A method for preparing a suspended core flexible optical fiber

Abstract

The present invention discloses a method for preparing a suspended core flexible optical fiber, which is composed of two different flexible materials. The two materials are used to prepare a suspended core optical fiber cladding and a suspended core optical fiber core by a sacrificial template method. When preparing the suspended core flexible optical fiber cladding, gravity is used in a static manner to form a specific hollow structure of the suspended core optical fiber cladding precursor liquid to prepare the suspended core optical fiber cladding for standby use; after preparing the suspended core optical fiber core, the suspended core optical fiber core is placed inside the suspended core optical fiber cladding, and the suspended core optical fiber cladding precursor liquid is added again and solidified to form a suspended core flexible optical fiber structure. The present invention makes full use of the characteristics of flexible materials, and the prepared optical fiber has good ductility and stretchability, high mechanical properties, and the materials used are safe and non-toxic, and have excellent water retention and low temperature performance. It can be used in microflow monitoring, intelligent sensing, flexible wearable devices and other fields, and has broad application prospects.

Description

Technical Field

[0001] The invention relates to the preparation of functional flexible optical fibers and the field of optical fiber sensing, and in particular to a method for preparing a suspended core flexible optical fiber. Background Art

[0002] Flexible optical fiber has received extensive attention in recent years due to its good flexibility and plasticity. Ordinary optical fiber is generally made of silica. Although it can complete the work of optical information transmission well, it is relatively fragile and has poor bending resistance. It cannot work under harsh conditions and cannot withstand most stretching and deformation. When using ordinary optical fiber, you must always pay attention to the state of the optical fiber. Whether it is excessive bending, high temperature, or large tension, it will cause the ordinary optical fiber to break or break. The light in ordinary optical fiber is transmitted by total reflection. Once the optical fiber is damaged, the internal light will leak into the environment, causing the signal transmission to fail. Unlike ordinary silica optical fiber, flexible optical fiber uses flexible materials to make the core and cladding structure of the optical fiber. Because flexible optical fiber has good flexibility and ductility, it can even bend freely. Not only can the probability of damage and breakage of the optical fiber be greatly reduced, but also based on the characteristics of the flexible optical fiber itself, many sensing methods that ordinary optical fibers cannot achieve can be developed.

[0003] With the development of science and technology, the needs of industrial production and the improvement of optical fiber manufacturing technology, special optical fiber components have received great attention. Among various special optical fibers, hollow optical fibers with air hole structures occupy an important position, such as suspended core optical fibers. Unlike solid ordinary optical fibers, suspended core optical fibers have a hollow structure inside. They are a type of hollow optical fiber that uses the core close to the cladding wall to transmit optical signals. There is a cavity inside the fiber cladding of the suspended core optical fiber. Its core is not in contact with the fiber cladding everywhere, but is close to the inner wall of the optical fiber. This hollow structure provides convenience for the production of sensor components. Due to the internal hollow structure of the suspended core optical fiber sensor, gas or liquid can be transmitted from the internal cavity. It has the characteristics of separating the object to be measured from the outside world, resisting external interference, and high measurement accuracy. When the suspended core optical fiber is used for sensing, it has more application methods than ordinary optical fibers. It has more advantages than ordinary optical fibers in many application fields and can replace ordinary optical fibers.

[0004] When using traditional methods to prepare hollow-core optical fibers, the preform rods must first be processed. Ordinary optical fiber preform rods cannot be used directly. Special preform rods must be used to prepare hollow-core optical fibers. After obtaining a suitable hollow-core optical fiber preform rod, it is necessary to go through cladding, drawing, polymer plating and other steps before it can be fiberized. The preparation process is complicated. However, although the traditional process for preparing hollow-core optical fibers has been developed for a long time, the success rate of preparation is still low. During the drawing process, due to the poor toughness of the optical fiber, it is very easy to break under high temperature and stretching. When making hollow-core optical fibers, slight changes in the size and shape of the core and the distribution of solid materials around the hollow core will significantly change the optical properties of the optical fiber, which means that the preparation results are uncontrollable and have a large randomness. At the same time, since the hollow interior of the hollow optical fiber occupies a large space, the supporting cladding structure in the hollow optical fiber is more scarce, making the traditional hollow optical fiber more fragile and fragile than the fragile ordinary optical fiber, and unable to work in a slightly special environment outside the laboratory. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a suspended core flexible optical fiber. The suspended core flexible optical fiber prepared by the method has higher strength and mechanical properties than ordinary optical fibers, is small in size, light in weight, bendable, and has a variable shape. It has a low production cost and a high overall cost performance. It can be applied to the fields of flexible optical fiber communication and flexible optical fiber sensing. It has a strong sensing ability inside the optical fiber cavity, an increased refractive index, and reduces the loss of light caused by internal refraction.

