A Hollow-Core Optical Fiber with Adjustable Support Structure and Its Fabrication Method

Abstract

This invention relates to an adjustable support structure hollow optical fiber and its fabrication method, comprising an outer cladding and an inner cladding. The inner cladding is composed of anti-resonant structural units arranged circumferentially along the inner wall of the outer cladding. The central cavity covered by the inner cladding forms the fiber core. Each anti-resonant structural unit includes at least two anti-resonant tubes, including one outer anti-resonant tube and one inner anti-resonant tube. The key feature is that the area where the outer anti-resonant tube contacts the inner wall of the outer cladding has a raised arc surface. The two ends of the raised arc surface are respectively connected to blocks installed between the inner and outer anti-resonant tubes, forming a closed hollow arc-shaped boss with the raised arc surface, the two side blocks, and the outer circumferential surface of the inner anti-resonant tube between the two side blocks. The raised arc surface of the hollow arc-shaped boss is connected to the inner wall of the outer cladding, used to adjust the spacing and orientation of the anti-resonant structural unit and the fiber core. This invention enables the hollow optical fiber to maintain good structural characteristics after drawing, improving the transmission performance of the hollow optical fiber.

Description

Technical Field

[0001] This invention relates to an adjustable support structure hollow optical fiber and its preparation method, belonging to the field of optical communication transmission technology. 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 bringing new technical solutions to these fields. Hollow-core antiresonant fiber, as a novel type of hollow fiber, has 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 theoretical and practical advantages of hollow-core optical fibers, their transmission loss has consistently exceeded that of traditional silica optical fibers. Recent discoveries have shown that hollow-core optical fibers based on the anti-resonance principle, with proper structural design, can effectively reduce transmission loss and possess the potential to serve as ultra-long-distance communication fibers. Existing technologies, such as CN110515152B, disclose an anti-resonance hollow-core fiber comprising a first tubular cladding element, multiple second tubular elements, and multiple third tubular elements. The first tubular cladding element defines the inner cladding surface. The multiple 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 multiple third tubular elements is nested within a corresponding second tubular element. The diameter, wall thickness, and circumferential spacing of the tubular elements must strictly satisfy the anti-resonance condition, but micron-level dimensional deviations are difficult to avoid in actual manufacturing. Fluctuations in the wall thickness of the tubular elements can lead to a significant reduction in the transmission bandwidth of the hollow-core optical fiber. Because this patented anti-resonant structure is formed by nesting multiple layers of tubular elements, and all tubular elements are in direct contact, uncontrolled adhesion can occur at the contact points during the fiber drawing process. This leads to 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 fiber structure along the fiber length, thus affecting the transmission attenuation and bandwidth of the hollow-core fiber. At the same time, after the drawing process, the anti-resonant ring often adheres to the cladding tube, making it difficult for higher-order modes to couple from the fiber core to the cladding tube, resulting in single-mode characterization degradation. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide an adjustable support structure hollow optical fiber and its preparation method to address the shortcomings of the prior art, so as to maintain good structural characteristics of the hollow optical fiber after drawing and improve the transmission performance of the hollow optical fiber.

[0006] The hollow-core optical fiber technology solution adopted by this invention to solve the above-mentioned problems 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 at least two anti-resonant tubes, including one outer anti-resonant tube and one inner anti-resonant tube. The key feature is that the area where the outer anti-resonant tube is connected to the inner wall of the outer cladding has a raised arc surface. The two ends of the raised arc surface are respectively connected to the blocks installed between the inner and outer anti-resonant tubes, so that the raised arc surface, the two side blocks, and the outer peripheral surface of the inner anti-resonant tube between the two side blocks form a closed hollow arc-shaped boss. The raised arc surface of the hollow arc-shaped boss is connected to the inner wall of the outer cladding to adjust the spacing and orientation of the anti-resonant structural unit and the fiber core.

[0007] According to the above scheme, the blocks on both sides of the hollow arc-shaped boss are installed radially, and the central angle θ formed by the lines connecting the two blocks and the center of the fiber core is less than or equal to 120°. Further, it is less than or equal to 90°, and even further, it is less than or equal to 60°.

