Hollow-core optical fiber with supporting structure and preparation method of hollow-core optical fiber

Abstract

The invention relates to a hollow-core optical fiber with a supporting structure and a preparation method, the hollow-core optical fiber comprises an outer cladding and an inner cladding, the inner cladding is composed of an anti-resonance structure unit, the anti-resonance structure unit comprises two or more than two layers of anti-resonance tubes with different radiuses, the anti-resonance tubes comprise an outer anti-resonance tube and an inner anti-resonance tube, and the outer anti-resonance tube and the inner anti-resonance tube are connected with each other. A supporting column is arranged between the outer anti-resonance tube of the anti-resonance structure unit and the inner wall of the outer cladding layer or / and between the outer anti-resonance tube and the inner anti-resonance tube, the upper surface and the lower surface of the supporting column are of curvature structures, and the curvature radius of the upper surface of the supporting column is consistent with the surface, making contact with the supporting column, of the anti-resonance tube. And the curvature radius of the lower surface is consistent with that of the anti-resonance tube or the surface of the inner wall of the outer cladding layer in contact with the supporting column. According to the hollow-core optical fiber, the supporting columns are arranged, so that all the tubular elements are separated, the phenomenon that pipe walls are easily adhered in the manufacturing process of the hollow-core optical fiber is reduced, and the problem that the manufactured hollow-core optical fiber is uneven in wall thickness, and consequently optical fiber loss and bandwidth are affected is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber communications, and in particular to a hollow-core optical fiber with a supporting structure and a preparation method thereof. Background Art

[0002] Currently, widely used solid-core optical fibers are severely limited in many fields due to intrinsic defects in their core quartz matrix materials, such as nonlinearity, dispersion, photodamage, and a lack of transmission in the ultraviolet and mid-infrared bands. This is particularly true in the field of communications and data transmission, where the explosive growth of data traffic and the increasing demands for transmission capacity and speed have severely limited the quality and distance of signal transmission, making it difficult to meet the ever-increasing communication needs. Hollow-core fiber, a key research area in microstructured optical fibers, offers significant advantages, including minimal nonlinearity, low modal dispersion, high damage threshold, wide transmission bandwidth, and near-light-speed transmission speeds. These advantages promise to overcome the bottlenecks of traditional optical fibers and provide new solutions for these applications. Hollow-core antiresonant fiber, a novel hollow-core fiber, possesses a unique structure that allows the vast majority of light energy (over 99%) to be transmitted within the air core. This significantly reduces the effects of fiber material absorption, reduces nonlinear effects and latency, and improves the damage threshold. This demonstrates significant advantages in flexible transmission of high-power and pulsed lasers, while also providing an efficient platform for light-matter interactions. It holds significant potential for applications in fields such as sensing.

[0003] Despite its significant theoretical and practical advantages, hollow-core fiber (HCF) has consistently exhibited higher transmission loss than traditional quartz fiber. Recent discoveries have shown that HCF, based on the principle of antiresonance, can effectively reduce transmission loss with appropriate structural design, demonstrating its potential as an ultra-long-haul 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), HCF's unique structure and manufacturing process enable further reduction of attenuation, increased fiber bandwidth, and increased fiber draw length, all challenges that have long been sought in the hollow-core fiber manufacturing industry.

[0004] Prior art, such as CN110515152B, discloses an antiresonant hollow-core fiber comprising 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 having an effective radius, the second tubular elements are spaced apart, with spaces 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 antiresonance requirements, but micron-level dimensional deviations are difficult to avoid in actual manufacturing. Fluctuations in the wall thickness of the tubular elements can significantly reduce the transmission bandwidth of the hollow-core fiber. Since this patent forms an anti-resonance structure by nesting and assembling multiple layers of tubular elements, 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. Especially in the drawing of long-distance hollow-core optical fibers, it is difficult to maintain good consistency in the optical fiber structure along the length of the optical fiber, thereby affecting the transmission attenuation and bandwidth of the hollow-core optical fiber. Summary of the Invention

