Metal coating layer anti-radiation optical fiber and manufacturing method thereof

Abstract

The invention belongs to the technical field of optical fiber coating materials, and particularly relates to a metal coating layer anti-radiation optical fiber and a manufacturing method thereof. According to the anti-radiation optical fiber provided by the invention, double coatings are arranged outside the bare optical fiber, the inner coating is an organic film layer, and the outer coating is a metal film layer. The optical fiber coating structure and the material composition are redesigned, so that the problems that the radiation resistance, the temperature resistance and the bending resistance of the existing radiation-resistant optical fiber are poor or cannot be considered at the same time are solved, and the continuous large-scale production of the high-temperature-resistant radiation-resistant optical fiber preparation process in the prior art cannot be realized; and the metal coating optical fiber with long section and long requirement cannot be prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber coating materials, and more specifically, relates to a metal coating layer radiation-resistant optical fiber and a manufacturing method thereof. Background Art

[0002] Optical fiber is widely used as an optical transmission medium in special irradiation environments such as oceans, nuclear power plants, and intelligent environmental monitoring due to its advantages of low loss, high transmission rate, small size, light weight, and anti-static interference. However, in these irradiation environments, the sensing capability and reliability of optical fiber communication tend to drop rapidly. The main reason is that ionizing radiation and high environmental temperature cause defective structures and coating damage in quartz optical fiber materials.

[0003] In special high temperature and radiation environments, the reliability of optical fiber applications is closely related to its coating material. Ordinary optical fibers are composed of bare optical fibers drawn from silica quartz glass and coatings applied on the surface of bare optical fibers. The coating of optical fibers is generally made of polyacrylate materials. Limited by the coating materials, the operating temperature of optical fibers does not exceed 85°C. In radiation environments, high-energy radiation rays can easily penetrate the organic coating of optical fibers and act on the glass part of the optical fibers, causing structural bond breakage or changes in the microstructure of silica. The additional absorption loss of optical fibers caused by irradiation deteriorates sharply, and the optical fibers will lose the function of transmitting optical signals. If the radiation scenario involves a high temperature environment, when the long-term use temperature of the optical fiber exceeds the normal use temperature, and under the effect of accelerated aging by high-energy rays, the radiation first acts on the organic coating of the optical fiber, causing oxidation, yellowing, aging, or even damage of the coating. The coating will lose its protective effect on the bare optical fiber, seriously affecting the strength, communication security, and life of the optical fiber. In addition, optical fibers play a role in long-distance data transmission in the nuclear power and marine fields, and are generally laid in cables. Whether in the process of cabling or laying, optical fiber will inevitably involve problems such as winding, bending, and twisting. The additional loss of the optical fiber in the bent state will increase significantly, deteriorating the transmission performance of the optical fiber.

[0004] Researchers at home and abroad have been committed to solving the design and preparation problems of high-temperature resistant and radiation-resistant optical fibers, and have improved the composition of optical fiber coating materials, coating structure design and preparation process to adapt to the application requirements of high-temperature and radiation environments. For example, in patent document CN102109636A, it discloses a high-temperature resistant and radiation-resistant optical fiber and its processing technology. The optical fiber coating described in the patent is designed as a double-layer metal coating, and the metal coating is prepared by metal sputtering and electroplating methods respectively. The metal coating includes one of an aluminum-plated layer, a copper-plated layer, a nickel-plated layer, a nickel-plated layer, a gold-plated layer, a lead-plated layer or a cobalt-plated layer, so that the obtained optical fiber can be well shielded from radiation and has the advantages of high temperature resistance, radiation resistance and corrosion resistance. However, since the process involves operations such as metal sputtering and electroplating, the single batch processing volume is small, the processed optical fiber segment is short, and the coating uniformity is poor. It cannot be used to prepare metal-coated optical fibers with long segment length requirements, and there is no continuous and industrial production capacity. In addition, the hardness of the metal coating is much greater than that of the organic polymer coating, and the thermal expansion coefficient of the metal coating is more different from that of the glass cladding. The intrinsic loss of the optical fiber in the conventional communication band reaches 5dB / km, and the bending resistance and anti-interference performance of the optical fiber are worse, which limits the long-distance transmission of the signal. For another example, in the patent document CN110133796A, a radiation-resistant optical fiber and its preparation method are also disclosed. The optical fiber coating is an inner, middle and outer three-layer organic silicon-containing and fluorine-containing modified acrylic resin. After being subjected to force, the coating plays a good buffering and protective role, and when subjected to radiation and high temperature, the coating has a good isolation effect. However, the optical fiber described in the patent is limited by the ordinary acrylic resin inner coating, and the maximum operating temperature does not exceed 85°C; in addition, when the optical fiber is laid in the circulating water of a nuclear power plant or in the ocean, under the action of radiation and high temperature, the organic coating material of the optical fiber ages, the organic coating is damaged and falls off and dissolves into the water, polluting the circulating water system, affecting the utilization efficiency of water resources and the safe and stable operation of the nuclear power plant. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a metal-coated radiation-resistant optical fiber and a method for manufacturing the same. By redesigning the optical fiber coating structure and material composition, an organic film layer and a low-melting-point alloy coating are sequentially arranged outside the optical fiber cladding, thereby overcoming the problems that the radiation resistance, temperature resistance and bending resistance of the existing high-temperature resistant radiation-resistant optical fiber are poor or cannot be taken into account at the same time, as well as the technical difficulties that the existing technology for preparing high-temperature resistant radiation-resistant optical fiber cannot be continuously mass-produced and cannot prepare metal-coated optical fibers with long length requirements.