[0008] According to the above scheme, the hollow arc-shaped protrusion has a radially symmetrical structure, and the protruding arc surface is composed of one or more arc surfaces. The distance d between the highest point of the protrusion and the fitted circle of the outer anti-resonance tube wall is 1~15μm. More specifically, it is 3~10μm.

[0009] According to the above scheme, there are 4 to 6 anti-resonance structure units, and each anti-resonance structure unit includes 2 to 4 anti-resonance tubes, including 1 external anti-resonance tube and 1 or more internal anti-resonance tubes.

[0010] According to the above scheme, the inner wall of the outer cladding is circular, and the anti-resonance structure unit includes one circular outer anti-resonance tube and one or two circular inner anti-resonance tubes with different radii. The area where the circular outer anti-resonance tube connects with the inner wall of the outer cladding is provided with a raised arc surface, which forms a hollow arc-shaped boss with the adjacent first circular inner anti-resonance tube.

[0011] According to the above scheme, a second circular inner anti-resonant tube is installed inside the first circular inner anti-resonant tube, and the second circular inner anti-resonant tube is tangent to the first circular inner anti-resonant tube.

[0012] According to the above scheme, a radial intermediate block is set in the middle of the hollow arc-shaped boss to divide the hollow arc-shaped boss into two separate closed cavities.

[0013] According to the above scheme, the outer diameter of the outer cladding layer is 100~500μm.

[0014] According to the above scheme, the outer diameter of the external anti-resonant tube is 20~60μm.

[0015] According to the above scheme, the outer diameter of the first circular inner anti-resonant tube is 10~50μm.

[0016] According to the above scheme, the outer diameter of the second circular inner anti-resonant tube is 4~40μm.

[0017] According to the above scheme, the fundamental mode transmission loss of the hollow-core optical fiber is less than or equal to 1 dB / km. Further, it is less than or equal to 0.1 dB / km.

[0018] According to the above scheme, the 3dB bandwidth of the hollow fiber is greater than or equal to 100nm.

[0019] According to the above scheme, the minimum high-order mode transmission loss of the hollow optical fiber is greater than or equal to 100dB / km.

[0020] According to the above scheme, the minimum high-order mode transmission loss of the hollow optical fiber is greater than or equal to 1000dB / km.

[0021] According to the above scheme, the minimum high-order mode transmission loss of the hollow optical fiber is greater than or equal to 5000dB / km.

[0022] The technical solution of the method for preparing hollow-core optical fiber of the present invention is as follows:

[0023] To fabricate an anti-resonant structural unit prefabrication, glass tubes of different radii are nested together, and fixed blocks are installed in the inner and outer nested tubes to form closed cavities in each nested tube.

[0024] An outer cladding glass sleeve is fabricated according to the dimensional proportions corresponding to the prefabricated anti-resonance structural unit.

[0025] Hollow-core optical fiber preforms are fabricated by inserting and fixing anti-resonant structural unit preforms into the inner wall of the outer cladding glass tube according to their orientation, and then heating and melting one end to draw a tapered shape to form a hollow-core optical fiber preform.

[0026] The process involves drawing hollow optical fiber preforms into hollow optical fibers by clamping them into an optical fiber drawing furnace.

[0027] According to the above scheme, during the fiber drawing process, multiple closed cavity regions formed by the anti-resonant structural unit are filled with gas at different pressures to ensure that the fiber structure after drawing meets expectations. Among them, the closed cavity region of the hollow arc-shaped boss is filled with gas at a higher pressure relative to the other closed cavity regions of the anti-resonant structural unit to form the convex arc surface of the hollow arc-shaped boss.

[0028] According to the above scheme, a radial intermediate block is set in the middle of the hollow arc-shaped boss to divide the hollow arc-shaped boss into two separate closed cavity areas. Different pressure gases are introduced into the two separate closed cavity areas, so that the swing angle of the anti-resonance unit can be adjusted during the wire drawing process, thereby adjusting the spacing between each anti-resonance unit.

