Hollow core optical fiber with support structure and method of manufacture

Abstract

The present application relates to a kind of hollow optical fiber with support structure and preparation method, hollow optical fiber includes cladding and inner cladding, the inner cladding is made of anti-resonant structure unit, the anti-resonant structure unit includes 2 or more than 2 different radius of anti-resonant tube, including outer anti-resonant tube and inner anti-resonant tube, the outer anti-resonant tube of the anti-resonant structure unit is equipped with support column between inner wall of outer cladding and / or with inner anti-resonant tube, the upper and lower surfaces of the support column are curvature structure, the curvature radius of its upper surface is consistent with the surface of anti-resonant tube that support column contacts, the curvature radius of its lower surface is consistent with the surface of anti-resonant tube or inner wall of outer cladding that support column contacts.The present application is equipped with support column, so as to isolate each tubular element, reduce the tube wall sticking phenomenon that hollow optical fiber is prone to appear in manufacturing process, further avoid the problem that the wall thickness of the hollow optical fiber made is uneven, so as to affect fiber loss and bandwidth.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication technology, specifically to a hollow optical fiber with a support structure and its preparation method. Background Technology

[0002] Currently, the widely used solid optical fiber suffers from intrinsic defects in its core silica matrix material, such as nonlinearity, dispersion, photodamage, and lack of light transmission in the ultraviolet and mid-infrared bands, which greatly limit its application in many fields. Especially in the field of communication data transmission, with the explosive growth of data traffic and the ever-increasing demands for transmission capacity and speed, the nonlinear effects of solid optical fiber severely restrict the quality and distance of signal transmission, making it difficult to meet the ever-growing communication needs.

[0003] Hollow-core fiber, as an important research direction in microstructured optical fibers, possesses significant advantages such as extremely low nonlinearity, low mode dispersion, high damage threshold, wide transmission band, and near-light-speed transmission. It holds promise for overcoming the bottlenecks of traditional optical fibers and providing new solutions for these fields. Hollow-core antiresonant fiber, as a novel type of hollow fiber, features a unique structure that allows the vast majority of optical energy (over 99%) to be transmitted within the air core. This greatly reduces the impact of optical transmission on fiber material absorption, lowers nonlinear effects and delays, and increases the damage threshold. It exhibits significant advantages in high-power and pulsed laser flexible transmission and also provides an efficient platform for light-matter interaction, showing important application potential in sensing and other fields.

[0004] Despite the significant advantages of hollow-core fiber in both theory and application, its transmission loss has consistently been higher than that of traditional silica fiber. Recent discoveries have shown that hollow-core fiber based on the anti-resonance principle, with proper structural design, can effectively reduce transmission loss and possesses the potential to serve as an ultra-long-distance communication fiber. However, according to the paper "15 km Continuous Length and Low Loss Hollow Core Fiber in 1μm, C and L Bands" (ECOC2024, Th1A.3), the unique structure and manufacturing process of hollow-core fiber have made further reducing attenuation, increasing fiber bandwidth, and extending fiber drawing length persistent challenges in the field of hollow-core fiber manufacturing.

[0005] In existing technologies, such as CN110515152B, an anti-resonant hollow fiber is disclosed. This anti-resonant hollow fiber includes a first tubular outer cladding element, a plurality of second tubular elements, and a plurality of third tubular elements. The first tubular outer cladding element defines an inner cladding surface. The plurality of second tubular elements are attached to the cladding surface and together define a core with an effective radius. The second tubular elements are spaced apart, with gaps between adjacent second tubular elements, and each of the plurality of third tubular elements is nested within a corresponding second tubular element. The diameter, wall thickness, and circumferential spacing of the tubular elements must strictly meet the anti-resonance condition, but micron-level dimensional deviations are difficult to avoid in actual manufacturing. Furthermore, fluctuations in the wall thickness of the tubular elements can lead to a significant reduction in the transmission bandwidth of the hollow fiber. Because this patent uses a multi-layered nested assembly of tubular elements to form an anti-resonant structure, and the tubular elements are in direct contact, uncontrolled adhesion will occur at the contact points of the tubular elements during the drawing process, resulting in uneven wall thickness near the contact points. This is especially true in the drawing of long-distance hollow optical fibers, where it is difficult to maintain good consistency of the optical fiber structure along the fiber length, thus affecting the transmission attenuation and bandwidth of the hollow optical fiber. Summary of the Invention

