Metal-coated radiation resistant optical fiber and method of making same

Abstract

The present application belongs to the technical field of optical fiber coating material, and more particularly relates to a metal-coated anti-radiation optical fiber and a manufacturing method thereof.The anti-radiation optical fiber provided by the present application is provided with a double coating layer outside the bare optical fiber, wherein the inner coating layer is an organic film layer, and the outer coating layer is a metal film layer.Through redesigning the structure and material composition of the optical fiber coating layer, the problems of poor anti-radiation performance, poor temperature resistance and poor bending resistance of the existing anti-radiation optical fiber or the problem of being unable to take into account all the above factors are overcome, and the technical difficulties that the preparation process of the existing high-temperature and anti-radiation optical fiber cannot be continuously produced on a large scale and that a long metal-coated optical fiber cannot be prepared are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical fiber coating materials, and more particularly relates to a metal-coated anti-radiation optical fiber and a manufacturing method thereof. BACKGROUND

[0002] Optical fibers are widely used as optical transmission media in special radiation environments such as oceans, nuclear power plants, and environmental intelligent monitoring due to their low loss, high transmission rate, small size, light weight, and resistance to static interference. However, in these radiation environments, the optical fiber communication transmission capability and reliability often decrease rapidly. The main reason is that ionizing radiation and high environmental temperature cause defect structures and coating damage in quartz optical fiber materials.

[0003] Under special high-temperature and radiation environments, the reliability of optical fiber application is closely related to its coating material. Ordinary optical fibers are composed of bare optical fibers made of silica quartz glass and coatings coated on the surface of the bare optical fibers. The coating of the optical fiber is generally a polyacrylate material. Due to the limitation of the coating material, the use temperature of the optical fiber does not exceed 85℃. In a radiation environment, high-energy radiation rays can easily penetrate the organic coating of the optical fiber and act on the glass part of the optical fiber, causing structural bond breaking or changes in the microstructure of silica. The additional absorption loss of the optical fiber caused by radiation deteriorates sharply, and the optical fiber 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 is accelerated by high-energy rays, radiation first acts on the organic coating of the optical fiber, causing the coating to oxidize, yellow, age, and even be damaged. The coating will lose its protective effect on the bare optical fiber, seriously affecting the strength, communication safety, and life of the optical fiber. In addition, optical fibers play a role in long-distance data transmission in the nuclear power field and the ocean field, and are generally cabled for laying. During cabling or laying, the optical fiber will inevitably involve problems such as coiling, bending, and twisting. The additional loss of the optical fiber under the bending state will increase significantly, deteriorating the transmission performance of the optical fiber.

[0004] Researchers at home and abroad have been committed to solving the problem of high-temperature and radiation-resistant optical fiber design and preparation, and through the improvement of the composition of the optical fiber coating material, the design and preparation process of the coating structure to adapt to the application requirements of high temperature and radiation environment. For example, in the patent document CN102109636A, a kind of high-temperature and radiation-resistant optical fiber and its processing technology are disclosed. The optical fiber coating described in the patent is designed as a double-layer metal coating, which is prepared by metal sputtering and electroplating. The metal coating includes one of aluminum plating layer, copper plating layer, nickel plating layer, gold plating layer, lead plating layer or cobalt plating layer, so that the obtained optical fiber can shield the irradiation well, and has the advantages of high temperature resistance, radiation resistance and corrosion resistance. However, since the process method involves metal sputtering and electroplating, the single batch processing capacity is small, the processing optical fiber segment length is short, the coating uniformity is poor, and it cannot be used to prepare long metal-coated optical fiber with long demand. Moreover, 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 much greater than that of the glass cladding. The intrinsic loss of the optical fiber in the conventional communication waveband is 5 dB / 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 example, in the patent document CN110133796A, a kind of radiation-resistant optical fiber and its preparation method are also disclosed. The optical fiber coating is a three-layer organic silicon-containing and fluorine-containing modified acrylic resin. The coating has good buffering and protection effect under stress, and good isolation effect under irradiation and high temperature. However, the optical fiber described in the patent is limited by the ordinary acrylic resin inner coating, and the maximum use temperature is not more than 85℃. In addition, when the optical fiber is laid in the circulating water of the nuclear power plant or in the sea, 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 and affecting the utilization efficiency of water resources and the safe and stable operation of the nuclear power plant. SUMMARY

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a kind of metal coating layer anti-radiation optical fiber and its manufacturing method. By redesigning the structure and material composition of the optical fiber coating, a metal film layer and a low-melting-point alloy coating layer are sequentially arranged outside the optical fiber cladding. The problems of poor radiation resistance, poor temperature resistance and poor bending resistance of existing high-temperature and radiation-resistant optical fibers are overcome, and the technical difficulties of the prior art in preparing high-temperature and radiation-resistant optical fibers, such as the inability to produce long metal-coated optical fibers with long demand and the inability to produce long metal-coated optical fibers with long demand, are overcome.

