Corrosion-resistant special optical fiber and preparation process thereof

Abstract

The invention belongs to the technical field of optical fibers, and particularly relates to a corrosion-resistant special optical fiber and a preparation process thereof, and the preparation process of the special optical fiber comprises the following steps: (1) doping quartz glass with F-Ge to prepare an optical fiber preform, and heating and drawing to obtain an optical fiber; (2) cleaning the optical fiber by using argon or oxygen plasma to remove surface pollutants and activate the surface; (3) depositing a nanoscale SiC film on the outer surface of the optical fiber by adopting an atomic layer deposition method; and (4) coating the outer surface of the optical fiber with a layer of polyether-ether-ketone coating, curing, then coating with a layer of polytetrafluoroethylene composite coating, and curing to obtain the corrosion-resistant special optical fiber. The special optical fiber prepared by the invention has the advantages of acid resistance, alkali resistance, high temperature and high humidity resistance, strong tensile and bending resistance, excellent corrosion resistance, high temperature and high humidity stability, mechanical property and optical property.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fibers, and in particular relates to a corrosion-resistant special optical fiber and a preparation process thereof. Background Art

[0002] As an advanced transmission medium, optical fiber has a wide range of applications in many fields due to its unique physical and chemical properties, mainly in the fields of communications, medical treatment, industry, automobiles, aerospace, and military. As the industrial environment becomes increasingly complex, the demand for corrosion-resistant special optical fibers continues to grow. Corrosion-resistant special optical fibers are optical fiber products that can work stably for a long time in harsh chemical environments and are widely used in corrosive environments such as the chemical, marine, petroleum, and nuclear industries.

[0003] In order to improve the corrosion resistance of the currently used optical fiber, specific elements are doped or a ceramic coating is applied on the outer surface of the optical fiber. Although the corrosion resistance of the optical fiber can be improved to a certain extent, the optical fiber will be hard and brittle, and its tensile and bending resistance will be reduced. It cannot withstand the harsh environment of high temperature and high humidity. The optical fiber transmission loss is large, and the durability of the optical fiber in a corrosive environment is not strong, that is, the optical fiber cannot take into account excellent corrosion resistance, high temperature and high humidity stability, mechanical properties and optical properties, which reduces the practicality of the optical fiber. Therefore, the present invention provides a special optical fiber that takes into account excellent corrosion resistance, high temperature and high humidity stability, mechanical properties and optical properties to solve the above-mentioned technical problems and meet the actual use needs. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a corrosion-resistant special optical fiber and a preparation process thereof. The special optical fiber is resistant to acid and alkali, high temperature and humidity, and has strong tensile and bending resistance, and has excellent corrosion resistance, high temperature and humidity stability, mechanical properties and optical properties.

[0005] The object of the present invention is achieved in that:

[0006] A preparation process of a corrosion-resistant special optical fiber comprises the following steps:

[0007] (1) F-Ge doped quartz glass is made into an optical fiber preform rod, and then heated and drawn into an optical fiber;

[0008] (2) Use argon or oxygen plasma to clean the optical fiber to remove surface contaminants and activate the surface;

[0009] (3) Depositing nanoscale SiC thin films on the outer surface of the optical fiber using atomic layer deposition;

[0010] (4) Coat a layer of polyetheretherketone coating on the outer surface of the optical fiber. After curing, coat a layer of polytetrafluoroethylene composite coating, and a corrosion-resistant special optical fiber is obtained after curing.

[0011] Preferably, the method for preparing the optical fiber preform in step (1) is as follows: First, clean the quartz glass liner to ensure that its surface is free of contamination. After drying, install it on the MCVD lathe and rotate it. Then, introduce silicon tetrachloride, germanium tetrachloride, carbon tetrafluoride, and oxygen into the quartz glass liner, and use inert gas helium as the carrier gas to ensure uniform mixing. At 1600-2000 °C, an oxidation reaction occurs on the inner wall of the liner, and an F-Ge co-doped quartz layer is deposited in the quartz glass tube to obtain the optical fiber preform.