[0006] To achieve the above object, the present invention provides a method for preparing a suspended core flexible optical fiber, comprising the following steps:

[0007] Step S1: mixing the first flexible material raw material and the second flexible material raw material in a certain proportion, and injecting a portion of the mixed suspension core optical fiber cladding precursor liquid into a cladding mold (1);

[0008] Step S2: standing for a period of time so that the suspension core optical fiber cladding precursor liquid attached to the inner wall of the cladding mold (1) forms a specific hollow structure, and curing the cladding mold (1) and the suspension core optical fiber cladding precursor liquid attached to the inner wall of the cladding mold (1) so that the suspension core optical fiber cladding precursor liquid in the cladding mold (1) is cured to form a suspension core optical fiber cladding (2) with a specific structure installed inside the cladding mold (1) for use;

[0009] Step S3: mixing the first flexible material raw material, the second flexible material raw material and the third flexible material raw material, injecting the mixture into the core mold, curing the core mold and the internal suspension core optical fiber core precursor liquid, so that the suspension core optical fiber core precursor liquid installed in the core mold is cured to obtain the suspension core optical fiber core (3);

[0010] Step S4: placing the core mold and the suspended core optical fiber core solidified inside the core mold into a liquid, taking out the suspended core optical fiber core (3) inside the core mold by dissolving the core mold, and installing the suspended core optical fiber core (3) into the hollow inner hole of the suspended core optical fiber cladding (2) installed inside the cladding mold (1);

[0011] Step S5: injecting the suspension core optical fiber cladding precursor liquid into the suspension core optical fiber cladding (2) of a specific structure that has been loaded into the suspension core optical fiber core (3), and subjecting the cladding mold (1) and the suspension core optical fiber cladding precursor liquid inside to a curing treatment, so that the suspension core optical fiber cladding precursor liquid in the cladding mold (1) is cured to produce a suspension core flexible optical fiber of a specific hollow structure loaded inside the cladding mold (1);

[0012] Step S6: immerse the suspended core flexible optical fiber and the cladding mold after high temperature treatment into the liquid, and take out the solidified suspended core flexible optical fiber inside the cladding mold by dissolving the mold.

[0013] Preferably, the mixed solution of the first flexible material raw material and the second flexible material raw material is one of a mixed adhesive A agent-mixed adhesive B agent solution, gelatin-water solution, which becomes solid by standing; or a polydimethylsiloxane-curing glue mixed solution, which becomes solid by high temperature treatment; or one of an acrylamide-N, N'-methylenebisacrylamide mixed solution, a polyethylene glycol diacrylate-2-hydroxy-2-methylpropiophenone mixed solution, which becomes solid by ultraviolet irradiation, and the third flexible material raw material is one or more of metal ion salts, sugars, and glycerol.

[0014] Preferably, the materials of the cladding mold (1) and the core mold are one or more of acrylonitrile-butadiene-styrene alcohol copolymer, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, glass, quartz glass, and organic glass.

[0015] Preferably, the specific hollow structure in step S2 is one of an eccentric annular structure, a deep crescent-shaped structure, a new moon-shaped structure, and an arch-shaped structure.

[0016] Preferably, the curing treatment in step S2, step S3 and step S5 is one or more of high temperature treatment, ultraviolet irradiation treatment and stirring treatment.

[0017] Preferably, the fiber core mold is a cylindrical hollow structure, the inner diameter of the tube is 0.2-0.5 mm, the wall thickness is 0.1-0.2 mm, and the length is 5-400 mm.

[0018] Preferably, the cladding mold (1) is a cylindrical hollow structure with an inner diameter of 0.5 to 2 mm, a wall thickness of 0.1 to 0.5 mm, and a length of 5 to 400 mm.

[0019] Preferably, the liquid is one or more of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, chloroform, dichloroethane, and ethanol.

[0020] Therefore, the present invention adopts the above-mentioned method for preparing a suspended core flexible optical fiber, which has the following beneficial effects:

[0021] (1) The suspended core flexible optical fiber prepared in the present invention is made entirely of flexible materials, and is formed by polydimethylsiloxane materials and base resins and other materials. Compared with ordinary optical fibers, the suspended core flexible optical fiber has higher strength and mechanical properties, is small in size, light in weight, bendable, and has a variable shape. It has a low production cost and a high overall cost-effectiveness, and can be applied to flexible optical fiber communications, flexible optical fiber sensing and other fields.

[0022] (2) When preparing the suspended core flexible optical fiber in the present invention, gravity is used to form a specific hollow shape in the precursor liquid of the suspended core optical fiber cladding, and the structure is solidified and retained by high temperature heating. When the core of the suspended core optical fiber is placed in a thicker part of the cladding wall of the suspended core optical fiber cladding, compared with the ordinary structure, this placement method can increase the distance between the core of the suspended core optical fiber and the external environment, so that the optical signal in the core of the suspended core optical fiber is less disturbed by the external environment, and the sensing ability of the suspended core optical fiber to the inside of the optical fiber cavity is enhanced.

[0023] (3) The core of the suspended core flexible optical fiber prepared in the present invention is made of materials such as polydimethylsiloxane, polyacrylamide, and polyethylene glycol diacrylate. In order to ensure the light wave propagation effect in the optical fiber and meet the total reflection condition, the present invention processes the core material of the suspended core optical fiber to increase its refractive index. After curing, its refractive index is in the range of 1.50 to 1.60, which can naturally meet the optical waveguide conditions of optical fiber light transmission, so that light will not be lost due to refraction inside, and no further processing is required.

