Radiation-resistant optical fiber and preparation method thereof
By introducing a gradient transition layer and doping it with fluoride into the radiation-resistant optical fiber, the problems of microcracks and bubble defects in the optical fiber during the drawing process are solved, thereby improving the reliability and radiation absorption capacity of the optical fiber.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-04
- Publication Date
- 2026-04-10
AI Technical Summary
Radiation-resistant optical fibers are prone to internal defects such as microcracks or bubbles during the fiber drawing process, which leads to a decrease in overall reliability.
A gradient transition layer design is adopted, in which the proportion of fluoride doping gradually changes from the core layer to the outer cladding layer. The radiation absorption characteristics of fluoride enhance the absorption capacity of the optical fiber for high-energy radiation, optimize the interface stress distribution, and avoid the introduction of structural defects such as air holes.
It effectively reduces the probability of internal defects such as bubbles and cracks during the fiber drawing process, and improves the overall reliability and radiation resistance of the optical fiber.
Smart Images
Figure CN121831995A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical fiber technology, and in particular to a radiation-resistant optical fiber and its preparation method. Background Technology
[0002] Radiation-resistant optical fiber is a special type of optical fiber designed for high-energy radiation environments. It is widely used in nuclear energy facilities, aerospace, medical equipment, high-energy physics experiments, and industrial radiation monitoring.
[0003] In related technologies, radiation-resistant optical fibers consist of a core layer and a cladding layer, with air hole structures designed in the cladding layer to absorb radiation energy and reduce the impact of radiation energy on the core layer.
[0004] However, the aforementioned radiation-resistant optical fibers are prone to internal defects such as microcracks or bubbles during the fiber drawing process, which leads to a decrease in the overall reliability of the radiation-resistant optical fibers. Summary of the Invention
[0005] This application provides a radiation-resistant optical fiber and its preparation method to solve the problem in related technologies that radiation-resistant optical fibers are prone to microcracks or bubbles during the drawing process, which leads to a decrease in the overall reliability of the radiation-resistant optical fiber.
[0006] On the one hand, this application provides a radiation-resistant optical fiber, comprising:
[0007] Core layer;
[0008] A gradient transition layer that encloses the core layer;
[0009] An outer layer that encloses the gradient transition layer;
[0010] The gradient transition layer is doped with fluoride, and the doping ratio of the fluoride gradually changes along the direction from the core layer to the outer cladding layer.
[0011] In one possible implementation, the gradient transition layer includes an inner cladding layer, a recessed layer, and a buffer layer, all of which are doped with the fluoride. The inner cladding layer encloses the core layer, the recessed layer encloses the inner cladding layer, the buffer layer encloses the recessed layer, and the outer cladding layer encloses the buffer layer.
[0012] The doping ratio of fluoride in the sunken layer is greater than that in the inner cladding layer, and the doping ratio of fluoride in the buffer layer is less than that in the sunken layer.
[0013] In one possible implementation, the doping ratio of the fluoride in the inner cladding is 0% to 1%;
[0014] And / or, the doping ratio of the fluoride in the sunken layer is 1% to 3.5%;
[0015] and / or, the doping ratio of the fluoride in the buffer layer is 0.5%~1.5%.
[0016] In a possible implementation, the buffer layer is further doped with hydroxyl.
[0017] In a possible implementation, the relative refractive index difference Δn1 of the core layer is 0.15%~0.25%;
[0018] and / or, the relative refractive index difference Δn2 of the inner cladding layer is -0.1%~-0.01%;
[0019] and / or, the relative refractive index difference Δn3 of the lower depression layer is -0.06%~-0.04%;
[0020] and / or, the relative refractive index difference Δn4 of the buffer layer is -0.15%~-0.05%;
[0021] and / or, the relative refractive index difference Δn5 of the outer cladding layer is 0.
[0022] In a possible implementation, the radius range of the core layer is 0~r1, and r1 is 4μm~4.7μm;
[0023] and / or, the radius range of the inner cladding layer is r1~r2, and the difference between r2 and r1 is 2μm~4μm;
[0024] and / or, the radius range of the lower depression layer is r2~r3, and the difference between r3 and r2 is 2μm~5μm;
[0025] and / or, the radius range of the buffer layer is r3~r4, and the difference between r4 and r3 is 4μm~15μm;
[0026] and / or, the radius range of the outer cladding layer is r4~r5, and r5 is 62μm~63μm.
[0027] In a possible implementation, the core layer comprises silicide, germanide, fluoride and potassium ion;
[0028] The ratio relationship between the silicide, the germanide, the fluoride and the potassium ion is (1-a-b-c):a:b:c, wherein a is 0.2%~1.2%, b is 0.05%~0.45%, and c is 0~0.25%.