[0005] The purpose of the present invention is to provide a hollow-core optical fiber with a support structure and a preparation method, so that the hollow-core optical fiber maintains good structural consistency before and after drawing, thereby improving the transmission performance of the hollow-core optical fiber.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A hollow-core optical fiber with a support structure comprises an outer cladding and an inner cladding, wherein the inner cladding is composed of antiresonance structural units arranged circumferentially along the inner wall of the outer cladding and in contact with the inner wall of the outer cladding; a central cavity enclosed by the inner cladding forms a fiber core; the antiresonance structural unit comprises two or more antiresonance tubes of different radii, including an outer antiresonance tube and an inner antiresonance tube; and is characterized in that a support column is provided between the outer antiresonance tube of the antiresonance structural unit and the inner wall of the outer cladding or / and the inner antiresonance tube; the upper and lower surfaces of the support column are curvature structures, the curvature radius of the upper surface is consistent with the surface of the antiresonance tube in contact with the support column, and the curvature radius of the lower surface is consistent with the surface of the antiresonance tube or the inner wall of the outer cladding in contact with the support column.

[0007] According to the above technical solution, at least two support columns are provided between the outer anti-resonance tube and the inner anti-resonance tube, and the support columns are arranged at intervals along the circumferential direction.

[0008] According to the above technical solution, when the anti-resonance structure unit includes three or more layers of anti-resonance tubes with different radii, support columns are further provided in two adjacent inner anti-resonance tubes in the anti-resonance structure unit. The support columns are radially stacked up and down, and the cross-sectional area of ​​the support columns increases sequentially from the inside to the outside.

[0009] According to the above technical solution, when the support column is arranged between the outer antiresonance tube and the inner wall of the outer cladding, the adjacent circular antiresonance tubes of the antiresonance structure unit are tangent to each other in sequence, and the tangent points overlap with each other, and the support column is located at the overlapping tangent points.

[0010] 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 tubes include a first inner anti-resonance tube and a second inner anti-resonance tube. When the support column is arranged between the outer anti-resonance tube and the first inner anti-resonance tube, the two adjacent inner anti-resonance tubes are tangent to each other, and the support column is located at the corresponding tangent point.

[0011] According to the above technical solution, the support columns are symmetrically arranged relative to the geometric center of the anti-resonance structure unit.

[0012] According to the above technical solution, 3-5 anti-resonance structural units are included, and the anti-resonance structural units include 2-4 circular anti-resonance tubes.

[0013] According to the above technical solution, five anti-resonance structural units are included, and the anti-resonance structural units include three circular anti-resonance tubes.

[0014] According to the above technical solution, the support column is an arc-shaped support column with parallel surfaces on both sides.

[0015] According to the above technical solution, the width of the support column is ≥2um and the height is 1~15um.

[0016] According to the above technical solution, the anti-resonance structure unit includes three layers of circular anti-resonance tubes with different radii, including an outer anti-resonance tube, a first inner anti-resonance tube, and a second inner anti-resonance tube from the outside to the inside. The outer radius of the outer anti-resonance tube is 10-30 μm, the outer radius of the first inner anti-resonance tube is 6-26 μm, and the outer radius of the second inner anti-resonance tube is 2-10 μm.

[0017] According to the above technical solution, the ratio of the sum of the cross-sectional areas of the support columns to the cross-sectional area formed by the inner diameter of the external anti-resonance tube is ≤10%.

[0018] According to the above technical solution, the cross-sectional shape of the anti-resonance tube of the anti-resonance structure unit is a combination of one or more of circular, elliptical, oval, and racetrack shapes.

[0019] According to the above technical solution, the wall thickness of the anti-resonance tubes of the anti-resonance structure unit is the same, which is 1.15±0.15 um.

[0020] According to the above technical solution, the support pillars are continuously distributed along the axial direction of the optical fiber.

[0021] According to the above technical solution, the refractive index ratio of the support column and the antiresonance tube is 80%~100%.