[0012] Preferably, the flow rates of the silicon tetrachloride, germanium tetrachloride, carbon tetrafluoride, and oxygen are 1000-2000 sccm, 200-400 sccm, 50-100 sccm, and 2000-4000 sccm respectively, and the treatment time is 20-60 min.

[0013] Preferably, the heating temperature in step (1) is 2000-2200 °C.

[0014] Preferably, the flow rate of argon or oxygen in step (2) is 20-50 sccm, and the treatment time is 15-30 min.

[0015] Preferably, the method for depositing the nanoscale SiC thin film in step (3) is: Place the optical fiber in an atomic layer deposition device, and alternately introduce silicon tetrachloride and propylene at 300-400 °C. A self-limiting surface reaction occurs on the surface of the optical fiber, and the SiC thin film grows layer by layer.

[0016] Preferably, the flow rates of the silicon tetrachloride and propylene are both 10-50 sccm, the pulse time is both 0.1-1.0 seconds, the number of cycles is 500-1000 times, and the thickness of the SiC thin film is 50-100 nm.

[0017] Preferably, the method for coating the polyetheretherketone coating in step (4) is: Mix 98% concentrated sulfuric acid and polyetheretherketone, stir at 75-85 °C for 2-4 h to obtain a coating solution with a concentration of 10-15% w / v, and then spray the coating solution on the outer surface of the optical fiber to form a liquid film, which is cured step by step to form a polyetheretherketone coating.

[0018] Preferably, the thickness of the polyetheretherketone coating is 5-10 μm, and the step-by-step curing process is: First, cure at 200-220 °C for 40-60 min, then cure at 280-320 °C for 40-60 min, and finally cure at 360-380 °C for 60-80 min under nitrogen protection.

[0019] Preferably, the polytetrafluoroethylene composite coating described in step (4) is made of the following raw materials by mass percentage: 65-85% of polytetrafluoroethylene, 10-30% of nano-aluminum oxide, and 2-6% of silane coupling agent. Among them, the particle size of the nano-aluminum oxide is 10-50 nm, and the silane coupling agent is KH-560 or A-171.

[0020] Preferably, the coating method of the polytetrafluoroethylene composite coating is spraying, the spraying thickness is 100-120 μm, and after spraying, curing is carried out. The heating rate is controlled at 3 °C / min, and the temperature is raised from room temperature to 360-380 °C, and cured for 20-40 min under nitrogen protection.

[0021] The present invention also discloses a corrosion-resistant special optical fiber, which is prepared by using the preparation process of the special optical fiber described above.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The optical fiber preform of the present invention deposits an F-Ge co-doped quartz layer in the quartz glass tube, which can reduce the optical fiber transmission loss, and improve the heat resistance and corrosion resistance of the optical fiber.

[0024] 2. The present invention uses atomic layer deposition to deposit a nanoscale SiC film on the outer surface of the optical fiber, which can block the penetration of corrosive media, thereby improving the corrosion resistance of the optical fiber.

[0025] 3. The present invention coats a layer of polyetheretherketone coating on the outer surface of the optical fiber, and then coats a layer of polytetrafluoroethylene composite coating after curing. Polyetheretherketone has excellent chemical stability and can maintain its performance in a variety of harsh chemical environments. It can not only improve the mechanical strength of the optical fiber, but also enhance the weather resistance of the optical fiber. The polytetrafluoroethylene composite coating is made of polytetrafluoroethylene, nano-aluminum oxide and silane coupling agent. Taking polytetrafluoroethylene as the main matrix can endow it with chemical inertness. Nano-aluminum oxide can enhance its denseness to block the entry of corrosive media. The silane coupling agent can improve the adhesion between the coating and the fiber core. Coating the polytetrafluoroethylene composite coating can further improve the corrosion resistance and wear resistance of the optical fiber. The double-layer step-by-step coating can ensure the uniformity and firmness of the coating, and can significantly improve the durability of the optical fiber in a corrosive environment.