[0029] In a possible implementation, a coating layer is further included, which is coated on the surface of the outer cladding layer.
[0030] In a possible implementation, the coating includes an inner coating and an outer coating, the inner coating is coated on the surface of the cladding layer, the outer coating is coated on the surface of the inner coating, the elastic modulus of the inner coating is less than or equal to 2 MPa, and the elastic modulus of the outer coating is greater than or equal to 500 MPa.
[0031] In another aspect, the application provides a preparation method for the radiation-resistant optical fiber in any of the above embodiments, including the following steps:
[0032] The gradient transition layer in the radiation-resistant optical fiber is wrapped around the core layer in the radiation-resistant optical fiber;
[0033] The cladding layer in the radiation-resistant optical fiber is wrapped around the gradient transition layer;
[0034] The gradient transition layer is doped with fluoride, and the doping proportion of the fluoride gradually changes in the direction from the core layer to the cladding layer.
[0035] The application provides a radiation-resistant optical fiber and a preparation method thereof, wherein the radiation-resistant optical fiber includes a core layer, a gradient transition layer, and a cladding layer, the gradient transition layer wraps the core layer, and the cladding layer wraps the gradient transition layer; the core layer, the gradient transition layer, and the cladding layer are sequentially wrapped from inside to outside, the gradient transition layer is doped with fluoride, and the doping proportion of the fluoride gradually changes in the direction from the core layer to the cladding layer. In this way, the core layer is connected to the cladding layer through the gradient transition layer, the absorption capacity of the optical fiber to high-energy radiation is enhanced through the radiation absorption characteristics of fluorine elements in the fluoride, and structural defects such as air holes are avoided. The doping proportion of the fluoride in the gradient transition layer gradually changes from inside to outside to realize the gradual matching of the viscosity and the refractive index among the core layer, the gradient transition layer, and the cladding layer. Therefore, the interface stress distribution is optimized, the material layering or structural instability caused by the viscosity difference is reduced, and the generation probability of internal defects such as bubbles and cracks in the optical fiber drawing process is reduced. The problem that the radiation-resistant optical fiber in the related art is prone to internal defects such as micro-cracks or bubbles in the drawing process, thereby reducing the overall reliability of the radiation-resistant optical fiber is solved. BRIEF DESCRIPTION OF DRAWINGS
[0036] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate an embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.
[0037] Figure 1 A structural schematic diagram of a radiation-resistant optical fiber provided by an embodiment of the application;
[0038] Figure 2 A refractive index and radius distribution diagram of a radiation-resistant optical fiber provided by an embodiment of the application;
[0039] Figure 3A structural diagram of an optical fiber processing apparatus used in a manufacturing method according to an embodiment of the present application.
[0040] Reference numerals:
[0041] 1 - optical fiber preform;
[0042] 10 - preform feeder;
[0043] 20 - drawing furnace;
[0044] 30 - holding furnace unit;
[0045] 40 - bare fiber testing unit;
[0046] 50 - bare fiber protection tube;
[0047] 60 - coating unit;
[0048] 70 - curing unit;
[0049] 80 - optical fiber size testing unit;
[0050] 90 - take-up unit;
[0051] 100 - core layer;
[0052] 200 - gradient transition layer; 210 - inner cladding layer; 220 - depressed layer; 230 - buffer layer;
[0053] 300 - outer cladding layer;
[0054] 400 - coating layer;
[0055] 410 - inner coating layer;
[0056] 420 - outer coating layer.
[0057] The above-described drawings have shown specific embodiments of the present application, which will be described in more detail hereinafter. These drawings and written description are not meant to limit the scope of the present application in any way, but merely to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION
[0058] Exemplary embodiments will be described in detail with reference to the drawings, of which examples are shown. Unless otherwise noted, the same numbers on different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments are not meant to represent all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the appended claims.
[0059] At present, several common high-energy radiation classifications are shown in Table 1. Among them, high-energy electromagnetic radiation and neutron (especially fast neutron) radiation have relatively large penetration ability, which can generally reach several centimeters; while the radiation penetration depth of particle beams such as alpha particles and deuterium nuclei can only reach the micron to millimeter range, only causing surface defects of the material. The research on the radiation resistance of optical fibers is mostly carried out in the first two radiation environments.
