A method for manufacturing a multi-core flexible optical fiber

Abstract

The present application relates to a kind of preparation methods of multi-core flexible optical fiber, the multi-core optical fiber is formed by two different flexible materials, respectively using flexible material to manufacture the cladding of multi-core flexible optical fiber and the core of multi-core flexible optical fiber, then the core and cladding are integrated using cladding flexible material, form the structure of multi-core flexible optical fiber.Compared with the traditional preparation method of multi-core optical fiber, the present application proposes to change flexible material from liquid to solid by cross-linking and polymerization method, which is lower in cost, and the manufacturing method is simpler and more reliable than traditional method, and different compositions and different core numbers of multi-core flexible optical fiber can be prepared by flexible use of manufacturing method, which can be applied to various complex scenes.The present application effectively utilizes the characteristics of flexible material, improves the structural strength of optical fiber under the condition of ensuring the light transmission efficiency, improves the yield of optical fiber, so that the prepared optical fiber has excellent mechanical properties and good light guide efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of multi-core optical fiber preparation, in particular to a multi-core flexible optical fiber preparation method BACKGROUND

[0002] Since the advent of optical fiber in 1970, it has been developed for more than 40 years. Optical fiber is generally composed of a core, a cladding and an external protective layer. Because the optical fiber itself is very fragile, the protective layer of the optical fiber is relatively thick and heavy compared to the core and cladding structure, so the size of the optical fiber is limited. For example, the bare fiber diameter of a common single-mode optical fiber for transmission is 250 μm, and the core and cladding structure that plays a decisive role in light wave transmission only has a diameter of 20 μm, that is, a similar light transmission effect can be achieved. Therefore, the ordinary optical fiber sacrifices a certain size, thickens the protective outer layer which has little effect on transmission, and obtains higher mechanical properties. In order to effectively improve the transmission rate of a single optical fiber, developing a multi-core optical fiber containing multiple cores in the cladding is a suitable solution. A multi-core optical fiber contains multiple parallel cores in one cladding. The cores are arranged in a certain shape and do not interfere with each other, serving as independent channels to achieve information transmission, with high integration and good stability. Compared with ordinary optical fiber, the space division multiplexing structure of multi-core optical fiber fully develops the spatial dimension, improves the utilization rate of space of a single optical fiber, effectively improves the transmission rate, and can significantly improve the transmission capacity bottleneck. However, multi-core optical fiber has problems and shortcomings while having many unique advantages. Although the multi-core optical fiber makes more full use of the 250 μm optical fiber diameter, it is made of silica material and is fragile and easy to break, so it often needs to be armored with a support material with high mechanical strength wrapped outside the optical fiber. Although the armor increases the structural strength of the multi-core optical fiber, it increases the preparation cost of the multi-core optical fiber and reduces the use flexibility of the multi-core optical fiber. Therefore, a simpler and more efficient method is needed to manufacture a multi-core optical fiber with high strength and low cost. SUMMARY

[0003] The purpose of the present application is to provide a multi-core flexible optical fiber preparation method, which can prepare a multi-core optical fiber with high strength and low cost by a simpler and more efficient method.

[0004] To achieve the above purpose, the present application provides a multi-core flexible optical fiber preparation method, comprising the following steps:

[0005] S1, mix the flexible material precursor liquid with the refractive index modulation solution to prepare a multi-core flexible optical fiber core precursor liquid A, take a plurality of hollow core molds with one end open and one end sealed, fill the hollow core molds with the multi-core flexible optical fiber core precursor liquid A, the multi-core flexible optical fiber core precursor liquid A fills the inside of the hollow core mold, and the multi-core flexible optical fiber core precursor liquid A is solidified by corresponding appropriate treatment to form a solidified flexible optical fiber core;

[0006] S2, put the hollow core mold and the inside solidified flexible optical fiber core into the core mold treatment liquid, dissolve / erode the hollow core mold with the core mold treatment liquid, take out the plurality of solidified flexible optical fiber cores, and wash the plurality of solidified flexible optical fiber cores with clean water for multiple times for standby use;

[0007] S3, take a hollow cladding mold with both ends open, fill the hollow cladding mold with a flexible optical fiber cladding precursor liquid B, the flexible optical fiber cladding precursor liquid B fills the inside of the hollow cladding mold, a small part of the flexible optical fiber cladding precursor liquid B adheres to the wall of the hollow cladding mold to form a thin layer of the flexible optical fiber cladding precursor liquid B, the rest of the flexible optical fiber cladding precursor liquid B flows out from the opening of the hollow cladding mold, and the flexible optical fiber cladding precursor liquid B is solidified by corresponding appropriate treatment to form a flexible hollow cladding structure;

[0008] S4, gather the plurality of flexible optical fiber cores, insert one end of the flexible optical fiber core bundle into the hollow cladding mold by 10 mm, take a syringe filled with clean water, inject the water from the hollow cladding mold where the one end of the flexible optical fiber core bundle is inserted, and use the water flow to bring the flexible optical fiber core bundle into the hollow cladding mold, separate the plurality of flexible optical fiber cores in the flexible optical fiber core bundle, make the flexible optical fiber cores tight by pulling the part of each flexible optical fiber core longer than the flexible hollow cladding structure, keep the state of the tight flexible optical fiber cores, and adhere the part of the plurality of flexible optical fiber cores longer than the flexible hollow cladding structure to the outer end of the hollow cladding mold by a temporary adhesive, so as to realize the temporary fixing of the flexible optical fiber cores, the hollow cladding mold and the flexible hollow cladding structure;

