeve to the core rod, with the H2 flow rate of 125L / min and the main flame lamp moving speed of 8mm / min. The core rod completes the sleeve process.

[0051] Embodiment 2

[0052] Step 1: Wipe the surface of the sleeve to be cleaned with alcohol.

[0053] Step 2: Place the casing to be cleaned into the casing cleaning device. The casing cleaning device first pickles the inner wall of the casing. The acid is pumped from the acid storage tank to the casing cleaning device to pickle the inside of the casing. The inner diameter of the casing after pickling meets the following requirements: D 酸洗后 -D 酸洗前 =0.1mm; then rinse the inner wall of the casing with pure water for 3 minutes.

[0054] like Figure 1 As shown, the casing cleaning device includes a cabinet, and a cover plate that can be opened and closed is provided on the cabinet to realize the closing or opening of the cabinet. A pad is provided in the cabinet, and the casing is placed on the pad. Seals are provided at both ends of the casing to seal the inside of the casing. The acid storage box is arranged below the cabinet, and the inlet end of the casing is connected to the acid storage box through a first connecting pipe, and the first end of the casing is connected to the acid storage box through a second connecting pipe. The acid in the acid storage box is pumped into the first connecting pipe by an acid pump and then flows into the casing for pickling, and then flows back to the acid storage box through the second connecting pipe. The acid in the acid storage box is a mixture of 50% HF and 63% HNO3, with HNO3:HF being 1:15, and the pickling time being 30 minutes. The acid is introduced into the casing through two connecting pipes, and is not exposed to the air throughout the process, which avoids the diffusion of HF into the air during the pickling process, and greatly reduces pollution.

[0055] The first connecting pipe is provided with a first pneumatic valve assembly, and the first pneumatic valve assembly is provided with a first air inlet and a first water inlet. The second connecting pipe is provided with a second pneumatic valve assembly, and the second pneumatic valve assembly is provided with a second air outlet and a second water outlet. Water flows into the casing through the first water inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second water outlet, and the water flushes the inside of the casing.

[0056] Step 3: After being rinsed with pure water, N2 at a temperature of 70°C is introduced into the casing to purge the inside of the casing for 15 minutes, and then the casing is taken out of the casing cleaning device. N2 flows into the casing through the first air inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second air outlet to purge the casing.

[0057] Step 4: Weld the mandrel handle to one end of the mandrel, clamp the mandrel handle to the chuck of the casing lathe, and straighten and polish the mandrel at a polishing flow rate of 125L / min.

[0058] Step 5: Weld the sleeve handle at one end of the sleeve taken out from the sleeve cleaning device, and clamp the sleeve handle to the other chuck of the sleeve lathe so that the sleeve and the core rod are arranged relative to each other. An adapter block is set at the end of the sleeve handle, and the adapter block is connected to the third connecting pipe, so that the third connecting pipe is connected to the inner cavity of the sleeve. The third connecting pipe is provided with a third pneumatic valve group, and the third pneumatic valve group is provided with a vacuum port and a gas inlet, and the vacuum port is connected to the vacuum pump. High-purity N2 is introduced into the third connecting pipe through the gas inlet, and then flows into the inner cavity of the sleeve. The gas flow rate is 100ML to straighten the sleeve.

[0059] Step 6: Move the machine base that holds the sleeve handle, and move the sleeve toward the core rod so that the core rod is inserted into the sleeve. Use the main flame of the lathe H2O2 to fuse one end of the sleeve with the core rod. The H2:O2 ratio is 2:1, and the H2 flow rate is 125L / Min.

[0060] Step 7: Close the gas inlet and stop introducing high-purity N2. Turn on the vacuum pump to evacuate the space between the sleeve and the core rod to a vacuum degree of 200 mbar. Move the main flame lamp of the H2O2 lathe toward the sleeve to fuse the sleeve to the core rod, with the H2 flow rate of 125 L / min and the main flame lamp moving speed of 10 mm / min. The core rod completes the sleeve process.

[0061] Embodiment 3

[0062] The HF in this example is from the same batch as that in Example 1. This example was implemented three months after Example 1 in order to verify that the HF in the casing cleaning device has less volatility and a good service life.

[0063] Step 1: Wipe the surface of the sleeve to be cleaned with alcohol.

[0064] Step 2: Place the casing to be cleaned into the casing cleaning device. The casing cleaning device first pickles the inner wall of the casing. The acid is pumped from the acid storage tank to the casing cleaning device to pickle the inside of the casing. The inner diameter of the casing after pickling meets the following requirements: D 酸洗后- D 酸洗前 =0.15mm; then rinse the inner wall of the casing with pure water for 3 minutes.

[0065] like Figure 1As shown, the casing cleaning device includes a cabinet, and a cover plate that can be opened and closed is provided on the cabinet to realize the closing or opening of the cabinet. A pad is provided in the cabinet, and the casing is placed on the pad. Seals are provided at both ends of the casing to seal the inside of the casing. The acid storage box is arranged below the cabinet, and the inlet end of the casing is connected to the acid storage box through a first connecting pipe, and the first end of the casing is connected to the acid storage box through a second connecting pipe. The acid in the acid storage box is pumped into the first connecting pipe by an acid pump and then flows into the casing for pickling, and then flows back to the acid storage box through the second connecting pipe. The acid in the acid storage box is a mixture of 40% HF and 63% HNO3, with HNO3:HF being 1:10, and the pickling time being 60 minutes. The acid is introduced into the casing through two connecting pipes, and is not exposed to the air throughout the process, which avoids the diffusion of HF into the air during the pickling process, and greatly reduces pollution.