[0060] Table 1:
[0061]
[0062] High-energy irradiation can easily cause displacement of electrons or atomic nuclei and structural changes in the glass. The so-called displacement of electrons is to deviate from the original motion track, such as bond breaking caused by radiation, and electrons are captured by adjacent impurity atoms or defect cores. The displacement of atomic nuclei refers to its deviation from the original equilibrium position, thereby leaving a vacancy (Schottky defect) or forming a vacancy-interstitial atom (Frenkel defect) on the lattice site. Specifically, high-energy radiation can cause physical and chemical changes (such as hardening, embrittlement, discoloration, etc.) in quartz optical fibers, produce various defects in the quartz core, and thus deteriorate the transmission performance of the optical fiber, mainly manifested as: ① formation of color centers, rapid increase of loss in the visible light band, and even excitation of fluorescence; ② moderate dose of radiation can cause changes in the internal density of the optical fiber and the corresponding refractive index, which changes the refractive index distribution of the optical fiber and affects its transmission performance and bandwidth; ③ high dose of radiation can cause the deterioration of the organic cladding layer, increase the cladding interface loss, and may also lead to the decrease of the mechanical properties of the optical fiber; ④ radiation can cause changes in the bond structure of the core glass, which changes the infrared absorption performance of the optical fiber.
[0063] In the related art, radiation-resistant optical fibers are special optical fibers designed for high-energy radiation environments, and are widely used in nuclear energy facilities, aerospace, medical equipment, high-energy physics experiments, and industrial radiation monitoring fields.
[0064] The radiation-resistant optical fiber includes a core layer and a cladding layer, and an air hole structure is designed in the cladding layer to absorb radiation energy and reduce the influence of the radiation energy on the core layer.
[0065] However, the introduction of the air hole can significantly weaken the mechanical strength of the optical fiber, and as a man-made structural defect, the air hole can easily cause micro-cracks or bubbles in the drawing process of the radiation-resistant optical fiber, resulting in a decrease in the overall reliability of the radiation-resistant optical fiber.
[0066] Therefore, the application provides a radiation-resistant optical fiber and a preparation method thereof. The radiation-resistant optical fiber comprises a core layer, a gradient transition layer, and an outer cladding layer. The gradient transition layer wraps the core layer, and the outer cladding layer wraps the gradient transition layer. The core layer, the gradient transition layer, and the outer cladding layer are sequentially wrapped from inside to outside. The gradient transition layer is doped with fluoride, and the doping proportion of the fluoride gradually changes along the direction from the core layer to the outer cladding layer. The core layer is connected with the outer cladding layer through the gradient transition layer. The absorption capacity of the optical fiber to high-energy radiation is enhanced through the radiation absorption characteristics of fluorine elements in the fluoride, and structural defects such as air holes are avoided. The doping proportion of the fluoride in the gradient transition layer gradually changes from inside to outside, so as to realize the gradual matching of the viscosity and the refractive index among the core layer, the gradient transition layer, and the outer cladding layer. The interface stress distribution is optimized, the material layering or structural instability caused by the viscosity difference is reduced, and then the generation probability of internal defects such as bubbles and cracks in the optical fiber drawing process is reduced. The problem that the radiation-resistant optical fiber in the related art is prone to generate internal defects such as micro-cracks or bubbles in the drawing process, and the overall reliability of the radiation-resistant optical fiber is reduced is solved.
[0067] The technical solutions of the application and how the technical solutions solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples. The embodiments of the application will be described below with reference to the drawings.
[0068] As shown in the drawings, the radiation-resistant optical fiber provided by the application comprises: Figure 1
[0069] a core layer 100;
[0070] a gradient transition layer 200, the gradient transition layer 200 wrapping the core layer 100;
[0071] an outer cladding layer 300, the outer cladding layer 300 wrapping the gradient transition layer 200;
[0072] The core layer 100, the gradient transition layer 200, and the outer cladding layer 300 are sequentially wrapped from inside to outside. The gradient transition layer 200 is doped with fluoride, and the doping proportion of the fluoride gradually changes along the direction from the core layer 100 to the outer cladding layer 300. The gradient transition layer 200 and the outer cladding layer 300 form a cladding whole.
[0073] In the embodiment, the main constituent substances in the core layer 100, the gradient transition layer 200, and the outer cladding layer 300 can be silicon dioxide (SiO2), and can also be silicon tetrachloride or other silicon oxides, which are not limited.
[0074] In addition, the fluoride is doped in the gradient transition layer 200, and the doping proportion of the fluoride gradually changes from inside to outside (i.e. in the direction from the core layer 100 to the outer cladding layer 300). For example, the doping proportion of the fluoride gradually increases first and then gradually decreases from inside to outside, or gradually increases or gradually decreases, or gradually decreases first and then gradually increases.
[0075] The doped fluoride can be ammonium fluoride, ammonium hexafluorosilicate, ammonium hexafluorophosphate, etc., and is not limited in this regard.