[0006] To achieve the above object, the present invention provides a metal-coated radiation-resistant optical fiber, which is provided with a core, a cladding, an inner coating and an outer coating in sequence from the inside to the outside, wherein the inner coating is an organic film layer, and the outer coating is a metal film layer; The organic film layer material is an acrylic resin polymer; the metal film layer is an alloy material film layer containing both heavy metal elements and low melting point metals, and the melting point of the alloy material is less than or equal to 220°C.

[0007] Preferably, the inner coating is one or more of acrylic resin, silicon-containing or fluorine-containing modified acrylic resin.

[0008] Further preferably, the melting point of the alloy material is less than or equal to 200°C.

[0009] Further preferably, the heavy metal element is lead and / or cadmium, and the low melting point metal is one or more of tin, indium and bismuth.

[0010] Further preferably, the content of the heavy metal element in the alloy material film layer is 20wt%~60wt%, and further preferably 30wt%~50wt%.

[0011] Preferably, the diameter of the cladding is 124-126 μm, the diameter of the inner coating is 170-210 μm, the diameter of the outer coating is 200-300 μm, and the thickness of the outer coating is greater than or equal to 20 μm.

[0012] According to another aspect of the present invention, there is provided a method for manufacturing the metal-coated radiation-resistant optical fiber, comprising the following steps: S1: Drawing a bare optical fiber including the core and the cladding; S2: cooling the bare optical fiber, and then sequentially performing melt coating of a resin material and UV curing to obtain an optical fiber with the inner coating formed thereon; S3: sequentially subjecting the optical fiber formed with the inner coating to melt-coating of alloy materials and cooling, forming the outer coating on the surface of the inner coating, and obtaining the metal-coated radiation-resistant optical fiber.

[0013] Preferably, in step S3, the optical fiber forming the inner coating is subjected to melt coating of an alloy material, the melt coating temperature is 70°C to 200°C, and the melt coating temperature is 3 to 15°C higher than the melting point of the alloy material.

[0014] Preferably, in step S3, the ratio of the height h of the alloy material solution to the drawing speed v of the optical fiber during the alloy material melt coating is <5 ms.

[0015] Further preferably, the ratio of the height h of the alloy material solution to the drawing speed v of the optical fiber during the melt coating of the metal material in step S3 is 2.5 ms ≤h / v≤4.5 ms, and further preferably 3 ms≤h / v≤4 ms.

[0016] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art: (1) The radiation-resistant optical fiber proposed in the present invention has a double coating on the outside of the bare optical fiber, wherein the inner coating is an organic film layer and the outer coating is a low-melting-point alloy material film layer; a soft-inside-hard-outside structure is formed, thereby avoiding the problem of stress concentration on the glass part and a sharp deterioration of intrinsic loss due to a single-layer metal coating, thereby optimizing the intrinsic loss level of the optical fiber; and the organic inner layer acts as a buffer layer, thereby enhancing the overall toughness of the optical fiber and optimizing the bending resistance and anti-interference ability of the optical fiber.

[0017] (2) However, the double coating structure of soft inside and hard outside poses a problem for its preparation. Because the melting point of the metal material is relatively high when the outer coating of the metal material is produced by melt coating, when it reaches the melting temperature, it often causes the internal organic film layer to age and yellow due to the high temperature, and the toughness and bending resistance of the optical fiber deteriorate. For this reason, the present invention proposes a radiation-resistant optical fiber, whose outer coating is an alloy coating that not only contains heavy metal elements but also low-melting-point metals; and by regulating the type and ratio of the alloy elements, the melting point of the alloy material is controlled to be no higher than 220°C. The melt coating temperature can ensure that the inner organic coating will not fail due to thermal aging, so that the quality of the internal organic film layer will not be affected during the melt coating process of the outer coating, and the melt coating process can realize the continuous production of optical fibers, which not only cleverly solves the contradiction of the double coating preparation process, but also can realize the continuous production of long-segment metal-coated optical fibers through the melt coating process. The organic inner coating and the metal outer coating of the present invention can be produced continuously, thereby ensuring that the radiation-resistant optical fiber of the present invention can achieve long-segment continuous production.