[0009] S5, fill the inside of the hollow cladding mold with the flexible optical fiber cladding precursor liquid B again, a part of the flexible optical fiber cladding precursor liquid B adheres to the wall of the intermediate cladding mold and the flexible optical fiber cores, and the flexible optical fiber cladding precursor liquid B is solidified by corresponding appropriate treatment to form a flexible optical fiber structure;

[0010] S6, cut the flexible optical fiber core longer than the flexible cavity cladding structure part at both ends of the hollow cladding mold, put the hollow cladding mold and the internal already solidified flexible optical fiber structure into the cladding mold processing liquid, dissolve / erode the cladding mold by the cladding mold processing liquid, take out the solidified flexible optical fiber structure, and obtain the multicore flexible optical fiber by washing with water for multiple times.

[0011] Preferably, the flexible material precursor liquid in the step S1 is one of mixed adhesive main agent-mixed adhesive secondary agent, gelatin-water solution, which is changed to solid state by static; or polydimethylsiloxane-cured glue mixed solution, which is changed to solid state by high temperature treatment; one of acrylamide-N,N'-methylene bisacrylamide mixed solution, polyethylene glycol bisacrylate-2-hydroxy-2-methylpropiophenone mixed solution, which is changed to solid state by ultraviolet irradiation.

[0012] Preferably, the refractive index modulation solution in the step S1 is one or a mixture of several of metal ion salt, sugar, glycerol.

[0013] Preferably, the material of the hollow core mold in the step S2 is one or a mixture of several of acrylonitrile-butadiene-styrene alcohol copolymer, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, glass, quartz glass, organic glass.

[0014] Preferably, the core mold processing liquid in the step S2 is one or a mixture of several of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, chloroform, dichloroethane, ethanol, toluene.

[0015] Preferably, the flexible optical fiber cladding precursor liquid B in the step S3 is one of mixed adhesive, gelatin water solution, which is changed to solid state by static; or polydimethylsiloxane-cured glue mixed solution, which is changed to solid state by high temperature treatment; one of acrylamide-N,N'-methylene bisacrylamide mixed solution, polyethylene glycol bisacrylate-2-hydroxy-2-methylpropiophenone mixed solution, which is changed to solid state by ultraviolet irradiation.

[0016] Preferably, the cladding mold processing liquid in the step S6 is one or a mixture of several of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, chloroform, dichloroethane, ethanol, toluene.

[0017] Therefore, the application adopts the above-mentioned preparation method of the multicore flexible optical fiber, and has the following beneficial effects:

[0018] 1) The present application makes full use of space division multiplexing structure, and a plurality of cores are arranged in one optical fiber to form a multicore optical fiber. The high-density cores greatly expand the signal transmission capacity and energy transmission capacity, and the utilization of the internal space of the optical fiber is more sufficient. Compared with ordinary single-mode optical fibers, the multicore optical fiber can simultaneously conduct a plurality of optical signals in a similar size, sufficiently increases the coupling light density, and has a wide application prospect in information transmission, high-energy laser, wide-spectrum supercontinuum output and the like.

[0019] 2) In the present application, the optical fiber is prepared from flexible materials. Since the flexible materials have excellent mechanical properties, the optical fiber has better bending and stretching properties than ordinary optical fibers, is easy to bend and not easy to break, and can better adapt to the flexible and complex deformation conditions of the human body, and therefore is very suitable for wearable devices.

[0020] 3) The process for preparing the multicore optical fiber in the present application has high flexibility, and can prepare optical fibers with various structures, which is embodied in the following two points: 1) During preparation, different numbers of flexible optical fiber cores can be filled into the optical fiber as needed, so that multicore optical fibers with different numbers of cores can be prepared. Different numbers of cores of the multicore optical fiber can be prepared according to different needs between high optical fiber strength and high light density. 2) When fixing the core and the cladding, a large amount of cladding precursor liquid can be poured to prepare a solid multicore flexible optical fiber, so as to obtain better mechanical properties. A small amount of cladding precursor liquid can also be poured to prepare a hollow multicore flexible optical fiber, which is used in special fields such as micro-flow sensing.

[0021] 4) The flexible material of the flexible optical fiber cladding is used again for curing when fixing the flexible optical fiber cladding and the flexible optical fiber core. Not only can the flexible optical fiber cladding and the flexible optical fiber core be reliably fixed and combined together, but also the third adhesive introduced by the optical fiber is avoided, so that the flexible optical fiber cladding and the flexible optical fiber core cannot effectively contact.

[0022] The technical solutions of the present application will be further described in detail through the following examples. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structure of two optical fiber cores in the multicore flexible optical fiber of the present application.

[0024] Figure 2 It is a structure of three optical fiber cores in the multicore flexible optical fiber of the present application.

[0025] Figure 3 It is a structure of four optical fiber cores in the multicore flexible optical fiber of the present application.

[0026] Figure 4 It is a schematic diagram of a device used when pouring the core precursor liquid into the flexible optical fiber core mold in Example 1 of the present application.