[0026] 4. The transmission loss increase of the special optical fiber prepared by the preparation process of the present invention is less than 0.2 dB / km after being immersed in 5% HCl or 5% NaOH solution for 30 days, less than 0.3 dB / km after 1000 hours at 85°C and 85% humidity, less than or equal to 0.15 dB / km when the tensile strength is 5 GPa and the bending radius is 5 mm, and less than or equal to 0.25 dB / km at a wavelength of 1550 nm. That is, the special optical fiber of the present invention is acid and alkali resistant, high temperature and high humidity resistant, has strong tensile and bending resistance, and has excellent corrosion resistance, high temperature and high humidity stability, mechanical properties and optical properties. Detailed implementation manners

[0027] The present invention will be described in more detail below through specific implementation manners.

[0028] Example 1

[0029] A preparation process of a corrosion-resistant special optical fiber includes the following steps:

[0030] (1) First, clean the quartz glass liner to ensure that its surface is pollution-free. After drying, install it on the MCVD lathe and rotate it. Then, introduce silicon tetrachloride with a flow rate of 1000 sccm, germanium tetrachloride with a flow rate of 200 sccm, carbon tetrafluoride with a flow rate of 50 sccm, and oxygen with a flow rate of 2000 sccm into the quartz glass liner for 60 minutes. Use inert gas helium as the carrier gas to ensure uniform mixing. At 1600°C, make the gas undergo an oxidation reaction on the inner wall of the liner, deposit an F-Ge co-doped quartz layer in the quartz glass tube to obtain an optical fiber preform, and finally draw the optical fiber by heating at 2000°C.

[0031] (2) Clean the optical fiber with argon plasma with a flow rate of 20 sccm for 30 minutes to remove surface contaminants and activate the surface.

[0032] (3) Place the optical fiber in an atomic layer deposition device, alternately introduce silicon tetrachloride and propylene at 300°C. The flow rates of silicon tetrachloride and propylene are both 10 sccm, the pulse time is 1.0 second for both, and the number of cycles is 500 times. A self-limiting surface reaction occurs on the surface of the optical fiber to grow a SiC thin film layer by layer. The total thickness of the SiC thin film is 50 nm.

[0033] (4) Mix 98% concentrated sulfuric acid and polyether ether ketone, stir for 4 h at 75 °C to obtain a coating solution with a concentration of 10% w / v, then spray the coating solution on the outer surface of the optical fiber to form a liquid film, cure at 200 °C for 60 min, then cure at 280 °C for 60 min, and finally cure at 360 °C for 80 min under nitrogen protection to form a polyether ether ketone coating with a thickness of 5 μm; spray a polytetrafluoroethylene composite coating made of 65 wt% polytetrafluoroethylene, 30 wt% nano-aluminum oxide (particle size of 10 nm), and 5 wt% silane coupling agent KH-560 on the outer surface of the optical fiber, with a spraying thickness of 100 μm, and cure after spraying. Control the heating rate at 3 °C / min, raise the temperature from room temperature to 360 °C, and cure for 40 min under nitrogen protection to obtain a corrosion-resistant special optical fiber.

[0034] Example 2

[0035] A preparation process for a corrosion-resistant special optical fiber, comprising the following steps:

[0036] (1) First, clean the quartz glass liner to ensure that its surface is pollution-free. After drying, install it on an MCVD lathe and rotate it. Then, introduce silicon tetrachloride with a flow rate of 1200 sccm, germanium tetrachloride with a flow rate of 250 sccm, carbon tetrafluoride with a flow rate of 65 sccm, and oxygen with a flow rate of 2500 sccm into the quartz glass liner for 50 min. Use inert gas helium as the carrier gas to ensure uniform mixing. At 1700 °C, allow the gas to undergo an oxidation reaction on the inner wall of the liner, deposit an F-Ge co-doped quartz layer in the quartz glass tube to obtain an optical fiber preform, and finally heat and draw it at 2100 °C to obtain an optical fiber;

