An anti-resonant hollow fiber

Abstract

This invention discloses an anti-resonant hollow-core optical fiber, comprising an outer tube extending along the central axis of the fiber, the outer surface of which forms the outer surface of the fiber cladding; multiple reinforcement members, the outer surfaces of which are attached to the inner surface of the outer tube, evenly spaced, with their inner surfaces facing the center of the fiber; multiple anti-resonant units disposed at the intervals between adjacent reinforcement members, their outer surfaces respectively contacting and connecting with the two reinforcement members; each anti-resonant unit not contacting the inner surface of the outer tube and having one or more nested tubular units; a hollow fiber core, a hollow cavity formed by the outer surfaces of the multiple anti-resonant units, extending along the central axis of the fiber; and multiple cladding cavities, hollow cavities formed by the inner surface of the outer tube, the sidewalls of adjacent reinforcement members, and the outer surfaces of the anti-resonant units. By designing the structure and layout of the anti-resonant units, reinforcement members, and cladding cavities, a balance between low loss and high mechanical strength is achieved in the optical fiber to meet the application requirements in communication, power transmission, and sensing fields.

Description

Technical Field

[0001] This invention belongs to the field of hollow optical fiber, and in particular refers to an anti-resonant hollow optical fiber. Background Technology

[0002] When the thickness of the capillary wall of the cladding in an antiresonant hollow fiber is proportional to the wavelength of light passing through the fiber, FP interference occurs, resulting in an antiresonance effect that confines the light passing through the fiber within the hollow core. In recent years, research institutions such as the University of Southampton in the UK and Jinan University in China have achieved ultra-low loss records of less than 0.1 dB / km in antiresonant hollow fibers. Simultaneously, antiresonant hollow fibers also possess characteristics such as a wide transmission window, low nonlinearity, low delay, and low thermal sensitivity, demonstrating the enormous application potential of this novel fiber technology in communication, power transmission, and sensing.

[0003] With the practical application of antiresonant hollow-core optical fibers, loss and strength are key performance indicators. Patent application number 201580042024.6 describes the structure of an antiresonant hollow-core optical fiber and the low-loss performance achieved under this structure, with nested tubular units (antiresonant units) attached to the inner wall of the outer tube. Patent application number 202380057271.8 describes adding a tubular support between two antiresonant units, preventing the antiresonant units from contacting the inner wall of the outer tube. Neither patent describes how to enhance the fiber strength. Furthermore, the addition of a tubular structure supporting the antiresonant units in the fiber cladding of patent application number 202380057271.8 actually results in a lower strength compared to the antiresonant hollow-core optical fiber described in patent application number 201580042024.6, given a fixed outer and core diameter. Similarly, the patent with application number 202211271487.8 aims to enhance the strength of optical fibers and prevent fiber breakage due to low fiber strength during the drawing process. However, in practice, because it adds support rods or tubes to support the anti-resonant unit, the fiber's strength is lower than that described in the patent with application number 202380057271.8, even with the same outer and core diameter. Furthermore, loss is a critical indicator for optical fibers, and further exploration of optimal structures is needed to reduce it further. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of existing technologies, and its main objective is to provide an anti-resonant hollow-core optical fiber to reduce fiber loss and enhance fiber strength while maintaining good optical transmission performance. By designing the structure and layout of the anti-resonant unit, reinforcement elements, and cladding cavity, a balance between low loss and high mechanical strength is achieved in the optical fiber to meet the application requirements in fields such as communication, power transmission, and sensing.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An anti-resonant hollow-core optical fiber, comprising:

[0007] The outer tube extends along the central axis of the optical fiber, and its outer surface forms the outer surface of the optical fiber cladding.

[0008] Multiple reinforcing members have their outer surfaces attached to the inner surface of the outer tube and are evenly spaced along the circumference of the outer tube, with their inner surfaces facing the center of the optical fiber.