[0027] Figure 5 A cross-sectional view of a sample after the hollow cladding mold is processed in Embodiment 1 of the present application, and the fiber cladding is attached to the inner wall of the hollow cladding mold;

[0028] Figure 6 A cross-sectional view of a sample after four flexible fiber cores are placed into the cladding mold in Embodiment 1 of the present application;

[0029] Figure 7 A cross-sectional view of a sample when the hot-melt glue after being heated appropriately is dropped at the contact position between the part of the multiple fiber cores longer than the fiber cladding and the cladding mold in Embodiment 1 of the present application;

[0030] Figure 8 A cross-sectional view of a sample after the four flexible fiber cores are fixed with the multi-core flexible fiber cladding in Embodiment 1 of the present application;

[0031] Figure 9 A cross-sectional view of a finished product of the multi-core flexible fiber prepared in Embodiment 1 of the present application;

[0032] Figure 10 A cross-sectional view of a sample after the four flexible fiber cores are fixed with the multi-core flexible fiber cladding in Embodiment 2 of the present application;

[0033] Figure 11 A cross-sectional view of a finished product of the multi-core flexible fiber prepared in Embodiment 2 of the present application;

[0034] Figure 12 A cross-sectional view of a sample after two flexible fibers are placed into the cladding mold in Embodiment 3 of the present application;

[0035] Figure 13 A cross-sectional view of a sample after the two flexible fiber cores are fixed with the multi-core flexible fiber cladding in Embodiment 3 of the present application;

[0036] Figure 14 A cross-sectional view of a finished product of the multi-core flexible fiber prepared in Embodiment 3 of the present application;

[0037] Figure 15 A cross-sectional view of a finished product of the multi-core flexible fiber prepared in Embodiment 3 of the present application.

[0038] BRIEF DESCRIPTION OF DRAWINGS: A, flexible fiber core precursor liquid; B, flexible fiber cladding precursor liquid; 1, hollow core mold; 2, flexible fiber core; 3, hollow cladding mold; 4, flexible hollow cladding structure; 5, temporary adhesive; 6, flexible fiber structure. DETAILED DESCRIPTION

[0039] The present application provides a preparation method of a multi-core flexible fiber, characterized by comprising the following steps:

[0040] S1, mix the flexible material precursor liquid with the refractive index modulation solution to make a multi-core flexible optical fiber core precursor liquid A, take a plurality of hollow core molds 1 with one end open and one end sealed, fill the hollow core molds 1 with the multi-core flexible optical fiber core precursor liquid A, the multi-core flexible optical fiber core precursor liquid A fills the inside of the hollow core molds 1, solidify the multi-core flexible optical fiber core precursor liquid A through appropriate treatment corresponding to the multi-core flexible optical fiber core precursor liquid A to form a solidified flexible optical fiber core 2; the flexible material precursor liquid is one of mixed adhesive main agent-mixed adhesive secondary agent, gelatin-water solution, which becomes solid through static state; or polydimethylsiloxane-cured glue mixed solution, which becomes solid through high temperature treatment; one of acrylamide-N,N'-methylene bisacrylamide mixed solution, polyethylene glycol bisacrylate-2-hydroxy-2-methylpropiophenone mixed solution, which becomes solid through ultraviolet irradiation. The refractive index modulation solution is one or a mixture of several of metal ion salt, sugar, glycerol.

[0041] S2, put the hollow core mold 1 and the inside already solidified flexible optical fiber core 2 into the core mold treatment liquid, dissolve / erode the hollow core mold 1 with the core mold treatment liquid, take out a plurality of solidified flexible optical fiber cores 2, and wash with clean water for multiple times for standby use; the material of the hollow core mold 1 is one or a mixture of several of acrylonitrile-butadiene-styrene alcohol copolymer, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, glass, quartz glass, organic glass. The core mold treatment liquid is one or a mixture of several of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, chloroform, dichloroethane, ethanol, toluene.

[0042] S3, take a hollow cladding mold 3 with both ends open, pour flexible optical fiber cladding precursor liquid B into the hollow cladding mold 3, the flexible optical fiber cladding precursor liquid B fills the inside of the hollow cladding mold 3, a small part of the flexible optical fiber cladding precursor liquid B sticks to the wall of the hollow cladding mold 3 to form a thin layer of flexible optical fiber cladding precursor liquid B, the rest of the flexible optical fiber cladding precursor liquid B flows out from the opening of the hollow cladding mold 3, solidify the flexible optical fiber cladding precursor liquid B through appropriate treatment corresponding to the flexible optical fiber cladding precursor liquid B to form a flexible hollow cladding structure 4; the flexible optical fiber cladding precursor liquid B is one of mixed adhesive, gelatin water solution, which becomes solid through static state; or polydimethylsiloxane-cured glue mixed solution, which becomes solid through high temperature treatment; one of acrylamide-N,N'-methylene bisacrylamide mixed solution, polyethylene glycol bisacrylate-2-hydroxy-2-methylpropiophenone mixed solution, which becomes solid through ultraviolet irradiation.

