Spiral architecture hollow core optical fiber and method of making same

Abstract

The application relates to a spiral architecture hollow core optical fiber and a preparation method thereof; the spiral architecture hollow core optical fiber comprises, from inside to outside, a spiral hollow light guide pipe, a biomimetic protective layer and a sheath layer; the spiral hollow light guide pipe comprises a nodeless anti-resonance structure composed of a plurality of hollow capillaries; the hollow capillaries are uniformly distributed in the circumferential direction and keep a gap from the inner wall of the biomimetic protective layer to eliminate contact nodes; the wall surface of the hollow capillaries towards the core side is a negative curvature surface; the air hole in the spiral hollow light guide pipe extends spirally along the optical fiber axial direction according to a set spiral pitch angle and spiral period; the biomimetic protective layer is coated on the outer surface of the outer cladding of the spiral hollow light guide pipe; and the sheath layer comprises a polymer sheath on the outermost layer and is used for protecting the optical fiber; according to the technical scheme, while excellent optical performance is maintained, the bending life is improved, the bending resistance is improved, the PMD stability is greatly improved, the interlayer bonding force is enhanced, and the interlayer bonding force is improved.

Description

Technical Field

[0001] This application relates to the field of optical fiber technology, and in particular to a spiral-structured hollow optical fiber and its fabrication method. Background Technology

[0002] Hollow-core optical fiber uses air as the light transmission medium and has significant advantages over traditional solid-core quartz optical fiber, such as ultra-low latency (light speed increased by about 47%), ultra-low nonlinear effects, and low dispersion. It is a key component for next-generation high-speed optical communication, computing network interconnection, and distributed sensing systems.

[0003] Traditional hollow-core optical fibers typically employ a vertical parallel tube support structure, with multiple air channels extending parallel to the fiber axis and the support wall perpendicular to the fiber cross-section. Currently, the mainstream structures of hollow-core antiresonant fibers include various tube number variations such as 3-tube, 4-tube, 5-tube, 6-tube, 7-tube, 8-tube, and 9-tube. Among them, the 5-tube structure (the NANF structure reported by OFC, with a core diameter of 34.5μm and a loss of 0.22dB / km@1060nm) and the 7-tube structure (the seven-ring cladding tube has been proven to be a "relatively excellent structure") are the mainstream solutions for industrial applications. The 4-tube structure (a regular quadrilateral outer cladding + 4 nested units, with a fundamental mode loss <0.1dB / km) and the 6-tube structure (a double-layer nested elliptical structure, limiting the loss to 0.015dB / km) also exhibit excellent performance. 7 to 8 tubes are considered the optimal choice, offering a good balance between loss performance and structural simplicity within a single-layer antiresonant structure.

[0004] However, when the optical fiber is bent, the vertical wall of the vertical parallel pipe support structure bears the maximum normal stress. The local stress concentration causes microcracks to propagate along the vertical wall, which seriously restricts the bending life and bending reliability of the optical fiber. Moreover, the vertical wall generates shear stress concentration when twisted, which leads to unstable polarization mode dispersion (PMD) and makes it difficult to meet the transmission requirements of 400G / 800G high-speed optical communication systems. Summary of the Invention

[0005] To address one of the aforementioned technical deficiencies, this application provides a helical hollow optical fiber and its fabrication method.

[0006] A spiral-structured hollow optical fiber, comprising, from the inside out: a spiral hollow light guide tube, a biomimetic protective layer, and a sheath layer; The spiral hollow light guide tube includes a nodeless anti-resonance structure composed of multiple hollow capillaries; The hollow capillaries are evenly distributed circumferentially and maintain a gap with the inner wall of the biomimetic protective layer to eliminate contact points. The wall surface of the hollow capillary facing the fiber core is a negative curvature surface; The air channels inside the spiral hollow light guide tube extend in a spiral shape along the optical fiber axis according to the set spiral angle and spiral period. The biomimetic protective layer is coated on the outer surface of the outer cladding layer of the spiral hollow light guide tube; The sheath layer includes an outermost polymer sheath for protecting the optical fiber.

[0007] In some embodiments, the biomimetic protective layer comprises, from the inside out: The stress buffer layer is an organic-inorganic gradient transition layer. The optical barrier layer is composed of a fluoropolymer with a set refractive index; A dense barrier layer, composed of oxides deposited at atomic layers; The intrinsic self-healing layer contains a Diels-Alder dynamic covalent polymer; The wear-resistant coating is a diamond-like carbon coating.

[0008] In some embodiments, the biomimetic protective layer further includes a hydrogen barrier layer disposed between the dense barrier layer and the intrinsic self-healing layer, wherein the hydrogen barrier layer is an amorphous high-entropy alloy layer or an oxide / nitride multilayer film.

[0009] In some embodiments, the biomimetic protective layer further includes a conductive shielding layer on the outermost layer, the conductive shielding layer being composed of a conductive polymer.

[0010] In some embodiments, the spiral hollow optical fiber further includes a silicon dioxide light guide layer, which covers the inner wall of the spiral hollow light guide tube, and the internal cavity of the spiral hollow light guide tube forms an air channel.

[0011] In some embodiments, the spiral hollow light guide tube comprises 3 to 9 hollow capillaries.

[0012] In some embodiments, the spiral helix angle of the spiral hollow light guide tube is 15° to 35°, and the spiral period is 5 mm to 20 mm; In some embodiments, the diameter of the air channels in the hollow capillary is 10 μm to 80 μm.

[0013] In some embodiments, the thickness of the stress buffer layer is 10 nm to 50 nm.

[0014] In some embodiments, the thickness of the optical barrier layer is 100 nm to 300 nm.

[0015] In some embodiments, the thickness of the dense barrier layer is 5 nm to 20 nm.

[0016] In some embodiments, the thickness of the intrinsic self-healing layer is 100 nm to 500 nm.