[0022] According to the above technical solution, the outer diameter of the outer cladding layer is greater than or equal to 100 um and less than or equal to 500 um.

[0023] According to the above technical solution, the transmission loss of the hollow-core optical fiber is ≤0.1dB / km.

[0024] According to the above technical solution, the 3dB bandwidth of the hollow-core optical fiber is ≥100nm.

[0025] A method for preparing a hollow-core optical fiber with a support structure, characterized in that it comprises the following steps: Preparing an anti-resonance structural unit preform: processing anti-resonance tubes of different radii and support columns with a surface curvature radius consistent with that of the anti-resonance tube or the inner wall of the outer cladding, and then connecting each anti-resonance tube and the support column by heat processing; Prepare the outer cladding glass sleeve: prepare the glass sleeve used as the outer cladding according to the size ratio corresponding to the anti-resonance structure unit prefabricated part; Preparation of a hollow-core optical fiber preform: nesting a preset number of anti-resonance structural units in an outer cladding glass sleeve, fixing the anti-resonance structural units and the outer cladding glass sleeve in a preset position, to form a hollow-core optical fiber preform with a support structure; Drawing process: The hollow-core optical fiber preform with a support structure is drawn through a drawing furnace at high temperature, and a certain gas pressure is introduced to control its structural parameters to obtain a hollow-core optical fiber with a support column structure.

[0026] Beneficial effects of the present invention: 1. The present invention provides support columns between the antiresonance tube and the inner wall of the outer cladding and / or the inner antiresonance tube, thereby isolating the tubular elements and avoiding direct contact between the antiresonance tubes. This reduces the tube wall adhesion that can easily occur during the manufacturing process of hollow-core optical fibers, thereby avoiding the problem of uneven wall thickness in the hollow-core optical fibers, which affects optical fiber loss and bandwidth. Furthermore, the support columns have a curvature structure that can better fit the tubular elements in contact with them during the production process, providing better fixation. The hollow-core optical fiber of the present invention has a higher tolerance for manufacturing errors during the manufacturing process and is more suitable for the preparation of low-loss, high-bandwidth, and long-distance hollow-core optical fibers.

[0027] 2. By providing at least two support columns in the circumferential direction between the outer antiresonance tube and the inner antiresonance tube, a gap is formed between the two support columns, which can provide more reflection interfaces and return more light leaking from between the antiresonance units to the fiber core, thereby reducing the attenuation of the optical fiber.

[0028] 3. By providing at least a plurality of support columns in the radial direction between the outer antiresonance tube and the inner antiresonance tube, a more stable structure is provided by the multiple supports, which can support the inner antiresonance tube more firmly, reduce manufacturing errors, improve the longitudinal uniformity of the optical fiber, and facilitate the drawing of low-loss long-distance hollow-core optical fibers.

[0029] 4. In the actual production process of optical fibers, the use of support columns made of materials with lower refractive index makes it easier to achieve a fixed connection between the support columns and the antiresonance tube, and further reduces the interaction between the light field and the glass material during light transmission, which can further improve process stability and transmission performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1( a ) is a schematic diagram of different anti-resonance tubes in an anti-resonance structure unit according to Example 1 of the present invention.

[0031] FIG1( b ) is a schematic diagram of a support column in an anti-resonance structure unit according to Example 1 of the present invention.

[0032] FIG1( c ) is a schematic diagram of a support column in Example 1 of the present invention, wherein the upper and lower surfaces have curvatures and the two side surfaces are not parallel.

[0033] FIG1( d ) is a schematic diagram of an anti-resonance structure unit according to embodiment 1 of the present invention.

[0034] Figure 2 It is a three-dimensional perspective view of the hollow-core optical fiber anti-resonance structure unit of Example 1 of the present invention.

[0035] Figure 3 It is a schematic diagram of the hollow-core optical fiber structure in Example 2 of the present invention.

[0036] Figure 4 Schematic diagram of the anti-resonance structure unit in embodiment 2 of the present invention.