[0043] S4, the plurality of flexible optical fiber cores 2 are aligned, one end of the flexible optical fiber core bundle is inserted into the hollow cladding mold 3 by 10 mm, a syringe filled with water is taken, water is injected from the hollow cladding mold 3 where the one end of the flexible optical fiber core bundle is inserted, the flexible optical fiber core bundle is brought into the hollow cladding mold by the water flow, the plurality of flexible optical fiber cores 2 in the flexible optical fiber core bundle are separated, the flexible optical fiber cores 2 are tightened by pulling the part longer than the flexible hollow cladding structure 4 at both ends of each flexible optical fiber core 2, the state of the flexible optical fiber cores 2 being tightened is maintained, the part of the plurality of flexible optical fiber cores 2 longer than the flexible hollow cladding structure 4 is adhered to the outer end of the hollow cladding mold 3 by the temporary adhesive 5, that is, the temporary fixing of the flexible optical fiber cores 2, the hollow cladding mold 3 and the flexible hollow cladding structure 4 is realized;

[0044] S5, the flexible optical fiber cladding precursor liquid B is poured into the hollow cladding mold 3 again, the flexible optical fiber cladding precursor liquid B fills the inside of the hollow cladding mold 3, the flexible optical fiber cladding precursor liquid B is partially adhered to the wall of the intermediate cladding mold 3 and the flexible optical fiber core 2, the flexible optical fiber cladding precursor liquid B is appropriately treated corresponding to the flexible optical fiber cladding precursor liquid B, the flexible optical fiber cladding precursor liquid B is solidified to form the flexible optical fiber structure 6;

[0045] S6, the part of the flexible optical fiber core 2 longer than the flexible hollow cladding structure 4 at both ends of the hollow cladding mold is cut off, the hollow cladding mold 3 and the flexible optical fiber structure 6 inside which has been solidified are put into the cladding mold treatment liquid, the cladding mold is dissolved / eroded by the cladding mold treatment liquid, the solidified flexible optical fiber structure 6 is taken out, and the multi-core flexible optical fiber is obtained by washing with water for several times. The cladding mold treatment liquid is one or several of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, chloroform, dichloroethane, ethanol and toluene.

[0046] The technical solutions of the present application are further illustrated by the following examples.

[0047] Example 1

[0048] S1, four glass cylindrical hollow structure pipes with an inner diameter of 0.5 mm, a wall thickness of 0.1 mm and a length of 350 mm are taken as flexible optical fiber core molds. 13.8 g of acrylamide, 0.2 g of N,N'-methylene bisacrylamide and 16 g of 60%wt lithium bromide aqueous solution are mixed to prepare a core precursor liquid. The opening at one end of the four core molds is blocked, and the prepared core precursor liquid is injected into the four flexible optical fiber core molds, as shown in Figure 4 .

[0049] S2, a UV light source with a main wavelength of 360 nm and an optical power of 10 mW / cm 2The above ultraviolet irradiation core mold, since the core mold is a transparent material, the core precursor liquid is directly irradiated by ultraviolet light at this time, thereby initiating polymerization of acrylamide to form polyacrylamide, forming a transparent and flexible solid structure. After 20 minutes of irradiation, the ultraviolet lamp is turned off, at which time the polyacrylamide has completely solidified.

[0050] S3, place the core mold in an appropriate amount of 40% hydrofluoric acid, and corrode the core mold by the sacrificial template method, take out the flexible optical fiber core, rinse the flexible optical fiber core with clean water 2-3 times, wipe the surface liquid clean, and place it in a dry place for standby.

[0051] S4, mix 20g of polydimethylsiloxane and 2g of polydimethylsiloxane special curing agent, gently stir for 5 minutes, and prepare a flexible optical fiber cladding precursor liquid. Note that the stirring intensity should not be too large, so as to avoid the presence of many bubbles in the precursor liquid. After stirring, the flexible optical fiber cladding precursor liquid is placed in a vacuum chamber, and the internal bubbles are removed by vacuum pumping.

[0052] S5, take a cylindrical hollow structure tube of acrylonitrile-butadiene-styrene alcohol copolymer, with an inner diameter of 2mm, a wall thickness of 0.2mm, and a length of 300mm, as a flexible optical fiber cladding mold, and place the mold vertically and fix it on the experimental table. Pour the flexible optical fiber cladding precursor liquid into the cladding mold from the top, and the flexible optical fiber cladding precursor liquid in the mold slowly flows down under the influence of gravity, most of the flexible optical fiber cladding precursor liquid drips from the bottom end of the cladding mold, and a small amount of flexible optical fiber cladding precursor liquid adheres to the cladding tube wall. This process can be repeated several times to ensure that the cladding mold inside the tube wall is covered with flexible optical fiber cladding precursor liquid.

[0053] S6, place the cladding mold in a constant temperature oven for high temperature treatment, and treat it in an environment of 80 degrees Celsius for 40 minutes. Under the action of high temperature, the polydimethylsiloxane with vinyl active groups in the polydimethylsiloxane crosslinks with the polydimethylsiloxane with hydrogen groups in the curing agent to form a transparent and flexible solid structure. After heating for 40 minutes, the cladding mold is taken out, at which time the polydimethylsiloxane has completely solidified, and the cross section of the cladding mold and the internal flexible solid cladding structure is as shown in Figure 5