[0029] The beneficial effects of this invention are as follows: 1. By setting a hollow arc-shaped boss, the inner and outer anti-resonant tubes can be spaced apart and the spacing can be adjusted. This not only reduces the tube wall adhesion phenomenon that easily occurs during the manufacturing process of the anti-resonant structural unit of the hollow fiber, thus avoiding the problem of uneven wall thickness in the manufactured hollow fiber, but also allows for a more precise spacing between the inner and outer anti-resonant tubes, ensuring that the hollow fiber maintains good structural characteristics after drawing. 2. The protrusion height of the hollow arc-shaped boss can be dynamically adjusted by voltage regulation during fiber drawing to adjust the spacing and orientation of the anti-resonant structural unit and the fiber core. It also increases the spacing between the anti-resonant structural element and the inner wall of the cladding, allowing for better coupling of higher-order modes of the fiber core into the cladding. This reduces the fundamental mode loss and improves the higher-order mode loss, thereby enhancing and optimizing the transmission performance of the hollow fiber. 3. This invention features a radial intermediate block in the center of the hollow arc-shaped protrusion, dividing it into two separate closed cavities. During fiber drawing, different air pressures can be introduced into the two closed spaces, altering the swing angle of the anti-resonant structural units. This results in a more uniform spacing between the anti-resonant structural units, with the spacing error controlled within ±10%, thereby improving the manufacturing precision of the hollow-core optical fiber. This invention offers higher tolerance for manufacturing errors and is more suitable for producing low-loss, high-bandwidth, long-distance hollow-core optical fibers. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the radial structure of an embodiment of the present invention.

[0031] Figure 2 yes Figure 1 A magnified schematic diagram of the anti-resonant structural unit.

[0032] Figure 3 This is a schematic diagram of the radial structure of the second embodiment of the present invention.

[0033] Figure 4 yes Figure 3 A magnified schematic diagram of the anti-resonant structural unit.

[0034] Figure 5 This is a schematic diagram of the radial structure of the third embodiment of the present invention.

[0035] Figure 6 yes Figure 5 A magnified schematic diagram of the anti-resonant structural unit.

[0036] Figure 7 This is a schematic diagram of the radial structure of the fourth embodiment of the present invention.

[0037] Figure 8 yes Figure 7 A magnified schematic diagram of the anti-resonant structural unit.

[0038] Figure 9 This is a schematic diagram of the radial structure of the fifth embodiment of the present invention.

[0039] Figure 10 yes Figure 9 A magnified schematic diagram of the anti-resonant structural unit.

[0040] Figure 11 This is a schematic diagram of the anti-resonance structure unit before and after the swing angle adjustment in the fifth embodiment of the present invention. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0042] The first embodiment of the invention is as follows: Figure 1 , Figure 2As shown, it includes an outer cladding layer 2 and an inner cladding layer. The outer cladding layer is circular with an outer diameter of 225 μm. The inner cladding layer consists of five anti-resonant structural units 3. Each anti-resonant structural unit has the same structure and is evenly distributed along the circumference of the inner wall of the outer cladding layer and is in contact with the inner wall of the outer cladding layer. The central cavity covered by the inner cladding layer forms a fiber core. Each anti-resonant structural unit includes two layers of anti-resonant tubes, including one circular outer anti-resonant tube 301 and one circular inner anti-resonant tube 302. The outer diameter of the circular outer anti-resonant tube is 33 μm, and the outer radius of the circular inner anti-resonant tube is 21 μm. The wall thickness of both the inner and outer anti-resonant tubes is 1.15 ± 0.15 μm. The area where the circular outer anti-resonant tube is in contact with the inner wall of the outer cladding layer is provided with a raised arc surface 5. 01. The two ends of the convex arc surface are respectively connected to the two side blocks 401 and 402 installed between the inner and outer anti-resonant tubes. The two side blocks are installed radially, and the central angle θ formed by the line connecting the two side blocks and the center of the fiber core is 120°, so that the convex arc surface, the two side blocks, and the outer peripheral surface of the inner anti-resonant tube between the two side blocks form a closed hollow arc-shaped protrusion. The hollow arc-shaped protrusion is a closed cavity B1. The hollow arc-shaped protrusion has a radially symmetrical structure. The convex arc surface is composed of an arc surface, and the distance d between the highest point of its protrusion and the fitted circle of the outer anti-resonant tube wall is 8.7μm, which reduces the distance between the anti-resonant structure unit and the fiber core by 8.7μm. The convex arc surface of the hollow arc-shaped protrusion is tangent to the inner wall of the outer cladding. During the fiber drawing process, the three closed cavity regions A1, A2, and B1 formed by the anti-resonant structure unit are filled with gas at different pressures to ensure that the fiber structure after drawing meets the expectations. The gas pressure introduced into B1 is greater than that introduced into A1 and A2, causing the enclosed space B1 to bulge after drawing, forming a convex arc surface. The minimum spacing between each anti-resonant structural unit 3 is maintained within the range of 5.0±0.7μm, thus forming the hollow-core optical fiber 1 with an adjustable support structure in this embodiment. In this embodiment, the outer cladding, inner and outer anti-resonant tubes, and baffles are all made of pure silicon dioxide. The hollow-core optical fiber has an attenuation of 0.13dB / km@1550nm and a minimum high-order mode transmission loss of 873dB / km.