[0037] Figure 5 It is a schematic diagram of the hollow-core optical fiber structure in Example 3 of the present invention.

[0038] Figure 6 It is a schematic structural diagram of the anti-resonance structural unit according to embodiment 3 of the present invention.

[0039] Figure 7 It is a schematic diagram of the hollow-core optical fiber structure in Example 4 of the present invention.

[0040] Figure 8It is a schematic structural diagram of the anti-resonance structural unit in Example 4 of the present invention.

[0041] Figure 9 It is a schematic diagram of the hollow-core optical fiber structure in Example 5 of the present invention.

[0042] Figure 10 It is a schematic structural diagram of the anti-resonance structural unit in Example 5 of the present invention.

[0043] Figure 11 It is a schematic diagram of the hollow core optical fiber structure of Example 6 of the present invention.

[0044] Figure 12 It is a schematic structural diagram of the anti-resonance structural unit in Example 6 of the present invention.

[0045] Figure 13 It is a schematic diagram of the hollow-core optical fiber structure in Example 7 of the present invention.

[0046] Figure 14 It is a schematic structural diagram of the anti-resonance structural unit in Example 7 of the present invention. DETAILED DESCRIPTION

[0047] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0048] Example 1: The present 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 antiresonance 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 a fiber core. The antiresonance structural unit comprises two or more antiresonance tubes of different radii, including an outer antiresonance tube and an inner antiresonance tube. A support column 2 is provided between the outer antiresonance tube of the antiresonance structural unit and the inner wall of the outer cladding or / and the inner antiresonance tube, that is, a support column is provided between the outer antiresonance tube of the antiresonance structural unit and the inner wall of the outer cladding; or a support column 2 is provided between the outer antiresonance tube of the antiresonance structural unit and the inner wall of the outer cladding; or a support column 2 is provided between the outer antiresonance tube of the antiresonance structural unit and the inner wall of the outer cladding and the inner antiresonance tube. The upper and lower surfaces of the support column 2 are curved structures. The radius of curvature of the upper surface is consistent with the surface of the antiresonance tube in contact with the support column, and the radius of curvature of the lower surface is consistent with the surface of the antiresonance tube or the inner wall of the outer cladding in contact with the support column. This embodiment is described as an example of having five groups of antiresonance structural units, each group of antiresonance structural units including two layers of antiresonance tubes of different radii.

[0049] As shown in Figure 1 (a), Figure 1 (b), Figure 1 (c), Figure 1 (d), Figure 2 As shown, the antiresonant structural unit of this embodiment includes two antiresonant tubes, an outer antiresonant tube 101 and an inner antiresonant tube 102. The outer diameter of the outer antiresonant tube 101 has a curvature radius of R1, and the outer diameter of the inner antiresonant tube 102 has a curvature radius of R2, as shown in Figure 1(a). A support column 2 is provided between the outer antiresonant tube 101 and the inner antiresonant tube 102, as shown in Figure 1(d). The support column 2 separates the outer antiresonant tube 101 and the inner antiresonant tube 102, reducing direct contact between the antiresonant tubular elements and preventing uneven tube wall thickness. The upper and lower surfaces of the support column 2 have a curvature structure. The upper surface has the same curvature radius R2 as the inner antiresonant tube 102, and the lower surface has the same curvature radius R2 as the outer antiresonant tube 101. The two side surfaces of the support column can be parallel, as shown in Figure 1(b), or they can be arranged at an angle to form an inclined structure, as shown in Figure 1(c). In order to make the support pillars better support the anti-resonance tubular element, the support pillars are continuously distributed along the axial direction of the optical fiber, such as Figure 2 The cross-sectional shape of the anti-resonance tube is a combination of one or more of a circular, elliptical, oval, and racetrack shape. This embodiment takes the anti-resonance tube as an example of a circular structure.