[0037] (2) Clean the optical fiber with oxygen plasma with a flow rate of 30 sccm for 25 min to remove surface contaminants and activate the surface;

[0038] (3) Place the optical fiber in an atomic layer deposition device, alternately introduce silicon tetrachloride and propylene at 320 °C. The flow rates of silicon tetrachloride and propylene are both 20 sccm, the pulse time is 0.8 s for both, and the number of cycles is 600 times. A self-limiting surface reaction occurs on the surface of the optical fiber, and a SiC thin film grows layer by layer. The total thickness of the SiC thin film is 60 nm;

[0039] (4) Mix 98% concentrated sulfuric acid and polyether ether ketone, stir for 3.5 h at 78 °C to obtain a coating solution with a concentration of 11% w / v, then spray the coating solution on the outer surface of the optical fiber to form a liquid film, cure at 205 °C for 55 min, then cure at 290 °C for 55 min, and finally cure at 365 °C for 70 min under nitrogen protection to form a polyether ether ketone coating with a thickness of 6 μm; spray a polytetrafluoroethylene composite coating made of 70 wt% polytetrafluoroethylene, 24 wt% nano-aluminum oxide (particle size of 20 nm), and 6 wt% silane coupling agent A-171 on the outer surface of the optical fiber, with a spraying thickness of 110 μm, and cure after spraying. Control the heating rate at 3 °C / min, raise the temperature from room temperature to 365 °C, and cure for 35 min under nitrogen protection to obtain a corrosion-resistant special optical fiber.

[0040] Example 3

[0041] A preparation process for a corrosion-resistant special optical fiber, comprising the following steps:

[0042] (1) First, clean the quartz glass liner to ensure its surface is pollution-free. After drying, install it on the MCVD lathe and rotate it. Then, introduce silicon tetrachloride with a flow rate of 1500 sccm, germanium tetrachloride with a flow rate of 300 sccm, carbon tetrafluoride with a flow rate of 80 sccm, and oxygen with a flow rate of 3000 sccm into the quartz glass liner for 40 min. Use inert gas helium as the carrier gas to ensure uniform mixing. At 1800 °C, allow the gas to undergo an oxidation reaction on the inner wall of the liner, deposit an F-Ge co-doped quartz layer in the quartz glass tube to obtain an optical fiber preform, and finally draw the optical fiber by heating at 2100 °C.

[0043] (2) Clean the optical fiber with argon plasma with a flow rate of 35 sccm for 20 min to remove surface contaminants and activate the surface.

[0044] (3) Place the optical fiber in an atomic layer deposition device, alternately introduce silicon tetrachloride and propylene at 350 °C. The flow rates of silicon tetrachloride and propylene are both 30 sccm, the pulse time is 0.5 s for both, and the number of cycles is 800 times. A self-limiting surface reaction occurs on the surface of the optical fiber, and the SiC thin film grows layer by layer. The total thickness of the SiC thin film is 80 nm.

[0045] (4) Mix 98% concentrated sulfuric acid and polyether ether ketone, stir for 3 h at 80 °C to obtain a coating solution with a concentration of 12% w / v, then spray the coating solution on the outer surface of the optical fiber to form a liquid film, cure at 210 °C for 50 min, then cure at 300 °C for 50 min, and finally cure at 370 °C for 70 min under nitrogen protection to form a polyether ether ketone coating with a thickness of 8 μm; spray a polytetrafluoroethylene composite coating made of 75 wt% polytetrafluoroethylene, 20 wt% nano-aluminum oxide (particle size of 30 nm), and 5 wt% silane coupling agent KH-560 on the outer surface of the optical fiber, with a spraying thickness of 110 μm, and cure after spraying. Control the heating rate at 3 °C / min, raise the temperature from room temperature to 370 °C, and cure for 30 min under nitrogen protection to obtain a corrosion-resistant special optical fiber.