[0043] Second embodiment of the present invention, for example Figure 3 , Figure 4As shown, its main difference from the previous embodiment is that the anti-resonance structure unit includes three layers of anti-resonance tubes, including one circular outer anti-resonance tube 301 and two circular inner anti-resonance tubes. The two circular inner anti-resonance tubes include a first circular inner anti-resonance tube 302 and a second circular inner anti-resonance tube 303. The outer diameter of the circular outer anti-resonance tube is 30μm, the outer radius of the first circular inner anti-resonance tube is 22μm, and the outer radius of the second circular inner anti-resonance tube is 9μm. The wall thickness of each inner and outer anti-resonance tube is 1.13±0.18μm. The two ends of the convex arc surface 501 are respectively connected to the two side blocks 401 and 402 installed between the inner and outer anti-resonance tubes. The two side blocks are installed radially, and the central angle θ formed by the line connecting the two side blocks and the center of the fiber core is 115°. Five identical anti-resonant structural units 3 are evenly distributed circumferentially along the inner wall of the outer cladding and are in contact with the inner wall of the outer cladding. The minimum spacing between each anti-resonant structural unit is maintained within the range of 4.3 ± 0.8 μm. The outer cladding is circular with an outer diameter of 235 μm. During the fiber drawing process, the four closed regions A1, A2, A3, and B1 formed by the anti-resonant structural units are vented with gases of different pressures to ensure that the fiber structure after drawing meets expectations. The gas pressure vented into B1 is greater than that vented into A1 and A2. After drawing, the closed space B1 bulges out, forming a convex arc surface 501. The distance d between the highest point of the convex surface and the fitted circle of the outer anti-resonant tube wall is 9.8 μm. Other structures are the same as in the previous embodiment. In this embodiment, the hollow fiber 1 has an attenuation of 0.10 dB / km@1550 nm and a minimum high-order mode transmission loss of 1033 dB / km.

[0044] Third embodiment of the present invention Figure 5 , Figure 6 As shown, its main difference from the second embodiment above is that the outer diameter of the circular outer anti-resonator is 37 μm, the outer radius of the first circular inner anti-resonator is 25 μm, the outer radius of the second circular inner anti-resonator is 11 μm, the wall thickness of each inner and outer anti-resonator is 1.16 ± 0.17 μm, and the outer diameter of the cladding is 265 μm. The two ends of the raised arc surface 501 are respectively connected to the two side blocks 401 and 402 installed between the inner and outer anti-resonator tubes. The side blocks are installed radially, and the central angle θ formed by the lines connecting the two side blocks and the fiber core center is 68°. The distance d between the highest point of the raised arc surface 501 and the fitted circle of the outer anti-resonator tube wall is 2.2 μm. The minimum spacing between each anti-resonator structural unit is maintained in the range of 4.8 ± 0.7 μm. In this embodiment, the hollow fiber 1 has an attenuation of 0.12 dB / km @ 1550 nm, and its minimum higher-order mode transmission loss is 238 dB / km.