[0018] (3) Common metal coating processes such as cold spraying, evaporation, electroplating, sputtering, etc. are intermittent coating processes. They can only coat a single batch of drawn optical fibers and cannot achieve continuous production. They have low production capacity and poor production stability. The present invention forms a low-melting point alloy coating by designing different metal types and contents, and combines the coating process of the metal melting method to achieve continuous metal film coating on the optical fiber, greatly improving the production capacity of metal-coated optical fiber. The present invention overcomes the barriers of too high metal melting points, inapplicability to the melting coating method, and inability to achieve continuous production, while taking into account the radiation resistance of the optical fiber. The alloy outer coating material composition comprising heavy metal elements lead / cadmium and low-melting point metals tin / bismuth / indium proposed in the present invention realizes the continuous production of metal-coated radiation-resistant optical fibers.

[0019] (4) During the melt coating process of the double-coated radiation-resistant optical fiber of the present invention, if h / v is too large or the coating temperature is too high, the coated alloy coating may melt due to the long residence time of the optical fiber coating in the metal solution and the high temperature, resulting in the alloy coating being unable to adhere to the optical fiber surface or the coating being thin, thereby reducing the optical fiber's radiation resistance; if the alloy coating temperature is too low, when the optical fiber at room temperature enters the secondary coater, the temperature in the coater is further reduced, the metal solution around the optical fiber solidifies and is no longer in a molten state, and the alloy coating is unable to adhere to the optical fiber surface. The present invention ensures the coating thickness of the alloy coating by regulating the height h of the metal solution in the secondary coater, the optical fiber drawing speed v, the coating temperature, etc.

[0020] (5) The intrinsic loss of the metal-coated radiation-resistant optical fiber provided in the preferred embodiment of the present invention in the 1310nm band is less than 1dB / km; when the metal-coated radiation-resistant optical fiber is wound one turn at a bending diameter of 30mm, the additional bending loss at 1310nm is less than 0.5dB. In an environment where the total radiation dose is 2MGy, the attenuation of the metal-coated radiation-resistant optical fiber in the 1310nm band is less than 20dB / km. And the relative change value Δn of the dynamic fatigue parameter of the metal-coated radiation-resistant optical fiber before and after aging is d Less than 15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a metal-coated radiation-resistant optical fiber provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of a device for manufacturing a metal-coated radiation-resistant optical fiber provided in an embodiment of the present invention.

[0022] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 10-fiber core; 11-cladding; 12-inner coating; 13-outer coating; 20-preform rod; 21-first heating furnace; 22-cooling furnace; 23-first coater; 24-ultraviolet curing furnace; 25-second coater; 26-second heating furnace; 27-cooler; 28-winding device. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0024] The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters of the following embodiments that do not specify specific conditions are usually based on conventional conditions.

[0025] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0026] In the present invention, unless otherwise specified and / or described, all numerical values ​​involving the amounts of components are "parts by weight" from beginning to end. The process parameters in the following examples without specifying specific conditions are usually based on conventional conditions.

[0027] The present invention provides a metal-coated radiation-resistant optical fiber, which is provided with a core, a cladding, an inner coating and an outer coating in sequence from the inside to the outside, wherein the inner coating is an organic film layer, and the outer coating is a metal film layer. The organic film layer material is an acrylic resin polymer, and the metal film layer is an alloy material film layer containing both heavy metal elements and low-melting-point metals, and the melting point of the alloy material film layer is less than or equal to 220°C. In the field of alloys with a melting point lower than 300°C, it is called a low-melting-point alloy. The alloy material used in the alloy material film layer of the present invention has a melting point lower than or equal to 220°C, and belongs to a low-melting-point alloy.

[0028] In some embodiments, the inner coating is one or more of acrylic resin, silicon-containing (10-30 mol % silicon content) or fluorine-containing (5-20 mol %) modified acrylic resin.

[0029] In a preferred embodiment, the outer coating layer is an alloy material film layer containing heavy metal elements and also a low melting point metal, and the melting point of the alloy material is less than or equal to 200°C.

[0030] In a more preferred embodiment, the heavy metal element is lead and / or cadmium, and the low melting point metal is one or more of tin, indium, and bismuth. In a preferred embodiment, the content of heavy metal elements in the outer coating in the alloy material film layer is 20wt%~60wt%, and more preferably 30wt%~50wt%, to ensure a suitable melting point of the alloy material, facilitate coating processing, and take into account excellent optical fiber performance.