[0046] Example 4

[0047] A preparation process for a corrosion-resistant special optical fiber, comprising the following steps:

[0048] (1) First, clean the quartz glass liner to ensure that its surface is pollution-free. After drying, install it on the MCVD lathe and rotate it. Then, introduce silicon tetrachloride with a flow rate of 1800 sccm, germanium tetrachloride with a flow rate of 350 sccm, carbon tetrafluoride with a flow rate of 90 sccm, and oxygen with a flow rate of 3500 sccm into the quartz glass liner for 30 min. Use inert gas helium as the carrier gas to ensure uniform mixing. Oxidation reaction occurs on the inner wall of the liner at 1900 °C, and an F-Ge co-doped quartz layer is deposited in the quartz glass tube to obtain an optical fiber preform. Finally, heat and draw at 2200 °C to obtain an optical fiber;

[0049] (2) Clean the optical fiber with oxygen plasma with a flow rate of 40 sccm for 20 min to remove surface contaminants and activate the surface;

[0050] (3) Place the optical fiber in an atomic layer deposition device, alternately introduce silicon tetrachloride and propylene at 380 °C. The flow rates of silicon tetrachloride and propylene are both 40 sccm, the pulse time is 0.3 s for both, and the number of cycles is 850 times. Self-limiting surface reactions occur on the surface of the optical fiber, and the SiC thin film grows layer by layer. The total thickness of the SiC thin film is 85 nm;

[0051] (4) Mix 98% concentrated sulfuric acid and polyether ether ketone, stir for 2.5 h at 82 °C to obtain a coating solution with a concentration of 13% w / v, then spray the coating solution on the outer surface of the optical fiber to form a liquid film, cure at 210 °C for 50 min, then cure at 310 °C for 50 min, and finally cure at 370 °C for 60 min under nitrogen protection to form a polyether ether ketone coating with a thickness of 8 μm; spray a polytetrafluoroethylene composite coating made of 80 wt% polytetrafluoroethylene, 18 wt% nano-aluminum oxide (particle size of 40 nm), and 2 wt% silane coupling agent A-171 on the outer surface of the optical fiber, with a spraying thickness of 110 μm, and cure after spraying. Control the heating rate at 3 °C / min, raise the temperature from room temperature to 370 °C, and cure for 30 min under nitrogen protection to obtain a corrosion-resistant special optical fiber.

[0052] Example 5

[0053] A preparation process for a corrosion-resistant special optical fiber, comprising the following steps:

[0054] (1) First, clean the quartz glass liner to ensure that its surface is pollution-free. After drying, install it on an MCVD lathe and rotate it. Then, introduce silicon tetrachloride with a flow rate of 2000 sccm, germanium tetrachloride with a flow rate of 400 sccm, carbon tetrafluoride with a flow rate of 100 sccm, and oxygen with a flow rate of 4000 sccm into the quartz glass liner for 20 min. Use inert gas helium as the carrier gas to ensure uniform mixing. At 2000 °C, the gas undergoes an oxidation reaction on the inner wall of the liner, and an F-Ge co-doped quartz layer is deposited in the quartz glass tube to obtain an optical fiber preform. Finally, heat and draw at 2200 °C to obtain an optical fiber;

[0055] (2) Clean the optical fiber with argon plasma with a flow rate of 50 sccm for 15 min to remove surface contaminants and activate the surface;

[0056] (3) Place the optical fiber in an atomic layer deposition device, alternately introduce silicon tetrachloride and propylene at 400 °C. The flow rates of silicon tetrachloride and propylene are both 50 sccm, the pulse time is 0.1 s for both, and the number of cycles is 1000 times. A self-limiting surface reaction occurs on the surface of the optical fiber, and the SiC thin film grows layer by layer. The total thickness of the SiC thin film is 100 nm;