[0006] The purpose of this invention is to provide a hollow optical fiber with a support structure and a method for its fabrication, so as to maintain good structural consistency of the hollow optical fiber before and after drawing, thereby improving the transmission performance of the hollow optical fiber.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A hollow-core optical fiber with a support structure includes an outer cladding and an inner cladding. The inner cladding is composed of anti-resonant structural units, which are arranged circumferentially along the inner wall of the outer cladding and connected to the inner wall of the outer cladding. The central cavity covered by the inner cladding forms the fiber core. The anti-resonant structural unit includes two or more layers of anti-resonant tubes with different radii, including an outer anti-resonant tube and an inner anti-resonant tube. The characteristic feature is that a support column is provided between the outer anti-resonant tube of the anti-resonant structural unit and the inner wall of the outer cladding or / and the inner anti-resonant tube. The upper and lower surfaces of the support column are curved structures. The radius of curvature of its upper surface is consistent with the surface of the anti-resonant tube in contact with the support column, and the radius of curvature of its lower surface is consistent with the surface of the anti-resonant tube or the inner wall of the outer cladding in contact with the support column.

[0009] According to the above technical solution, at least two support columns are provided between the outer anti-resonant tube and the inner anti-resonant tube, and each support column is arranged at intervals along the circumference.

[0010] According to the above technical solution, when the anti-resonance structure unit includes three or more layers of anti-resonance tubes with different radii, the two adjacent inner anti-resonance tubes in the anti-resonance structure unit are also provided with support columns, and each support column is arranged radially stacked up and down, and the cross-sectional area of ​​the support column increases sequentially from the inside to the outside.

[0011] According to the above technical solution, when the support column is set between the outer anti-resonant tube and the inner wall of the outer cladding, each adjacent circular anti-resonant tube of the anti-resonant structure unit is tangent to each other in sequence, and each tangent point coincides with the other, and the support column is located at the coinciding tangent point.

[0012] According to the above technical solution, when the anti-resonance structure unit includes three or more layers of circular anti-resonance tubes with different radii, the inner anti-resonance tube includes a first inner anti-resonance tube and a second inner anti-resonance tube. When the support column is set between the outer anti-resonance tube and the first inner anti-resonance tube, the two adjacent inner anti-resonance tubes are tangent, and the support column is located at the corresponding tangent point.

[0013] According to the above technical solution, each support column is symmetrically arranged relative to the geometric center of the anti-resonance structural unit.

[0014] According to the above technical solution, it includes 3-5 anti-resonance structural units, and the anti-resonance structural units include 2-4 circular anti-resonance tubes.

[0015] According to the above technical solution, it includes 5 anti-resonance structural units, and the anti-resonance structural units include 3 circular anti-resonance tubes.

[0016] According to the above technical solution, the support column is an arc-shaped support column with parallel surfaces on both sides.

[0017] According to the above technical solution, the width of the support column is ≥2um and the height is 1~15um.

[0018] According to the above technical solution, the anti-resonance structure unit includes three layers of circular anti-resonance tubes with different radii. From the outside to the inside, it includes an outer anti-resonance tube, a first inner anti-resonance tube, and a second inner anti-resonance tube. The outer radius of the outer anti-resonance tube is 10~30um, the outer radius of the first inner anti-resonance tube is 6~26um, and the outer radius of the second inner anti-resonance tube is 2~10um.

[0019] According to the above technical solution, the ratio of the sum of the cross-sectional areas of each support column to the cross-sectional area formed by the inner diameter of the outer anti-resonance tube is ≤10%.

[0020] According to the above technical solution, the cross-sectional shape of the anti-resonant tube of the anti-resonant structure unit is one or more combinations of circular, elliptical, oval, and racetrack shapes.

[0021] According to the above technical solution, the anti-resonant tubes of the anti-resonant structure unit have the same wall thickness, which is 1.15±0.15um.

[0022] According to the above technical solution, the support columns are continuously distributed along the axial direction of the optical fiber.

[0023] According to the above technical solution, the ratio of the refractive index of the support column to that of the anti-resonance tube is 80%~100%.

[0024] According to the above technical solution, the outer diameter of the outer cladding layer is greater than or equal to 100 μm and less than or equal to 500 μm.

[0025] According to the above technical solution, the transmission loss of the hollow optical fiber is ≤0.1dB / km.

[0026] According to the above technical solution, the 3dB bandwidth of hollow optical fiber is ≥100nm.