[0017] In some embodiments, the thickness of the wear-resistant coating is 50 nm to 150 nm.

[0018] In some embodiments, the thickness of the hydrogen barrier layer is 5 nm to 20 nm.

[0019] In some embodiments, the thickness of the silicon dioxide light guide layer is 210 nm to 800 nm.

[0020] In some embodiments, the thickness of the conductive shielding layer is <1 μm.

[0021] In some embodiments, when the number of hollow capillaries is odd, the spiral helix angle of the spiral hollow light guide tube ranges from (25°, 35°); when the number of hollow capillaries is even, the spiral helix angle of the spiral hollow light guide tube ranges from [15°, 25°].

[0022] In some embodiments, a passive RFID chip is embedded within the sheath layer, the RFID chip being used to store optical fiber characteristic data; wherein, the characteristic data includes drawing time, measured loss value, PMD value and / or self-healing layer activity data.

[0023] A method for fabricating the aforementioned helical hollow-core optical fiber, the method comprising: The rotating core micro-injection molding process is used to inject heat-resistant optical-grade polymer into the mold. During the injection process, the core rotates synchronously at a set speed to form a support skeleton with a spiral outer surface. A silica light guide layer is deposited conformally on the surface of the support frame to form a spiral hollow light guide tube composed of multiple hollow capillaries; wherein, the multiple hollow capillaries constitute a nodeless anti-resonance structure, the silica light guide layer covers the surface of the support frame, and the unfilled part inside the support frame constitutes the air channel of the hollow capillaries. A biomimetic protective layer is coated on the outer surface of the outer cladding layer of the spiral hollow light guide tube; After coating with a biomimetic protective layer, a sheath layer is co-extruded on the outer layer of the spiral hollow light guide tube using a co-extrusion process to obtain a spiral-structured hollow optical fiber.

[0024] In some embodiments, the support frame includes: a solid bracket located at the center, and a plurality of C-shaped tubes spirally wound around the periphery of the solid bracket; wherein, a protruding core column is connected to the center of each C-shaped tube.

[0025] In some embodiments, after forming a support skeleton with a helical outer surface, the method further includes: subjecting the surface of the support skeleton to a low-temperature fluorination treatment to reduce the surface energy of the support skeleton surface and enhance adhesion.

[0026] In some embodiments, depositing a silicon dioxide light guide layer on a support frame includes: using a low-temperature plasma-enhanced chemical vapor deposition process to deposit a silicon dioxide light guide layer on the surface of the support frame at a set temperature, forming a spiral hollow light guide tube composed of multiple hollow capillaries.

[0027] In some embodiments, the heat-resistant optical grade polymer is polyetheretherketone or a modified cyclic olefin copolymer with a glass transition temperature higher than 160°C; the core rotation speed is 10 to 100 rpm.

[0028] In some embodiments, a biomimetic protective layer is coated on the outer surface of the outer cladding of the spiral hollow light guide tube, including: A stress buffer layer and an optical barrier layer are sequentially deposited and coated on the surface of the support frame; A dense barrier layer, a coated functional protective layer, and a deposited conductive shielding layer are sequentially deposited on the surface of the support frame.

[0029] In some embodiments, the method of depositing a stress buffer layer includes: using plasma polymerization to deposit an organic-inorganic gradient transition layer of 10 nm to 50 nm on the surface of the support skeleton. Methods for coating optical barrier layers include: using dip coating or ultrasonic spraying to coat a fluoropolymer layer with a refractive index ≤1.38, a thickness of 100nm to 300nm, and then performing ultraviolet low-temperature curing at a temperature <80°C. Methods for depositing dense barrier layers include: using atomic layer deposition (ALD) to deposit Al2O3 dense barrier layers with a thickness of 5 nm to 20 nm by alternately introducing precursors at temperatures below 100°C. The method for coating a functional protective layer includes: sequentially coating a hydrogen barrier layer, an intrinsic self-healing layer, and a wear-resistant coating using microfluidic coating technology, and then performing corresponding low-temperature curing at a temperature <100°C. Methods for depositing conductive shielding layers include: using spraying or dip coating to attach a conductive polymer layer to the surface with a thickness of <1μm, followed by low-temperature drying and curing.

[0030] In some embodiments, during the deposition of the silicon dioxide light guide layer, a rotating magnetic field is used to assist in generating a vortex in the reactive ion flow, and in-situ spectral monitoring and closed-loop feedback are used to dynamically adjust the film thickness; an excimer laser is used for pulsed line scanning annealing, and ultraviolet photon energy is used to break and recombine the weak Si-O bonds, thereby achieving low-temperature densification of the silicon dioxide light guide layer.

[0031] In some embodiments, during the co-extrusion molding of the sheath layer, a two-layer co-extrusion process is used to extrude the sheath layer. When the sheath is in a semi-molten state, a passive RFID chip is embedded inside the sheath layer through a side-feeding device.

[0032] As described in the above embodiments, the spiral hollow light guide tube transforms stress into tangentially dispersed stress during bending, thereby improving bending life while maintaining excellent optical performance. The spiral hollow light guide tube transforms bending stress from "point concentration" to "surface dispersion," improving bending resistance. The spiral hollow light guide tube conforms to the torsional direction to resist deformation, significantly improving PMD stability and enhancing interlayer bonding. The spiral interface forms a three-dimensional mechanical interlocking structure between the multiple protective layers, further enhancing interlayer bonding.