[0057] (4) Mix 98% concentrated sulfuric acid and polyether ether ketone, stir for 2 h at 85 °C to obtain a coating solution with a concentration of 15% w / v, then spray the coating solution on the outer surface of the optical fiber to form a liquid film, cure at 220 °C for 40 min, then cure at 320 °C for 40 min, and finally cure at 380 °C for 60 min under nitrogen protection to form a polyether ether ketone coating with a thickness of 10 μm; spray a polytetrafluoroethylene composite coating composed of 85 wt% polytetrafluoroethylene, 10 wt% nano-aluminum oxide (particle size of 50 nm), and 5 wt% silane coupling agent KH-56 on the outer surface of the optical fiber, with a spraying thickness of 120 μm, and cure after spraying. Control the heating rate at 3 °C / min, raise the temperature from room temperature to 380 °C, and cure for 20 min under nitrogen protection to obtain a corrosion-resistant special optical fiber.

[0058] Comparative Example 1

[0059] The difference between Comparative Example 1 and Example 3 lies in step (1): First, clean the quartz glass liner to ensure its surface is pollution-free. After drying, install it on the MCVD lathe and rotate it. Then, introduce silicon tetrachloride with a flow rate of 1500 sccm, carbon tetrafluoride with a flow rate of 80 sccm, and oxygen with a flow rate of 3000 sccm into the quartz glass liner for 40 min. Use inert gas helium as the carrier gas to ensure uniform mixing. At 1800 °C, the gas undergoes an oxidation reaction on the inner wall of the liner, and an F-Ge co-doped quartz layer is deposited in the quartz glass tube to obtain an optical fiber preform. Finally, draw the optical fiber by heating at 2100 °C. The remaining steps are the same as those in Example 3.

[0060] Comparative Example 2

[0061] The difference between Comparative Example 2 and Example 3 is that step (3) is not included, and the remaining steps are the same as those in Example 3.

[0062] Comparative Example 3

[0063] The difference between Comparative Example 3 and Example 3 lies in step (4): Mix 98% concentrated sulfuric acid and polyether ether ketone, stir for 3 h at 80 °C to obtain a coating solution with a concentration of 12% w / v, then spray the coating solution on the outer surface of the optical fiber to form a liquid film, cure at 210 °C for 50 min, then cure at 300 °C for 50 min, and finally cure at 370 °C for 70 min under nitrogen protection to form a polyether ether ketone coating with a thickness of 8 μm, thus obtaining the special optical fiber; the remaining steps are the same as those in Example 3.

[0064] Comparative Example 4

[0065] The difference between Comparative Example 4 and Example 3 lies in step (4): spraying a polytetrafluoroethylene composite coating made of 75 wt% polytetrafluoroethylene, 20 wt% nano-aluminum oxide (particle size of 30 nm), and 5 wt% silane coupling agent KH-560 on the outer surface of the optical fiber, with a spraying thickness of 110 μm. After spraying, curing is carried out, controlling the heating rate at 3 °C / min, raising the temperature from room temperature to 370 °C, and curing for 30 min under nitrogen protection to obtain a special optical fiber; the remaining steps are the same as those in Example 3.

[0066] Performance testing was carried out on the special optical fibers prepared in Examples 1-5 and Comparative Examples 1-4, and the test results are shown in Table 1.

[0067] Corrosion resistance testing: Immerse the special optical fibers prepared in Examples 1-5 and Comparative Examples 1-4 in 5% HCl or 5% NaOH solution for 30 days, and measure the increase in transmission loss after immersion compared to before immersion.

[0068] High-temperature and high-humidity stability testing: Place the special optical fibers prepared in Examples 1-5 and Comparative Examples 1-4 at 85 °C and 85% humidity for 1000 hours, and measure the increase in transmission loss after treatment compared to before treatment.

[0069] Mechanical property testing: Measure the increase in transmission loss of the special optical fibers prepared in Examples 1-5 and Comparative Examples 1-4 at a tensile strength of 5 GPa and a bending radius of 5 mm.