[0024] (4) When fixing the hanging core fiber cladding and the hanging core fiber core, the hanging core fiber cladding precursor liquid is used again for solidification, which not only allows the hanging core fiber cladding and the hanging core fiber core to be reliably fixed together, but also avoids the introduction of a third adhesive into the optical fiber so that the hanging core fiber cladding and the hanging core fiber core cannot effectively contact each other.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is a schematic structural diagram of a suspended core flexible optical fiber of the present invention that is not immersed in a liquid to dissolve the cladding mold;

[0027] Figure 2 It is a cross-sectional schematic diagram of the "eccentric annular structure" formed by the precursor liquid of the suspended core optical fiber cladding under the influence of gravity in Example 1 of the present invention;

[0028] Figure 3 It is a cross-sectional schematic diagram of the position of the core when the core of the suspension core optical fiber is placed at the thickest part of the cladding wall in the specific structure of the suspension core optical fiber cladding in Example 1 of the present invention;

[0029] Figure 4 This is a schematic cross-sectional view of a finished product of a suspended core flexible optical fiber prepared in Example 1 of the present invention;

[0030] Figure 5 It is a cross-sectional schematic diagram of the formation of a "deep crescent-shaped structure" by the precursor liquid of the suspended core optical fiber cladding under the influence of gravity in Example 2 of the present invention;

[0031] Figure 6 It is a cross-sectional schematic diagram of the formation of a "crescent-shaped structure" by the precursor liquid of the suspended core optical fiber cladding under the influence of gravity in Example 3 of the present invention;

[0032] Figure 7 It is a cross-sectional schematic diagram of the "bow structure" formed by the precursor liquid of the suspended core optical fiber cladding under the influence of gravity in Example 4 of the present invention;

[0033] Reference numerals

[0034] 1. Cladding mold; 2. Suspended core optical fiber cladding; 3. Suspended core optical fiber core. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, simplifications made without violating the spirit and principle of the present invention should all be equivalent replacement methods and are included in the protection scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0036] The present invention provides a method for preparing a suspended core flexible optical fiber, comprising the following steps:

[0037] Step S1: mixing the first flexible material raw material and the second flexible material raw material in a certain proportion, and injecting a part of the mixed suspension core optical fiber cladding precursor liquid into the cladding mold 1;

[0038] Step S2: standing for a period of time to allow the suspension core optical fiber cladding precursor liquid attached to the inner wall of the cladding mold 1 to form a specific hollow structure, and curing the cladding mold 1 and the suspension core optical fiber cladding precursor liquid attached to the inner wall of the cladding mold 1 to cure the suspension core optical fiber cladding precursor liquid in the cladding mold 1 to form a suspension core optical fiber cladding 2 with a specific structure installed inside the cladding mold 1 for standby use;

[0039] Step S3: mixing the first flexible material raw material, the second flexible material raw material and the third flexible material raw material, injecting the mixture into the core mold, curing the core mold and the internal suspension core optical fiber core precursor liquid, so that the suspension core optical fiber core precursor liquid installed in the core mold is cured to obtain the suspension core optical fiber core 3;

[0040] Step S4: placing the core mold and the suspended core optical fiber core solidified inside the core mold into the liquid, taking out the suspended core optical fiber core 3 inside the core mold by dissolving the core mold, and installing the suspended core optical fiber core 3 into the hollow inner hole of the suspended core optical fiber cladding 2 installed inside the cladding mold 1;

[0041] Step S5: injecting the suspension core optical fiber cladding precursor liquid into the suspension core optical fiber cladding 2 of the specific structure which has been loaded into the suspension core optical fiber core 3, and subjecting the cladding mold 1 and the suspension core optical fiber cladding precursor liquid inside to curing, so that the suspension core optical fiber cladding precursor liquid in the cladding mold 1 is cured to form a suspension core flexible optical fiber of the specific hollow structure loaded inside the cladding mold 1;

[0042] Step S6: immerse the suspended core flexible optical fiber and the cladding mold after high temperature treatment into the liquid, and take out the solidified suspended core flexible optical fiber inside the cladding mold by dissolving the mold.

[0043] Preferably, the mixed solution of the first flexible material raw material and the second flexible material raw material is one of a mixed adhesive A agent-mixed adhesive B agent solution, gelatin-water solution, which becomes solid by standing; or a polydimethylsiloxane-curing glue mixed solution, which becomes solid by high temperature treatment; or one of an acrylamide-N, N'-methylenebisacrylamide mixed solution, a polyethylene glycol diacrylate-2-hydroxy-2-methylpropiophenone mixed solution, which becomes solid by ultraviolet irradiation, and the third flexible material raw material is one or more of metal ion salts, sugars, and glycerol.

[0044] Preferably, the materials of the cladding mold 1 and the core mold are one or more of acrylonitrile-butadiene-styrene alcohol copolymer, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, glass, quartz glass, and organic glass.

[0045] Preferably, the specific hollow structure in step S2 is one of an eccentric annular structure, a deep crescent-shaped structure, a new moon-shaped structure, and an arch-shaped structure.

[0046] Preferably, the curing treatment in step S2, step S3 and step S5 is one or more of high temperature treatment, ultraviolet irradiation treatment and stirring treatment.

[0047] Preferably, the fiber core mold is a cylindrical hollow structure, the inner diameter of the tube is 0.2-0.5 mm, the wall thickness is 0.1-0.2 mm, and the length is 5-400 mm.

[0048] Preferably, the cladding mold 1 is a cylindrical hollow structure with an inner diameter of 0.5 to 2 mm, a wall thickness of 0.1 to 0.5 mm, and a length of 5 to 400 mm.

[0049] Preferably, the liquid is one or more of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, chloroform, dichloroethane, and ethanol.