[0009] Multiple anti-resonance units are disposed at the interval between two adjacent reinforcement members, and their outer surfaces are respectively in contact with the two reinforcement members; the anti-resonance units do not contact the inner surface of the outer tube and have one or more nested tubular units;

[0010] The hollow fiber core is a hollow cavity formed by the outer surfaces of multiple anti-resonant units, which extends along the central axis of the optical fiber.

[0011] Multiple cladding cavities, a hollow cavity formed by the inner surface of the outer tube, the sidewalls of two adjacent reinforcing members, and the outer surface of the anti-resonance unit.

[0012] As a preferred embodiment, the plurality of anti-resonant units are spaced apart from each other, with the shortest interval between two adjacent anti-resonant units being 2μm-5μm.

[0013] As a preferred embodiment, the plurality of anti-resonant units are distributed along the radial direction of the optical fiber, and the outer surface of the anti-resonant unit forms point contact or line contact with the outer surface of two adjacent reinforcement members.

[0014] As a preferred embodiment, the reinforcement is a solid structure with a tile-shaped or semi-cylindrical cross-section.

[0015] As a preferred embodiment, the cross-section of the reinforcement is tile-shaped.

[0016] As a preferred embodiment, the tubular unit of the anti-resonance unit has a circular, elliptical, or oval cross-section, and the wall thickness of a single tubular unit is 100nm-1800nm.

[0017] As a preferred embodiment: the cross-sectional area A of the outer tube jecket and the cross-sectional area A of the reinforcement reforcement The sum of these is approximately equal to the effective physical cross-sectional area of ​​the glass material in the hollow optical fiber, from which the following formula is derived:

[0018] F max =σ⋅A effective ≈σ⋅(A jecket +A reforcement );

[0019] in:

[0020] F max The maximum tensile strength of optical fiber, in N;

[0021] A effective The actual effective cross-sectional area of ​​an optical fiber, in m².

[0022] A jecket Cross-sectional area of ​​the fiber optic outer tube, unit: m²;

[0023] A reforcement The sum of the cross-sectional areas of all fiber reinforcement components, in m².

[0024] As a preferred embodiment: the line connecting the connection point of the reinforcement member and the anti-resonance unit does not exceed the line connecting the widest point of the anti-resonance unit perpendicular to the radial direction of the optical fiber; and the ratio of the line distance between the connection point of the reinforcement member and the anti-resonance unit to the line distance between the widest point of the anti-resonance unit is ≤0.8.

[0025] As a preferred option: when the cross-section of the cladding cavity is rectangular, its length-to-width ratio is 0.2-5; when it is an irregular shape, the ratio of the maximum length of the cladding cavity cross-section to the diameter of the hollow fiber core is 0.1-0.95.

[0026] As a preferred embodiment, the outer tube, reinforcing member, and anti-resonance unit are made of glass with a refractive index ≥ 1.37.

[0027] Compared with the prior art, the present invention has significant advantages and beneficial effects. Specifically, as can be seen from the above technical solution,

[0028] First, it reduces loss. The presence of the cladding cavity in the anti-resonant hollow fiber reduces the field strength of the core mode at the outer tube location, suppressing mode coupling and thus reducing fiber loss. In a hollow anti-resonant fiber, when the core mode propagates alongside the lossy anti-resonant unit modes and the outer tube modes, it couples with these modes, leading to additional loss. In this invention, an additional cavity is added between the anti-resonant units and between the outer tube to form the cladding cavity. With a fixed fiber outer diameter and core diameter, adding the cladding cavity reduces the field strength of the core mode at the outer tube location, suppressing mode coupling and thus reducing fiber loss.

[0029] Secondly, the presence of the cladding cavity in the anti-resonant hollow fiber provides an additional way to adjust the fiber mode. Traditional anti-resonant hollow fiber structures adjust the higher-order mode suppression ratio (HMR) to achieve single-mode transmission by changing the gap between the outer and inner (or middle) rings of the anti-resonant unit. However, the hollow anti-resonant fiber described in this invention, in addition to the above methods, can also improve the HMR by adjusting the shape and size of the cladding cavity to make it similar to the effective refractive index of the higher-order modes in the fiber core. This couples the higher-order modes into the cladding, causing them to be lost, thus improving the HMR and allowing the fiber to maintain single-mode transmission as much as possible. Specifically, by adjusting the ratio of the maximum length of the cladding cavity cross-section to the diameter of the hollow fiber core, the HMR can be adjusted, thereby controlling the mode of light transmitted in the hollow fiber core.