[0006] To achieve the above purpose, the present application provides a kind of metal coating layer anti-radiation optical fiber, which is sequentially provided with a core, a cladding, an inner coating and an outer coating from inside to outside. The inner coating is an organic film layer, and the outer coating is a metal film layer.

[0007] The organic material film layer is an acrylic resin polymer; the metal film layer is an alloy material film layer containing heavy metal elements and low melting point metals, and the melting point of the alloy material is less than or equal to 220℃.

[0008] Preferably, the inner coating layer is one or more of an acrylic resin, a silicon-containing modified acrylic resin, or a fluorine-containing modified acrylic resin.

[0009] Further preferably, the melting point of the alloy material is less than or equal to 200℃.

[0010] Further preferably, the heavy metal elements are lead and / or cadmium, and the low melting point metals are one or more of tin, indium, and bismuth.

[0011] Further preferably, the content of the heavy metal elements in the alloy material film layer is 20wt% to 60wt%, and more preferably 30wt% to 50wt%.

[0012] Preferably, the diameter of the cladding layer is 124 to 126 μm, the diameter of the inner coating layer is 170 to 210 μm, the diameter of the outer coating layer is 200 to 300 μm, and the thickness of the outer coating layer is greater than or equal to 20 μm.

[0013] According to another aspect of the present application, a method for manufacturing the metal-coated radiation-resistant optical fiber is provided, comprising the following steps:

[0014] S1: drawing a bare optical fiber comprising the core and the cladding;

[0015] S2: after cooling the bare optical fiber, sequentially performing resin material melting coating and ultraviolet curing to obtain an optical fiber forming the inner coating layer;

[0016] S3: sequentially performing alloy material melting coating and cooling on the optical fiber forming the inner coating layer to form the outer coating layer on the surface of the inner coating layer, thereby obtaining the metal-coated radiation-resistant optical fiber.

[0017] Preferably, in step S3, the optical fiber forming the inner coating layer is subjected to alloy material melting coating, the temperature of the melting coating is 70℃ to 200℃, and the temperature of the melting coating is 3 to 15℃ higher than the melting point of the alloy material.

[0018] Preferably, in step S3, the ratio h / v of the height h of the alloy material solution to the drawing speed v of the optical fiber is less than 5 ms.

[0019] Further preferably, the ratio of the height h of the alloy material solution during the metal material melt coating of step S3 to the drawing speed v of the optical fiber is 2.5 ms ≤ h / v ≤ 4.5 ms, and more preferably 3 ms ≤ h / v ≤ 4 ms.

[0020] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0021] (1) The anti-radiation optical fiber proposed by the present application is provided with a double coating layer outside the bare optical fiber, wherein the inner coating layer is an organic film layer, and the outer coating layer is a low-melting-point alloy material film layer; a soft-outer-hard structure is formed, avoiding the problem of stress concentration in the glass part and the sharp deterioration of intrinsic loss due to a single metal coating layer, and optimizing the intrinsic loss level of the optical fiber; and the organic inner layer acts as a buffer layer, enhancing the toughness of the optical fiber as a whole and optimizing the bending resistance and anti-interference capability of the optical fiber.

[0022] (2) However, the double-coating structure of soft-outer-hard poses a problem for its preparation. Because the metal material outer coating layer is melt coated, the metal material has a high melting point, and when reaching the melting temperature, the internal organic film layer often ages and yellows due to high temperature, deteriorating the toughness and bending resistance of the optical fiber. Therefore, the present application proposes an anti-radiation optical fiber, the outer coating layer of which is not only composed of heavy metal elements but also includes a low-melting-point metal alloy coating layer; and by adjusting the types and proportions of alloy elements, the melting point of the alloy material is controlled to be not higher than 220℃, the melt coating temperature can ensure that the inner organic coating layer does not fail due to thermal aging, so that the melt coating process of the outer coating layer does not affect the quality of the internal organic film layer, and the melt coating process can realize continuous production of the optical fiber, thereby not only ingeniously solving the contradiction of the double-coating preparation process, but also realizing continuous production of long-section long metal coating layer optical fibers through the melt coating process. The organic inner coating layer and the metal outer coating layer of the present application can be continuously produced, thereby ensuring that the anti-radiation optical fiber of the present application can realize long-section continuous production.

[0023] (3) Common metal coating processes such as cold spraying, evaporation, electroplating, and sputtering are intermittent coating processes, and can only coat single batches of drawn optical fibers, and cannot realize continuous production, with low production capacity and poor production stability. The present application forms a low-melting-point alloy coating layer by designing different metal types and contents, and combines a metal melt coating process to realize continuous metal film coating of the optical fiber, greatly improving the production capacity of the metal coating optical fiber. The present application overcomes the barriers of high metal melting point, unsuitability for melt coating, and inability for continuous production, while taking into account the anti-radiation performance of the optical fiber. The alloy outer coating material composition proposed by the present application, which contains heavy metal elements lead / cadmium and low-melting-point metals tin / bismuth / indium, realizes continuous production of the metal coating layer anti-radiation optical fiber.