[0050] Example 1

[0051] Step S1: First, prepare the suspension core flexible optical fiber cladding. Mix 20g of polydimethylsiloxane and 2g of polydimethylsiloxane special curing agent, gently stir for 5 minutes, and prepare the suspension core optical fiber cladding precursor liquid. Note that the stirring force should not be too large to avoid the appearance of many bubbles in the suspension core optical fiber cladding precursor liquid. If a large number of bubbles appear in the suspension core optical fiber cladding precursor liquid after stirring, the internal bubbles can be removed by vacuuming. Take part of the prepared suspension core optical fiber cladding precursor liquid and suck it into the syringe, and the remaining part is placed in a sealed environment for standby use. 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 suspension core optical fiber cladding mold, and place the mold vertically and fix it on the laboratory table. The suspension core optical fiber cladding precursor liquid in the syringe is slowly dripped from the hole above the mold so that the suspension core optical fiber cladding precursor liquid fills the inside of the mold. Since the hanging core fiber cladding precursor liquid drips in slowly, the hanging core fiber cladding precursor liquid in the mold slowly flows down under the influence of gravity, and most of the hanging core fiber cladding precursor liquid drips from the bottom of the mold, and a small part of the hanging core fiber cladding precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with the hanging core fiber cladding precursor liquid.

[0052] Step S2: Place the mold with the suspension core optical fiber cladding precursor liquid attached to the inner wall horizontally, and fix it appropriately to ensure that the mold does not rotate, and let it stand for 30 minutes. At this time, the precursor liquid attached to the inner wall is affected by gravity and forms a Figure 2 The "eccentric ring structure" shown in the figure. The mold after standing is placed in a constant temperature box for high temperature treatment, and treated 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 and the polydimethylsiloxane with hydrogen groups in the curing agent are cross-linked and cured to form a transparent and flexible solid structure.

[0053] Step S3: Take another glass cylindrical hollow structure tube with an inner diameter of 0.5mm, a wall thickness of 0.1mm and a length of 300mm as a suspension core optical fiber core mold. Mix 13.8g of acrylamide, 0.2g of N,N'-methylenebisacrylamide and 16g of 60%wt lithium bromide aqueous solution, stir them thoroughly to make a suspension core optical fiber core precursor liquid, and inject an appropriate amount of the just configured suspension core optical fiber core precursor liquid into the suspension core optical fiber core mold. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the suspension core optical fiber core mold. Since the suspension core optical fiber core mold is a transparent material, the suspension core optical fiber core precursor liquid is directly irradiated by ultraviolet light, thereby inducing acrylamide polymerization to form polyacrylamide, forming a transparent and flexible solid structure. After irradiation for 20 minutes, turn off the ultraviolet lamp, and the polyacrylamide is completely cured.

[0054] Step S4: Place the suspension core fiber core mold in an appropriate amount of hydrofluoric acid, corrode the mold by sacrificial template method, take out the suspension core fiber core, rinse the suspension core fiber core with clean water 2-3 times, wipe off the liquid on its surface, and ensure that it is free of bending, adhesion, twisting, etc. Place the suspension core fiber cladding mold vertically, insert the suspension core fiber core into the suspension core fiber cladding mold from above, and try to place the suspension core fiber core at the thickest cladding wall in the specific structure of the suspension core fiber cladding, such as Figure 3 shown.

[0055] Step S5: After fixing the core of the hanging core fiber and the hanging core fiber cladding mold, place the mold vertically and fix it on the laboratory table. Take out the flexible material hanging core fiber cladding precursor liquid sealed for use in step S1, suck it into the syringe, and slowly drip the hanging core fiber cladding precursor liquid in the syringe from the hole above the mold drop by drop, so that the hanging core fiber cladding precursor liquid fills the interior of the mold again. Similar to the production of the hanging core fiber cladding, since the precursor liquid drips in at a slow speed, the precursor liquid in the mold slowly flows down under the influence of gravity, and most of the hanging core fiber cladding precursor liquid drips from the bottom of the mold, and a small part of the hanging core fiber cladding precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with the precursor liquid. The mold is placed in a constant temperature box for high-temperature treatment in an environment of 80 degrees Celsius for 60 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 cross-linked and cured to form a transparent and flexible solid structure, which fixes the core of the suspended core optical fiber and the cladding of the suspended core optical fiber.

[0056] Step S6: Place the suspension core optical fiber cladding mold in an appropriate amount of ether, corrode the mold by a sacrificial template method, take out the suspension core optical fiber, rinse the inner and outer walls of the suspension core optical fiber with methanol for 2 to 3 times, wipe off the liquid on its surface and dry it, and then obtain the suspension core flexible optical fiber, such as Figure 4 shown.

[0057] The resulting suspended core optical fiber has excellent mechanical and optical properties. Its core structure and cladding structure work together to propagate optical signals. The internal hollow hole can be used for microflow sensing of liquids and gases, and has good sensitivity and resistance to external interference.

[0058] The suspended core flexible optical fiber prepared in this embodiment uses more polydimethylsiloxane material than the suspended core flexible optical fibers prepared in other embodiments, and has better mechanical properties and tensile resistance than the suspended core flexible optical fibers prepared in other embodiments, and has good recovery ability. In addition, the cladding of the suspended core flexible optical fiber prepared in this embodiment is an eccentric annular distribution, which is relatively evenly distributed, but the average cladding thickness is thicker than that of the suspended core flexible optical fibers prepared in other embodiments, which can obtain better anti-interference ability when sensing the transmission of microfluidic substances inside the suspended core optical fiber, thereby improving the sensing effect.