[0070] Optical property testing: Measure the transmission loss of the special optical fibers prepared in Examples 1-5 and Comparative Examples 1-4 at a wavelength of 1550 nm.

[0071] Table 1

[0072]

[0073]

[0074] It can be seen from the above test results that: the increase in transmission loss of the special optical fibers prepared in Examples 1-5 of the present invention after being immersed in 5% HCl or 5% NaOH solution for 30 days is less than 0.2 dB / km, while the increase in transmission loss of the special optical fibers prepared in Comparative Examples 1-4 after being immersed in 5% HCl or 5% NaOH solution for 30 days is greater than 0.4 dB / km. In particular, the increase in transmission loss of the special optical fiber prepared in Comparative Example 4 without coating the polytetrafluoroethylene composite coating is as high as 0.55 dB / km, indicating that the special optical fibers prepared in Examples 1-5 of the present invention are acid and alkali resistant and have excellent corrosion resistance.

[0075] The transmission loss increase of the special optical fibers prepared in Examples 1-5 of the present invention after 1000 hours at 85°C and 85% humidity is less than 0.3 dB / km, while the transmission loss increase of the special optical fibers prepared in Comparative Examples 1-4 after 1000 hours at 85°C and 85% humidity is greater than 0.45 dB / km. In particular, the transmission loss increase of the special optical fiber prepared in Comparative Example 3 without the polyetheretherketone coating is as high as 0.60 dB / km, indicating that the special optical fibers prepared in Examples 1-5 of the present invention can withstand high temperature and high humidity and have excellent high temperature and high humidity stability.

[0076] The transmission loss increase of the special optical fibers prepared in Examples 1-5 of the present invention at a tensile strength of 5 GPa and a bending radius of 5 mm is less than or equal to 0.15 dB / km, while the transmission loss increase of the special optical fibers prepared in Comparative Examples 1-4 at a tensile strength of 5 GPa and a bending radius of 5 mm is greater than 0.3 dB / km. In particular, the transmission loss increase of the special optical fiber prepared in Comparative Example 3 without the polyetheretherketone coating is as high as 0.57 dB / km, indicating that the special optical fibers prepared in Examples 1-5 of the present invention have strong tensile and bending resistance and excellent mechanical properties.

[0077] The transmission loss of the special optical fibers prepared in Examples 1-5 of the present invention at a wavelength of 1550 nm is less than or equal to 0.25 dB / km, while the transmission loss of the special optical fibers prepared in Comparative Examples 1-4 at a wavelength of 1550 nm is greater than 0.4 dB / km. In particular, the transmission loss of the special optical fiber prepared in Comparative Example 3 without the polyetheretherketone coating is as high as 0.58 dB / km, indicating that the special optical fibers prepared in Examples 1-5 of the present invention have excellent optical properties.

[0078] Therefore, it can be seen that the special optical fibers prepared in Examples 1-5 of the present invention can not only resist acids and alkalis and have excellent corrosion resistance, but also withstand high temperature and high humidity, have strong tensile and bending resistance, and have excellent high temperature and high humidity stability, mechanical properties and optical properties.

[0079] The above embodiments are only explanations of the present invention, and they do not limit the present invention. For those of ordinary skill in the art, any obvious changes made without departing from the principle and spirit of the present invention should be considered to be included within the protection scope of the claims of the present invention.

Claims

1. A preparation process of a corrosion-resistant special optical fiber, characterized in that, It includes the following steps: (1) A fiber preform is made by doping F-Ge into fused silica glass, and then the fiber is obtained by heating and drawing. (2) The fiber is cleaned using argon or oxygen plasma to remove surface contaminants and activate the surface. (3) A nanoscale SiC film is deposited on the outer surface of the fiber by atomic layer deposition. (4) A layer of polyetheretherketone (PEEK) coating is applied to the outer surface of the fiber, and after curing, a layer of polytetrafluoroethylene (PTFE) composite coating is applied, and a corrosion-resistant special fiber is obtained after curing.