[0033] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0034] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the cross-sectional structure of an example spiral-structured hollow optical fiber; Figure 2 This is an example of a multi-tube hollow light source side perspective structure; Figure 3 This is a schematic diagram comparing the stress of an example spiral hollow light guide tube in a bent state; Figure 4 This is a schematic diagram comparing the air pore capillary force liquid surface morphology of an example hollow capillary. Figure 5 This is a schematic diagram of the radial cross-sectional structure of an example biomimetic protective layer; Figure 6 This is a flowchart illustrating a method for fabricating a helical hollow-core optical fiber according to one embodiment. Figure 7 This is a schematic diagram of an example support skeleton structure; Figure 8 This is a schematic diagram of an example silicon dioxide light guide layer structure; Figure 9 This is a flowchart of a method for fabricating a helical hollow-core optical fiber according to another embodiment; Figure 10 This is a flowchart illustrating an example of a five-tube spiral structure hollow optical fiber fabrication method. Detailed Implementation

[0035] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0036] Those skilled in the art will understand that, unless otherwise stated, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the word “comprising” as used in this application’s specification means the presence of the stated feature, integer, step, or operation, but does not preclude the presence or addition of one or more other features, integers, steps, or operations.

[0037] The technical solution of this application, in the fabrication of helical hollow optical fiber, replaces the vertical pipe support with a helical pipe support, and combines a nodeless negative curvature anti-resonant structure composed of multiple hollow capillaries. The helical structure is used to achieve multiple functions such as stress dispersion and mechanical locking. Furthermore, a multi-layer biomimetic protection system is constructed on the surface of the optical fiber, resulting in a more stable structure, longer service life, better polarization mode dispersion stability, stronger self-healing ability, and higher manufacturing yield.

[0038] Based on this, this application provides a helical hollow-core optical fiber, with reference to... Figure 1 As shown, Figure 1 This is a schematic diagram of the cross-sectional structure of an example helical hollow optical fiber, which, from the inside out, includes: a helical hollow light guide tube, a biomimetic protective layer, and a sheath layer; wherein, the helical hollow light guide tube comprises a nodeless anti-resonant structure composed of multiple hollow capillaries. Figure 1 The diagram shows the structure of a hollow capillary tube; the hollow capillary tubes are evenly distributed circumferentially and maintain a gap with the inner wall of the biomimetic protective layer to eliminate contact nodes; the wall surface of the hollow capillary tube facing the fiber core is a negative curvature surface.

[0039] like Figure 2 As shown, Figure 2 This is an example of a multi-tube hollow optical fiber side-view structure. The air channels inside the spiral hollow light guide tube extend spirally along the optical fiber axis according to a set spiral angle and spiral period. A biomimetic protective layer is coated on the outer surface of the outer cladding of the spiral hollow light guide tube. The sheath layer includes the outermost polymer sheath for protecting the optical fiber.

[0040] For example, the spiral hollow light guide tube can be composed of 3-9 hollow capillaries forming a nodeless anti-resonance structure, and the diameter of the air channel of the hollow capillaries can be 10μm to 80μm; preferably, the spiral helix angle can be 15° to 35°, and the spiral helix angle is preferably 30°; the spiral period of the spiral hollow light guide tube can be 5mm to 20mm.

[0041] For example, the following scheme can be adopted for the coordinated design of the number of hollow capillaries and the spiral hollow light guide: When the number of hollow capillaries is odd, such as 3, 5, 7, or 9, the spiral helix angle of the spiral hollow light guide tube ranges from 25° to 35°. The spiral hollow light guide tube with this structure is a non-centrosymmetric structure, and the larger spiral angle can enhance the structural stability without significantly affecting the optical performance.

[0042] When the number of hollow capillaries is even, such as 4 or 6, the spiral helix angle of the spiral hollow light guide tube ranges from [15° to 25°]. The inner cavity of the outer cladding layer has a polygonal cross-section that matches the number of capillaries. This spiral hollow light guide tube has strong central symmetry and needs to be combined with a nested structure. A smaller spiral angle can avoid disrupting the anti-resonance condition.

[0043] refer to Figure 3 As shown, Figure 3 This is a schematic diagram comparing the stress distribution of an example spiral hollow light guide tube in a bent state. The diagram shows a comparison between the uniform stress distribution along the spiral path of the spiral support frame and the spiral hollow light guide tube when the latter is bent. The left diagram shows that when the spiral hollow light guide tube is bent, stress concentration points will be generated, as shown by the black dots in the diagram, which are prone to microcracks. The right diagram shows that when the spiral hollow light guide tube of this application is bent, there are no stress concentration points, and the stress is converted into tangential dispersed stress and dispersed.

[0044] refer to Figure 4 As shown, Figure 4 This is a schematic diagram comparing the capillary force and liquid surface morphology of the air pores in an example hollow capillary tube. The left image shows the capillary force situation of the air pores in a conventional vertical hollow capillary tube. The vertical air pores generate continuous capillary force, causing the tube wall to deform under pressure. Continuous capillary force can easily lead to tube wall collapse. The right image shows the capillary force situation of the air pores in the hollow capillary tube of this application. The surface tension vector of the spiral air pores in the hollow capillary tube is dispersed, the radial resultant force tends to zero, the tube wall is under force balance, the structure is stable, the capillary force is blocked, and the tube wall is ensured to remain undamaged and not collapse.

[0045] As described in the above embodiments, the spiral hollow light guide tube transforms stress into tangentially dispersed stress when bent, thereby improving bending life while maintaining excellent optical performance. The spiral hollow light guide tube transforms bending stress from "point concentration" to "surface dispersion," improving bending resistance. The spiral hollow light guide tube resists deformation by conforming to the torsional direction, significantly improving PMD (Polarization Mode Dispersion) stability and enhancing interlayer bonding. The spiral interface forms a three-dimensional mechanical interlocking structure between the multiple protective layers, further enhancing interlayer bonding.

[0046] Experimental data show that the spiral-structured hollow optical fiber of this application, through the spiral hollow light guide tube, transforms the stress concentration on the vertical wall into tangentially dispersed stress along the spiral interface when the fiber is bent, thus improving the bending life by more than 300%. The spiral structure conforms to the torsional direction to resist deformation, eliminates shear stress concentration, and improves PMD stability by more than 50%. The spiral interface forms a three-dimensional mechanical interlocking structure between multiple protective layers, improving the interlayer bonding force by more than 200%. The spiral structure breaks the longitudinal translational symmetry, introduces chirality to suppress surface modes, reduces bending loss, and suppresses higher-order modes.