[0054] S7, take out the four flexible optical fiber cores prepared in S3, and place the four flexible optical fiber cores together, and insert one end of the flexible optical fiber core bundle into the cladding mold by 10mm. Take a syringe filled with clean water, and inject water from the cladding mold where the flexible optical fiber core bundle is inserted, and use the water flow to bring the flexible optical fiber core bundle into the cladding mold, and separate the four flexible optical fiber cores in the flexible optical fiber core bundle, at which time the cross section of the cladding mold is as shown in Figure 6 ​As shown. Since the flexible optical fiber core is 50 mm longer than the flexible optical fiber cladding, the optical fiber core is tightened by pulling the part of each optical fiber core which is 25 mm longer than the optical fiber cladding. The heated hot melt adhesive is dropped on the part of the optical fiber core which is longer than the optical fiber cladding and the contact part of the cladding mold after being heated appropriately, so that the optical fiber core is adhered to the outer end of the cladding mold, i.e. the temporary fixing of the flexible optical fiber core, the cladding mold and the flexible optical fiber core cladding is realized. Figure 7 As shown. Since the flexible optical fiber core is 50 mm longer than the flexible optical fiber cladding, the optical fiber core is tightened by pulling the part of each optical fiber core which is 25 mm longer than the optical fiber cladding. The heated hot melt adhesive is dropped on the part of the optical fiber core which is longer than the optical fiber cladding and the contact part of the cladding mold after being heated appropriately, so that the optical fiber core is adhered to the outer end of the cladding mold, i.e. the temporary fixing of the flexible optical fiber core, the cladding mold and the flexible optical fiber core cladding is realized.

[0055] S8, the cladding precursor liquid is poured into the cladding mold from above. The precursor liquid in the mold slowly flows under the influence of gravity. Most of the precursor liquid drips from the bottom end of the cladding mold. A small amount of the precursor liquid adheres to the cladding wall and the optical fiber core. This process can be repeated several times to ensure that the cladding wall and the optical fiber core inside the cladding mold are covered with the precursor liquid.

[0056] S9, the cladding mold is placed in an incubator for high temperature treatment. The cladding mold is treated in an environment of 80 degrees Celsius for 40 minutes. Under the action of high temperature, the polydimethylsiloxane with a vinyl active group in the polydimethylsiloxane crosslinks with the polydimethylsiloxane with a hydrogen group in the curing agent to form a transparent and flexible solid structure. After heating for 40 minutes, the cladding mold is taken out. At this time, the polydimethylsiloxane has been completely cured. The cross section of the cladding mold and the internal flexible optical fiber structure is as shown in Figure 8 .

[0057] S10, the part of the flexible optical fiber core which is longer than the cladding is cut off. The cladding mold is placed in an appropriate amount of acetone. The cladding mold is corroded by the sacrifice template method. The prepared four-core flexible optical fiber is taken out. The four-core flexible optical fiber is washed with clean water for 2-3 times. The surface liquid is wiped clean. The four-core flexible optical fiber is obtained as shown in Figure 9 .

[0058] The obtained four-core flexible optical fiber has excellent mechanical properties and optical properties. The core structure and cladding structure jointly act to propagate optical signals. The internal hollow hole can reduce the crosstalk inside the optical fiber as much as possible while maintaining sufficient mechanical strength, and has high versatility.

[0059] The four-core flexible optical fiber prepared in this embodiment uses flexible materials for the cladding and the core. The texture is soft and easy to bend. The four cores can simultaneously transmit optical signals, have high propagation bandwidth and large information density.

[0060] In the preparation of flexible optical fiber, the core and cladding of the flexible optical fiber meet the total reflection condition to realize the total reflection propagation of light by mixing the refractive index modulation solution into the flexible material core precursor liquid to increase the core refractive index. The hollow hole in the interior can isolate the four cores in the optical fiber, so that the leaked light energy in the core will not propagate to other cores to cause crosstalk.

[0061] Example 2

[0062] S1, take four organic glass cylindrical hollow structure tubes, the inner diameter is 0.3mm, the wall thickness is 0.2mm, and the length is 550mm, as the flexible optical fiber core mold. Take 10g of ultraviolet curing glue as the core precursor liquid, block the opening of the four core molds, and fill the four flexible optical fiber core molds with the just prepared core precursor liquid respectively.

[0063] S2, use a main wavelength of 360nm, and the light power is 10mW / cm 2 The above ultraviolet light irradiates the core mold. Since the core mold is a transparent material, the core precursor liquid is directly irradiated by ultraviolet light at this time, thereby causing the internal resin of the ultraviolet curing glue to polymerize and form a transparent and flexible solid structure. After irradiation for 20 minutes, the ultraviolet lamp is turned off, and at this time the ultraviolet curing glue has been completely cured.

[0064] S3, place the core mold in an appropriate amount of dimethylformamide, and corrode the core mold by the sacrificial template method. Take out the flexible optical fiber core, rinse the flexible optical fiber core with clean water for 2-3 times, wipe the surface liquid clean, and place it in a dry place for standby.

[0065] S4, mix 20g of polydimethylsiloxane and 2g of polydimethylsiloxane special curing agent, and gently stir for 5 minutes to prepare the flexible optical fiber cladding precursor liquid. Note that the stirring intensity should not be too large, so as to avoid too many bubbles in the flexible optical fiber cladding precursor liquid. After stirring, the flexible optical fiber cladding precursor liquid is placed in a vacuum chamber, and the internal bubbles are removed by vacuumizing.