[0076] In this way, the core layer 100 is connected to the outer cladding layer 300 through the gradient transition layer 200, the absorption capacity of the optical fiber to high-energy radiation is enhanced through the radiation absorption characteristics of the fluorine element in the fluoride, and structural defects such as air holes are avoided. In addition, the doping proportion of the fluoride in the gradient transition layer 200 gradually changes from inside to outside, so as to realize the gradual matching of the viscosity and the refractive index among the core layer 100, the gradient transition layer 200 and the outer cladding layer 300. Thus, the interface stress distribution is optimized, the material layering or structural instability caused by the viscosity difference is reduced, and the generation probability of internal defects such as bubbles and cracks in the optical fiber drawing process is further reduced. The problem of the internal defects such as micro-cracks or bubbles in the radiation-resistant optical fiber in the drawing process in the related art, which leads to the decline of the overall reliability of the radiation-resistant optical fiber, is solved.
[0077] In the embodiment, as shown in FIG. 1, the gradient transition layer 200 includes an inner cladding layer 210, a depression layer 220 and a buffer layer 230, which are all doped with fluoride. The inner cladding layer 210 wraps the core layer 100, the depression layer 220 wraps the inner cladding layer 210, the buffer layer 230 wraps the depression layer 220, and the outer cladding layer 300 wraps the buffer layer 230. Figure 1
[0078] The doping proportion of the fluoride in the depression layer 220 is greater than that in the inner cladding layer 210, and the doping proportion of the fluoride in the buffer layer 230 is less than that in the depression layer 220.
[0079] Thus, through the inner cladding layer 210, the depression layer 220 and the buffer layer 230, the doping proportion of the fluoride in the gradient transition layer 200 gradually increases first and then decreases in the direction from the core layer 100 to the outer cladding layer 300, so as to realize the gradual matching of the viscosity and the refractive index among the core layer 100, the gradient transition layer 200 and the outer cladding layer 300. Thus, the interface stress distribution is optimized, the material layering or structural instability caused by the viscosity difference is reduced, and the generation probability of internal defects such as bubbles and cracks in the optical fiber drawing process is further reduced.
[0080] It can be understood that the main constituent substances in the inner cladding layer 210, the depression layer 220 and the buffer layer 230 can also be silicon dioxide (SiO2).
[0081] In some embodiments, the doping ratio of fluoride in the inner cladding 210 is 0% to 1%;
[0082] And / or, the fluoride doping ratio in the sunken layer 220 is 1%~3.5%;
[0083] And / or, the fluoride doping ratio in the buffer layer 230 is 0.5%~1.5%.
[0084] In this embodiment, the inner cladding layer 210 is composed of silicon dioxide and fluoride, with SiO2:F = (1-a):a, where a ranges from 0% to 1%. The recessed layer 220 is composed of silicon dioxide and fluoride, with SiO2:F = (1-a):a, where a ranges from 1% to 3.5%. The buffer layer 230 is composed of silicon dioxide and fluorine, with SiO2:F = (1-a):a, where a ranges from 0.5% to 1.5%.
[0085] Therefore, during implementation, the fluoride doping ratios in the inner cladding 210, the recessed layer 220, and the buffer layer 230 can be reasonably controlled. This allows the radiation absorption characteristics of fluorine in the fluoride to enhance the optical fiber's absorption capacity for high-energy radiation, while avoiding the introduction of structural defects such as air holes. In other words, fluorine doping alters the electronic structure of the glass matrix, enhancing its ability to capture radiation energy and thus suppressing the formation of color center defects. Consequently, without sacrificing mechanical strength, the radiation resistance of the optical fiber can be significantly improved, enabling long-term stable operation in environments such as nuclear reactors and particle accelerators.
[0086] Meanwhile, the buffer layer 230 is also doped with hydroxyl groups (-OH), with a concentration between 500 and 1500 ppm. Among them, -OH is a derivative product and can be classified into the SiO2 concentration.
[0087] Therefore, by adding a certain concentration of -OH to the buffer layer 230, the -OH will preferentially absorb high-energy particles (such as free electrons and holes) generated by irradiation under irradiation environments such as γ-rays and ultraviolet rays, thereby increasing the absorption of irradiation by the buffer layer 230 and also increasing the radiation resistance of the optical fiber.
[0088] like Figure 2 As shown, in some embodiments, the relative refractive index difference Δn1 of the core layer 100 is 0.15%~0.25%;
[0089] And / or, the relative refractive index difference Δn2 of the inner cladding 210 is -0.1% to -0.01%;
[0090] And / or, the relative refractive index difference Δn3 of the depressed layer 220 is -0.06% to -0.04%;
[0091] And / or, the relative refractive index difference Δn4 of the buffer layer 230 is -0.15% to -0.05%;
[0092] And / or, the relative refractive index difference Δn5 of the outer cladding 300 is 0.