[0030] Third, the strength of the optical fiber is improved. Multiple reinforcement elements in the anti-resonant hollow fiber increase the cross-sectional area, thereby increasing the fiber strength and facilitating manufacturing and application. With a fixed outer and core diameter, increasing the sum of the cross-sectional areas of the reinforcement elements increases the fiber strength. Because the reinforcement elements are positioned between two anti-resonant units, light leakage is minimal in their direction. The presence of the reinforcement elements enhances the fiber strength without affecting fiber loss.

[0031] To more clearly illustrate the structural features and effects of the present invention, a detailed description is provided below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the cross-sectional structure of the anti-resonant hollow fiber of the present invention;

[0033] Figure 2 This is a schematic diagram showing the relationship between the optical leakage direction and optical loss in a hollow anti-resonant fiber.

[0034] Figure 3 This is a schematic cross-sectional view of the anti-resonant hollow fiber according to Embodiment 1 of the present invention;

[0035] Figure 4 This is a schematic diagram of the cross-sectional structure of the anti-resonant hollow optical fiber according to Embodiment 2 of the present invention;

[0036] Figure 5 This is a schematic diagram of the cross-sectional structure of the anti-resonant hollow fiber according to Embodiment 3 of the present invention.

[0037] Explanation of reference numerals in the attached diagram:

[0038] 100. Anti-resonant hollow fiber; 101. Outer tube; 102. Reinforcement element; 103. Anti-resonant unit; 104. First nested tube; 105. Second nested tube; 106. Cladding cavity; 107. Hollow fiber core; 200. Reinforcement element a; 201. High aspect ratio cladding cavity; 202. Semi-circular anti-resonant unit; 300. Reinforcement element b; 301. Low aspect ratio cladding cavity; 302. Circular anti-resonant unit; 400. Semi-cylindrical reinforcement element; 401. Trapezoidal cladding cavity; 402. Fan-shaped anti-resonant unit. Detailed Implementation

[0039] To more clearly illustrate the structural features and effects of the present invention, the technical solutions in the embodiments of this application are described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] Specifically, such as Figure 1 As shown, this embodiment of the invention addresses the aforementioned problems in the prior art by providing an anti-resonant hollow-core optical fiber 100, which features low loss and high strength, and comprises:

[0041] The outer tube 101 extends along the central axis of the optical fiber, and its outer surface forms the cladding outer surface of the anti-resonant hollow optical fiber.

[0042] Multiple reinforcing members 102 are solid structures, and their cross-sections are preferably tile-shaped. The outer surface of the reinforcing member 102 is attached to the inner surface of the outer tube 101 and is evenly spaced along the circumference of the outer tube 101. The inner surface of the reinforcing member 102 faces the center of the optical fiber.

[0043] Multiple anti-resonance units 103 are disposed at the interval between two adjacent reinforcement members 102, and their outer surfaces are respectively in contact with the surfaces of the two adjacent reinforcement members 102. None of the multiple anti-resonance units 103 are in contact with the inner surface of the outer tube 101. Each anti-resonance unit 103 has one or more nested tubular units, such as... Figure 1 As shown, both the first nested tube 104 and the second nested tube 105 are tubular units. The plurality of anti-resonant units 103 are distributed along the radial direction of the optical fiber, and the outer surface of the anti-resonant unit 103 forms point contact or line contact with the outer surface of two adjacent reinforcement members 102. The cross-section of the tubular unit is circular, elliptical, oval, or other shapes with closed cross-sectional contours, and the wall thickness of a single tubular unit is 100nm-1800nm.