[0045] Fourth embodiment of the present invention Figure 7 , Figure 8As shown, its main difference from the second embodiment above is that the outer diameter of the circular outer anti-resonator is 35 μm, the outer radius of the first circular inner anti-resonator is 21 μm, the outer radius of the second circular inner anti-resonator is 9 μm, the wall thickness of each inner and outer anti-resonator is 1.12 ± 0.12 μm, and the outer diameter of the outer cladding is 230 μm. The two ends of the raised arc surface 501 are respectively connected to the two side blocks 401 and 402 installed between the inner and outer anti-resonator tubes. The side blocks are installed radially, and the central angle θ formed by the lines connecting the two side blocks and the center of the fiber core is 108°. The raised arc surface is composed of three arc surfaces, with the middle arc surface having a larger radius of curvature and the two side arc surfaces having smaller radii of curvature, forming a flattened circular raised arc surface. The distance d between the highest point of the raised arc surface 501 and the fitted circle of the outer anti-resonator tube wall is 5.3 μm. The minimum spacing between each anti-resonator structural unit is maintained within the range of 4.4 ± 0.6 μm. In this embodiment, the hollow fiber 1 has an attenuation of 0.08dB / km@1550nm and a minimum high-order mode transmission loss of 1869dB / km.

[0046] Fifth embodiment of the present invention Figure 9 , Figure 10 , Figure 11 As shown, its main difference from the fourth embodiment above is that the outer diameter of the circular outer anti-resonant tube is 34 μm, the outer radius of the first circular inner anti-resonant tube is 20 μm, the outer radius of the second circular inner anti-resonant tube is 10 μm, the wall thickness of each inner and outer anti-resonant tube is 1.18 ± 0.11 μm, and the outer diameter of the outer cladding is 244 μm. The two ends of the raised arc surface 501 are respectively connected to the two side blocks 401 and 402 installed between the inner and outer anti-resonant tubes. The side blocks are installed radially, and the central angle θ formed by the lines connecting the two side blocks and the center of the fiber core is 117°. A radial intermediate block 403 is set in the middle of the hollow arc-shaped boss, dividing the hollow arc-shaped boss into two separate closed cavities B1 and B2. The minimum spacing between each anti-resonant structural unit is maintained within the range of 4.8 ± 0.3 μm. During the fiber drawing process, the five closed regions A1, A2, A3, B1, and B2 formed by the anti-resonant unit are vented with gas of varying pressure to ensure that the fiber structure after drawing meets expectations. Hollow-core fibers may have certain geometric errors during fabrication, resulting in a slight tilt angle in the anti-resonant structural units, such as... Figure 11 As shown, by introducing gases of different pressures into the enclosed regions B1 and B2, the swing angle of the anti-resonant unit 3 can be adjusted during the fiber drawing process, and the centerline swings from Z1 to Z2, thereby adjusting and optimizing the spacing between the anti-resonant units 3. The hollow-core optical fiber 1 of this embodiment has an attenuation of 0.06dB / km@1550nm and a minimum high-order mode transmission loss of 716dB / km.

Claims

1. An adjustable support structure hollow optical fiber, 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 unit comprising at least two layers of anti-resonant tubes, including one outer anti-resonant tube and one inner anti-resonant tube, characterized in that... The area where the outer anti-resonant tube connects with the inner wall of the outer cladding is provided with a raised arc surface. The two ends of the raised arc surface are respectively connected to the blocks installed between the inner and outer anti-resonant tubes, so that the raised arc surface, the two side blocks, and the outer peripheral surface of the inner anti-resonant tube between the two side blocks form a closed hollow arc-shaped boss. The raised arc surface of the hollow arc-shaped boss is connected to the inner wall of the outer cladding to adjust the spacing and orientation of the anti-resonant structural unit and the fiber core.

2. The adjustable support structure hollow optical fiber according to claim 1, characterized in that... The blocks on both sides of the hollow arc-shaped boss are installed radially, and the central angle θ formed by the lines connecting the two blocks and the center of the fiber core is less than or equal to 120°.

3. The adjustable support structure hollow optical fiber according to claim 1 or 2, characterized in that... The hollow arc-shaped protrusion has a radially symmetrical structure, and the protruding arc surface is composed of one or more arc surfaces. The distance d between the highest point of the protrusion and the fitted circle of the outer anti-resonance tube wall is 1~15μm.