[0066] S5, take a polyvinyl chloride cylindrical hollow structure tube, the inner diameter is 1mm, the wall thickness is 0.2mm, and the length is 500mm, as the flexible optical fiber cladding mold, and place the mold vertically and fix it on the experimental table. Pour the flexible optical fiber cladding precursor liquid into the cladding mold from the top, and the flexible optical fiber cladding precursor liquid in the mold slowly flows down under the influence of gravity. Most of the flexible optical fiber cladding precursor liquid drips from the bottom end of the cladding mold, and a small amount of flexible optical fiber cladding precursor liquid adheres to the cladding tube wall. This process can be repeated several times to ensure that the cladding tube wall is covered with flexible optical fiber cladding precursor liquid.

[0067] S6, the cladding mold is put into the thermostat for high temperature treatment, and is treated in the environment of 80 degrees Celsius for 40 minutes. Under the action of high temperature, the polydimethylsiloxane with vinyl active groups in the polydimethylsiloxane and the polydimethylsiloxane with hydrogen groups in the curing agent are crosslinked and cured to form a transparent and flexible solid structure. After heating for 40 minutes, the cladding mold is taken out, and the polydimethylsiloxane has been completely cured.

[0068] S7, the four flexible optical fiber cores prepared in S3 are taken out, the four flexible optical fiber cores are gathered together, and one end of the flexible optical fiber core bundle is inserted into the cladding mold by 10 mm. A syringe filled with clean water is taken, and water is injected from the cladding mold at the one end of the flexible optical fiber core bundle, so that the flexible optical fiber core bundle is brought into the cladding mold by the water flow. The four flexible optical fiber cores in the flexible optical fiber core bundle are separated, and since the flexible optical fiber core is 50 mm longer than the flexible optical fiber cladding, the part of each optical fiber core which is 25 mm longer than the optical fiber cladding is pulled to make the optical fiber core tight. The optical fiber core is kept in the tight state, and the hot melt adhesive which is properly heated is dropped on the part of the multiple optical fiber cores which is longer than the optical fiber cladding and contacts the cladding mold, so that the optical fiber core is adhered to the outer end of the cladding mold, and the temporary fixing of the flexible optical fiber core and the cladding mold and the flexible optical fiber core cladding is realized.

[0069] S8, the flexible optical fiber core and the cladding mold are fixed, the opening at one end of the cladding mold is blocked, and the cladding precursor liquid is filled into the flexible optical fiber cladding mold.

[0070] S9, the cladding mold is put into the thermostat for high temperature treatment, and is treated in the environment of 80 degrees Celsius for 40 minutes. Under the action of high temperature, the polydimethylsiloxane with vinyl active groups in the polydimethylsiloxane and the polydimethylsiloxane with hydrogen groups in the curing agent are crosslinked and cured to form a transparent and flexible solid structure. After heating for 40 minutes, the cladding mold is taken out, and the polydimethylsiloxane has been completely cured, and the cross section of the cladding mold and the internal flexible optical fiber structure at this time is as shown in Figure 10

[0071] S10, the part of the flexible optical fiber which is longer than the cladding at both ends is cut off. The cladding mold is placed in a proper amount of cyclohexanone, and the cladding mold is corroded by the sacrifice template method. The prepared four-core flexible optical fiber is taken out, washed with clean water for 2-3 times, and the surface liquid is wiped clean, so that the four-core flexible optical fiber is obtained, as shown in Figure 11

[0072] The obtained four-core flexible optical fiber has excellent mechanical properties and optical properties, and the core structure and the cladding structure jointly act to propagate the optical signal. The flexible material used as the cladding is large in amount, and therefore the four-core flexible optical fiber has better bending characteristics and stretching characteristics, is easy to bend, and is not easy to break. ​​

[0073] The cladding and the cores of the four-core flexible optical fiber prepared in this embodiment are all prepared using flexible materials with excellent mechanical properties. Compared with the flexible materials inside the multi-core flexible optical fibers prepared in other embodiments, the amount of the flexible material used as the cladding is larger, and thus the mechanical properties can reach the upper limit of this type of structure. However, the distance between the four cores inside the four-core flexible optical fiber prepared in this embodiment is small, and there is no optical isolation structure between the cores. Therefore, after the signals between the four cores leak into the cladding, crosstalk occurs in other cores, which may cause certain noise interference in the process of signal transmission.

[0074] Embodiment 3

[0075] S1, two polystyrene cylindrical hollow structure tubes with an inner diameter of 0.3 mm, a wall thickness of 0.1 mm, and a length of 250 mm were taken as flexible optical fiber core molds. 8 g of gelatin, 12 g of water, and 5 g of sucrose were mixed, heated to 80°C, and fully stirred to prepare a core precursor liquid. The opening of one end of the two core molds was blocked, and the just prepared core precursor liquid was injected into the two flexible optical fiber core molds.

[0076] S2, the two core molds filled with the core precursor liquid were placed in a cool place and left to room temperature. After the temperature of the core precursor liquid decreased, the gelatin inside attracted and interwove with each other, thereby forming a transparent and flexible solid structure.

[0077] S3, the core mold was placed in an appropriate amount of toluene, and the core mold was corroded by the sacrificial template method. The flexible optical fiber core was taken out, washed with clean water for 1-2 times, the surface liquid was wiped clean, and placed in a dry place for standby.