[0027] A method for fabricating a hollow optical fiber with a support structure, characterized by comprising the following steps:

[0028] Prefabricating anti-resonant structural unit prefabricated parts: respectively process anti-resonant tubes with different radii and support columns with the same surface curvature radius as the anti-resonant tubes or the inner wall of the outer cladding layer, and then connect each anti-resonant tube and support column to form a shape through hot working;

[0029] Preparation of the outer cladding glass sleeve: Prepare the glass sleeve to be used as the outer cladding according to the size ratio corresponding to the prefabricated anti-resonance structural unit;

[0030] Preparation of hollow fiber preform: A predetermined number of anti-resonant structural units are nested in the outer cladding glass tube, and the anti-resonant structural units and the outer cladding glass tube are fixed in a predetermined position to form a hollow fiber preform with a support structure.

[0031] Fiber drawing process: Hollow-core optical fiber preforms with supporting structures are heated at high temperature in a fiber drawing furnace and drawn into fibers. A certain air pressure is introduced to control its structural parameters, resulting in hollow-core optical fibers with supporting column structures.

[0032] The beneficial effects of this invention are:

[0033] 1. This invention uses support pillars between the anti-resonant tube and the inner wall of the outer cladding, and / or with the inner anti-resonant tube, to isolate the tubular elements, avoiding direct contact between the anti-resonant tubes. This reduces the tube wall adhesion phenomenon that easily occurs during the manufacturing process of hollow-core optical fibers, thus preventing uneven wall thickness in the manufactured hollow-core optical fibers, which affects fiber loss and bandwidth. Simultaneously, the support pillars have a curved structure, allowing for better contact with the tubular elements during production, providing better fixation. The hollow-core optical fiber of this invention has a higher tolerance for manufacturing errors and is more suitable for the preparation of low-loss, high-bandwidth, long-distance hollow-core optical fibers.

[0034] 2. By providing at least two support pillars in the circumferential direction between the outer and inner anti-resonant tubes, and forming a gap between the two support pillars, more reflection interfaces can be provided, allowing more light leaking from between the anti-resonant units to return to the fiber core, thereby reducing fiber attenuation.

[0035] 3. By providing at least a number of support pillars in the radial direction between the outer anti-resonant tube and the inner anti-resonant tube, the multiple support pillars provide a more stable structure, which can more firmly support the inner anti-resonant tube, reduce manufacturing errors, improve the longitudinal uniformity of the optical fiber, and facilitate the drawing of low-loss long-distance hollow optical fibers.

[0036] 4. In the actual fabrication of optical fibers, the use of support pillars made of materials with lower refractive index makes it easier to achieve a fixed connection between the support pillars and the anti-resonant tube. Furthermore, during optical transmission, the interaction between the light field and the glass material is further reduced, which can further improve the process stability and transmission performance. Attached Figure Description

[0037] Figure 1(a) is a schematic diagram of different anti-resonant tubes in the anti-resonant structure unit of Embodiment 1 of the present invention.

[0038] Figure 1(b) is a schematic diagram of the support column in the anti-resonance structural unit of Embodiment 1 of the present invention.

[0039] Figure 1(c) is a schematic diagram of a support column with curvature on the top and bottom surfaces and non-parallel sides in Embodiment 1 of the present invention.

[0040] Figure 1(d) is a schematic diagram of the anti-resonant structure unit of Embodiment 1 of the present invention.

[0041] Figure 2 This is a three-dimensional perspective view of the hollow fiber anti-resonant structure unit of Embodiment 1 of the present invention.

[0042] Figure 3 This is a schematic diagram of the hollow optical fiber structure in Embodiment 2 of the present invention.

[0043] Figure 4 This is a schematic diagram of the anti-resonance structure unit in Embodiment 2 of the present invention.

[0044] Figure 5 This is a schematic diagram of the hollow optical fiber structure in Embodiment 3 of the present invention.

[0045] Figure 6 This is a schematic diagram of the anti-resonance structure unit in Embodiment 3 of the present invention.

[0046] Figure 7 This is a schematic diagram of the hollow fiber structure in Embodiment 4 of the present invention.

[0047] Figure 8This is a schematic diagram of the anti-resonance structure unit in Embodiment 4 of the present invention.

[0048] Figure 9 This is a schematic diagram of the hollow fiber structure in Embodiment 5 of the present invention.

[0049] Figure 10 This is a schematic diagram of the anti-resonance structure unit in Embodiment 5 of the present invention.

[0050] Figure 11 This is a schematic diagram of the hollow fiber structure in Embodiment 6 of the present invention.

[0051] Figure 12 This is a schematic diagram of the anti-resonance structure unit in Embodiment 6 of the present invention.

[0052] Figure 13 This is a schematic diagram of the hollow fiber structure in Embodiment 7 of the present invention.