[0024] (4) In the process of the double-coating radiation-resistant optical fiber fusion coating, 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 and high temperature of the optical fiber coating in the metal solution, resulting in the alloy coating failing to adhere to the surface of the optical fiber or the coating being too thin, thereby reducing the radiation resistance of the optical fiber; if the alloy coating temperature is too low, when the room temperature optical fiber enters the secondary coating applicator, the temperature in the coating applicator 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 surface of the optical fiber. The present application controls the height h of the metal solution in the secondary coating applicator, the fiber drawing speed v, and the coating temperature, to ensure the coating thickness of the alloy coating.

[0025] (5) The intrinsic loss of the metal-coated radiation-resistant optical fiber provided in the preferred embodiment of the present application is less than 1 dB / km at a wavelength of 1310 nm; the bending additional loss of the metal-coated radiation-resistant optical fiber is less than 0.5 dB at 1310 nm when it is wound for 1 turn at a bending diameter of 30 mm. The attenuation of the metal-coated radiation-resistant optical fiber is less than 20 dB / km at a wavelength of 1310 nm in an environment with a total radiation dose of 2 MGy. The relative change value Δn of the dynamic fatigue parameters of the metal-coated radiation-resistant optical fiber before and after aging is less than 15%. d BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of a metal-coated radiation-resistant optical fiber provided by an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of a manufacturing device of a metal-coated radiation-resistant optical fiber provided by an embodiment of the present application.

[0028] In all the drawings, the same reference numerals are used to represent the same elements or structures, wherein:

[0029] 10 - fiber core; 11 - cladding; 12 - inner coating; 13 - outer coating;

[0030] 20 - preform; 21 - first heating furnace; 22 - cooling furnace; 23 - first coating applicator; 24 - ultraviolet curing furnace; 25 - second coating applicator; 26 - second heating furnace; 27 - cooler; 28 - take-up device. DETAILED DESCRIPTION

[0031] ​In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Those skilled in the art should understand that the embodiments are only used to understand the present application and should not be regarded as a specific limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0032] The embodiments of the present application are implemented on the premise of the technical solutions of the present application, and detailed implementation manners and processes are given, but the protection scope of the present application is not limited to the following embodiments. The process parameters not specified in the following embodiments are usually according to the conventional conditions.

[0033] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values stated. The ranges or values should be construed to be approximations that allow for significant variation. Various embodiments can vary from one another, not merely consistent with the recited ranges of values. At the very least, it will be apparent that the parameters of the present application can be practiced according to the claims and the examples without resorting to unclaimed embodiments, and equivalents thereof, that do not fall within the scope of the claims.

[0034] In the present application, unless otherwise specified and / or described, all the numerical values related to the amount of components are "parts by weight". The process parameters not specified in the following embodiments are usually according to the conventional conditions.

[0035] The present application provides a kind of metal coating layer anti-radiation optical fiber, it is sequentially provided with fiber core, cladding, inner coating and outer coating from inside to outside, the inner coating is organic film layer, the outer coating is metal film layer. Wherein, organic film layer material is acrylic resin polymer, metal film layer is alloy material film layer containing heavy metal element and low melting point metal, and the melting point of alloy material film layer is less than or equal to 220 DEG C. Alloy field is called low melting point alloy in the field below 300 DEG C, the alloy material used in the alloy material film layer of the present application is less than or equal to 220 DEG C, and it is low melting point alloy.

[0036] In some embodiments, the inner coating is one or more of acrylic resin, modified acrylic resin containing silicon (10-30 mol%) or fluorine (5-20 mol%).

[0037] In preferred embodiments, the outer coating is alloy material film layer containing heavy metal element and low melting point metal, and the melting point of the alloy material is less than or equal to 200 DEG C.

[0038] In more preferred embodiments, the heavy metal element is lead and / or cadmium, and the low melting point metal is one or more of tin, indium and bismuth.

[0039] In the preferred embodiment, the content of the heavy metal element in the outer coating layer is 20wt%-60wt% in the alloy material film layer, more preferably 30wt%-50wt%, to ensure a suitable alloy material melting point, facilitate coating processing, and take into account excellent optical fiber performance.