[0031] In some embodiments, the diameter of the cladding is 124-126 μm, the diameter of the inner coating is 170-210 μm, the diameter of the outer coating is 200-300 μm, and preferably, the thickness of the outer coating is greater than or equal to 20 μm, more preferably, less than or equal to 50 μm. The radius difference between the inner coating and the cladding is the coating thickness of the inner coating, and the appropriate inner coating coating thickness ensures the excellent bending resistance of the optical fiber; the radius difference between the outer coating and the inner coating is the coating thickness of the outer coating. The coating thickness of the outer coating and the inner coating is controlled within a suitable range to ensure that the optical fiber has both radiation resistance and bending resistance. It can be understood that the cladding diameter, the inner coating diameter and the outer coating diameter of the present invention respectively refer to the diameter of the outer circle of the ring where the cladding, inner coating and outer coating of the metal-coated radiation-resistant optical fiber of the present invention are located.

[0032] The present invention also provides a method for manufacturing the metal-coated radiation-resistant optical fiber, comprising the following steps: S1: Drawing a bare optical fiber including the core and the cladding; S2: cooling the bare optical fiber, and then sequentially performing melt coating of a resin material and UV curing to obtain an optical fiber with the inner coating formed thereon; S3: sequentially subjecting the optical fiber formed with the inner coating to melt-coating of alloy materials and cooling, forming the outer coating on the surface of the inner coating, and obtaining the metal-coated radiation-resistant optical fiber.

[0033] In some embodiments, step S3 is to melt-coat the optical fiber forming the inner coating with an alloy material, and the temperature of the melt-coating of the alloy material is 70° C. to 200° C., and the temperature of the melt-coating is 3 to 15° C. higher than the melting point of the alloy material. The coating temperature is higher than the melting point of the alloy material to ensure that the alloy is coated in a molten state, and the temperature of the melt-coating is controlled at 70-200° C. to melt-coat the outer coating while preventing the inner coating from aging.

[0034] In a preferred embodiment, the ratio of the height h of the alloy material solution to the drawing speed v of the optical fiber during the alloy material melt coating in step S3 is h / v<5 ms, and more preferably, 2.5 ms≤h / v≤4.5 ms, to ensure the coating thickness of the appropriate alloy coating, thereby ensuring the performance of the optical fiber. In some embodiments of the present invention, the height h of the alloy material solution during the alloy material melt coating is in mm, and the optical fiber drawing speed v is in mm / ms, so the unit of h / v is ms, which is a time unit. The ratio of the height of the alloy material solution to the optical fiber drawing speed of the present invention is controlled within a suitable range, which can be understood as the coating residence time of the optical fiber in the molten alloy solution needs to be controlled within a suitable range to ensure the appropriate coating thickness of the alloy material, so h / v can also be referred to as the coating time in the present invention. The specific values ​​of the alloy material solution height h and the optical fiber drawing speed v can be set as needed, as long as they meet the above-mentioned h / v requirements. For example, in some embodiments, the height h of the alloy material solution during the alloy material melt coating in step S3 is 20~30mm, and the drawing speed v is 5~10m / s.

[0035] The present invention designs the outer coating material of the optical fiber to be an alloy outer coating containing heavy metal elements such as lead and cadmium, which significantly reduces the radiation energy entering the fiber core and reduces the radiation loss generated by the optical fiber. Even when used in extreme areas such as high temperature and high radiation dose, it can also have good high temperature resistance and radiation resistance: ①Radiation energy is mainly transmitted in the form of electromagnetic waves. Lead and cadmium, as heavy metal elements, have large atomic weight and high density, and can better block radiation energy. At the same time, when radiation energy interacts with metals, metals can quickly conduct energy to their surroundings and disperse the energy through their excellent conductivity, thereby absorbing radiation energy and protecting the glass structure that plays a role in optical communication from damage by radiation energy.

[0036] ② The temperature resistance of optical fiber is mainly limited by the temperature resistance range of its coating. The high temperature resistance of metal materials is significantly better than that of conventional organic coatings for optical fiber. When the optical fiber is in a high temperature environment for a long time, the metal coating is more stable and less likely to deform, corrode, age, etc., thereby improving the overall high temperature resistance reliability of the optical fiber.

[0037] The present invention designs the coating structure of the optical fiber to be a double-layer structure in which the inner coating is an organic film layer such as polyester and the outer coating is an alloy film layer, forming a structure that is soft inside and hard outside, thereby avoiding the problem of stress concentration on the glass part and a sharp deterioration of intrinsic loss due to a single-layer metal coating, and optimizing the intrinsic loss level of the optical fiber; and the organic inner layer acts as a buffer layer, which enhances the overall toughness of the optical fiber and optimizes the bending resistance and anti-interference ability of the optical fiber.