[0050] This embodiment also provides a method for preparing a hollow-core optical fiber with a support structure, comprising the following steps: Preparation of the antiresonant structural unit preform: First, the antiresonant tube and support columns with a surface curvature radius consistent with that of the antiresonant tube or the inner wall of the outer cladding are separately machined. The antiresonant tubular element can be produced through methods such as tube drawing, extrusion, and 3D structure printing, while the support columns can be produced through mechanical cutting, laser cutting, 3D structure printing, and drawing. The antiresonant tubular element and support columns are then connected and formed through thermal processing. To ensure that the support columns better support the antiresonant tubular element, they are distributed continuously along the axial direction of the optical fiber.

[0051] Prepare the outer cladding glass sleeve: prepare the glass sleeve used as the outer cladding according to the size ratio corresponding to the anti-resonance structure unit prefabricated part; Preparation of a hollow-core optical fiber preform: nesting a preset number of anti-resonance structural units in an outer cladding hollow-core sleeve, fixing the anti-resonance structural units and the outer cladding hollow-core sleeve in a preset position, to form a hollow-core optical fiber preform with a support structure; The drawing process of optical fiber preform rods: The hollow-core optical fiber preform rod with a supporting structure is heated and drawn in a drawing furnace at high temperature, and a certain gas pressure is introduced to control its structural parameters to obtain a hollow-core optical fiber with a supporting column structure.

[0052] Example 2: like Figure 3 、 4 As shown, the structure of this embodiment is basically the same as that of Example 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, wherein a support column 201 is provided between the outer anti-resonance tube 101 and the inner wall of the outer cladding 4, a support column 202 is provided between the outer anti-resonance tube 101 and the first inner anti-resonance tube 102, and a support column 203 is provided between the first inner anti-resonance tube 102 and the second inner anti-resonance tube 103, each support column is radially stacked up and down, and each support column is symmetrically arranged relative to the geometric center of the anti-resonance structure unit, and the cross-sectional area of ​​the support column increases from the inside to the outside. The sum of the cross-sectional areas of the support columns accounts for 10% of the cross-sectional area formed by the inner diameter of the outer anti-resonance tube, which not only effectively separates the adjacent anti-resonance tubes, but also does not introduce additional resonance loss. In addition, the refractive index ratio of the support column and the antiresonance tube is 80%. In the actual production process of optical fibers, the support column made of a material with a lower refractive index can more easily achieve a fixed connection between the support column and the antiresonance tube, and further reduce the interaction between the light field and the glass material during light transmission, which can further improve the process stability and transmission performance.

[0053] The outer radius of the outer anti-resonance tube 101 is 14.3um, the outer radius of the first inner anti-resonance tube 102 is 8.2um, and the outer radius of the second inner anti-resonance tube 103 is 4.2um. The wall thickness of each anti-resonance tube is 1.15±0.15um. The curvatures of the upper and lower surfaces of the three support columns are consistent with the surface of the inner wall of the anti-resonance tube or outer cladding with which they are in contact. The width of the support column 203 is 2.4um and the height is 3.7um. The width of the support column 202 is 4.7um and the height is 3.9um. The width of the support column 201 is 11.3um and the height is 4.3um. The anti-resonance tubular element and the support column constituting the anti-resonance structural unit 3 are as follows: Figure 3 The symmetrical arrangement is shown in FIG. 5 . Five groups of antiresonance structural units 3 are distributed cyclically and periodically on the inner wall of the outer cladding 4, and the minimum spacing between the antiresonance structural units is maintained in the range of 5.1±0.8um, thereby forming a hollow-core optical fiber 5 with a support structure in Example 2. The outer diameter of the tubular outer cladding 4 of the hollow-core optical fiber 5 is 220um. The outer cladding, antiresonance structural units and support columns in this embodiment are all made of high-purity silica. The hollow-core optical fiber with a support column structure formed has an attenuation of 0.18dB / km@1550nm and a 3dB bandwidth of 190nm.