[0040] In some embodiments, the diameter of the cladding layer is 124-126 μm, the diameter of the inner coating layer is 170-210 μm, the diameter of the outer coating layer is 200-300 μm, and preferably, the thickness of the outer coating layer is greater than or equal to 20 μm, more preferably, also less than or equal to 50 μm. The difference between the radii of the inner coating layer and the cladding layer is the coating thickness of the inner coating layer, and a suitable inner coating layer coating thickness ensures excellent bending resistance of the optical fiber; the difference between the radii of the outer coating layer and the inner coating layer is the coating thickness of the outer coating layer. The coating thickness of the outer coating layer and the inner coating layer 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 diameter of the cladding layer, the diameter of the inner coating layer, and the diameter of the outer coating layer of the metal-coated radiation-resistant optical fiber of the present application refer to the diameter of the outer circle of the circular ring in which the cladding layer, the inner coating layer, and the outer coating layer of the metal-coated radiation-resistant optical fiber of the present application are located.

[0041] The present application also provides a manufacturing method of the metal-coated radiation-resistant optical fiber, comprising the following steps:

[0042] S1: drawing a bare optical fiber comprising the core and the cladding layer;

[0043] S2: after cooling the bare optical fiber, sequentially performing resin material melting coating and ultraviolet curing to obtain an optical fiber forming the inner coating layer;

[0044] S3: sequentially performing alloy material melting coating and cooling on the optical fiber forming the inner coating layer to form the outer coating layer on the surface of the inner coating layer, to obtain the metal-coated radiation-resistant optical fiber.

[0045] In some embodiments, the optical fiber forming the inner coating layer is subjected to alloy material melting coating in step S3, and the temperature of the alloy material melting coating is 70-200℃, and the temperature of the melting coating is higher than the melting point of the alloy material by 3-15℃. The coating temperature is higher than the melting point of the alloy material to ensure that the alloy is in a molten state for coating, and the temperature of the melting coating is controlled within 70-200℃ to perform melting coating of the outer coating layer while preventing aging of the inner coating layer.

[0046] In the preferred embodiment, the ratio h / v of the height h of the alloy material solution to the drawing speed v of the optical fiber during the alloy material melt coating of step S3 is less than 5 ms, and more preferably, 2.5 ms≤h / v≤4.5 ms, to ensure the appropriate coating thickness of the alloy coating and thus the performance of the optical fiber. In some embodiments of the present application, the height h of the alloy material solution is in mm, the drawing speed v of the optical fiber is in mm / ms, and thus the h / v is in ms, which is a time unit. The ratio of the height of the alloy material solution to the drawing speed of the optical fiber in the present application is controlled within an appropriate range, which can be understood as the coating residence time of the optical fiber in the melt alloy solution needs to be controlled within an appropriate range to ensure the appropriate coating thickness of the alloy material. Therefore, h / v in the present application can also be referred to as the coating time. The specific values of the height h of the alloy material solution and the drawing speed v of the optical fiber can be set as needed, as long as the above requirements of h / v are met. For example, in some embodiments, the height h of the alloy material solution during the alloy material melt coating of step S3 is 20-30 mm, and the drawing speed v is 5-10 m / s.

[0047] The outer coating layer material of the optical fiber is designed as an alloy outer coating layer containing heavy metal elements such as lead and cadmium, which significantly reduces the radiation energy entering the core and reduces the radiation-induced loss of the optical fiber. Even if it is applied to extreme areas such as high temperature and high radiation dose, it also has good high-temperature resistance and radiation resistance:

[0048] ①Radiation energy mainly propagates in the form of electromagnetic waves. Lead and cadmium elements are heavy metal elements with large atomic weight and high density, which can better block radiation energy. When radiation energy interacts with metal, the metal can quickly conduct energy to its surroundings and disperse energy through its excellent electrical conductivity, thereby absorbing radiation energy and protecting the glass structure for optical communication from damage by radiation energy.

[0049] ②The temperature resistance of the 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 of optical fibers. When the optical fiber is in a high-temperature environment for a long time, the metal coating has stronger stability and is less likely to deform, corrode, age, etc., thereby improving the overall high-temperature resistance and reliability of the optical fiber.

[0050] The coating layer structure of the optical fiber is designed as a double-layer structure with a polyester or other organic film layer as the inner coating layer and an alloy film layer as the outer coating layer, forming an inner-soft outer-hard structure. This avoids the problem of stress concentration in the glass part and the sharp deterioration of intrinsic loss due to a single-layer metal coating, and optimizes the intrinsic loss level of the optical fiber. The organic inner layer as a buffer layer enhances the overall toughness of the optical fiber and optimizes the bending resistance and anti-interference ability of the optical fiber.

[0051] The application realizes the double-coating structure of the organic inner coating and the metal outer coating of the optical fiber by regulating the different metal ratios of the outer coating of the optical fiber, the coating temperature and the coating time in the drawing coating process, and guarantees the continuous manufacturability thereof.