[0078] S4, 16 g of polyethylene glycol diacrylate and 1 g of 2-hydroxy-2-methylpropiophenone were mixed in 3 g of water to prepare a flexible optical fiber cladding precursor liquid.

[0079] S5, a quartz cylindrical hollow structure tube with an inner diameter of 1 mm, a wall thickness of 0.2 mm, and a length of 200 mm was taken as a flexible optical fiber cladding mold, and the mold was placed vertically and fixed on the experimental table. The flexible optical fiber cladding precursor liquid was poured into the cladding mold from the top, and the flexible optical fiber cladding precursor liquid in the mold slowly flowed down under the influence of gravity. Most of the flexible optical fiber cladding precursor liquid dripped from the bottom end of the cladding mold, and a small amount of the precursor liquid adhered to the cladding tube wall. This process can be repeated several times to ensure that the cladding tube wall inside the cladding mold is covered with the flexible optical fiber cladding precursor liquid.

[0080] S6, a 360 nm wavelength laser with an optical power of 10 mW / cm 2The above ultraviolet irradiation cladding mold, since the cladding mold is a transparent material, at this time the flexible optical fiber cladding precursor liquid is directly irradiated by ultraviolet light, thereby initiating crosslinking and curing of the polyethylene glycol diacrylate, forming a transparent and flexible solid structure. After 15 minutes of irradiation, the ultraviolet lamp is turned off, at this time the polyethylene glycol diacrylate has been completely cured.

[0081] S7, the four flexible optical fiber cores prepared in S3 are taken out, the four flexible optical fiber cores are gathered together, and one end of the flexible optical fiber core bundle is inserted into the cladding mold by 10 mm. A syringe filled with clean water is used to inject water from the cladding mold at the end of the flexible optical fiber core bundle, and the water flow is used to bring the flexible optical fiber core bundle into the cladding mold. The four flexible optical fiber cores in the flexible optical fiber core bundle are separated, and at this time the cross section of the cladding mold is as shown in Figure 12 The four flexible optical fiber cores are separated, and at this time the cross section of the cladding mold is as shown in

[0082] S8, the cladding precursor liquid is poured into the cladding mold from above, and the precursor liquid in the mold slowly flows down under the influence of gravity, most of the precursor liquid drips from the bottom end of the cladding mold, and a small amount of the precursor liquid adheres to the cladding wall and the optical fiber core. This process can be repeated several times to ensure that the cladding wall and the optical fiber core inside the cladding mold are covered with the precursor liquid.

[0083] S9, a UV light source with a main wavelength of 360 nm and a light power of 10 mW / cm 2 The above ultraviolet irradiation cladding mold, since the cladding mold is a transparent material, at this time the flexible optical fiber cladding precursor liquid is directly irradiated by ultraviolet light, thereby initiating crosslinking and curing of the polyethylene glycol diacrylate, forming a transparent and flexible solid structure. After 15 minutes of irradiation, the ultraviolet lamp is turned off, at this time the polyethylene glycol diacrylate has been completely cured. Figure 15 The cross section of the cladding mold and the internal flexible optical fiber structure is as shown in

[0084] S10, the core of the flexible optical fiber longer than the cladding at both ends is cut off. The cladding mold is placed in an appropriate amount of 50% sodium hydroxide solution, and the sodium hydroxide solution is heated. The cladding mold is corroded by the sacrifice template method, and the prepared double-core flexible optical fiber is taken out. The double-core flexible optical fiber is washed with clean water for 2-3 times, and the surface liquid is wiped clean, to obtain the double-core flexible optical fiber, as shown in Figure 14

[0085] ​The obtained double-core flexible optical fiber has excellent mechanical and optical properties, and the core structure and cladding structure thereof jointly act to propagate optical signals. The air hole inside and the large core spacing make the leaked signals in the cladding lower, and the crosstalk is smaller when the double-core flexible optical fiber is used.

[0086] The cladding and core of the double-core flexible optical fiber prepared in the embodiment are all prepared from biocompatible materials, and no allergy, inflammation or other symptoms are caused when the double-core flexible optical fiber is in contact with biological tissues, and the double-core flexible optical fiber can be used in the fields of biological sensing and optogenetic therapy. The double-core flexible optical fiber prepared in the embodiment has two cores inside as main light transmission channels, and the distance between the cores is larger than that of the multi-core flexible optical fiber prepared in other embodiments. When used, the optical signals leaked from one core into the cladding are difficult to enter the other core, the internal optical signals do not interfere with each other, are independent of each other, and the crosstalk is avoided in the process of optical signal transmission, and the reliability and sensitivity of information transmission are improved.

[0087] The raw materials and equipment used in the application are common raw materials and equipment in the field unless otherwise specified, and the methods used in the application are conventional methods in the field unless otherwise specified.

[0088] The application effectively utilizes the characteristics of flexible materials, improves the structural strength of the optical fiber under the condition of ensuring the light transmission efficiency, improves the yield of the optical fiber, and makes the prepared optical fiber have excellent mechanical properties and good light transmission efficiency.

[0089] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application but not to limit it, although the application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the application.