[0059] Example 2

[0060] Step S1: First, prepare the cladding of a suspended core flexible optical fiber. Mix 20g of polydimethylsiloxane and 2g of a special curing agent for polydimethylsiloxane, stir gently for 5 minutes, and prepare a suspension core optical fiber cladding precursor liquid. Note that the stirring force should not be too large to avoid the appearance of many bubbles in the suspension core optical fiber cladding precursor liquid. If a large number of bubbles appear in the suspension core optical fiber cladding precursor liquid after stirring, the internal bubbles can be removed by vacuuming. Take part of the prepared suspension core optical fiber cladding precursor liquid and suck it into the syringe, and place the remaining part in a sealed environment for standby use. Take a cylindrical hollow structure tube of a polyvinyl chloride copolymer with an inner diameter of 2mm, a wall thickness of 0.5mm, and a length of 300mm as a suspension core optical fiber cladding mold, place the mold vertically, and fix it on the laboratory table. Slowly drip the precursor liquid in the syringe from the hole above the mold so that the precursor liquid fills the inside of the mold. Since the precursor liquid drips in slowly, the precursor liquid in the mold slowly flows down under the influence of gravity, most of the precursor liquid drips from the bottom of the mold, and a small part of the precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with the precursor liquid.

[0061] Step S2: Place the mold with the suspension core optical fiber cladding precursor liquid attached to the inner wall horizontally, and fix it appropriately to ensure that the mold does not rotate, and let it stand for a period of time. At this time, the precursor liquid attached to the inner wall is affected by gravity and forms a Figure 5 The "deep crescent-shaped structure" shown in the figure. The mold after standing is placed in a constant temperature box for high temperature treatment at 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 cross-linked and cured to form a transparent and flexible solid structure.

[0062] Step S3: Take another cylindrical hollow structure tube of organic glass with an inner diameter of 0.5mm, a wall thickness of 0.2mm and a length of 300mm as a suspension core optical fiber core mold. Mix 10g of UV curing glue and 2g of leveling agent, stir them thoroughly to make a suspension core optical fiber core precursor liquid, and inject an appropriate amount of the just configured suspension core optical fiber core precursor liquid into the suspension core optical fiber core mold. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the suspension core optical fiber core mold. Since the suspension core optical fiber core mold is a transparent material, the suspension core optical fiber core precursor liquid is directly exposed to ultraviolet light at this time, thereby inducing the cross-linking and curing of the resin inside the UV curing glue to form a transparent and flexible solid structure. After 8 minutes of irradiation, turn off the UV lamp, and the UV curing glue is now completely cured.

[0063] Step S4: Place the core mold of the hanging core fiber in an appropriate amount of dimethylformamide, corrode the mold by a sacrificial template method, take out the core of the hanging core fiber, rinse the core of the hanging core fiber with clean water for 2 to 3 times, wipe off the liquid on its surface, and ensure that it is free of bending, adhesion, twisting, etc. Place the hanging core fiber cladding mold vertically, insert the hanging core fiber core into the hanging core fiber cladding mold from above, and try to place the hanging core fiber core at the thickest part of the cladding wall in the specific structure of the hanging core fiber cladding.

[0064] Step S5: After fixing the suspension core fiber core and the suspension core fiber cladding mold, place the mold vertically and fix it on the laboratory table. Take out the suspension core fiber cladding precursor liquid sealed for use in step S1, suck it into the syringe, and slowly drip the suspension core fiber cladding precursor liquid in the syringe from the hole above the mold drop by drop, so that the suspension core fiber cladding precursor liquid fills the interior of the mold again. Similar to the production of the suspension core fiber cladding, since the speed of dripping the suspension core fiber cladding precursor liquid is slow, the suspension core fiber cladding precursor liquid in the mold slowly flows down under the influence of gravity, and most of the suspension core fiber cladding precursor liquid drips from the bottom of the mold, and a small part of the suspension core fiber cladding precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with the suspension core optical fiber cladding precursor liquid. The mold is placed in a constant temperature box for high-temperature treatment in an environment of 80 degrees Celsius for 60 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 cross-linked and cured to form a transparent and flexible solid structure, which fixes the suspension core optical fiber core and the suspension core optical fiber cladding.

[0065] Step S6: Place the hanging core optical fiber cladding mold in an appropriate amount of cyclohexanone, corrode the mold by a sacrificial template method, take out the hanging core optical fiber, rinse the inner and outer walls of the hanging core optical fiber with methanol for 2 to 3 times, wipe off the liquid on its surface and dry it to obtain a hanging core flexible optical fiber.

[0066] The resulting suspended core optical fiber has excellent mechanical and optical properties. Its core structure and cladding structure work together to propagate optical signals. The internal hollow hole can be used for microflow sensing of liquids and gases, and has good sensitivity and resistance to external interference.