[0052] ①The continuous large-scale production of the long-section long-demand optical fiber can be realized by using the melting coating process, however, for the radiation-resistant optical fiber comprising the organic inner coating and the alloy outer coating, if the content of the heavy metal lead and cadmium in the outer coating is too low, the radiation resistance of the alloy coating is poor and the high-energy rays cannot be shielded, if the content of the heavy metal lead and cadmium is too high, the melting temperature and the coating temperature of the alloy are high (>220℃), and in the process of coating the alloy film layer for the second time, the organic inner coating is aged and yellowed due to the high temperature, and the toughness and the bending resistance of the optical fiber are deteriorated. The application regulates the ratio of the alloy elements selected in the second coating device, reduces the melting temperature of the alloy under the premise of maintaining the radiation resistance of the metal coating, and guarantees the effective coating of the organic coating and the alloy coating.

[0053] ②In the melting coating process of the double-coating radiation-resistant optical fiber, it is found that if h / v is too large or the coating temperature is too high, the residence time of the optical fiber coating in the metal solution is too long and the temperature is high, the coated alloy coating is melted, the alloy coating cannot be attached to the surface of the optical fiber, or the coating is thin, and the radiation resistance of the optical fiber is reduced, if the alloy coating temperature is too low, when the optical fiber at room temperature enters the second coating device, the temperature in the coating device is further reduced, the metal solution around the optical fiber is solidified and is no longer in the molten state, and the alloy coating cannot be attached to the surface of the optical fiber. The application regulates the height h of the metal solution in the second coating device, the fiber drawing speed v and the coating temperature, and guarantees the coating thickness of the alloy coating.

[0054] ③The common metal coating process such as the cold spraying method, the evaporation method, the electroplating method and the sputtering method is an intermittent coating process, and can only coat the drawn single batch of optical fiber, and cannot realize the continuous production, and the production capacity is low and the production stability is poor. The application can realize the continuous metal film layer coating of the optical fiber by designing the low-melting-point alloy coating with different metal contents and combining the coating process of the metal melting method, and greatly improves the production capacity of the metal-coated optical fiber. The application overcomes the barrier that the metal melting point is too high to be suitable for the melting coating method and cannot be continuously produced, and takes into account the radiation resistance of the optical fiber, so that the alloy coating comprising the heavy metal elements lead / cadmium and also comprising tin / bismuth / indium is designed, and the continuous production of the metal-coated radiation-resistant optical fiber is realized.

[0055] Reference Figure 1As shown, the metal-coated anti-radiation optical fiber provided by the present application comprises a core (core layer) 10 and a cladding layer 11, and an organic inner coating layer 12 and an alloy outer coating layer 13 are arranged outside the cladding layer 11, and the organic inner coating layer 12 and the alloy outer coating layer 13 jointly constitute the coating layer of the anti-radiation optical fiber. The anti-radiation optical fiber can be prepared by using the following process, and a schematic diagram of a preparation process device is as shown in Figure 2 As shown:

[0056] S1: Under the action of the first heating furnace 21, the preform rod 20 is drawn into a bare optical fiber comprising the core 10 and the cladding layer 11 according to a conventional process.

[0057] S2: The bare optical fiber passes through the cooling pipe of the cooling furnace 22 and then enters the first coating device 23 and the ultraviolet curing furnace 24 in sequence to obtain an optical fiber with the organic inner coating layer 12.

[0058] S3: The alloy material is coated outside the inner coating layer 12 by using a melting process. Specifically, the optical fiber with the inner coating layer 12 obtained in step S2 passes through the second coating device 25 and the cooler 27 in sequence, the second coating device 25 contains metal alloy, the second heating furnace 26 arranged around the second coating device 25 maintains the metal alloy in a molten state, and the cooler 27 promotes the solidification of the alloy coating on the surface of the optical fiber to form the outer coating layer 13 on the surface of the inner coating layer 12. Finally, the metal-coated anti-radiation optical fiber is obtained through the take-up device 28.

[0059] The preform rod in step S1 can be made by plasma chemical vapor deposition (PCVD), modified chemical vapor deposition (MCVD), outside vapor deposition (OVD) or vapor axial deposition (VAD). After the preform rod is prepared, the fiber is drawn on the drawing tower, the drawing speed of the fiber preform rod is not higher than 200 m / min, and the drawing tension is not higher than 60 g. In some embodiments of the present application, a silica bare optical fiber with a cladding diameter of 124-126 μm is drawn.

[0060] In some embodiments, the first coating device in step S2 contains acrylic resin or modified acrylic resin containing silicon or fluorine for coating to obtain an organic film layer, i.e., the inner coating layer.

[0061] The present application will be described in detail below in conjunction with specific examples and comparative examples.

[0062] Example 1

[0063] The optical fiber of Example 1 is composed of a core layer and a cladding layer, the cladding layer is arranged outside the core layer, and the inner coating layer and the outer coating layer are arranged outside the cladding layer in sequence, the inner coating layer is acrylic resin, and the outer coating layer is lead-tin alloy. The content of lead in the outer coating layer of Example 1 is 30 wt%, and the content of tin is 70 wt%.