[0054] Example 3: like Figure 5 、 6 As shown, the structure of this embodiment is basically the same as that of Example 2, except that: in this embodiment, a support column 201 is provided between the outer anti-resonance tube and the first inner anti-resonance tube, and a support column 202 is provided between the first inner anti-resonance tube and the second inner anti-resonance tube. The outer radius of the anti-resonance structural unit is 15.6um, 8.9um, and 3.8um from large to small. The wall thickness of each anti-resonance tube is 1.15±0.15um. The curvature of the upper and lower surfaces of the two support columns is consistent with the curvature of the anti-resonance tubes they contact. The width of the first small support column 202 is 2.6um and the height is 2.2um. The width of the second large support column 201 is 5.8um and the height is 2.9um. The sum of the cross-sectional areas of each support column accounts for 8% of the cross-sectional area formed by the inner diameter of the outer anti-resonance tube. This not only effectively separates adjacent anti-resonance tubes, but also does not introduce additional resonance loss. The refractive index ratio of the support column to the anti-resonance tube is 90%.

[0055] Five groups of antiresonant structural units are periodically distributed circumferentially on the inner wall of the outer cladding 4, and the minimum spacing between each antiresonant structural unit is maintained in the range of 4.8±1.0 μm, thereby forming the hollow-core optical fiber 6 with a support structure of Example 3. The outer cladding 4 of the hollow-core optical fiber 6 has an outer diameter of 230 μm. The outer cladding, antiresonant structural units, and support columns in this embodiment are all made of fluorine-doped silica. The formed support structure hollow-core optical fiber 6 has an attenuation of 0.11 dB / km@1550 nm and a 3 dB bandwidth of 210 nm.

[0056] Example 4: like Figure 7 、 8 As shown, the structure of this embodiment is basically the same as that of Example 2, except that a support column 2 is provided only between the outer anti-resonance tube and the first inner anti-resonance tube, wherein the first inner anti-resonance tube and the second inner anti-resonance tube are tangent, and the support column is located at the overlapping tangent point, and is symmetrically arranged relative to the line connecting the tangent point and the center of the fiber core. The outer radius of each anti-resonance tube of the anti-resonance structural unit is 15.1um, 9.1um, and 4.2um from large to small. The wall thickness of each anti-resonance tube is 1.15±0.15um. The curvature of the upper and lower surfaces of the support column is consistent with the curvature of the anti-resonance tube with which it contacts. The width of the support column is 4.9um and the height is 2.9um. The cross-sectional area of ​​the support column accounts for 5% of the cross-sectional area formed by the inner diameter of the outer anti-resonance tube, which not only effectively separates the adjacent anti-resonance tubes but also does not introduce additional resonance loss. The refractive index ratio of the support column to the anti-resonance tube is 100%.

[0057] Five groups of antiresonant structural units are periodically distributed circumferentially on the inner wall of the tubular outer cladding 4, and the minimum spacing between the antiresonant structural units is maintained in the range of 4.9±0.7um, thereby forming the hollow-core optical fiber 7 with a support structure of Example 4. The outer cladding 4 of the hollow-core optical fiber 7 with a support column structure has an outer diameter of 240um. The outer cladding, antiresonant structural units, and support columns in this embodiment are all made of pure silica. The hollow-core optical fiber 7 with a support structure has an attenuation of 0.08dB / km@1550nm and a 3dB bandwidth of 205nm.

[0058] Example 5: like Figure 9 、 10As shown, the structure of this embodiment is basically the same as that of Example 4, except that: three circumferentially evenly arranged support columns 201, 202, and 203 are provided between the outer anti-resonance tube and the first inner anti-resonance tube, and the outer radius of each anti-resonance tube of the anti-resonance structural unit is 16.4um, 10.3um, and 5.1um from large to small. The wall thickness of each anti-resonance tube is 1.15±0.15um. The curvature of the upper and lower surfaces of the three support columns is consistent with the curvature of the anti-resonance tubes they are in contact with. The three support columns are arranged symmetrically and evenly spaced, with a spacing of 4.2um, and have a similar width of 4.5um and a height of 3.2um. 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-resonance tube. This not only effectively separates adjacent anti-resonance tubes, but also does not introduce additional resonance losses.