2. The preparation process of the corrosion-resistant special optical fiber according to claim 1, characterized in that, The preparation method of the fiber preform in step (1) is as follows: First, clean the fused silica glass liner to ensure its surface is contamination-free. After drying, install it on an MCVD lathe and rotate it. Then, introduce silicon tetrachloride, germanium tetrachloride, carbon tetrafluoride, and oxygen into the fused silica glass liner, and use the inert gas helium as the carrier gas to ensure uniform mixing. An oxidation reaction occurs on the inner wall of the liner at 1600 - 2000 °C, and an F-Ge co-doped silica layer is deposited in the fused silica glass tube to obtain the fiber preform.

3. The preparation process of the corrosion-resistant special optical fiber according to claim 2, characterized in that, The flow rates of the silicon tetrachloride, germanium tetrachloride, carbon tetrafluoride, and oxygen are 1000 - 2000 sccm, 200 - 400 sccm, 50 - 100 sccm, and 2000 - 4000 sccm respectively, and the treatment time is 20 - 60 min.

4. The preparation process of the corrosion-resistant special optical fiber as described in claim 1, characterized in that, The heating temperature in step (1) is 2000 - 2200 °C.

5. The preparation process of the corrosion-resistant special optical fiber according to claim 1, characterized in that, The flow rate of the argon or oxygen in step (2) is 20 - 50 sccm, and the treatment time is 15 - 30 min.

6. The preparation process of the corrosion-resistant special optical fiber according to claim 1, characterized in that, The deposition method of the nanoscale SiC film in step (3) is: Place the fiber in an atomic layer deposition device, and alternately introduce silicon tetrachloride and propylene at 300 - 400 °C. A self-limiting surface reaction occurs on the fiber surface, and the SiC film grows layer by layer. Among them, the flow rates of the silicon tetrachloride and propylene are both 10 - 50 sccm, the pulse time is both 0.1 - 1.0 seconds, the number of cycles is 500 - 1000 times, and the thickness of the SiC film is 50 - 100 nm.

7. The preparation process of the corrosion-resistant special optical fiber according to claim 1, characterized in that, The coating method of the polyetheretherketone coating in step (4) is: Mix 98% concentrated sulfuric acid and polyetheretherketone, stir at 75 - 85 °C for 2 - 4 h to obtain a coating solution with a concentration of 10 - 15% w / v, and then spray the coating solution on the outer surface of the fiber to form a liquid film, which becomes a polyetheretherketone coating after stepwise curing. Among them, the thickness of the polyetheretherketone coating is 5 - 10 μm, and the stepwise curing process is: First, cure at 200 - 220 °C for 40 - 60 min, then cure at 280 - 320 °C for 40 - 60 min, and finally cure at 360 - 380 °C for 60 - 80 min under nitrogen protection.

8. The preparation process of the corrosion-resistant special optical fiber according to claim 1, characterized in that, The polytetrafluoroethylene composite coating in step (4) is made of the following raw materials by mass percentage: 65 - 85% polytetrafluoroethylene, 10 - 30% nano-aluminum oxide, and 2 - 6% silane coupling agent; among them, the particle size of the nano-aluminum oxide is 10 - 50 nm, and the silane coupling agent is KH-560 or A-171.

9. The preparation process of the corrosion-resistant special optical fiber according to claim 8, characterized in that, The coating method of the polytetrafluoroethylene composite coating is spraying, the spraying thickness is 100 - 120 μm, and after spraying, curing is carried out. The heating rate is controlled at 3 °C / min, the temperature is raised from room temperature to 360 - 380 °C, and curing is carried out for 20 - 40 min under nitrogen protection.

10. A corrosion-resistant special optical fiber, characterized in that, It is prepared by using the preparation process of the special optical fiber described in any one of claims 1 - 9.

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