[0064] The preparation device and process are shown in Figure 2 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 the acrylic resin and the ultraviolet curing furnace 24 in sequence to form the organic inner coating. Then, the alloy material coating is performed outside the inner coating. The melting process is adopted. The optical fiber passes through the second coating device 25 containing the lead-tin alloy and the cooler 27 in sequence. The second heating furnace 26 around the second coating device 25 maintains the alloy in the molten state. The cooler 27 promotes the alloy coating to solidify on the surface of the optical fiber to obtain the metal-coated optical fiber.

[0065] The ratio of the height h (24 mm) of the alloy solution in the second coating device to the fiber drawing speed v (6 mm / ms) is 4. The secondary coating temperature, that is, the melting coating temperature, is 175°C. The specific parameters are shown in Table 1.

[0066] Example 2, Example 4

[0067] The optical fiber of Example 2 and Example 4 is composed of a core layer and a cladding layer. The cladding layer is around the core layer. The inner coating layer and the outer coating layer are around the cladding layer in sequence. The inner coating layer is a silicon-containing acrylic resin with a silicon content of 20 mol%. The outer coating layer is a cadmium-indium alloy. In the outer coating layer of Example 2, the cadmium element accounts for 40 wt%, and the indium element accounts for 60 wt%. In the outer coating layer of Example 4, the cadmium element accounts for 20 wt%, and the indium element accounts for 80 wt%.

[0068] The preparation device and process are shown in Figure 2 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 the acrylic resin and the ultraviolet curing furnace 24 in sequence to form the organic inner coating. Then, the alloy material coating is performed outside the inner coating. The melting process is adopted. The optical fiber passes through the second coating device 25 containing the lead-tin alloy and the cooler 27 in sequence. The second heating furnace 26 around the second coating device 25 maintains the alloy in the molten state. The cooler 27 promotes the alloy coating to solidify on the surface of the optical fiber to obtain the metal-coated optical fiber.

[0069] In Example 2, the ratio of the height h (24 mm) of the alloy solution in the second coating device to the fiber drawing speed v (8 mm / ms) is 3. The secondary coating temperature, that is, the melting coating temperature, is 150°C.

[0070] In Example 4, the ratio of the height h (24 mm) of the alloy solution in the second coating device to the fiber drawing speed v (6 mm / ms) is 4. The secondary coating temperature, that is, the melting coating temperature, is 124°C.

[0071] Example 3, Comparative Example 4

[0072] The optical fiber of Example 3 and Comparative Example 4 is composed of a core layer and a cladding layer, and the cladding layer is surrounded by the core layer, and the inner coating layer is surrounded by the cladding layer, and the outer coating layer is surrounded by the inner coating layer, and the inner coating layer is an acrylic resin, and the outer coating layer is a lead-bismuth alloy. The content of lead in the outer coating layer of Example 3 is 60 wt%, and the content of bismuth is 40 wt%; the content of lead in the outer coating layer of Comparative Example 4 is 50 wt%, and the content of bismuth is 50 wt%.

[0073] The preparation device and process are shown in Figure 2 The bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling pipe of the cooling furnace 22, and then enters the first coating device 23 containing the acrylic resin and the ultraviolet curing furnace 24 in sequence to form the inner coating layer of the organic matter; then the alloy material is coated outside the inner coating layer, and a melting process is adopted, and the optical fiber passes through the second coating device 25 containing the lead-bismuth alloy and the cooler 27 in sequence, the second heating furnace 26 surrounding the second coating device 25 maintains the alloy in a molten state, and the cooler 27 promotes the solidification of the alloy coating on the surface of the optical fiber to obtain the optical fiber with the metal coating layer.

[0074] In Example 3, the ratio of the height h (24 mm) of the alloy solution in the second coating device to the fiber drawing speed v (6 mm / ms) is 4, and the secondary coating temperature, i.e. the melting coating temperature, is 200°C.

[0075] In Comparative Example 4, the ratio of the height h (24 mm) of the alloy solution in the second coating device to the fiber drawing speed v (4 mm / ms) is 6, and the secondary coating temperature, i.e. the melting coating temperature, is 183°C.

[0076] Comparative Example 1

[0077] The optical fiber of Comparative Example 1 is composed of a core layer and a cladding layer, and the cladding layer is surrounded by the core layer, and the single-layer lead metal coating layer is surrounded by the cladding layer.

[0078] This comparative example prepares a single-layer lead metal coating layer, and the preparation device is the same as Figure 2 except that the first coating device 23 and the ultraviolet curing furnace 24 are omitted, and the bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling pipe of the cooling furnace 22 and directly enters the second coating device 25 containing the lead metal and the cooler 27, and the second heating furnace 26 surrounding the second coating device 25 maintains the lead metal in a molten state, and the cooler 27 promotes the solidification of the lead coating on the surface of the optical fiber to obtain the optical fiber with the single-layer lead metal coating layer.