[0093] In this embodiment, the relative refractive index difference Δn1 of the core layer 100 is 0.15%~0.25%; the relative refractive index difference Δn2 of the inner cladding layer 210 is -0.1%~-0.01%; the relative refractive index difference Δn3 of the recessed layer 220 is -0.06%~-0.04%; the relative refractive index difference Δn4 of the buffer layer 230 is -0.15%~-0.05%; and the relative refractive index difference Δn5 of the outer cladding layer 300 is 0.
[0094] Therefore, by using a gradient relative refractive index difference distribution, the relative refractive index difference between layers can be smoothly transitioned, further optimizing the distribution of radiated energy, reducing material damage caused by local energy concentration, and simultaneously reducing the viscosity difference between layers.
[0095] like Figure 2 As shown, in some embodiments, the radius of the core layer 100 ranges from 0 to r1, where r1 is 4 μm to 4.7 μm;
[0096] And / or, the radius of the inner cladding 210 is in the range of r1~r2, and the difference between r2 and r1 is 2μm~4μm;
[0097] And / or, the radius of the sunken layer 220 is in the range of r2~r3, and the difference between r3 and r2 is 2μm~5μm;
[0098] And / or, the radius of the buffer layer 230 is in the range of r3~r4, and the difference between r4 and r3 is 4μm~15μm;
[0099] And / or, the radius of the outer cladding 300 ranges from r4 to r5, where r5 is 62 μm to 63 μm.
[0100] In this embodiment, the radius of the core layer 100 ranges from 0 to r1, where r1 is 4 μm to 4.7 μm; the radius of the inner cladding layer 210 ranges from r1 to r2, where the difference between r2 and r1 is 2 μm to 4 μm; the radius of the recessed layer 220 ranges from r2 to r3, where the difference between r3 and r2 is 2 μm to 5 μm; the radius of the buffer layer 230 ranges from r3 to r4, where the difference between r4 and r3 is 4 μm to 15 μm; and the radius of the outer cladding layer 300 ranges from r4 to r5, where r5 is 62 μm to 63 μm.
[0101] Therefore, by precisely controlling the radius range of the core layer 100, inner cladding layer 210, recessed layer 220, buffer layer 230, and outer cladding layer 300, and combining this with a smooth transition of relative refractive index difference, performance can be improved while ensuring mechanical stability.
[0102] In some embodiments, the core layer 100 comprises silicate, germanate, fluoride and potassium ions;
[0103] The ratio between the silicate, germanate, fluoride and potassium ions is (1-a-b-c):a:b:c, wherein a is 0.2%~1.2%, b is 0.05%~0.45%, and c is 0~0.25%.
[0104] In this embodiment, the silicate can be silicon dioxide (SiO2), the germanate can be germanium dioxide (GeO2), the fluoride can be ammonium fluoride, ammonium hexafluorosilicate, ammonium hexafluorophosphate, etc.; the potassium ion (K + ) can be doped with potassium bromide, potassium chloride or other raw materials to achieve the purpose of doping potassium ions.
[0105] So that SiO2:GeO2:F:K + =(1-a-b-c):a:b:c, wherein a is 0.2%~1.2%, b is 0.05%~0.45%, and c is 0~0.25%.
[0106] Therefore, by doping K + in the core layer 100, the refractive index is ensured while the viscosity of the core layer 100 is reduced, so that the viscosity of the core layer 100 and the cladding layer is more matched, the relative expansion coefficient is reduced, and it is beneficial to the drawing forming.
[0107] In other embodiments, the silicate can also be silicon tetrachloride or other, and the germanate can also be germanium tetrachloride or other, which is not limited.
[0108] In addition, the radiation-resistant optical fiber designed according to the above has good bending resistance and fiber attenuation characteristics. The bending resistance can achieve a loss of ≥0.5dB at a bending radius of 7.5mm at a wavelength of 1550nm, a loss of ≤1dB at a wavelength of 1625nm, a loss of ≤0.33dB / km at a wavelength of 1310nm, and a loss of ≤0.18dB / km at a wavelength of 1550nm.
[0109] As shown in Figure 1 , in some embodiments, a coating layer 400 is further included, which is coated on the surface of the outer cladding layer 300.
[0110] The coating layer 400 can be a resin coating or other high-molecular organic coating. After the coating layer 400 is cured, the core layer 100 and the cladding layer as a whole can be mechanically protected by the coating layer 400, reducing the possibility of mechanical damage to the radiation-resistant optical fiber as a whole by external forces, and improving the corrosion resistance of the radiation-resistant optical fiber.
[0111] As shown in Figure 1As shown, in some embodiments, the coating layer 400 comprises an inner coating layer 410 coated on the surface of the outer cladding layer 300 and an outer coating layer 420 coated on the surface of the inner coating layer 410, the inner coating layer 410 has an elastic modulus ≤ 2 MPa, and the outer coating layer 420 has an elastic modulus ≥ 500 MPa.