[0038] The present invention realizes the optical fiber double coating structure of organic inner coating and metal outer coating by regulating the different metal ratios of the optical fiber outer coating, the coating temperature and the coating time in the wire drawing coating process, and ensures its continuous manufacturability: ① The use of melt coating technology is expected to achieve continuous large-scale production of optical fibers with long segment length requirements. However, for the radiation-resistant optical fiber of the present invention comprising an organic inner coating and an alloy outer coating, if the content of heavy metal lead and cadmium in the outer coating is too low, the alloy coating has poor radiation resistance and cannot shield high-energy rays; if the content of heavy metal lead and cadmium is too high, the melting temperature and coating temperature of the alloy are high (>220°C). During the secondary coating of the alloy film layer, the organic inner coating will age and yellow due to high temperature, and the toughness and bending resistance of the optical fiber will deteriorate. The present invention reduces the melting temperature of the alloy while maintaining the radiation resistance of the metal coating by regulating the ratio of the alloy elements selected in the secondary coater, thereby ensuring the effective coating of the organic coating and the alloy coating.

[0039] ② In the process of melt coating of the double-coated radiation-resistant optical fiber of the present invention, it is found experimentally that if h / v is too large or the coating temperature is too high, the optical fiber coating stays in the metal solution for too long and the temperature is too high, the coated alloy coating melts, and the alloy coating cannot adhere to the optical fiber surface or the coating is thin, which reduces the radiation resistance of the optical fiber; if the alloy coating temperature is too low, when the optical fiber at room temperature enters the secondary coater, the temperature in the coater is further reduced, the metal solution around the optical fiber solidifies and is no longer in a molten state, and the alloy coating cannot adhere to the optical fiber surface. The present invention ensures the coating thickness of the alloy coating by regulating the height h of the metal solution in the secondary coater, the optical fiber drawing speed v, the coating temperature, etc.

[0040] ③ Common metal coating processes such as cold spraying, evaporation, electroplating, sputtering, etc. are intermittent coating processes, which can only coat a single batch of drawn optical fibers, and cannot achieve continuous production, low production capacity, and poor production stability. The present invention can achieve continuous metal film coating of optical fibers by designing a coating process with different metal contents to form a low melting point alloy coating and combining it with a metal melting method, thereby greatly improving the production capacity of metal-coated optical fibers. The present invention overcomes the barriers of too high metal melting points, the inability to apply the melt coating method, and the inability to achieve continuous production, while taking into account the radiation resistance of the optical fiber, thereby designing an alloy coating containing heavy metal elements lead / cadmium and tin / bismuth / indium, and realizing the continuous production of metal-coated radiation-resistant optical fibers.

[0041] refer to Figure 1As shown, the metal-coated radiation-resistant optical fiber proposed in the present invention comprises a core (core layer) 10 and a cladding 11, and an organic inner coating 12 and an alloy outer coating 13 are arranged outside the cladding, and the organic inner coating 12 and the alloy outer coating 13 together constitute the coating layer of the radiation-resistant optical fiber of the present invention. The following process can be used to prepare the radiation-resistant optical fiber of the present invention, and the schematic diagram of the preparation process device is shown in Figure 2 As shown: S1: Under the action of the first heating furnace 21, the preform rod 20 is drawn into a bare optical fiber including a core 10 and a cladding 11 according to a conventional process.

[0042] S2: The bare optical fiber passes through the cooling tube of the cooling furnace 22 and then enters the first coating device 23 and the UV curing furnace 24 in sequence to obtain an optical fiber with an organic inner coating 12; S3: coating the inner coating 12 with alloy material by a melting process, specifically, passing the optical fiber with the inner coating 12 obtained in step S2 through a second coater 25 and a cooler 27 in sequence, wherein the second coater 25 contains a metal alloy, and a second heating furnace 26 arranged around the second coater 25 maintains the metal alloy in a molten state, and the cooler 27 causes the alloy coating to solidify on the surface of the optical fiber, and an outer coating 13 is obtained on the surface of the inner coating 12, and finally the metal-coated radiation-resistant optical fiber is obtained through a take-up device 28.

[0043] The preform described in step S1 of the present invention can be made by plasma chemical vapor deposition (PCVD), modified chemical vapor deposition (MCVD), external vapor deposition (OVD) or vapor axial deposition (VAD). After the preform is prepared, the optical fiber is drawn on a drawing tower, and the drawing speed of the optical fiber preform is not higher than 200m / min, and the drawing tension is not higher than 60g. In some embodiments of the present invention, a bare silica optical fiber with a cladding diameter of 124-126μm is drawn.