[0059] Five groups of antiresonant structural units are periodically distributed on the inner wall of the outer cladding 4 in a circular direction, and the minimum spacing between the antiresonant structural units is maintained in the range of 4.2±0.8um, thereby forming a hollow-core optical fiber 8 with a support structure in Example 5. The outer cladding 4 of the hollow-core optical fiber 8 with a support column structure has an outer diameter of 255um. The outer cladding, antiresonant structural units, and support columns in this embodiment are all made of pure silica. The hollow-core optical fiber 8 with a support column structure has an attenuation of 0.09dB / km@1550nm and a 3dB bandwidth of 212nm.

[0060] Example 6: like Figure 11 、 12As shown, the structure of this embodiment is basically the same as that of Example 4, except that two circumferentially arranged support columns 201, 202 are provided between the outer anti-resonance tube and the first inner anti-resonance tube. The outer radius of each anti-resonance tube of the anti-resonance structural unit is 15.5um, 11.6um, and 3.8um, respectively, from large to small. The wall thickness of each anti-resonance tube is 1.15±0.15um. The curvature of the upper and lower surfaces of the two support columns is consistent with the curvature of the anti-resonance tubes they are in contact with. The two support columns are both located between the outer anti-resonance tube and the first inner anti-resonance tube and are arranged symmetrically. The two support columns are closest to each other at 5.3um and have a similar width of 4.9um and a height of 1.3um. The sum of the cross-sectional areas of the support columns accounts for 6% of the cross-sectional area formed by the inner diameter of the outer anti-resonance tube. This not only effectively separates the adjacent anti-resonance tubes, but also does not introduce additional resonance losses. Five groups of antiresonant structural units are periodically distributed on the inner wall of the outer cladding 4 in a circular direction, and the minimum spacing between the antiresonant structural units is maintained in the range of 4.0±0.9 μm, thereby forming the hollow-core optical fiber 9 with a support structure of Example 6. The outer diameter of the outer cladding 4 of the hollow-core optical fiber 9 with a support structure is 235 μm. The outer cladding 4, the antiresonant structural units, and the support columns in this embodiment are all made of pure silica. The 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.

[0061] Example 7: like Figure 13 、 14 As shown, the structure of this embodiment is basically the same as that of Example 2, except that a support column 2 is provided between the outer antiresonance tube 101 and the outer cladding, wherein the outer antiresonance tube, the first inner antiresonance tube, and the second inner antiresonance tube are tangent to each other in sequence, and the tangent points overlap with each other, and the support column is located at the overlapping tangent points and is symmetrically arranged relative to the line connecting the tangent points and the center of the fiber core. The outer radius of each antiresonance tube of the antiresonance structure unit is 15.2um, 11.2um, and 4.1um from large to small. The wall thickness of each antiresonance tube is 1.15±0.15um. 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 antiresonance tube, respectively. The support column is located between the outer antiresonance tube and the outer cladding and has a width of 12.5um and a height of 6.2um. The cross-sectional area of ​​the support column accounts for 6% of the cross-sectional area formed by the inner diameter of the outer antiresonance tube, which not only effectively separates adjacent antiresonance tubes but also does not introduce additional resonance loss.

[0062] Five groups of antiresonant structural units are periodically distributed circumferentially on the inner wall of the outer cladding 4, and the minimum spacing between the antiresonant structural units is maintained in the range of 4.4±0.6 μm, thereby forming the hollow-core optical fiber 10 with a support structure of Example 6. The outer cladding 4 of the hollow-core optical fiber 10 with a support structure has an outer diameter of 225 μm. The outer cladding, antiresonant structural units, and support columns in this embodiment are all made of pure silica. 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 antiresonance structural units, the antiresonance structural units being arranged circumferentially along and in contact with the inner wall of the outer cladding, the central cavity enclosed by the inner cladding forming a fiber core, the antiresonance structural units comprising two or more antiresonance tubes of different radii, including an outer antiresonance tube and an inner antiresonance tube, characterized in that: A support column is provided between the outer anti-resonance tube and the inner wall of the outer cladding or / and the inner anti-resonance tube of the anti-resonance structural unit. The upper and lower surfaces of the support column are curvature structures. The curvature radius of the upper surface is consistent with the surface of the anti-resonance tube in contact with the support column, and the curvature radius 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.