[0047] To make the technical solution of this application clearer, more embodiments are described below.

[0048] In some embodiments, a silicon dioxide (SiO2) light guide layer is further provided between the spiral hollow light guide tube and the biomimetic protective layer. The silicon dioxide light guide layer covers the inner wall of the spiral hollow light guide tube and has a thickness of 210 nm to 800 nm, which is used to correct the surface morphology error of the spiral hollow light guide tube.

[0049] Specifically, since it is difficult to directly form a smooth and flat inner wall surface when preparing the hollow capillary of the spiral hollow light guide tube, a smooth light guide interface can be obtained by conformally depositing a silicon dioxide light guide layer.

[0050] In some embodiments, the biomimetic protective layer of the helical hollow optical fiber comprises, from the inside out: The stress buffer layer is an organic-inorganic gradient transition layer (silane coupling agent) with a thickness of 10nm to 50nm. Optical barrier layer, made of refractive index n Composed of fluorinated polymers with a density of ≤1.38 and a thickness of 100 nm to 300 nm; A dense barrier layer, composed of atomically deposited oxides, with a thickness of 5 nm to 20 nm; The intrinsic self-healing layer contains a Diels-Alder dynamic covalent polymer with a thickness of 100 nm to 500 nm; The wear-resistant coating is a diamond-like carbon (DLC) coating with a thickness of 50 nm to 150 nm.

[0051] In some embodiments, the biomimetic protective layer further includes a hydrogen barrier layer disposed between the dense barrier layer and the intrinsic self-healing layer, wherein the hydrogen barrier layer is an amorphous high-entropy alloy layer or an oxide / nitride multilayer film; for example, the thickness of the hydrogen barrier layer can be from 5 nm to 20 nm.

[0052] In some embodiments, the biomimetic protective layer further includes: a conductive shielding layer on the outermost layer, the conductive shielding layer being composed of a conductive polymer and having a thickness of <1μm.

[0053] refer to Figure 5 As shown, Figure 5 This is a schematic diagram of a radial cross-sectional structure of an example biomimetic protective layer, which includes, from the inside out: L1: Stress buffer layer (10-50nm); L2: Optical barrier layer (refractive index n≤1.38); L3: Dense barrier layer (5-20nm); L4: Hydrogen barrier layer (5-20nm); L5: Intrinsic self-healing layer (100-500nm); L6: Wear-resistant coating (50-150nm); L7: Conductive shielding layer (<1μm).

[0054] In the above embodiment, a multi-layered biomimetic protection system is formed by coating a biomimetic protective layer on the outer surface of the outer cladding of the spiral hollow light guide tube. Among them, the stress buffer layer has the function of buffering thermal stress and chemical bonding; the optical barrier layer has the function of blocking evanescent field penetration; the dense barrier layer has the function of blocking ultra-high density water vapor / chemical corrosion; the hydrogen barrier layer can prevent "hydrogen loss" caused by hydrogen penetration; the intrinsic self-healing layer can realize infinite self-healing of microcracks with a repair efficiency of ≥98%; the wear-resistant coating can achieve ultra-high hardness and scratch resistance (≥30GPa); and the conductive shielding layer can achieve electromagnetic pulse (EMP) resistance, electromagnetic compatibility (EMC) and other properties.

[0055] In some embodiments, a passive RFID chip is embedded within the sheath layer. The RFID chip is used to store optical fiber characteristic data. The characteristic data may include drawing time, measured loss value, PMD value, and / or self-healing layer activity data, etc.

[0056] Specifically, a passive UHF RFID chip can be embedded in the co-extruded fiber during the sheath extrusion process to store characteristic data of the entire life cycle of the optical fiber, including drawing time, measured loss value, PMD value, self-healing layer activity data, etc.; to achieve full life cycle data traceability of the optical fiber from production to deployment, and to provide users with a verifiable warranty of "no performance degradation" for 50 years.

[0057] The spiral-structured hollow-core optical fiber of this application avoids the direct contact between the capillary and the outer cladding to form "nodes" as in traditional multi-tube anti-resonant hollow-core optical fibers; it avoids node leakage, reduces loss, and improves the theoretical minimum loss limit of the hollow-core optical fiber. It also avoids the risk of peeling caused by the parallel stacking structure of the multi-layer protective coating on the vertical wall surface in traditional multi-tube anti-resonant hollow-core optical fibers, which results in weak interlayer bonding. Through systematic protection against hydrogen darkening and electromagnetic pulse (EMP) interference caused by hydrogen permeation, it provides better protection. When microcracks appear in the hollow-core optical fiber coating, it can self-repair, preventing the penetration of harmful substances such as water vapor and hydrogen, thus extending the fiber's lifespan.

[0058] The following describes an embodiment of the fabrication method of helical hollow optical fiber.

[0059] refer to Figure 6 As shown, Figure 6 This is a flowchart illustrating a method for fabricating a helical hollow-core optical fiber according to one embodiment. This method is used to fabricate helical hollow-core optical fibers according to any of the aforementioned embodiments. The method includes: S10 uses a rotating core micro-injection molding process to inject heat-resistant optical-grade polymer into the mold. During the injection process, the core rotates synchronously at a set speed to form a support skeleton with a spiral outer surface.

[0060] For example, the heat-resistant optical grade polymer can be polyetheretherketone (PEEK) or a modified cyclic olefin copolymer (COC) with a glass transition temperature higher than 160°C, and the core rotation speed can be 10 to 100 rpm.