[0112] That is, the coating layer 400 comprises the inner coating layer 410 and the outer coating layer 420 coated on the outer cladding layer 300 in sequence, and both the inner coating layer 410 and the outer coating layer 420 are resin materials.
[0113] For example, the inner coating layer 410 can be configured to have an elastic modulus ≤ 2 MPa after curing, an elongation at break ≥ 120%, a material density of the inner coating layer 410 being 0.95-1.3 g / cm3, a glass transition temperature ≥ 0 ℃, a material viscosity of the inner coating layer 410 at 25 ℃ being 2500-7500 cps, a coating temperature being 28-60 ℃, a material viscosity of the inner coating layer 410 during coating being 1500-3000 cps, a thermal weight loss ≤ 10% after 48 h at 200 ℃, a coating pressure of the inner coating layer 410 during coating being 0.04-0.5 MPa, and a total diameter of the radiation-resistant optical fiber after coating and curing of the inner coating layer 410 being 180-200 μm.
[0114] For example, the outer coating layer 420 can be configured to have an elastic modulus ≥ 500 MPa after curing, an elongation at break ≥ 10%, a material density of the outer coating layer 420 being 0.95-1.3 g / cm3, a glass transition temperature ≥ 50 ℃, a material viscosity of the outer coating layer 420 at 25 ℃ being 2500-6500 cps, a coating temperature being 25-55 ℃, a material viscosity of the outer coating layer 420 during coating being 1500-3500 cps, a thermal weight loss ≤ 10% after 48 h at 200 ℃, a coating pressure of the outer coating layer 420 during coating being 0.04-0.5 MPa, and a total diameter of the radiation-resistant optical fiber after coating of the outer coating layer 420 being 235-255 μm.
[0115] Thus, the inner coating layer 410 and the outer coating layer 420 are coated in steps, the inner coating layer 410 has soft hardness and good elasticity, and the outer coating layer 420 has high hardness and good wear resistance. The inner coating layer 410 can play a role of buffering and damping, and the outer coating layer 420 can play a role of resisting external mechanical wear and protecting the internal structure, thereby avoiding the defects of a single coating layer.
[0116] In summary, the radiation-resistant optical fiber provided by the embodiments of the present application has the core layer 100 connected with the outer cladding layer 300 through the gradient transition layer 200, the radiation absorption capability of the optical fiber to high-energy radiation is enhanced through the radiation absorption characteristics of fluorine elements in the fluorides, and structural defects such as air holes are avoided. In addition, the doping proportion of the fluorides in the gradient transition layer 200 gradually changes from the inside to the outside, so as to realize the gradual matching of the viscosity and the refractive index among the core layer 100, the gradient transition layer 200 and the outer cladding layer 300. Thus, the interface stress distribution is optimized, the material layering or structural instability caused by the viscosity difference is reduced, and then the generation probability of internal defects such as bubbles and cracks in the optical fiber drawing process can be reduced. The problem that the radiation-resistant optical fiber in the related art is prone to generate internal defects such as micro-cracks or bubbles in the drawing process, and thus the overall reliability of the radiation-resistant optical fiber is reduced, is solved.
[0117] The preparation method provided by the embodiments of the present application is used for preparing the radiation-resistant optical fiber in any of the above embodiments, and includes the following steps:
[0118] The gradient transition layer 200 in the radiation-resistant optical fiber is wrapped around the core layer 100 in the radiation-resistant optical fiber;
[0119] The outer cladding layer 300 in the radiation-resistant optical fiber is wrapped around the gradient transition layer 200, so as to form the optical fiber preform 1;
[0120] The fluorides are doped in the gradient transition layer 200, and the doping proportion of the fluorides gradually changes along the direction from the core layer 100 to the outer cladding layer 300;
[0121] The optical fiber preform 1 is sequentially subjected to the steps of melt drawing, annealing, coating, solidification and irradiation treatment.
[0122] In the implementation, the optical fiber preform 1 including the core layer 100, the gradient transition layer 200 and the outer cladding layer 300 can be prepared by using a vapor deposition method. Subsequently, the optical fiber preform 1 can be subjected to the steps of melt drawing, annealing, coating and solidification treatment by using an optical fiber processing device.
[0123] For example, as shown in Figure 3 The optical fiber processing device can include a preform feeder 10, a drawing furnace 20, a holding furnace unit 30, a bare fiber testing unit 40, a bare fiber protection tube 50, a coating unit 60, a solidification unit 70, an optical fiber size testing unit 80 and a take-up unit 90. Of course, an existing optical fiber processing device can also be used.