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

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

4. A hollow-core optical fiber with a support structure according to claim 2 or 3, characterized in that: The distance between adjacent support pillars is 1-15 μm, and the support pillars are 1-15 μm wide and 1-15 μm high.

5. The hollow-core optical fiber with a support structure according to claim 1, wherein: When the anti-resonance structure unit includes three or more layers of anti-resonance tubes with different radii, support columns are further provided in two adjacent inner anti-resonance tubes in the anti-resonance structure unit. The support columns are radially stacked up and down, and the cross-sectional area of ​​the support columns increases sequentially from the inside to the outside.

6. The hollow-core optical fiber with a support structure according to claim 1, wherein: When the support column is arranged between the outer antiresonance tube and the inner wall of the outer cladding, the adjacent circular antiresonance tubes of the antiresonance structure unit are sequentially tangent to each other, and the tangent points overlap with each other, and the support column is located at the overlapping tangent points.

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

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

9. The hollow-core optical fiber with a support structure according to claim 1, characterized in that: It comprises 3-5 anti-resonance structural units, and the anti-resonance structural units comprise 2-4 circular anti-resonance tubes.

10. The hollow-core optical fiber with a support structure according to claim 9, characterized in that: It comprises five anti-resonance structural units, each of which comprises three circular anti-resonance tubes.

11. The hollow-core 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. The hollow-core optical fiber with a support structure according to claim 1, characterized in that: The support column is an arc-shaped support column structure with two inclined sides.

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

14. The hollow-core 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, including an outer anti-resonance tube, a first inner anti-resonance tube, and a second inner anti-resonance tube from the outside to the inside. The outer radius of the outer anti-resonance tube is 10-30 μm, the outer radius of the first inner anti-resonance tube is 6-26 μm, and the outer radius of the second inner anti-resonance tube is 2-10 μm.

15. The hollow-core optical fiber with a support structure according to claim 1 or 2, characterized in that: The ratio of the sum of the cross-sectional areas of the support columns to the cross-sectional area formed by the inner diameter of the outer anti-resonance tube is ≤10%.

16. The hollow-core optical fiber with a support structure according to claim 1 or 2, characterized in that: The cross-sectional shape of the anti-resonance tube of the anti-resonance structure unit is a combination of one or more of a circle, an ellipse, an oval, and a racetrack.

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

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

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

20. The hollow-core 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 um and less than or equal to 500 um.

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

22. The hollow-core optical fiber with a support structure according to claim 1 or 2, characterized in that: The 3dB bandwidth of hollow-core optical fiber is ≥100nm.

23. A method for preparing a hollow-core optical fiber with a support structure, characterized in that: The steps include: Preparing an anti-resonance structural unit preform: processing anti-resonance tubes of different radii and support columns with a surface curvature radius consistent with that of the anti-resonance tube or the inner wall of the outer cladding, and then connecting each anti-resonance tube and the support column by heat processing; Prepare the outer cladding glass sleeve: prepare the glass sleeve used as the outer cladding according to the size ratio corresponding to the anti-resonance structure unit prefabricated part; Preparation of a hollow-core optical fiber preform: nesting a preset number of anti-resonance structural units in an outer cladding glass sleeve, fixing the anti-resonance structural units and the outer cladding glass sleeve in a preset position, to form a hollow-core optical fiber preform with a support structure; Drawing process: The hollow-core optical fiber preform with a support structure is drawn through a drawing furnace at high temperature, and a certain gas pressure is introduced to control its structural parameters to obtain a hollow-core optical fiber with a support column structure.

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