[0079] In Comparative Example 1, the ratio of the height h (24 mm) of the alloy solution in the second coating device to the fiber drawing speed v (8 mm / ms) is 3, and the melting coating temperature of the metal lead is 335°C.

[0080] Comparative Example 2

[0081] The optical fiber of Comparative Example 2 is a conventional optical fiber, which is composed of a core layer and a cladding layer, and the cladding layer is arranged outside the core layer, and the inner coating layer and the outer coating layer are arranged outside the cladding layer in sequence, the inner coating layer is an acrylic resin, and the outer coating layer is a silicon-containing acrylic resin, and the content of the silicone is 20 mol%.

[0082] The preparation device and process of the present comparative example are the same as those of the present example. Figure 2 Only the second coating applicator 25, the second heating furnace 26 and the cooler 27 are removed, and are replaced by a second coating applicator containing a silicon-containing acrylic resin and another ultraviolet curing furnace, and the bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling pipe of the cooling furnace 22, and then enters the first coating applicator 23 containing the acrylic resin and the ultraviolet curing furnace 24 in sequence, to form an acrylic inner coating layer; then the coating of the silicon-containing acrylic resin is performed outside the inner coating layer, and the optical fiber passes through the second coating applicator containing the silicon-containing acrylic resin and another ultraviolet curing furnace in sequence, and is cured to obtain a double-coated optical fiber.

[0083] Comparative Example 3

[0084] The optical fiber of Comparative Example 3 is composed of a core layer and a cladding layer, and the cladding layer is arranged outside the core layer, and the inner coating layer and the outer coating layer are arranged outside the cladding layer in sequence, the inner coating layer is an acrylic resin, and the outer coating layer is a cadmium-bismuth alloy. The content of the cadmium element in the outer coating layer of Comparative Example 3 is 50 wt%, and the content of the bismuth element is 50 wt%.

[0085] The preparation device and process are as shown in Figure 2 The bare optical fiber drawn by the preform rod 20 under the action of the first heating furnace 21 passes through the cooling pipe of the cooling furnace 22, and then enters the first coating applicator 23 containing the acrylic resin and the ultraviolet curing furnace 24 in sequence, to form an organic inner coating layer; then the coating of the alloy material is performed outside the inner coating layer, and a melting process is adopted, and the optical fiber passes through the second coating applicator 25 containing the cadmium-bismuth alloy and the cooler 27 in sequence, the second heating furnace 26 surrounding the second coating applicator 25 maintains the alloy in a molten state, and the cooler 27 promotes the solidification of the alloy coating layer on the surface of the optical fiber, to obtain a metal-coated optical fiber.

[0086] The ratio of the height h (24 mm) of the alloy solution in the second coating applicator in Comparative Example 3 to the fiber drawing speed v (8 mm / ms) is 3, and the secondary coating temperature, that is, the melting coating temperature, is 164℃.

[0087] Comparative Example 5

[0088] The optical fiber of Comparative Example 5 is composed of a core layer and a cladding layer, and the cladding layer is arranged outside the core layer, and the inner coating layer and the outer coating layer are arranged outside the cladding layer in sequence, the inner coating layer is an acrylic resin, and the outer coating layer is a cadmium-tin alloy. The content of the cadmium element in the outer coating layer of Comparative Example 5 is 30 wt%, and the content of the tin element is 70 wt%.

[0089] The preparation device and process are as shown inFigure 2 As shown, the bare optical fiber drawn from the preform 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 applicator 23 containing the acrylic resin and the ultraviolet curing furnace 24, to form the organic inner coating layer; then the alloy material is coated outside the inner coating layer, and the melting process is adopted, the optical fiber passes through the second coating applicator 25 containing the cadmium-tin alloy and the cooler 27 in sequence, the second heating furnace 26 around the second coating applicator 25 is used to maintain the alloy in a molten state, and the cooler 27 is used to promote the alloy coating to solidify on the surface of the optical fiber, so as to obtain the metal-coated optical fiber.

[0090] In the comparative example 5, the ratio of the height h (24 mm) of the alloy solution in the second coating applicator to the fiber drawing speed v (6 mm / ms) is 4, and the secondary coating temperature, i.e. the melting coating temperature, is 250°C.

[0091] The specific structural parameters and preparation process parameters of the anti-radiation optical fibers according to the above examples and comparative examples are shown in Table 1.

[0092] Table 1: Cross-sectional design parameters of the optical fibers of the examples and comparative examples

[0093]

[0094] The detection method used in the optical fibers of the examples and comparative examples of the present application is as follows:

[0095] At a temperature of 25±3°C, the optical fiber is irradiated using a cobalt-60 radiation source, and the total dose is 2 MGy. During the irradiation, a light source with a wavelength of 1310 nm is used to test the attenuation of the optical fiber caused by the irradiation.