[0124] The fiber preform 1 is placed in the drawing furnace 20 by the rod feeder 10. The drawing furnace 20 is used to melt the fiber preform 1 to draw it into a bare fiber. The annealing furnace unit 30 is used to anneal and heat the bare fiber to gradually reduce the temperature of the bare fiber. The bare fiber testing unit 40 is used to test the bare fiber to detect the relevant parameters of the bare fiber. The bare fiber protection tube 50 is used to protect the extension process of the bare fiber. The coating unit 60 is used to coat the bare fiber. The curing unit 70 is used to cure the coated bare fiber. The fiber size testing unit 80 is used to test the size of the cured fiber. The take-up unit 90 is used to collect the fiber.
[0125] Based on the fiber processing equipment, the melting and drawing can include: placing the fiber preform 1 in the drawing furnace 20 by the rod feeder 10, the drawing furnace 20 being one of an induction drawing furnace and a graphite drawing furnace, the temperature of the drawing furnace 20 being raised to 1800-2200°C and the fiber preform 1 being placed in the drawing furnace 20 to melt, the melting environment being filled with a protective gas, the protective gas being preferably an inert gas, and the gas being one of argon or helium or a mixture of the two, the flow rate of the mixture being 10-30 L / min, and the oxygen content in the protective gas environment being ≤200 ppm. The fiber drawing speed is 20-300 m / min.
[0126] The annealing can include: installing n annealing furnace units 30 (1≤n≤2) on the fiber path, the temperatures of the different annealing furnace units 30 being set in a gradient from top to bottom, the temperature of the fiber entering the annealing furnace unit 30 being between 1100°C and 1600°C, and the temperature of the fiber after completing the annealing being 750°C-900°C. The entire annealing process is completed in a nitrogen environment, and the oxygen content in the nitrogen environment is less than 200 ppm. Compared with other processes, the fiber with the above structural design only needs at most two annealing furnace units 30 to achieve the annealing effect.
[0127] The coating can include: using the coating unit 60 to perform inner coating 410 and outer coating 420 coating in turn. ① Inner coating 410 coating: after curing, the elastic modulus is ≤2 MPa, the elongation at break is ≥120%, the inner coating 410 material density is 0.95-1.3 g / cm3, the glass transition temperature is ≥0℃, the inner coating 410 material viscosity at 25℃ is 2500-7500 cps, the coating temperature is 28-60℃, the inner coating 410 material viscosity during coating is 1500-3000 cps, the thermal weight loss after 48 h at 200℃ is ≤10%, the coating process pressure is set to 0.04-0.5 Mpa, and the fiber diameter after the inner coating 410 coating is cured is 180-200 μm. ② Outer coating 420 coating: after curing, the elastic modulus is ≥500 MPa, the elongation at break is ≥10%, the outer coating 420 material density is 0.95-1.3 g / cm3, the glass transition temperature is ≥50℃, the outer coating 420 material viscosity at 25℃ is 2500-6500 cps, the coating temperature is 25-55℃, the outer coating 420 material viscosity during coating is 1500-3500 cps, the thermal weight loss after 48 h at 200℃ is ≤10%, the coating process outer coating 420 coating pressure is set to 0.04-0.5 Mpa, and the fiber diameter after coating is 235-255 μm.
[0128] The curing can include: the curing unit 70 can use one of UV curing or LED curing, the curing environment is isolated using a non-oxygen gas, the gas used is one of nitrogen, helium, argon or a mixed gas of any ratio of them. The single curing furnace gas flow is 20-30 L, and the oxygen content in the curing environment is less than 50 ppm. During the curing process, the optical fiber passes through different curing furnaces, and after curing by the curing furnaces, the inner coating 410 curing degree is 87-92%, and the outer coating 420 curing degree is 90-100%, wherein the outer coating 420 curing degree cannot be less than the inner coating 410 curing degree.
[0129] The irradiation treatment includes: placing the optical fiber in an irradiation environment (the radiation source can be cobalt 60), the total dose of a single time is 200 rad, and the total time length is 30-60 min. After the optical fiber is irradiated and taken out, it is placed for 1-2 h and then repeatedly irradiated, the total number of times is 10-20 times, if the optical fiber appears a slight yellowing phenomenon at a certain time, it is completed, and if there is no yellowing phenomenon, it can be continuously performed for 20 times until the end.
[0130] Thus, by doping potassium ions in the core layer 100, the viscosity matching problem of the core layer 100 and the cladding layer can be solved; at the same time, by doping fluorides in the cladding layer, the irradiation absorption problem can be solved without creating internal defects; and the irradiation pretreatment of the original irradiation further improves the irradiation resistance of the optical fiber.