[0067] Compared with the suspension core flexible optical fibers prepared in other embodiments, the suspension core flexible optical fiber prepared in this embodiment uses polydimethylsiloxane material and ultraviolet curing adhesive material to prepare the optical fiber. Compared with the suspension core flexible optical fibers prepared in other embodiments, the suspension core flexible optical fiber has better high temperature resistance and stability, the material is not easy to age, and the service life is longer. In addition, although the cladding of the suspension core flexible optical fiber of this embodiment is similar to the eccentric annular distribution, the distribution is more uneven, and it has a thinner cladding thickness than Example 1, which can sense the parameters in the environment to a certain extent when sensing the transmission of microfluidic substances inside the suspension core optical fiber, thereby improving the sensing effect.

[0068] Example 3

[0069] Step S1: First, prepare the cladding of a suspended core flexible optical fiber. Mix 13.8g of acrylamide and 0.2g of N,N'-methylenebisacrylamide, stir gently for 5 minutes, and prepare a precursor liquid for the cladding of a suspended core flexible optical fiber. Take part of the prepared cladding precursor liquid of the suspended core optical fiber and suck it into a syringe, and place the remaining part in a sealed environment for standby use. Take a cylindrical hollow structure tube of quartz glass with an inner diameter of 2mm, a wall thickness of 0.2mm, and a length of 400mm, as a cladding mold for the suspended core optical fiber, and place the mold vertically and fix it on the laboratory table. The precursor liquid in the syringe is slowly dripped from the hole above the mold, so that the precursor liquid fills the inside of the mold. Since the speed of dripping the cladding precursor liquid of the suspended core optical fiber is slow, the precursor liquid in the mold slowly flows down under the influence of gravity, most of the precursor liquid drips from the bottom of the mold, and a small part of the precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with precursor liquid.

[0070] Step S2: Place the mold with the suspension core optical fiber cladding precursor liquid attached to the inner wall horizontally, and fix it appropriately to ensure that the mold does not rotate, and let it stand for a period of time. At this time, the precursor liquid attached to the inner wall is affected by gravity and forms a Figure 6 The "crescent-shaped structure" shown. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the suspended core fiber cladding mold. Since the suspended core fiber cladding mold is a transparent material, the suspended core fiber cladding precursor liquid is directly irradiated by ultraviolet light, thereby inducing acrylamide cross-linking and curing to form a transparent and flexible solid structure. After 8 minutes of irradiation, turn off the ultraviolet lamp, and the polyacrylamide has been completely cured.

[0071] Step S3: Take another polystyrene cylindrical hollow structure tube with an inner diameter of 0.4mm, a wall thickness of 0.1mm, and a length of 400mm as a suspension core optical fiber core mold. Mix 10g of UV curing glue and 2g of leveling agent, stir them thoroughly to make a suspension core optical fiber core precursor liquid, and inject an appropriate amount of the just configured suspension core optical fiber core precursor liquid into the suspension core optical fiber core mold. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the suspension core optical fiber core mold. Since the suspension core optical fiber core mold is a transparent material, the suspension core optical fiber core precursor liquid is directly exposed to ultraviolet light at this time, thereby inducing the cross-linking and curing of the resin inside the UV curing glue to form a transparent and flexible solid structure. After irradiation for 20 minutes, turn off the UV lamp, and the UV curing glue is now completely cured.

[0072] Step S4: Place the suspension core fiber core mold in an appropriate amount of 40% hydrofluoric acid, corrode the mold by sacrificial template method, take out the suspension core fiber core, rinse the suspension core fiber core with clean water 2-3 times, wipe the liquid on its surface clean, and ensure that it is free of bending, adhesion, twisting, etc. Place the suspension core fiber cladding mold vertically, insert the suspension core fiber core into the suspension core fiber cladding mold from above, and try to place the suspension core fiber core at the thickest cladding wall in the specific structure of the suspension core fiber cladding.

[0073] Step S5: After fixing the core of the hanging core fiber and the hanging core fiber cladding mold, place the mold vertically and fix it on the experimental table. Take out the hanging core fiber cladding precursor liquid sealed for standby use in step S1, suck it into the syringe, and slowly drip the hanging core fiber cladding precursor liquid in the syringe from the hole above the mold, so that the hanging core fiber cladding precursor liquid fills the inside of the mold again. Similar to the production of the hanging core fiber cladding, since the speed of dripping the hanging core fiber cladding precursor liquid is slow, the precursor liquid in the mold slowly flows down under the influence of gravity, most of the precursor liquid drips from the bottom of the mold, and a small part of the precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with the precursor liquid. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the mold. Since the hanging core fiber cladding mold is a transparent material, the hanging core fiber cladding precursor liquid is directly exposed to ultraviolet light at this time, thereby inducing acrylamide cross-linking and curing. After irradiation for 5 minutes, the UV lamp is turned off. At this time, the polyacrylamide has been completely cured to form a transparent and flexible solid structure, which fixes the core of the hanging core optical fiber and the cladding of the hanging core optical fiber.

[0074] Step S6: Place the hanging core optical fiber cladding mold in an appropriate amount of 50% sodium hydroxide, corrode the mold by a sacrificial template method, take out the hanging core optical fiber, rinse the inner and outer walls of the hanging core optical fiber with clean water 2 to 3 times, wipe off the liquid on its surface and dry it to obtain a hanging core flexible optical fiber.

[0075] The resulting suspended core optical fiber has excellent mechanical and optical properties. Its core structure and cladding structure work together to propagate optical signals. Its semi-open and semi-closed cladding structure is very convenient for implanting or removing supporting objects or sensing media in later use, and has high versatility and multiplexing.