[0061] In some embodiments, reference Figure 7 As shown, Figure 7 This is a schematic diagram of an example support frame structure, shown in a cross-sectional view. It may include a solid support located at the center and multiple C-shaped tubes spirally wound around the periphery of the solid support. Each C-shaped tube has a protruding core column connected to its center, and the air gap between the protruding core column and the C-shaped tube forms part of the anti-resonance cavity.

[0062] For example, the figure shows a spiral hollow light guide tube composed of 5 hollow capillaries. First, a solid support at the center is prepared to provide core support. Five C-shaped tubes are spirally wound around the solid support. The C-shaped tubes are circular with openings and are connected to a protruding core column located at the center of the C-shaped tube.

[0063] In some embodiments, after forming a support skeleton with a helical outer surface, the surface of the support skeleton may be subjected to low-temperature fluorination treatment to reduce the surface energy of the support skeleton surface and enhance adhesion.

[0064] Specifically, carbon tetrafluoride (CF4) plasma is used to perform low-temperature fluorination treatment on the surface of the support skeleton (temperature <80°C, power 100 to 300W, time 1 to 5min) to reduce surface energy and enhance the adhesion of subsequent coatings.

[0065] S20, a silicon dioxide light guide layer is deposited conformally on the surface of the support frame to form a spiral hollow light guide tube composed of multiple hollow capillaries; wherein, the multiple hollow capillaries constitute a nodeless anti-resonant structure, the silicon dioxide light guide layer covers the surface of the support frame, and the unfilled part inside the support frame constitutes the air channel of the hollow capillaries.

[0066] Specifically, a silicon dioxide light guide layer is deposited conformally on the spiral support frame, forming a uniformly covered SiO2 film on the inner wall of the C-shaped tube and the outer wall of the protruding core column; the internal cavity between the C-shaped tube and the protruding core column, surrounded by the SiO2 film, constitutes the air channel of the hollow capillary. The air channel is a light guide cavity completely sealed by the silicon dioxide film, used for low-loss transmission of optical signals.

[0067] Preferably, a low-temperature plasma-enhanced chemical vapor deposition (PECVD) process can be used to deposit a silicon dioxide light guide layer on the surface of the support frame at a set temperature.

[0068] Specifically, such as Figure 8 As shown, Figure 8 This is a schematic diagram of an example silicon dioxide light guide layer structure. The dashed lines in the diagram indicate the location of the silicon dioxide light guide layer. The silicon dioxide light guide layer is applied to the inner wall of the C-shaped tube and the outer wall of the protruding core pillar through a conformal deposition process, forming a light guide cavity that is completely sealed by the silicon dioxide film. The light guide cavity is the air channel of the hollow capillary, which is used to constrain the low-loss transmission of optical signals in the air medium.

[0069] For example, such as Figure 8 As shown, according to design requirements, several layers of fiber optic wrapping can be applied to the support frame. The fiber optic wrapping can be made of quartz cladding tube to wrap the fiber core.

[0070] In some embodiments, during the deposition process, a rotating magnetic field can be used to assist in generating vortices in the reactive ion flow, and in-situ spectral monitoring and closed-loop feedback can be used to dynamically adjust the film thickness.

[0071] Specifically, during the deposition of the silicon dioxide light guide layer, a rotating magnetic field is used to assist in generating a vortex in the reactive ion flow, and in-situ spectral monitoring and closed-loop feedback are used to dynamically adjust the film thickness. Excimer laser is used for pulsed line scanning annealing, and ultraviolet photon energy is used to break and recombine the weak Si-O bonds, thereby achieving low-temperature densification of the silicon dioxide light guide layer.

[0072] For example, a low-temperature continuous slit plasma-enhanced chemical vapor deposition (LT-PECVD) process is used, with the reaction chamber temperature controlled at 80-150°C (preferably 80-120°C, which can be adjusted according to the heat distortion temperature of the skeleton material), to deposit a silicon dioxide light guide layer with a thickness of 210 nm to 800 nm on the spiral surface.

[0073] A rotating magnetic field is used to assist in creating a vortex in the reactive ion flow, uniformly covering the spiral surface, and in-situ spectral monitoring with closed-loop feedback (real-time measurement of film thickness and dynamic adjustment of deposition parameters) to dynamically adjust the film thickness and "smooth out" manufacturing errors in the supporting framework. Excimer laser (wavelength 248nm or 308nm) is used for pulsed line scanning annealing with an energy density of 200-400 mJ / cm². 2 By using ultraviolet photon energy to break and recombine the weak Si-O bonds, the SiO2 light guide layer is densified at low temperature, avoiding thermal stress damage to the support skeleton.

[0074] S30, a biomimetic protective layer is coated on the outer surface of the outer cladding layer of the spiral hollow light guide tube.

[0075] In some embodiments, the process of coating a biomimetic protective layer may include: S301, a stress buffer layer and an optical blocking layer are sequentially deposited on the surface of the support frame.

[0076] An exemplary method for depositing a stress buffer layer includes: depositing an organic-inorganic gradient transition layer of 10 nm to 50 nm on the surface of the support skeleton using plasma polymerization.

[0077] For example, a method for coating an optical barrier layer includes: coating a fluoropolymer layer with a refractive index ≤1.38 and a thickness of 100 nm to 300 nm by dip coating or ultrasonic spraying, and then subjecting it to ultraviolet (UV) low-temperature curing at a temperature <80°C.

[0078] S302, a dense barrier layer, a coated functional protective layer, and a deposited conductive shielding layer are sequentially deposited on the surface of the support frame.

[0079] For example, a method for depositing a dense barrier layer may include: using an atomic layer deposition (ALD) process to deposit a dense alumina (Al2O3) barrier layer of 5 nm to 20 nm thickness by alternately introducing a precursor (such as trimethylaluminum and water vapor) at a temperature below 100°C.

[0080] For example, a method for coating a functional protective layer may include: sequentially coating a hydrogen barrier layer, an intrinsic self-healing layer, and a wear-resistant coating using microfluidic coating technology, and then performing corresponding low-temperature curing at a temperature <100°C.