[0053] Figure 14 This is a schematic diagram of the anti-resonance structure unit in Embodiment 7 of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0055] Example 1:

[0056] This invention provides a hollow-core optical fiber with a support structure, comprising an outer cladding and an inner cladding. The inner cladding is composed of anti-resonant structural units, which are arranged circumferentially along the inner wall of the outer cladding and connected to the inner wall. The central cavity covered by the inner cladding forms the fiber core. Each anti-resonant structural unit includes two or more layers of anti-resonant tubes with different radii, including an outer anti-resonant tube and an inner anti-resonant tube. A support column 2 is provided between the outer anti-resonant tube of the anti-resonant structural unit and the inner wall of the outer cladding, or between the outer anti-resonant tube and the inner anti-resonant tube; or between the outer anti-resonant tube and the inner anti-resonant tube of the anti-resonant structural unit, and between the outer anti-resonant tube and the inner anti-resonant tube. The upper and lower surfaces of the support column 2 are curved structures. The radius of curvature of its upper surface is consistent with the surface of the anti-resonant tube in contact with the support column, and the radius of curvature of its lower surface is consistent with the surface of the anti-resonant tube or the inner wall of the outer cladding layer in contact with the support column. This embodiment is illustrated by taking an example with 5 sets of anti-resonant structural units, each set of anti-resonant structural units including 2 layers of anti-resonant tubes with different radii.

[0057] Figures 1(a), 1(b), 1(c), and 1(d) Figure 2 As shown in Figure 1(a), the anti-resonance structure unit of this embodiment includes two anti-resonance tubes, namely an outer anti-resonance tube 101 and an inner anti-resonance tube 102. The outer diameter of the outer anti-resonance tube 101 has a radius of curvature of R1, and the outer diameter of the inner anti-resonance tube 102 has a radius of curvature of R2. A support column 2 is provided between the outer anti-resonance tube 101 and the inner anti-resonance tube 102, as shown in Figure 1(d). By setting the support column 2, the outer anti-resonance tube 101 and the inner anti-resonance tube 102 of the anti-resonance tubular element are separated, reducing direct contact between the anti-resonance tubular elements and avoiding uneven wall thickness. The upper and lower surfaces of the support column 2 have curvature structures. The upper curvature has the same radius of curvature R2 as the inner anti-resonance tube 102, and the lower curvature has the same radius of curvature R2 as the outer anti-resonance tube 101. The two sides of the support column can be parallel, as shown in Figure 1(b); or the two sides can be set at a certain angle to form an inclined structure, as shown in Figure 1(c). To ensure the support columns effectively support the anti-resonant tubular element, the support columns are continuously distributed along the fiber optic axis, such as... Figure 2 As shown. The cross-sectional shape of the anti-resonant tube is one or more combinations of circular, elliptical, oval, and racetrack shapes. This embodiment uses a circular structure as an example for illustration.

[0058] This embodiment also provides a method for fabricating a hollow optical fiber with a support structure, comprising the following steps:

[0059] Fabrication of the anti-resonant structural unit prefabrication: First, anti-resonant tubes and support columns with the same surface curvature radius as the anti-resonant tubes or the inner wall of the outer cladding are fabricated. The anti-resonant tubular element can be achieved through methods such as tube pulling, extrusion, or 3D structural printing, while the support columns can be achieved through methods such as mechanical cutting, laser cutting, 3D structural printing, or drawing. Then, the anti-resonant tubular element and the support columns are connected and formed using thermal processing. To ensure better support for the anti-resonant tubular element, the support columns are continuously distributed along the optical fiber axis.

[0060] Preparation of the outer cladding glass sleeve: Prepare the glass sleeve to be used as the outer cladding according to the size ratio corresponding to the prefabricated anti-resonance structural unit;

[0061] Preparation of hollow fiber preform: A predetermined number of anti-resonant structural units are nested in the outer cladding hollow sleeve, and the anti-resonant structural units and the outer cladding hollow sleeve are fixed in a predetermined position to form a hollow fiber preform with a support structure.

[0062] Fiber preform drawing process: Hollow fiber preforms with support structures are drawn into fibers by high-temperature heating in a drawing furnace, and a certain air pressure is introduced to control their structural parameters to obtain hollow fiber with support column structure.