[0044] In some embodiments, in step S2, acrylic resin or silicon- or fluorine-containing modified acrylic resin is placed in the first coater for coating to obtain an organic film layer, namely, an inner coating layer.

[0045] The present invention is described in detail below with reference to specific embodiments and comparative examples.

[0046] Example 1 The optical fiber of Example 1 is composed of a core layer and a cladding layer, the cladding layer surrounds the core layer, and the inner coating layer and the outer coating layer surround the cladding layer in sequence, the inner coating layer is acrylic resin, and the outer coating layer is lead-tin alloy. In the outer coating layer of Example 1, lead element accounts for 30wt%, and tin element accounts for 70wt%.

[0047] Preparation equipment and process such as Figure 2As shown, the bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling tube of the cooling furnace 22 and then enters the first coater 23 containing acrylic resin and the ultraviolet curing furnace 24 in sequence to form an organic inner coating; then the alloy material is coated on the outside of the inner coating, and the optical fiber passes through the second coater 25 containing lead-tin alloy and the cooler 27 in sequence by a melting process. The second heating furnace 26 surrounding the second coater 25 maintains the alloy in a molten state, and the cooler 27 causes the alloy coating to solidify on the surface of the optical fiber to obtain a metal-coated optical fiber.

[0048] The ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (6 mm / ms) is 4, and the secondary coating temperature, i.e., the melt coating temperature, is 175°C. See Table 1 for specific parameters.

[0049] Embodiment 2, Embodiment 4 The optical fiber of Example 2 and Example 4 is composed of a core layer and a cladding layer. The cladding layer surrounds the core layer, and the inner coating layer and the outer coating layer surround the cladding layer. The inner coating layer is a silicon-containing acrylic resin, and the organic silicon content is 20 mol%. The outer coating layer is a cadmium-indium alloy. The cadmium element accounts for 40wt% and the indium element accounts for 60wt% in the outer coating layer of Example 2; the cadmium element accounts for 20wt% and the indium element accounts for 80wt% in the outer coating layer of Example 4.

[0050] Preparation equipment and process such as Figure 2 As shown, the bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling tube of the cooling furnace 22 and then enters the first coating device 23 containing acrylic resin and the ultraviolet curing furnace 24 in sequence to form an organic inner coating; then the alloy material is coated on the outside of the inner coating, and the optical fiber passes through the second coating device 25 containing cadmium indium alloy and the cooler 27 in sequence by a melting process. The second heating furnace 26 surrounding the second coating device 25 maintains the alloy in a molten state, and the cooler 27 causes the alloy coating to solidify on the surface of the optical fiber to obtain a metal-coated optical fiber.

[0051] In Example 2, the ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (8 mm / ms) is 3, and the secondary coating temperature, i.e., the melt coating temperature, is 150°C.

[0052] In Example 4, the ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (6 mm / ms) is 4, and the secondary coating temperature, i.e., the melt coating temperature, is 124°C.

[0053] Example 3, Comparative Example 4 The optical fiber of Example 3 and Comparative Example 4 consists of a core layer and a cladding layer, the cladding layer surrounds the core layer, and the inner coating layer and the outer coating layer surround the cladding layer in sequence, the inner coating layer is acrylic resin, and the outer coating layer is lead-bismuth alloy. The lead element accounts for 60wt% and the bismuth element accounts for 40wt% in the outer coating layer of Example 3; the lead element accounts for 50wt% and the bismuth element accounts for 50wt% in the outer coating layer of Comparative Example 4.

[0054] Preparation equipment and process such as Figure 2 As shown, the bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling tube of the cooling furnace 22 and then enters the first coating device 23 containing acrylic resin and the ultraviolet curing furnace 24 in sequence to form an organic inner coating; then the alloy material is coated on the outside of the inner coating, and the optical fiber passes through the second coating device 25 containing lead-bismuth alloy and the cooler 27 in sequence by a melting process. The second heating furnace 26 surrounding the second coating device 25 maintains the alloy in a molten state, and the cooler 27 causes the alloy coating to solidify on the surface of the optical fiber to obtain a metal-coated optical fiber.

[0055] In Example 3, the ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (6 mm / ms) is 4, and the secondary coating temperature, i.e., the melt coating temperature, is 200°C.

[0056] In Comparative Example 4, the ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (4 mm / ms) is 6, and the secondary coating temperature, i.e., the melt coating temperature, is 183°C.

[0057] Comparative Example 1 The optical fiber of Comparative Example 1 consists of a core layer and a cladding layer, the cladding layer surrounds the core layer, and a single-layer lead metal coating layer surrounds the cladding layer.