[0081] For example, a method for depositing a conductive shielding layer may include: attaching a conductive polymer layer with a thickness of <1 μm to the surface by spraying or dip coating, and then drying and curing it at low temperature.

[0082] Specifically, the process involves sequentially coating a hydrogen barrier layer (amorphous high-entropy alloy or oxide / nitride multilayer film, 5 nm to 20 nm thick), an intrinsic self-healing layer (polymer containing Diels-Alder dynamic covalent bonds, 100 nm to 500 nm thick), and a wear-resistant coating (diamond-like carbon precursor, 50 nm to 150 nm thick) using microfluidic coating technology, followed by low-temperature curing (temperature <100°C).

[0083] S40, after coating with a biomimetic protective layer, a sheath layer is co-extruded on the outer layer of the spiral hollow light guide tube using a co-extrusion process to obtain a spiral-structured hollow optical fiber.

[0084] In some embodiments, during the co-extrusion molding of the sheath layer, a two-layer co-extrusion process is used to extrude the sheath layer. When the sheath is in a semi-molten state, a passive RFID chip is embedded inside the sheath layer through a side-feeding device.

[0085] Specifically, the outer sheath of the optical fiber is extruded using a double-layer co-extrusion process. When the sheath is in a semi-molten state, a passive UHF RFID chip is embedded inside the sheath through a side-feeding device. After cooling and shaping, the final product is formed.

[0086] For a detailed fabrication process of the spiral-structured hollow optical fiber and its fabrication method described in the above embodiments, please refer to [reference needed]. Figure 9 As shown, Figure 9 Here is a flowchart of a method for fabricating a helical hollow-core optical fiber according to another embodiment, including the following: S101, support frame core mold injection molding; S102, surface pretreatment of the support skeleton (low-temperature fluorination). S103, low-temperature PECVD deposition of silicon dioxide light guide layer; s104, Determine if the thickness of the light guide layer has reached the target value? If yes, proceed to s105; otherwise, continue to s103. S105, UV / excimer laser cold annealing; S106, a deposition stress buffer layer; S107, coated with an optical barrier layer; S108 uses the ALD process to deposit a dense barrier layer; S109, a coating and curing functional protective layer; S110, deposited conductive shielding layer; s111 uses supercritical CO2 for drying to remove residual solvent or moisture; S112, the sheath layer is formed by co-extrusion process to obtain optical fiber products; S113: Perform full-performance testing on the fiber optic product; the test ends once it passes.

[0087] Based on the spiral-structured hollow optical fiber and its fabrication method provided in this application, several examples of spiral hollow light guides using different numbers of hollow capillaries are described below.

[0088] Example 1: The spiral hollow light guide tube of the spiral structure hollow optical fiber uses 5 hollow capillaries for single-mode transmission. The fiber core support is distributed in a ring to support and protect multiple fiber cores. Multiple air channels are set inside the fiber core support. The fiber core support is optimized to extend spirally along the fiber axis.

[0089] The fiber has 5 hollow capillaries, a helix angle of 30°, a helix period of 10 mm, an outer diameter of 400 μm, an air channel diameter of 40 μm (suitable for single-mode transmission), and a silica light guide layer thickness of 500 nm. The skeleton material is a modified cyclic olefin copolymer (COC) with a glass transition temperature higher than 160°C, which is retained in the final product for life.

[0090] The spiral-structured hollow fiber in this example is referenced. Figure 10 As shown, Figure 10 This is a flowchart illustrating an example of a five-tube spiral structure hollow optical fiber fabrication method, which may include the following: S201 uses a rotary core micro-injection molding process to inject modified COC (Tg>160°C) into the mold. The core rotates at 50 rpm, and the injection tolerance is ±10 μm, forming a support skeleton with a helix angle of 30°.

[0091] S202 uses CF4 plasma to fluorinate the skeleton surface at a power of 200W for 3 minutes at a temperature of <80°C.

[0092] S203 uses a low-temperature continuous slit PECVD equipment to deposit a silicon dioxide light guide layer with a thickness of 500 nm at 120°C and a belt speed of 2 m / min. During the deposition process, a rotating magnetic field is used for assistance and in-situ spectral monitoring closed-loop feedback.

[0093] S204 was annealed using an excimer laser (248 nm) with a line scan energy density of 350 mJ / cm². 2 .

[0094] S205 uses plasma polymerization to deposit a silane coupling agent gradient transition layer with a thickness of 30 nm to form a stress buffer layer.

[0095] S206 is coated with a fluoropolymer optical barrier layer by dip coating, with a refractive index of 1.38 and a thickness of 200 nm, and then UV cured.

[0096] S207 uses a spatial ALD device to deposit an Al2O3 layer with a thickness of 10 nm at 100°C.

[0097] S208 was coated sequentially with a hydrogen barrier layer (amorphous high-entropy alloy nano-dispersion, 8nm thick), a DA self-healing layer (350nm thick), and a DLC wear-resistant coating precursor (80nm thick) using microfluidic coating technology, and then cured at low temperature.

[0098] S209 uses a spray coating method to apply a conductive polymer shielding layer with a thickness of 0.8 μm, followed by low-temperature drying.

[0099] The S210 uses a double-layer co-extrusion process to extrude the outer sheath of the optical fiber and embed a passive UHF RFID chip.

[0100] The performance test results of the spiral-structured hollow fiber prepared in the above example compared with the vertically supported spiral-structured hollow fiber are shown in the table below:

[0101] Example 2: The spiral hollow light guide tube of the spiral structure hollow optical fiber uses 7 hollow capillaries, and the spiral angle is 28°; the other process parameters are the same as those in Example 1.