[0076] Compared with the suspension core flexible optical fibers made in other embodiments, the suspension core flexible optical fiber made in this embodiment uses two flexible materials with very close refractive indices, and is more likely to meet the single-mode waveguide propagation conditions and has better optical performance. In addition, the cladding of the suspension core flexible optical fiber of this embodiment is a crescent-shaped structure, and the relatively closed cladding can be used to store the support structure to enhance the mechanical properties; or to insert the sensing medium to add a sensing mechanism, and the added object can be taken out from the cladding opening, and the use direction is more flexible.

[0077] Example 4

[0078] Step S1: First, prepare the cladding of a suspended core flexible optical fiber. Mix 16g of polyethylene glycol diacrylate and 1g of 2-hydroxy-2-methylpropiophenone in 3g of water, and stir gently for 5 minutes to prepare a precursor liquid for the cladding of a suspended core optical fiber. Take part of the prepared precursor liquid for the cladding of a suspended core optical fiber and suck it into a syringe, and place the remaining part in a sealed environment for standby use. Take a polystyrene cylindrical hollow structure tube with an inner diameter of 0.5mm, a wall thickness of 0.1mm, and a length of 100mm as a suspended core optical fiber cladding mold, and place the mold vertically and fix it on the laboratory table. The precursor liquid in the syringe is slowly dripped from the hole above the mold, so that the precursor liquid fills the inside of the mold. Due to the slow dripping speed of the precursor liquid, the precursor liquid in the mold slowly flows down under the influence of gravity, most of the precursor liquid drips from the bottom of the mold, and a small part of the precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with precursor liquid.

[0079] Step S2: Place the mold with the suspension core optical fiber cladding precursor liquid attached to the inner wall horizontally, and fix it appropriately to ensure that the mold does not rotate, and let it stand for a period of time. At this time, the suspension core optical fiber cladding precursor liquid attached to the inner wall is affected by gravity and forms a Figure 7The "bow structure" shown. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the suspended core fiber cladding mold. Since the suspended core fiber cladding mold is a transparent material, the suspended core fiber cladding precursor liquid is directly irradiated by ultraviolet light, thereby inducing the cross-linking and curing of polyethylene glycol diacrylate to form a transparent and flexible solid structure. After 15 minutes of irradiation, turn off the ultraviolet lamp, and the polyethylene glycol diacrylate has been completely cured.

[0080] Step S3: Take another glass cylindrical hollow structure tube with an inner diameter of 0.2mm, a wall thickness of 0.1mm and a length of 100mm as a suspension core optical fiber core mold. Mix 13.8g of acrylamide, 0.2g of N, N'-methylenebisacrylamide and 16g of 60%wt sucrose aqueous solution, stir them thoroughly to make a suspension core optical fiber core precursor liquid, and inject an appropriate amount of the suspension core optical fiber core precursor liquid just configured into the suspension core optical fiber core mold. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the suspension core optical fiber core mold. Since the suspension core optical fiber core mold is a transparent material, the soft suspension core optical fiber core precursor liquid is directly exposed to ultraviolet light, thereby inducing acrylamide polymerization to form polyacrylamide, forming a transparent and flexible solid structure. After irradiation for 20 minutes, turn off the ultraviolet lamp, and the polyacrylamide is completely cured.

[0081] Step S4: Place the suspension core fiber core mold in an appropriate amount of 85% pyrophosphoric acid, corrode the mold by a sacrificial template method, take out the suspension core fiber core, rinse the suspension core fiber core with clean water for 2 to 3 times, wipe off the liquid on its surface, and ensure that it is free of bending, adhesion, twisting, etc. Place the suspension core fiber cladding mold vertically, insert the suspension core fiber core into the suspension core fiber cladding mold from above, and try to place the suspension core fiber core at the thickest part of the cladding wall in the specific structure of the suspension core fiber cladding.

[0082] Step S5: After fixing the core of the hanging core optical fiber and the hanging core optical fiber cladding mold, place the mold vertically and fix it on the experimental table. Take out the hanging core optical fiber cladding precursor liquid sealed for standby use in step S1, suck it into the syringe, and slowly drip the hanging core optical fiber cladding precursor liquid in the syringe from the hole above the mold drop by drop, so that the hanging core optical fiber cladding precursor liquid fills the inside of the mold again. Similar to the production of the hanging core optical fiber cladding, due to the slow dripping speed of the precursor liquid, the precursor liquid in the mold slowly flows down under the influence of gravity, most of the precursor liquid drips from the bottom of the mold, and a small part of the precursor liquid adheres to the tube wall. This process can be repeated several times to ensure that the tube wall inside the mold is covered with precursor liquid. Use ultraviolet light with a main wavelength of 360nm and an optical power of more than 10mW / cm2 to irradiate the mold. Since the hanging core optical fiber cladding mold is a transparent material, the hanging core optical fiber cladding precursor liquid is directly exposed to ultraviolet light at this time, thereby initiating cross-linking and curing of polyethylene glycol diacrylate. After 8 minutes of irradiation, the UV lamp was turned off. At this time, the polyethylene glycol diacrylate had been completely cured to form a transparent and flexible solid structure, which fixed the core of the hanging core optical fiber and the cladding of the hanging core optical fiber.