4. The adjustable support structure hollow optical fiber according to claim 1 or 2, characterized in that... The number of anti-resonance structure units is 4 to 6, and each anti-resonance structure unit includes 2 to 4 anti-resonance tubes, including 1 external anti-resonance tube and 1 or more internal anti-resonance tubes.

5. The adjustable support structure hollow optical fiber according to claim 1 or 2, characterized in that... The inner wall of the outer cladding is circular, and the anti-resonance structure unit includes one circular outer anti-resonance tube and one or two circular inner anti-resonance tubes with different radii. The area where the circular outer anti-resonance tube connects with the inner wall of the outer cladding is provided with a raised arc surface, which forms a hollow arc-shaped boss with the adjacent first circular inner anti-resonance tube.

6. The adjustable support structure hollow optical fiber according to claim 5, characterized in that... The first circular inner anti-resonant tube is fitted with a second circular inner anti-resonant tube, and the second circular inner anti-resonant tube is tangent to the first circular inner anti-resonant tube.

7. The adjustable support structure hollow optical fiber according to claim 1 or 2, characterized in that... A radial intermediate block is provided in the middle of the hollow arc-shaped boss, which divides the hollow arc-shaped boss into two separate closed cavities.

8. The adjustable support structure hollow optical fiber according to claim 5, characterized in that... The outer diameter of the outer cladding layer is 100~500μm.

9. The adjustable support structure hollow optical fiber according to claim 6, characterized in that... The outer diameter of the external anti-resonant tube is 20~60μm.

10. The adjustable support structure hollow optical fiber according to claim 6, characterized in that... The outer diameter of the first circular inner anti-resonant tube is 10~50μm.

11. The adjustable support structure hollow optical fiber according to claim 6, characterized in that... The outer diameter of the second circular inner anti-resonant tube is 4~40μm.

12. The adjustable support structure hollow optical fiber according to claim 1 or 2, characterized in that... The fundamental mode transmission loss of the hollow-core optical fiber is less than or equal to 1 dB / km.

13. The adjustable support structure hollow optical fiber according to claim 1 or 2, characterized in that... The hollow-core optical fiber has a 3dB bandwidth greater than or equal to 100nm.

14. The adjustable support structure hollow optical fiber according to claim 1 or 2, characterized in that... The minimum high-order mode transmission loss of hollow-core optical fiber is greater than or equal to 100 dB / km.

15. A method for preparing a hollow optical fiber with an adjustable support structure according to any one of claims 1-14, characterized in that... To fabricate an anti-resonant structural unit prefabrication, glass tubes of different radii are nested together, and fixed blocks are installed in the inner and outer nested tubes to form closed cavities in each nested tube. An outer cladding glass sleeve is fabricated according to the dimensional proportions corresponding to the prefabricated anti-resonance structural unit. Hollow-core optical fiber preforms are fabricated by inserting and fixing anti-resonant structural unit preforms into the inner wall of the outer cladding glass tube according to their orientation, and then heating and melting one end to draw a tapered shape to form a hollow-core optical fiber preform. The process involves drawing hollow optical fiber preforms into hollow optical fibers by clamping them into an optical fiber drawing furnace.

16. The method for fabricating the adjustable support structure hollow optical fiber according to claim 15, characterized in that... During the fiber drawing process, multiple closed cavity regions formed by the anti-resonant structural unit are filled with gas at different pressures to ensure that the fiber structure after drawing meets expectations. Among them, the closed cavity region of the hollow arc-shaped boss is filled with gas at a higher pressure than the other closed cavity regions of the anti-resonant structural unit to form the convex arc surface of the hollow arc-shaped boss.

17. The method for fabricating the adjustable support structure hollow optical fiber according to claim 15 or 16, characterized in that... A radial intermediate block is set in the middle of the hollow arc-shaped boss, which divides the hollow arc-shaped boss into two separate closed cavity areas. Different pressure gases are introduced into the two separate closed cavity areas. During the wire drawing process, the swing angle of the anti-resonance unit is adjusted, thereby adjusting the spacing between each anti-resonance unit.

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