[0102] The performance test results of the spiral-structured hollow fiber in this example are as follows: The 7-tube structure has a more enclosed core profile and stronger light-binding ability; at the same time, the cladding tube gap is smaller, and the spiral angle needs to be precisely controlled to avoid inter-tube resonance. After optimization, the loss can be further reduced to below 0.08dB / km.

[0103] Example 3: The spiral hollow light guide tube of the spiral structure hollow optical fiber adopts 4 hollow capillaries, the inner cavity of the outer cladding adopts a regular quadrilateral cross section, and the 4 nested structural units are located at the four corners respectively, with a spiral rise angle of 18°; the remaining process parameters are the same as those in Example 1.

[0104] The performance test results of the helical hollow-core fiber in this example are as follows: fundamental mode loss <0.1dB / km, and the loss of higher-order modes differs from that of the fundamental mode by 2-3 orders of magnitude, enabling single-mode transmission. The small helical angle avoids mode coupling caused by symmetry breaking.

[0105] Example 4: The spiral hollow optical fiber uses six hollow capillaries in a double-layer nested structure (outer layer + inner layer), with a spiral angle of 20°. All other process parameters are the same as in Example 1.

[0106] The performance test results of the spiral-structured hollow fiber in this example are as follows: Simulation results show that the confinement loss of this structure can be reduced to 0.015dB / km at 1550nm.

[0107] In summary, the spiral-structured hollow-core optical fiber of this application has the following technical effects: Achieving synergistic effects between anti-resonant light guiding and helical mechanics: The helical hollow light guide tube consists of 3 to 9 negative curvature hollow capillaries forming a nodeless anti-resonant structure, eliminating light leakage caused by contact nodes; 4 tubes combined with a regular quadrilateral outer cladding can achieve a fundamental mode loss of <0.1dB / km; the 6-tube double-layer nested structure can reduce the limiting loss to 0.015dB / km; the 7-tube structure has been proven to be a "relatively excellent structure"; the helical structure converts stress into tangential dispersed stress when bending, which greatly improves bending life while maintaining excellent optical performance.

[0108] Its various performance characteristics are as follows: Significantly improves bending resistance: The spiral structure transforms bending stress from "point concentration" to "surface dispersion", resulting in a significantly longer bending life compared to vertical support structures.

[0109] Significantly improves polarization mode dispersion (PMD) stability: The spiral structure conforms to the torsional direction to resist deformation, and the PMD stability is improved by more than 50% compared with the vertical support structure.

[0110] Enhanced interlayer bonding: The spiral interface creates a three-dimensional mechanical interlocking structure between the multiple protective layers, significantly improving the interlayer bonding strength compared to vertical support structures.

[0111] Improved self-healing efficiency: The spiral structure lengthens the crack propagation path, and the Diels-Alder dynamic covalent bonds are activated from multiple directions, resulting in a self-healing efficiency of over 98%, which is far superior to the one-time repair solutions of existing microcapsule technologies.

[0112] Achieving systematic hydrogen protection: Amorphous alloy or oxide / nitride multilayer films have excellent gas tightness to hydrogen (reducing hydrogen permeability by 4 orders of magnitude), which can effectively prevent "hydrogen loss" caused by hydrogen permeation and extend the life of optical fibers.

[0113] Achieving electromagnetic pulse resistance and distributed sensing: The conductive shielding layer provides electromagnetic pulse protection and electromagnetic compatibility (EMC) protection, while the distributed acoustic sensing (DAS) function of the hollow optical fiber enables the integration of communication and sensing.

[0114] Achieving full lifecycle traceability: RFID chips enable full lifecycle data traceability for optical fibers from production to deployment, providing users with a verifiable 50-year warranty against performance degradation.

[0115] Achieve low-cost continuous mass production: Adopt domestically produced LT-PECVD, ALD and other equipment and fault-tolerant production processes (tolerance ±10μm + deposition and gap filling compensation), production line equipment investment is controllable, and unit manufacturing cost is controllable.

[0116] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A spiral architecture hollow core optical fiber, characterized in that, From the inside out, it consists of: a spiral hollow light guide tube, a biomimetic protective layer, and a sheath layer; The spiral hollow light guide tube includes a nodeless anti-resonance structure composed of multiple hollow capillaries; The hollow capillaries are evenly distributed circumferentially and maintain a gap with the inner wall of the biomimetic protective layer to eliminate contact points. The wall surface of the hollow capillary facing the fiber core is a negative curvature surface; The air channels inside the spiral hollow light guide tube extend in a spiral shape along the optical fiber axis according to the set spiral angle and spiral period. The biomimetic protective layer is coated on the outer surface of the outer cladding layer of the spiral hollow light guide tube; The sheath layer includes an outermost polymer sheath for protecting the optical fiber.

2. The helical hollow-core optical fiber according to claim 1, characterized in that, The biomimetic protective layer comprises, from the inside out: The stress buffer layer is an organic-inorganic gradient transition layer. The optical barrier layer is composed of a fluoropolymer with a set refractive index; A dense barrier layer, composed of oxides deposited at atomic layers; The intrinsic self-healing layer contains a Diels-Alder dynamic covalent polymer; The wear-resistant coating is a diamond-like carbon coating.

3. The spiral-structured hollow optical fiber according to claim 2, characterized in that, The biomimetic protective layer further includes a hydrogen barrier layer disposed between the dense barrier layer and the intrinsic self-healing layer, wherein the hydrogen barrier layer is an amorphous high-entropy alloy layer or an oxide / nitride multilayer film.

4. The helical hollow-core optical fiber according to claim 3, characterized in that, The biomimetic protective layer further includes a conductive shielding layer on the outermost layer, which is composed of a conductive polymer.

5. The helical hollow-core optical fiber according to claim 4, characterized in that, Also includes: A silicon dioxide light guide layer is applied to the inner wall of the spiral hollow light guide tube, and the internal cavity of the spiral hollow light guide tube forms an air channel.