Claims

1. A method of making a multi-core flexible optical fiber, characterized by, The method comprises the following steps: S1, mixing a flexible material precursor liquid with a refractive index modulation solution to prepare a multi-core flexible optical fiber core precursor liquid (A), taking a plurality of hollow core molds (1) with one end open and one end sealed, filling the hollow core mold (1) with the multi-core flexible optical fiber core precursor liquid (A), the multi-core flexible optical fiber core precursor liquid (A) filling the inside of the hollow core mold (1), treating the multi-core flexible optical fiber core precursor liquid (A) by standing, high temperature or ultraviolet irradiation to make the multi-core flexible optical fiber core precursor liquid (A) solidify, and forming a solidified flexible optical fiber core (2); S2, placing the hollow core mold (1) and the inside solidified flexible optical fiber core (2) into a core mold treatment liquid, dissolving / eroding the hollow core mold (1) with the core mold treatment liquid, taking out the plurality of solidified flexible optical fiber cores (2), and washing the plurality of solidified flexible optical fiber cores (2) with clean water for multiple times for standby; S3, taking a hollow cladding mold (3) with both ends open, filling the hollow cladding mold (3) with a flexible optical fiber cladding precursor liquid (B), the flexible optical fiber cladding precursor liquid (B) filling the inside of the hollow cladding mold (3), a small part of the flexible optical fiber cladding precursor liquid (B) adhering to the wall of the hollow cladding mold (3) to form a layer of flexible optical fiber cladding precursor liquid (B), and the rest of the flexible optical fiber cladding precursor liquid (B) flowing out from the opening of the hollow cladding mold (3), treating the flexible optical fiber cladding precursor liquid (B) by standing, high temperature or ultraviolet irradiation to make the flexible optical fiber cladding precursor liquid (B) solidify, and forming a flexible cavity cladding structure (4); S4, gathering the plurality of flexible optical fiber cores (2), inserting one end of the flexible optical fiber core bundle into the hollow cladding mold (3) by 10 mm, taking a syringe filled with clean water, injecting water from the hollow cladding mold (3) where the one end of the flexible optical fiber core bundle is inserted, using the water flow to bring the flexible optical fiber core bundle into the hollow cladding mold, separating the plurality of flexible optical fiber cores (2) in the flexible optical fiber core bundle, making the flexible optical fiber cores (2) tight by pulling the part of each flexible optical fiber core (2) longer than the flexible cavity cladding structure (4) at both ends, keeping the flexible optical fiber cores (2) tight, and adhering the part of the plurality of flexible optical fiber cores (2) longer than the flexible cavity cladding structure (4) to the outer end of the hollow cladding mold (3) by a temporary adhesive (5), that is, realizing the temporary fixing of the flexible optical fiber cores (2) and the hollow cladding mold (3) and the flexible cavity cladding structure (4); S5, filling the inside of the hollow cladding mold (3) with the flexible optical fiber cladding precursor liquid (B) again, the flexible optical fiber cladding precursor liquid (B) filling the inside of the hollow cladding mold (3), a part of the flexible optical fiber cladding precursor liquid (B) adhering to the wall of the intermediate cladding mold (3) and the flexible optical fiber cores (2), treating the flexible optical fiber cladding precursor liquid (B) by standing, high temperature or ultraviolet irradiation to make the flexible optical fiber cladding precursor liquid (B) solidify, and forming a flexible optical fiber structure (6); S6, cut the flexible optical fiber core (2) longer than the flexible cavity cladding structure (4) at both ends of the hollow cladding mold, put the hollow cladding mold (3) and the internal already solidified flexible optical fiber structure (6) into the cladding mold treatment liquid, dissolve / erode the cladding mold with the cladding mold treatment liquid, take out the solidified flexible optical fiber structure (6), and obtain a multi-core flexible optical fiber by washing with water multiple times.

2. The method of claim 1, wherein: The flexible material precursor liquid in the step S1 is one of mixed adhesive main agent-mixed adhesive secondary agent, gelatin-water solution, which becomes solid by standing; or polydimethylsiloxane and curing glue mixed solution, which becomes solid by high temperature treatment; or one of acrylamide and N,N'-methylene bisacrylamide mixed solution, polyethylene glycol bisacrylate and 2-hydroxy-2-methylbenzophenone mixed solution, which becomes solid by ultraviolet irradiation.

3. The method of claim 1, wherein: The refractive index modulation solution in the step S1 is one or a mixture of several of metal ion salt, sugar, glycerol.

4. The method of claim 1, wherein: The material of the hollow core mold (1) in the step S2 is one or a mixture of several of acrylonitrile-butadiene-styrene alcohol copolymer, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, glass, quartz glass, organic glass.

5. The method of claim 1, wherein: The core mold treatment liquid in the step S2 is one or a mixture of several of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, dichloroethane, ethanol, toluene.

6. The method of claim 1, wherein: The flexible optical fiber cladding precursor liquid (B) in the step S3 is one of mixed adhesive, gelatin water solution, which becomes solid by standing; or polydimethylsiloxane and curing glue mixed solution, which becomes solid by high temperature treatment; or one of acrylamide and N,N'-methylene bisacrylamide mixed solution, polyethylene glycol bisacrylate and 2-hydroxy-2-methylbenzophenone mixed solution, which becomes solid by ultraviolet irradiation.

7. The method of claim 1, wherein: The cladding mold treatment liquid in the step S6 is one or a mixture of several of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, dichloroethane, ethanol, toluene.

Images