[0063] Example 2:

[0064] like Figure 3 , 4 As shown, the structure of this embodiment is basically the same as that of Embodiment 1, except that the anti-resonance structure unit 3 in this embodiment includes three layers of anti-resonance tubes with different radii, including an outer anti-resonance tube 101, a first inner anti-resonance tube 102, and a second inner anti-resonance tube 103. A support column 201 is provided between the outer anti-resonance tube 101 and the inner wall of the outer cladding layer 4. Support columns 202 are also provided between the outer anti-resonance tube 101 and the first inner anti-resonance tube 102, and a support column 203 is also provided between the first inner anti-resonance tube 102 and the second inner anti-resonance tube 103. The support columns are arranged radially stacked vertically, and each support column is symmetrically arranged relative to the geometric center of the anti-resonance structure unit. The cross-sectional area of ​​the support columns increases sequentially from the inside to the outside. The sum of the cross-sectional areas of all support columns accounts for 10% of the cross-sectional area formed by the inner diameter of the outer anti-resonance tube. This effectively separates adjacent anti-resonance tubes without introducing additional resonance losses. In addition, the refractive index ratio of the support column to the anti-resonant tube is 80%. In the actual optical fiber manufacturing process, the support column made of a material with a lower refractive index is easier to fix and connect with the anti-resonant tube. Furthermore, during optical transmission, the interaction between the light field and the glass material is further reduced, which can further improve the process stability and transmission performance.

[0065] The outer anti-resonant tube 101 has an outer radius of 14.3 μm, the first inner anti-resonant tube 102 has an outer radius of 8.2 μm, and the second inner anti-resonant tube 103 has an outer radius of 4.2 μm. The wall thickness of each anti-resonant tube is 1.15 ± 0.15 μm. The curvature of the upper and lower surfaces of the three support pillars is consistent with the surfaces of the anti-resonant tubes or the inner walls of the outer cladding that they contact. Support pillar 203 has a width of 2.4 μm and a height of 3.7 μm. Support pillar 202 has a width of 4.7 μm and a height of 3.9 μm. Support pillar 201 has a width of 11.3 μm and a height of 4.3 μm. The anti-resonant tubular elements and support pillars constituting the anti-resonant structural unit 3 are as follows: Figure 3 The optical fiber is arranged symmetrically as shown. Five sets of anti-resonant structural units 3 are periodically distributed circumferentially on the inner wall of the outer cladding 4, ensuring that the minimum spacing between the anti-resonant structural units is maintained within the range of 5.1 ± 0.8 μm, thereby forming the hollow-core optical fiber 5 with a support structure as described in Example 2. The outer diameter of the tubular outer cladding 4 of this hollow-core optical fiber 5 is 220 μm. In this example, the outer cladding, anti-resonant structural units, and support pillars are all made of high-purity silicon dioxide. The resulting hollow-core optical fiber with a support pillar structure has an attenuation of 0.18 dB / km @ 1550 nm and a 3 dB bandwidth of 190 nm.

[0066] Example 3:

[0067] like Figure 5 , 6 As shown, this embodiment is basically the same as embodiment 2 in structure, except that: in this embodiment, a support column 201 is provided between the outer anti-resonant tube and the first inner anti-resonant tube, and a support column 202 is provided between the first inner anti-resonant tube and the second inner anti-resonant tube. The outer radii of the anti-resonant structural units are 15.6 μm, 8.9 μm, and 3.8 μm respectively, from largest to smallest. The wall thickness of each anti-resonant tube is 1.15 ± 0.15 μm. The curvatures of the upper and lower surfaces of the two support columns are consistent with the curvatures of the anti-resonant tubes they contact. The width of the first small support column 202 is 2.6 μm and the height is 2.2 μm. The width of the second large support column 201 is 5.8 μm and the height is 2.9 μm. The sum of the cross-sectional areas of all support columns accounts for 8% of the cross-sectional area formed by the inner diameter of the outer anti-resonant tube. This not only effectively separates adjacent anti-resonant tubes but also avoids introducing additional resonance losses. The refractive index ratio of the support columns to the anti-resonant tubes is 90%.

[0068] Five sets of anti-resonant structural units are periodically distributed circumferentially on the inner wall of the cladding 4, ensuring that the minimum spacing between each anti-resonant structural unit is maintained within the range of 4.8 ± 1.0 μm, thereby forming the hollow-core optical fiber 6 with a support structure as described in Example 3. The outer diameter of the cladding 4 of this hollow-core optical fiber 6 is 230 μm. In this example, the cladding, anti-resonant structural units, and support pillars are all made of fluorine-doped silicon dioxide. The formed hollow-core optical fiber 6 with a support structure has an attenuation of 0.11 dB / km @ 1550 nm and a 3 dB bandwidth of 210 nm.