[0131] It should be understood that many of the materials and devices exemplified in this disclosure are articles of manufacture (i.e., articles of manufacture) according to this disclosure. The articles of manufacture can be manufactured as such or can be manufactured by combining the materials and devices exemplified in this disclosure. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It should be understood that, in some embodiments, equivalents to the specific electrode structures and / or methods described herein can be employed without departing from the scope of the application. Accordingly, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," "characterized by," "characterized into," and variations thereof herein, is meant to encompass the items listed thereafter, and equivalents thereof as well as additional items. Although the foregoing application has been described in some detail by way of illustration and example, it is not to be limited thereby, but rather, only by the scope of the appended claims.
Claims
1. A radiation-resistant optical fiber, characterized in that, include: Core layer (100); A gradient transition layer (200) wraps the core layer (100). An outer layer (300) encloses the gradient transition layer (200); The gradient transition layer (200) is doped with fluoride, and the doping ratio of the fluoride gradually changes along the direction from the core layer (100) to the outer cladding layer (300).
2. The radiation-resistant optical fiber according to claim 1, characterized in that, The gradient transition layer (200) includes an inner cladding layer (210) and a recessed layer (220) all doped with the fluoride, and a buffer layer (230). The inner cladding layer (210) encloses the core layer (100), the recessed layer (220) encloses the inner cladding layer (210), the buffer layer (230) encloses the recessed layer (220), and the outer cladding layer (300) encloses the buffer layer (230). The doping ratio of fluoride in the sunken layer (220) is greater than that in the inner cladding layer (210), and the doping ratio of fluoride in the buffer layer (230) is less than that in the sunken layer (220).
3. The radiation-resistant optical fiber according to claim 2, characterized in that, The doping ratio of the fluoride in the inner cladding (210) is 0% to 1%; And / or, the doping ratio of the fluoride in the recessed layer (220) is 1% to 3.5%; And / or, the doping ratio of the fluoride in the buffer layer (230) is 0.5% to 1.5%.
4. The radiation-resistant optical fiber according to claim 3, characterized in that, The buffer layer (230) is also doped with hydroxyl groups.
5. The radiation-resistant optical fiber according to claim 2, characterized in that, The relative refractive index difference Δn1 of the core layer (100) is 0.15%~0.25%; And / or, the relative refractive index difference Δn2 of the inner cladding (210) is -0.1% to -0.01%; And / or, the relative refractive index difference Δn3 of the sunken layer (220) is -0.06% to -0.04%; And / or, the relative refractive index difference Δn4 of the buffer layer (230) is -0.15% to 0.05%; And / or, the relative refractive index difference Δn5 of the outer cladding layer (300) is 0.
6. The radiation-resistant optical fiber according to claim 2, characterized in that, The radius of the core layer (100) ranges from 0 to r1, where r1 is 4 μm to 4.7 μm. And / or, the radius of the inner cladding (210) ranges from r1 to r2, and the difference between r2 and r1 is 2μm to 4μm; And / or, the radius of the sunken layer (220) ranges from r2 to r3, and the difference between r3 and r2 is 2μm to 5μm; And / or, the radius of the buffer layer (230) is in the range of r3~r4, and the difference between r4 and r3 is 4μm~15μm; And / or, the radius of the outer cladding layer (300) is in the range of r4~r5, where r5 is 62μm~63μm.
7. The radiation-resistant optical fiber according to any one of claims 1-6, characterized in that, The core layer (100) comprises silicide, germanide, fluoride and potassium ions; The ratio of the silicide, germanide, fluoride and potassium ions is (1-abc):a:b:c, where a is 0.2%~1.2%, b is 0.05%~0.45%, and c is 0~0.25%.
8. The radiation-resistant optical fiber according to any one of claims 1-6, characterized in that, It also includes a coating (400) applied to the surface of the outer cladding layer (300).
9. The radiation-resistant optical fiber according to claim 8, characterized in that, The coating (400) includes an inner coating (410) and an outer coating (420). The inner coating (410) is coated on the surface of the outer cladding (300), and the outer coating (420) is coated on the surface of the inner coating (410). The elastic modulus of the inner coating (410) is ≤2MPa, and the elastic modulus of the outer coating (420) is ≥500MPa.
10. A preparation method for preparing the radiation-resistant optical fiber according to any one of claims 1-9, characterized in that, Includes the following steps: The gradient transition layer (200) in the radiation-resistant optical fiber is wrapped around the core layer (100) in the radiation-resistant optical fiber. The gradient transition layer (200) is wrapped around the outer cladding layer (300) in the radiation-resistant optical fiber. Fluoride is doped in the gradient transition layer (200), and the doping ratio of the fluoride gradually changes along the direction from the core layer (100) to the outer cladding layer (300).