[0083] Step S6: Place the suspension core optical fiber cladding mold in an appropriate amount of chloroform, corrode the mold by a sacrificial template method, take out the suspension core optical fiber, rinse the inner and outer walls of the suspension core optical fiber with methanol for 2 to 3 times, wipe off the liquid on its surface and dry it to obtain a suspension core flexible optical fiber.

[0084] The resulting suspended core optical fiber has excellent mechanical and optical properties. Its core structure and cladding structure work together to propagate optical signals. The open interior greatly reduces interference with the implanted environment and provides a solution for preparing optical fibers using other flexible materials with less precursor liquid tension.

[0085] Compared with the suspension core flexible optical fibers prepared in other embodiments, the suspension core flexible optical fiber prepared in this embodiment uses more biocompatible materials, such as polyethylene glycol diacrylate, sucrose, etc., and has better biocompatibility than the suspension core flexible optical fibers prepared in other embodiments. In addition, the overall structure of the suspension core flexible optical fiber prepared in this embodiment is thinner, and combined with its biocompatible characteristics, it can be conveniently implanted in a living body for physiological sensing without affecting the living body, and is applied in the fields of biomedicine and modern medicine.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a suspended core flexible optical fiber, Features: The following steps are involved: Step S1: mixing the first flexible material raw material and the second flexible material raw material in a certain proportion, and injecting a portion of the mixed suspension core optical fiber cladding precursor liquid into a cladding mold (1); Step S2: standing for a period of time so that the suspension core optical fiber cladding precursor liquid attached to the inner wall of the cladding mold (1) forms a specific hollow structure, and curing the cladding mold (1) and the suspension core optical fiber cladding precursor liquid attached to the inner wall of the cladding mold (1) so that the suspension core optical fiber cladding precursor liquid in the cladding mold (1) is cured to form a suspension core optical fiber cladding (2) installed in the cladding mold (1) for use; The specific hollow structure in step S2 is one of an eccentric annular structure, a deep crescent structure, a new moon structure, and an arcuate structure; Step S3: mixing the first flexible material raw material, the second flexible material raw material and the third flexible material raw material, injecting the mixture into the core mold, curing the core mold and the internal suspension core optical fiber core precursor liquid, so that the suspension core optical fiber core precursor liquid installed in the core mold is cured to obtain the suspension core optical fiber core (3); Step S4: placing the core mold and the suspended core optical fiber core solidified inside the core mold into a dissolving liquid, taking out the suspended core optical fiber core (3) inside the core mold by dissolving the core mold, and inserting the suspended core optical fiber core (3) into the hollow inner hole of the suspended core optical fiber cladding (2) installed inside the cladding mold (1); Step S5: injecting the suspension core optical fiber cladding precursor liquid into the suspension core optical fiber cladding (2) of a specific structure that has been loaded into the suspension core optical fiber core (3), and subjecting the cladding mold (1) and the suspension core optical fiber cladding precursor liquid inside to a curing treatment, so that the suspension core optical fiber cladding precursor liquid in the cladding mold (1) is cured to produce a suspension core flexible optical fiber of a specific hollow structure loaded inside the cladding mold (1); Step S6: immerse the suspended core flexible optical fiber and the cladding mold after high temperature treatment into the liquid, and take out the solidified suspended core flexible optical fiber inside the cladding mold by dissolving the mold.

2. A method for preparing a suspended core flexible optical fiber according to claim 1, Features: The mixed solution of the first flexible material raw material and the second flexible material raw material is one of a mixed adhesive A agent-mixed adhesive B agent solution and a gelatin-water solution, which becomes solid by standing; or a polydimethylsiloxane-curing glue mixed solution, which becomes solid by high temperature treatment; or one of an acrylamide-N, N'-methylenebisacrylamide mixed solution and a polyethylene glycol diacrylate-2-hydroxy-2-methylpropiophenone mixed solution, which becomes solid by ultraviolet irradiation.

3. A method for preparing a suspended core flexible optical fiber according to claim 1, Features: The raw material of the third flexible material is one or more of metal ion salts, sugars, and glycerol.

4. A method for preparing a suspended core flexible optical fiber according to claim 1, Features: The materials of the cladding mold (1) and the core mold are one or more of acrylonitrile-butadiene-styrene alcohol copolymer, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, glass, quartz glass, and organic glass.

5. A method for preparing a suspended core flexible optical fiber according to claim 1, Features: The curing treatment in step S2, step S3 and step S5 is one or more of high temperature treatment, ultraviolet irradiation treatment and stirring treatment.

6. A method for preparing a suspended core flexible optical fiber according to claim 1, Features: The fiber core mold is a cylindrical hollow structure, the inner diameter of the tube is 0.2-0.5 mm, the wall thickness is 0.1-0.2 mm, and the length is 5-400 mm.

7. A method for preparing a suspended core flexible optical fiber according to claim 1, Features: The cladding mold (1) is a cylindrical hollow structure with an inner diameter of 0.5 to 2 mm, a wall thickness of 0.1 to 0.5 mm, and a length of 5 to 400 mm.

8. A method for preparing a suspended core flexible optical fiber according to claim 1, Features: The dissolving liquid is one or more of acetone, chloroform, cyclohexanone, dimethylformamide, sodium hydroxide, hydrofluoric acid, concentrated phosphoric acid, chloroform, dichloroethane, and ethanol.

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