[0058] This comparative example prepares a single-layer lead metal coating, and the preparation device is the same as Figure 2 , only the first coater 23 and the UV curing furnace 24 are omitted. The bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 directly enters the second coater 25 and the cooler 27 containing lead metal after passing through the cooling tube of the cooling furnace 22. The second heating furnace 26 surrounding the second coater 25 maintains the lead metal in a molten state. The cooler 27 promotes the solidification of the lead coating on the surface of the optical fiber to obtain a single-layer lead metal coated optical fiber.

[0059] In Comparative Example 1, the ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (8 mm / ms) is 3, and the metal lead molten coating temperature is 335°C.

[0060] Comparative Example 2 The optical fiber of Comparative Example 2 is a conventional optical fiber, consisting of a core layer and a cladding layer. The cladding layer surrounds the core layer, and the inner coating layer and the outer coating layer surround the cladding layer in sequence. The inner coating layer is an acrylic resin, and the outer coating layer is a silicon-containing acrylic resin with a silicone content of 20 mol%.

[0061] The preparation device and process of this comparative example are the same Figure 2 , only the second coater 25, the second heating furnace 26 and the cooler 27 are removed and replaced with a second coater containing silicone acrylic resin and another UV curing furnace. The bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling tube of the cooling furnace 22 and then enters the first coater 23 containing acrylic resin and the UV curing furnace 24 in sequence to form an acrylic ester inner coating; then the silicone-containing acrylic resin is coated on the outside of the inner coating, and passes through the second coater containing silicone acrylic resin and another UV curing furnace in sequence to be cured to obtain a double-coated optical fiber.

[0062] Comparative Example 3 The optical fiber of comparative example 3 is composed of a core layer and a cladding layer, the cladding layer surrounds the core layer, and the inner coating layer and the outer coating layer surround the cladding layer in sequence, the inner coating layer is acrylic resin, and the outer coating layer is cadmium-bismuth alloy. In the outer coating layer of comparative example 3, cadmium element accounts for 50wt%, and bismuth element accounts for 50wt%.

[0063] Preparation equipment and process such as Figure 2 As shown, the bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling tube of the cooling furnace 22 and then enters the first coating device 23 containing acrylic resin and the ultraviolet curing furnace 24 in sequence to form an organic inner coating; then the alloy material is coated on the outside of the inner coating, and the optical fiber passes through the second coating device 25 containing cadmium-bismuth alloy and the cooler 27 in sequence by a melting process. The second heating furnace 26 surrounding the second coating device 25 maintains the alloy in a molten state, and the cooler 27 causes the alloy coating to solidify on the surface of the optical fiber to obtain a metal-coated optical fiber.

[0064] In Comparative Example 3, the ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (8 mm / ms) is 3, and the secondary coating temperature, i.e., the melt coating temperature, is 164°C.

[0065] Comparative Example 5 The optical fiber of comparative example 5 is composed of a core layer and a cladding layer, the cladding layer surrounds the core layer, and the inner coating layer and the outer coating layer surround the cladding layer in sequence, the inner coating layer is acrylic resin, and the outer coating layer is cadmium-tin alloy. The cadmium element accounts for 30wt% and the tin element accounts for 70wt% in the outer coating layer of comparative example 5.

[0066] Preparation equipment and process such as Figure 2As shown, the bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling tube of the cooling furnace 22 and then enters the first coating device 23 containing acrylic resin and the ultraviolet curing furnace 24 in sequence to form an organic inner coating; then the alloy material is coated on the outside of the inner coating, and the optical fiber passes through the second coating device 25 containing cadmium tin alloy and the cooler 27 in sequence by a melting process. The second heating furnace 26 surrounding the second coating device 25 maintains the alloy in a molten state, and the cooler 27 causes the alloy coating to solidify on the surface of the optical fiber to obtain a metal-coated optical fiber.

[0067] In Comparative Example 5, the ratio of the height h (24 mm) of the alloy solution in the second coater to the optical fiber drawing speed v (6 mm / ms) is 4, and the secondary coating temperature, i.e., the melt coating temperature, is 250°C.

[0068] The specific structural parameters and preparation process parameters of the radiation-resistant optical fiber according to the above-mentioned embodiments and comparative examples are shown in Table 1.

[0069] Table 1 Fiber profile design parameters of the embodiment and comparative example

[0070] The detection method used for the optical fiber in the embodiments and comparative examples of the present invention is: The optical fiber was irradiated with a cobalt-60 radiation source at a temperature of 25±3°C, with a total dose of 2MGy. During the irradiation, a light source with a wavelength of 1310nm was used to test the attenuation of the optical fiber caused by radiation.

[0071] The intrinsic loss and bending additional loss of the optical fiber were tested using an optical analyzer (PK Company). The optical fiber was wound once with a bending diameter of 30 mm to test the attenuation difference before and after bending.