[0069] Example 4:

[0070] like Figure 7 , 8 As shown, this embodiment is basically the same as embodiment 2 in structure, except that a support column 2 is provided only between the outer anti-resonant tube and the first inner anti-resonant tube. The first and second inner anti-resonant tubes are tangent, and the support column is located at the coinciding tangency point, and the line connecting the tangency point and the fiber core center is symmetrically arranged. The outer radii of each anti-resonant tube in the anti-resonant structure unit are 15.1 μm, 9.1 μm, and 4.2 μm in descending order. The wall thickness of each anti-resonant tube is 1.15 ± 0.15 μm. The curvature of the upper and lower surfaces of the support column is consistent with the curvature of the anti-resonant tubes it contacts. The width of the support column is 4.9 μm and the height is 2.9 μm. The cross-sectional area of ​​the support column is 5% of the cross-sectional area formed by the inner diameter of the outer anti-resonant tube, which not only effectively separates adjacent anti-resonant tubes but also avoids introducing additional resonance losses. The refractive index ratio of the support column to the anti-resonant tube is 100%.

[0071] Five sets of anti-resonant structural units are periodically distributed circumferentially on the inner wall of the tubular outer cladding 4, ensuring that the minimum spacing between the anti-resonant structural units is maintained within the range of 4.9 ± 0.7 μm, thereby forming the hollow-core optical fiber 7 with a support structure in Embodiment 4. The outer diameter of the outer cladding 4 of this hollow-core optical fiber 7 with support pillar structure is 240 μm. In this embodiment, the outer cladding, anti-resonant structural units, and support pillars are all made of pure silicon dioxide. The resulting hollow-core optical fiber 7 with support structure has an attenuation of 0.08 dB / km @ 1550 nm and a 3 dB bandwidth of 205 nm.

[0072] Example 5:

[0073] like Figure 9 , 10As shown, this embodiment is basically the same as embodiment 4 in structure, except that: three circumferentially uniformly arranged support columns 201, 202, and 203 are provided between the outer anti-resonant tube and the first inner anti-resonant tube. The outer radii of each anti-resonant tube in the anti-resonant structure unit are 16.4 μm, 10.3 μm, and 5.1 μm respectively, from largest to smallest. The wall thickness of each anti-resonant tube is 1.15 ± 0.15 μm. The curvature of the upper and lower surfaces of the three support columns is consistent with the curvature of the anti-resonant tubes they contact. The three support columns are arranged symmetrically and equally spaced, with a spacing of 4.2 μm, and have similar widths of 4.5 μm and heights of 3.2 μm. The sum of the cross-sectional areas of each support column accounts for 7% of the cross-sectional area formed by the inner diameter of the outer anti-resonant tube. This not only effectively separates adjacent anti-resonant tubes but also avoids introducing additional resonance losses.

[0074] Five sets of anti-resonant structural units are periodically distributed circumferentially on the inner wall of the outer cladding 4, ensuring that the minimum spacing between the anti-resonant structural units is maintained within the range of 4.2 ± 0.8 μm, thereby forming the hollow-core optical fiber 8 with a support structure as described in Example 5. The outer diameter of the outer cladding 4 of this support-pillar hollow-core optical fiber 8 is 255 μm. In this example, the outer cladding, anti-resonant structural units, and support pillars are all made of pure silicon dioxide. The formed support-pillar hollow-core optical fiber 8 has an attenuation of 0.09 dB / km @ 1550 nm and a 3 dB bandwidth of 212 nm.

[0075] Example 6:

[0076] like Figure 11 , 12As shown, this embodiment is basically the same as embodiment 4 in structure, except that two circumferentially arranged support columns 201 and 202 are provided between the outer anti-resonant tube and the first inner anti-resonant tube. The outer radii of each anti-resonant tube in the anti-resonance structure unit are 15.5 μm, 11.6 μm, and 3.8 μm in descending order. The wall thickness of each anti-resonant tube is 1.15 ± 0.15 μm. The curvatures of the upper and lower surfaces of the two support columns are consistent with the curvatures of the anti-resonant tubes they contact. The two support columns are located between the outer anti-resonant tube and the first inner anti-resonant tube and are arranged symmetrically. The closest distance between the two support columns is 5.3 μm, and they have similar widths of 4.9 μm and heights of 1.3 μm. The sum of the cross-sectional areas of each support column accounts for 6% of the cross-sectional area formed by the inner diameter of the outer anti-resonant tube. This not only effectively separates adjacent anti-resonant tubes but also avoids introducing additional resonance losses. Five sets of anti-resonant structural units are periodically distributed circumferentially on the inner wall of the outer cladding 4, ensuring that the minimum spacing between the anti-resonant structural units is maintained within the range of 4.0 ± 0.9 μm, thereby forming the hollow-core optical fiber 9 with a support structure as described in Example 6. The outer diameter of the outer cladding 4 of this hollow-core optical fiber 9 with a support structure is 235 μm. In this example, the outer cladding 4, the anti-resonant structural units, and the support pillars are all made of pure silicon dioxide. The resulting hollow-core optical fiber 9 with a support structure has an attenuation of 0.05 dB / km @ 1550 nm and a 3 dB bandwidth of 200 nm.