[0096] The intrinsic loss and the bending additional loss of the optical fiber are tested using an optical analyzer (PK company), the bending diameter is 30 mm, and the attenuation difference before and after the bending is tested.

[0097] The dynamic fatigue parameters of the optical fiber before and after aging are tested according to GB / T 15972.33-2008, the aging refers to the process that the optical fiber is subjected to 2 MGy irradiation aging and 125°C high-temperature aging for 250 h in sequence, so as to calculate the percentage change Δn of the dynamic fatigue parameters. d .

[0098] The test results of the examples 1-4 and the comparative examples 1-5 are shown in Table 2.

[0099] Table 2: Test results of the optical fibers of the examples and comparative examples

[0100]

[0101] As can be seen from Table 1 and Table 2, in Examples 1 to 4, by disposing the acrylate polymer inner coating and the low-melting alloy material outer coating outside the optical fiber cladding, in combination with appropriate coating thickness parameters and melting coating process parameters, long-section long-melting coating preparation of the optical fiber can be realized, and the prepared optical fiber has excellent intrinsic loss, radiation additional loss, bending additional attenuation and dynamic fatigue parameters. Compared with the examples, in Comparative Example 1, the optical fiber surface only has the heavy metal coating, and the optical fiber has higher intrinsic loss and bending additional attenuation; in Comparative Example 2, the optical fiber only has the acrylate polymer coating, and the optical fiber has deteriorated radiation additional loss and dynamic fatigue parameters; in Comparative Example 3, the inner coating diameter of the optical fiber is too small, and the measured intrinsic loss and bending additional attenuation are too 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, which leads to a small outer coating diameter, and the radiation additional loss and dynamic fatigue parameters of the optical fiber are significantly deteriorated; in Comparative Example 5, the secondary coating temperature is too high, which may affect the quality of the inner coating, and the outer coating thickness is too small, which leads to high intrinsic loss, bending additional attenuation and radiation additional loss of the optical fiber, and the dynamic fatigue parameters are reduced.

[0102] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A metal-coated radiation resistant optical fiber, characterized in that, The core, the cladding, the inner coating layer and the outer coating layer are sequentially arranged from inside to outside, the inner coating layer is an organic film layer, and the outer coating layer is a metal film layer; The material of the organic film layer is an acrylic resin polymer, the metal film layer is an alloy material film layer containing heavy metal elements and low-melting-point metals, and the melting point of the alloy material is less than or equal to 220℃. The diameter of the inner coating layer is 170-210μm. When the outer coating layer is prepared by melt coating of the alloy material outside the inner coating layer, the temperature of the melt coating is 70-200℃, and the temperature of the melt coating is 3-15℃ higher than the melting point of the alloy material; the ratio h / v of the height h of the alloy material solution to the drawing speed v of the optical fiber during the melt coating of the alloy material is less than 5 ms.

2. The metal-coated radiation resistant optical fiber of claim 1, wherein, The inner coating layer is one or more of an acrylic resin, a silicon-containing modified acrylic resin or a fluorine-containing modified acrylic resin.

3. The metal-coated radiation resistant optical fiber of claim 1, wherein, The melting point of the alloy material is less than or equal to 200℃.

4. The metal-coated radiation resistant optical fiber of claim 1, wherein, The heavy metal elements are lead and / or cadmium, and the low-melting-point metals are one or more of tin, indium and bismuth.

5. The metal-coated radiation resistant optical fiber of claim 1, wherein, The content of the heavy metal elements in the alloy material film layer is 20wt%-60wt%.

6. The metal-coated radiation resistant optical fiber of claim 1, wherein, The diameter of the cladding is 124-126μm, the diameter of the outer coating layer is 200-300μm, and the thickness of the outer coating layer is greater than or equal to 20μm.

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 method comprises the following steps: S1: drawing a bare optical fiber comprising the core and the cladding; S2: after the bare optical fiber is cooled, melt coating of a resin material and ultraviolet curing are sequentially performed to obtain an optical fiber with the inner coating layer; S3: the optical fiber with the inner coating layer is sequentially subjected to melt coating of an alloy material and cooling to form the outer coating layer on the surface of the inner coating layer, thereby obtaining the metal-coated anti-radiation optical fiber; In step S3, the melt coating of the alloy material is performed at a temperature of 70-200℃, and the temperature of the melt coating is 3-15℃ higher than the melting point of the alloy material; and the ratio h / v of the height h of the alloy material solution to the drawing speed v of the optical fiber during the melt coating of the alloy material is less than 5 ms.

8. The production method according to claim 7, characterized in that: In step S3, the ratio h / v of the height h of the alloy material solution to the drawing speed v of the optical fiber during the melt coating of the alloy material is 2.5 ms ≤h / v≤4.5 ms.

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