[0066] The first connecting pipe is provided with a first pneumatic valve assembly, and the first pneumatic valve assembly is provided with a first air inlet and a first water inlet. The second connecting pipe is provided with a second pneumatic valve assembly, and the second pneumatic valve assembly is provided with a second air outlet and a second water outlet. Water flows into the casing through the first water inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second water outlet, and the water flushes the inside of the casing.

[0067] Step 3: After being rinsed with pure water, N2 at a temperature of 65°C is introduced into the casing to purge the inside of the casing for 30 minutes, and then the casing is taken out of the casing cleaning device. N2 flows into the casing through the first air inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second air outlet to purge the casing.

[0068] Step 4: Weld the mandrel handle to one end of the mandrel, clamp the mandrel handle to the chuck of the casing lathe, and straighten and polish the mandrel at a polishing flow rate of 110 L / min.

[0069] Step 5: Weld the sleeve handle at one end of the sleeve taken out from the sleeve cleaning device, and clamp the sleeve handle to the other chuck of the sleeve lathe so that the sleeve and the core rod are arranged relative to each other. An adapter block is set at the end of the sleeve handle, and the adapter block is connected to the third connecting pipe, so that the third connecting pipe is connected to the inner cavity of the sleeve. The third connecting pipe is provided with a third pneumatic valve group, and the third pneumatic valve group is provided with a vacuum port and a gas inlet, and the vacuum port is connected to the vacuum pump. High-purity O2 is introduced into the third connecting pipe through the gas inlet, and then flows into the inner cavity of the sleeve. The gas flow rate is 50ML to straighten the sleeve.

[0070] Step 6: Move the machine base that holds the sleeve handle, and move the sleeve toward the core rod so that the core rod is inserted into the sleeve. Use the main flame of the lathe H2O2 to fuse one end of the sleeve with the core rod. The H2:O2 ratio is 2:1, and the H2 flow rate is 125L / Min.

[0071] Step 7: Close the gas inlet and stop introducing high-purity O2. Turn on the vacuum pump to evacuate the space between the sleeve and the core rod to a vacuum degree of 200mbar. Move the main flame lamp of the H2O2 lathe toward the sleeve to fuse the sleeve to the core rod, with the H2 flow rate of 125L / min and the main flame lamp moving speed of 8mm / min. The core rod completes the sleeve process.

[0072] Table 1

[0073]

[0074] The above embodiment

[0075] Table 1 shows the results of the above three embodiments, from which it can be seen that there are no bubbles or impurities at the interface between the core rod and the sleeve, which reduces the defects in the cladding. After drawing and loading into the laser, there is no fiber burning and laser burning, which improves the service life of the laser.

[0076] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A casing process method for solving the bright spots of rare earth-doped optical fiber cladding, characterized in that: The casing process method comprises the following steps: Step 1: Wipe the surface of the sleeve to be cleaned with alcohol; Step 2: Put the cleaned casing into the casing cleaning device, and pickle the inside of the casing. The inner diameter of the casing after pickling meets the following requirements: D 酸洗后- D 酸洗前 =0.1-0.2mm, then wash with water; the washing time is 2-5min; Step 3: Pass gas into the casing to purge the inside of the casing, and then take it out from the casing cleaning device. The gas purge time is 10-30 minutes; The casing cleaning device comprises a cabinet, on which an openable cover is provided, and inside the cabinet a pad is provided, on which the casing is placed, and sealing members are provided at both ends of the casing to seal the inside of the casing; an acid storage box is provided below the cabinet, one end of the casing is connected to the acid storage box through a first connecting pipe, and the other end of the casing is connected to the acid storage box through a second connecting pipe, and the acid in the acid storage box enters the casing through the first connecting pipe to pickle it, and then flows back to the acid storage box through the second connecting pipe; The first connecting pipe is provided with a first pneumatic valve group, and the first pneumatic valve group is provided with a first air inlet and a first water inlet; the second connecting pipe is provided with a second pneumatic valve group, and the second pneumatic valve group is provided with a second air outlet and a second water outlet; water flows into the casing through the first water inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second water outlet to wash the inside of the casing; the gas flows into the casing through the first air inlet and the first connecting pipe, and then flows out through the second connecting pipe and the second air outlet to purge the casing; Step 4: Fix the mandrel handle to one end of the mandrel, and clamp the mandrel handle on a chuck of the casing lathe to straighten and polish the mandrel; the mandrel polishing flow rate is 100~120L / min; Step 5: Fix a casing handle at one end of the casing taken out from the casing cleaning device, and clamp the casing handle on another chuck of the casing lathe, and arrange the casing and the core rod opposite to each other; introduce gas into the casing to straighten the casing; An adapter block is provided at the end of the sleeve handle, and a third connecting pipe is connected to the adapter block, so that the air pipe is connected to the inner cavity of the sleeve; a third pneumatic valve group is provided on the air pipe, and a vacuum port and a gas inlet are provided on the third pneumatic valve group; Step 6: Move the sleeve so that the core rod is placed inside the sleeve; then fuse one end of the sleeve with the core rod through the flame main lamp; Step 7: Turn off the gas and evacuate the inside of the casing. The flame main lamp moves toward the casing side and the mandrel completes the casing process.

2. The method for solving the problem of bright spots in the cladding of rare earth-doped optical fibers according to claim 1, characterized in that: The acid solution is a mixture of 40%-50% HF and 60%-65% HNO3, the ratio of HNO3 to HF is 1:10-1:15, and the pickling time is 20-60 minutes.

3. The method for solving the problem of bright spots in the cladding of rare earth-doped optical fibers according to claim 1, characterized in that: The flow rate of the gas introduced in step 5 is 50ML-100ML.

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