[0077] Example 7:

[0078] like Figure 13 , 14 As shown, this embodiment has a structure that is basically the same as that of Embodiment 2, except that a support column 2 is provided between the outer anti-resonant tube 101 and the outer cladding. The outer anti-resonant tube, the first inner anti-resonant tube, and the second inner anti-resonant tube are sequentially tangent to each other, and the tangent points coincide with each other. The support column is located at the coinciding tangent points and is symmetrically arranged relative to the line connecting the tangent point and the fiber core center. The outer radii of each anti-resonant tube in the anti-resonant structure unit are 15.2 μm, 11.2 μm, and 4.1 μm, respectively, from largest to smallest. The wall thickness of each anti-resonant tube is 1.15 ± 0.15 μm. The curvature of the upper and lower surfaces of the support column is consistent with the curvature of the inner wall of the outer cladding and the outer anti-resonant tube, respectively. The support column is located between the outer anti-resonant tube and the outer cladding and has a width of 12.5 μm and a height of 6.2 μm. The cross-sectional area of ​​the support column accounts for 6% of the cross-sectional area formed by the inner diameter of the outer anti-resonant tube, which not only effectively separates adjacent anti-resonant tubes but also does not introduce additional resonance losses.

[0079] Five sets of anti-resonant structural units are periodically distributed circumferentially on the inner wall of the outer cladding 4, ensuring that the minimum spacing between the anti-resonant structural units is maintained within the range of 4.4 ± 0.6 μm, thereby forming the hollow-core optical fiber 10 with a support structure as described in Example 6. The outer diameter of the outer cladding 4 of this hollow-core optical fiber 10 with a support structure is 225 μm. In this example, the outer cladding, anti-resonant structural units, and support pillars are all made of pure silicon dioxide. The resulting hollow-core optical fiber 10 with a support structure has an attenuation of 0.07 dB / km @ 1550 nm and a 3 dB bandwidth of 190 nm.

Claims

1. A hollow-core optical fiber with a support structure, comprising an outer cladding and an inner cladding, wherein the inner cladding is composed of anti-resonant structural units, the anti-resonant structural units being arranged circumferentially along the inner wall of the outer cladding and connected to the inner wall of the outer cladding, the central cavity covered by the inner cladding forming the fiber core, and the anti-resonant structural units comprising two or more layers of anti-resonant tubes with different radii, including an outer anti-resonant tube and an inner anti-resonant tube, characterized in that: The anti-resonance structure unit has a support column between the outer anti-resonance tube and the inner wall of the outer cladding and / or the inner anti-resonance tube. The upper and lower surfaces of the support column are curved structures. The radius of curvature of the upper surface is consistent with the surface of the anti-resonance tube in contact with the support column, and the radius of curvature of the lower surface is consistent with the surface of the anti-resonance tube or the inner wall of the outer cladding in contact with the support column. The support column is 1~15um wide and 1~15um high. The ratio of the sum of the cross-sectional areas of all support columns to the cross-sectional area formed by the inner diameter of the outer anti-resonance tube is ≤10%.

2. The hollow optical fiber with a support structure according to claim 1, characterized in that: At least two support columns are provided between the outer anti-resonant tube and the inner anti-resonant tube, and the support columns are arranged at intervals along the circumference.

3. The hollow optical fiber with a support structure according to claim 2, characterized in that: The central angle θ formed by the line connecting the center line of two adjacent support columns and the center of the fiber core is 5~145°.

4. A hollow optical fiber with a support structure according to claim 2 or 3, characterized in that: The distance between adjacent support columns is 1~15um.

5. The hollow optical fiber with a support structure according to claim 1, characterized in that: When the anti-resonance structure unit includes three or more layers of anti-resonance tubes with different radii, the two adjacent inner anti-resonance tubes in the anti-resonance structure unit are also provided with support columns. Each support column is arranged radially and stacked vertically, and the cross-sectional area of ​​the support column increases sequentially from the inside to the outside.