6. The spiral-structured hollow optical fiber according to claim 5, characterized in that, The spiral hollow light guide tube comprises 3 to 9 hollow capillaries; The spiral hollow light guide tube has a spiral helix angle of 15° to 35° and a spiral period of 5 mm to 20 mm. The diameter of the air channels in the hollow capillary is 10 μm to 80 μm; The thickness of the stress buffer layer is 10 nm to 50 nm. The thickness of the optical barrier layer is 100 nm to 300 nm; The thickness of the dense barrier layer is 5 nm to 20 nm; The thickness of the intrinsic self-healing layer is 100 nm to 500 nm; The thickness of the wear-resistant coating is 50 nm to 150 nm; The thickness of the hydrogen barrier layer is 5 nm to 20 nm; The thickness of the silicon dioxide light guide layer is 210 nm to 800 nm; The thickness of the conductive shielding layer is <1μm.

7. The helical hollow-core optical fiber according to claim 6, characterized in that, When the number of hollow capillaries is odd, the spiral helix angle of the spiral hollow light guide tube ranges from (25°, 35°); when the number of hollow capillaries is even, the spiral helix angle of the spiral hollow light guide tube ranges from [15°, 25°].

8. The helical hollow-core optical fiber according to claim 1, characterized in that, A passive RFID chip is embedded within the sheath layer, and the RFID chip is used to store optical fiber characteristic data; wherein, the characteristic data includes drawing time, measured loss value, PMD value and / or self-healing layer activity data.

9. A method for preparing a helical hollow-core optical fiber according to any one of claims 1 to 8, characterized in that, The method includes: The rotating core micro-injection molding process is used to inject heat-resistant optical-grade polymer into the mold. During the injection process, the core rotates synchronously at a set speed to form a support skeleton with a spiral outer surface. A silica light guide layer is deposited conformally on the surface of the support frame to form a spiral hollow light guide tube composed of multiple hollow capillaries; wherein, the multiple hollow capillaries constitute a nodeless anti-resonance structure, the silica light guide layer covers the surface of the support frame, and the unfilled part inside the support frame constitutes the air channel of the hollow capillaries. A biomimetic protective layer is coated on the outer surface of the outer cladding layer of the spiral hollow light guide tube; After coating with a biomimetic protective layer, a sheath layer is co-extruded on the outer layer of the spiral hollow light guide tube using a co-extrusion process to obtain a spiral-structured hollow optical fiber.

10. The method for preparing a helical hollow-core optical fiber according to claim 9, characterized in that, The supporting frame includes: a solid bracket located at the center, and multiple C-shaped tubes spirally wound around the periphery of the solid bracket; wherein, a protruding core column is connected to the center of each C-shaped tube.

11. The method for fabricating a helical hollow-core optical fiber according to claim 9, characterized in that, After forming the support skeleton with a spiral outer surface, the process further includes: performing a low-temperature fluorination treatment on the surface of the support skeleton to reduce the surface energy of the support skeleton surface and enhance adhesion.

12. The method for fabricating a helical hollow-core optical fiber according to claim 10, characterized in that, Depositing a silicon dioxide light guide layer on a support frame includes: using a low-temperature plasma-enhanced chemical vapor deposition process, depositing a silicon dioxide light guide layer on the surface of the support frame at a set temperature to form a spiral hollow light guide tube composed of multiple hollow capillaries.

13. The method for preparing a helical hollow-core optical fiber according to claim 9, characterized in that, The heat-resistant optical grade polymer is polyetheretherketone or a modified cyclic olefin copolymer with a glass transition temperature higher than 160°C; the core rotation speed is 10 to 100 rpm.

14. The method for fabricating a helical hollow-core optical fiber according to claim 9, characterized in that, A biomimetic protective layer is coated on the outer surface of the outer cladding of the spiral hollow light guide tube, including: A stress buffer layer and an optical barrier layer are sequentially deposited and coated on the surface of the support frame; A dense barrier layer, a coated functional protective layer, and a deposited conductive shielding layer are sequentially deposited on the surface of the support frame.

15. The method for preparing a helical hollow-core optical fiber according to claim 9, characterized in that, The method for depositing a stress buffer layer includes: using plasma polymerization to deposit an organic-inorganic gradient transition layer of 10 nm to 50 nm on the surface of the support skeleton; Methods for coating optical barrier layers include: using dip coating or ultrasonic spraying to coat a fluoropolymer layer with a refractive index ≤1.38, a thickness of 100nm to 300nm, and then performing ultraviolet low-temperature curing at a temperature <80°C. Methods for depositing dense barrier layers include: using atomic layer deposition (ALD) to deposit Al2O3 dense barrier layers with a thickness of 5 nm to 20 nm by alternately introducing precursors at temperatures below 100°C. The method for coating a functional protective layer includes: sequentially coating a hydrogen barrier layer, an intrinsic self-healing layer, and a wear-resistant coating using microfluidic coating technology, and then performing corresponding low-temperature curing at a temperature <100°C. Methods for depositing conductive shielding layers include: using spraying or dip coating to attach a conductive polymer layer to the surface with a thickness of <1μm, followed by low-temperature drying and curing.

16. The method for preparing a helical hollow-core optical fiber according to claim 9, characterized in that, During the deposition of the silicon dioxide light guide layer, a rotating magnetic field is used to assist in generating a vortex in the reaction ion flow, and in-situ spectral monitoring and closed-loop feedback are used to dynamically adjust the film thickness. Excimer laser is used for pulsed line scanning annealing, and ultraviolet photon energy is used to break the weak Si-O bonds and recombine them to achieve low-temperature densification of the silicon dioxide light guide layer.

17. The method for fabricating a helical hollow-core optical fiber according to claim 9, characterized in that, During the co-extrusion molding of the sheath layer, a double-layer co-extrusion process is used to extrude the sheath layer. When the sheath is in a semi-molten state, a passive RFID chip is embedded inside the sheath layer through a side feeding device.

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