[0072] The dynamic fatigue parameters of the optical fiber before and after aging are tested with reference to GB / T 15972.33-2008. Aging refers to the process in which the optical fiber undergoes 2MGy irradiation aging and 125°C, 250h high temperature aging in sequence, thereby calculating the percentage change of the dynamic fatigue parameter Δn d .

[0073] The test results of Examples 1-4 and Comparative Examples 1-5 are shown in Table 2.

[0074] Table 2 Test results of optical fiber performance of the embodiment and the comparative example

[0075] It is not difficult to see from Table 1 and Table 2 that in Examples 1 to 4, by arranging an acrylic acid ester polymer inner coating and a low melting point alloy material outer coating outside the optical fiber cladding, and matching appropriate coating thickness parameters and melt coating process parameters, long-segment melt coating preparation of optical fiber can be achieved, and the prepared optical fiber has excellent intrinsic loss, radiation additional attenuation, bending additional attenuation and dynamic fatigue parameters. Compared with the embodiments, when only heavy metal coating is provided on the surface of the optical fiber in comparative example 1, the intrinsic loss and additional bending attenuation of the optical fiber are relatively high; when only acrylic polymer coating is provided on the optical fiber in comparative example 2, the additional radiation attenuation value and dynamic fatigue parameter of the optical fiber deteriorate; the inner coating diameter of the optical fiber in comparative example 3 is relatively small, and the measured intrinsic loss and additional bending attenuation are relatively high; in comparative example 4, the ratio of the height of the alloy solution to the secondary coating speed h / v is greater than 5, resulting in a relatively small outer coating diameter, and significantly deteriorated additional radiation attenuation and dynamic fatigue parameters of the optical fiber; in comparative example 5, the secondary coating temperature is relatively high, which may affect the quality of the inner coating, and makes the thickness of the outer coating relatively small, resulting in high values ​​of intrinsic loss, additional bending attenuation, and additional radiation attenuation of the optical fiber, and reduced dynamic fatigue parameters.

[0076] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A metal-coated radiation-resistant optical fiber, characterized in that: A fiber core, a cladding, an inner coating and an outer coating are sequentially arranged from the inside to the outside, wherein the inner coating is an organic film layer and the outer coating is a metal film layer; The organic film layer material is an acrylic resin polymer; the metal film layer is an alloy material film layer containing both heavy metal elements and low melting point metals, and the melting point of the alloy material is less than or equal to 220°C.

2. The metal-coated radiation-resistant optical fiber according to claim 1, characterized in that: The inner coating is one or more of acrylic resin, silicon-containing or fluorine-containing modified acrylic resin.

3. The metal-coated radiation-resistant optical fiber according to claim 1, characterized in that: The melting point of the alloy material is less than or equal to 200°C.

4. The metal-coated radiation-resistant optical fiber according to claim 1, characterized in that: The heavy metal element is lead and / or cadmium, and the low melting point metal is one or more of tin, indium and bismuth.

5. The metal-coated radiation-resistant optical fiber according to claim 1, characterized in that: The content of the heavy metal element in the alloy material film layer is 20wt%~60wt%.

6. The metal-coated radiation-resistant optical fiber according to claim 1, characterized in that: The diameter of the cladding is 124-126 μm, the diameter of the inner coating is 170-210 μm, the diameter of the outer coating is 200-300 μm, and the thickness of the outer coating is greater than or equal to 20 μm.

7. The method for manufacturing a metal-coated radiation-resistant optical fiber according to any one of claims 1 to 6, characterized in that: The steps include: S1: Drawing a bare optical fiber including the core and the cladding; S2: cooling the bare optical fiber, and then sequentially performing melt coating of a resin material and UV curing to obtain an optical fiber with the inner coating formed thereon; S3: sequentially subjecting the optical fiber formed with the inner coating to melt-coating of alloy materials and cooling, forming the outer coating on the surface of the inner coating, and obtaining the metal-coated radiation-resistant optical fiber.

8. The method according to claim 7, characterized in that: Step S3: melt-coating the optical fiber with the inner coating with an alloy material, wherein the temperature of the melt-coating is 70° C. to 200° C., and the temperature of the melt-coating is 3° C. to 15° C. higher than the melting point of the alloy material.

9. The method of claim 8, wherein: In step S3, the ratio of the height h of the alloy material solution to the drawing speed v of the optical fiber during the alloy material molten coating is <5 ms.

10. The method according to claim 8, characterized in that: In step S3, the ratio of the height h of the alloy material solution to the drawing speed v of the optical fiber during the molten coating of the metal material is 2.5 ms ≤h / v≤4.5 ms.

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