6. The hollow optical fiber with a support structure according to claim 1, characterized in that: When the support column is placed between the outer anti-resonant tube and the inner wall of the outer cladding, the adjacent circular anti-resonant tubes of the anti-resonant structure unit are tangent to each other in sequence, and the tangent points coincide with each other, and the support column is located at the coinciding tangent points.

7. The hollow optical fiber with a support structure according to claim 1, characterized in that: When the anti-resonance structure unit includes three or more layers of circular anti-resonance tubes with different radii, the inner anti-resonance tube includes a first inner anti-resonance tube and a second inner anti-resonance tube. When the support column is set between the outer anti-resonance tube and the first inner anti-resonance tube, the two adjacent inner anti-resonance tubes are tangent, and the support column is located at the corresponding tangent point.

8. A hollow optical fiber with a support structure according to claim 5, 6, or 7, characterized in that: Each support column is symmetrically arranged relative to the geometric center of the anti-resonance structural unit.

9. A hollow optical fiber with a support structure according to claim 1, characterized in that: It includes 3-5 anti-resonance structural units, and each anti-resonance structural unit includes 2-4 circular anti-resonance tubes.

10. A hollow optical fiber with a support structure according to claim 9, characterized in that: It includes 5 anti-resonance structural units, each of which includes 3 circular anti-resonance tubes.

11. A hollow optical fiber with a support structure according to claim 1, characterized in that: The support column is an arc-shaped support column with parallel surfaces on both sides.

12. A hollow optical fiber with a support structure according to claim 1, characterized in that: The support column is an arc-shaped support column structure with sloping sides.

13. A hollow optical fiber with a support structure according to claim 5, 6, or 7, characterized in that: The support column has a width of ≥2µm and a height of 1~15µm.

14. A hollow optical fiber with a support structure according to claim 1 or 2, characterized in that: The anti-resonance structure unit includes three layers of circular anti-resonance tubes with different radii. From the outside to the inside, it includes an outer anti-resonance tube, a first inner anti-resonance tube, and a second inner anti-resonance tube. The outer radius of the outer anti-resonance tube is 10~30um, the outer radius of the first inner anti-resonance tube is 6~26um, and the outer radius of the second inner anti-resonance tube is 2~10um.

15. A hollow optical fiber with a support structure according to claim 1 or 2, characterized in that: The cross-sectional shape of the anti-resonant tube of the anti-resonant structure unit is one or more of the following: circular, elliptical, oval, and racetrack-shaped.

16. A hollow optical fiber with a support structure according to claim 1 or 2, characterized in that: The anti-resonant tubes of the anti-resonant structure unit have the same wall thickness, which is 1.15±0.15um.

17. A hollow optical fiber with a support structure according to claim 1 or 2, characterized in that: The support columns are continuously distributed along the axial direction of the optical fiber.

18. A hollow optical fiber with a support structure according to claim 2, 5, 6, or 7, characterized in that: The ratio of the refractive index of the support column to that of the anti-resonant tube is 80%~100%.

19. A hollow optical fiber with a support structure according to claim 1 or 2, characterized in that: The outer diameter of the outer cladding layer is greater than or equal to 100 μm and less than or equal to 500 μm.

20. A hollow optical fiber with a support structure according to claim 1 or 2, characterized in that: The transmission loss of the hollow optical fiber is ≤0.1dB / km.

21. A hollow optical fiber with a support structure according to claim 1 or 2, characterized in that: Hollow-core optical fiber has a 3dB bandwidth ≥ 100nm.

22. A method for preparing a hollow optical fiber with a support structure as described in any one of claims 1-21: characterized in that: Includes the following steps: Prefabricating anti-resonant structural unit prefabricated parts: respectively process anti-resonant tubes with different radii and support columns with the same surface curvature radius as the anti-resonant tubes or the inner wall of the outer cladding layer, and then connect each anti-resonant tube and support column to form a shape through hot working; Preparation of the outer cladding glass sleeve: Prepare the glass sleeve to be used as the outer cladding according to the size ratio corresponding to the prefabricated anti-resonance structural unit; Preparation of hollow fiber preform: A predetermined number of anti-resonant structural units are nested in the outer cladding glass tube, and the anti-resonant structural units and the outer cladding glass tube are fixed in a predetermined position to form a hollow fiber preform with a support structure. Fiber drawing process: Hollow-core optical fiber preforms with supporting structures are heated at high temperature in a fiber drawing furnace and drawn into fibers. A certain air pressure is introduced to control its structural parameters, resulting in hollow-core optical fibers with supporting column structures.

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