[0044] The line a1-a2 connecting the connection point of the reinforcement 102 and the anti-resonance unit 103 shall not exceed the line b1-b2 connecting the widest point of the anti-resonance unit 103 perpendicular to the radial direction of the optical fiber, as shown in the example. Figure 1 As shown; and the ratio of the distance a1-a2 between the connection point of the reinforcing member 102 and the connection point of the anti-resonance unit 103 to the distance b1-b2 between the widest point of the anti-resonance unit 103 is ≤0.8.

[0045] The hollow fiber core 107 is a hollow cavity formed by the outer surfaces of multiple anti-resonance units 103, which extends along the central axis of the optical fiber.

[0046] Multiple cladding cavities 106 are hollow cavities formed by the inner surface of the outer tube 101, the spacer surfaces of two adjacent reinforcing members 102 (sidewalls of the reinforcing members 102), and the outer surface of the anti-resonance unit 103. When the cross-section of the cladding cavity 106 is rectangular, its aspect ratio is 0.2-5; when it is irregularly shaped, the ratio of the maximum length of the cross-section of the cladding cavity 106 to the diameter of the hollow fiber core 107 is 0.1-0.95.

[0047] In the structure of the anti-resonant hollow-core optical fiber 100 of this embodiment, multiple cladding cavities 106 are provided to reduce the confinement loss of the optical fiber, and multiple reinforcing members 102 are added to improve the strength of the optical fiber without affecting the fiber loss. (Refer to...) Figure 2 The relationship between optical leakage direction and optical loss in hollow antiresonant optical fiber, among which, Figure 2 The upper part is a schematic diagram of the contour lines of the hollow fiber core module field and a schematic diagram of leakage loss in each direction. Figure 2 The lower half is a schematic diagram of the Boynting vector streamline, indicating the direction of energy leakage. Light radiates outward from the center of the hollow fiber core. The direction of the gap between two adjacent anti-resonant units is the low-loss direction, while the direction of the line connecting the center point of the hollow fiber core and the center point of the anti-resonant unit is the high-loss direction. A cladding cavity is placed in the high-loss direction to increase the distance between the hollow fiber core mode and the outer tube mode, thereby reducing loss. In the low-loss direction, reinforcement elements are added without affecting loss, thus achieving the goal of enhancing fiber strength without increasing loss.

[0048] By setting different cladding cavities, reinforcement components, anti-resonant unit structures and their combinations, and balancing various indicators such as fiber loss, strength, manufacturing difficulty, and ease of application, anti-resonant hollow-core fibers for different applications can be designed and manufactured. The following embodiments further describe the technical solution in a more specific, clear, and complete manner.

[0049] Example 1:

[0050] This implementation example Figure 3As shown, the outer tube 101 of the hollow antiresonant fiber has an outer diameter of 125 μm and an inner diameter of 69 μm, while the hollow fiber core 107 has a diameter of 16 μm. The four tile-shaped reinforcing members a200 have a thickness of 10 μm and a length of 34 μm. The four semicircular antiresonant units 202 have an outer diameter of 23.5 μm, and each semicircular antiresonant unit 202 has a nested tube inside. The wall thickness of the nested tube is the same as the wall thickness of the outer tube of the semicircular antiresonant unit 202, which is 370 nm. The four high aspect ratio cladding cavities 201 have a rectangular cross-section with a length of 12 μm, a width of 3 μm, and an aspect ratio of 4. The ratio of the width of the cross section of the reinforcing member a200 to the outer diameter of the semi-circular anti-resonant unit 202 is 0.43, the ratio of the length of the cross section of the high aspect ratio cladding cavity 201 to the diameter of the hollow fiber core 107 is 0.75, and the ratio of the maximum length of the cross section of the high aspect ratio cladding cavity 201 to the outer diameter of the semi-circular anti-resonant unit 202 is 0.51.

[0051] This antiresonant hollow fiber transmits light in the 1100nm-1500nm band, with a confinement loss of approximately 0.4dB / km at 1310nm. Numerical calculations show that the fiber strength is nearly 10% higher than that of an antiresonant hollow fiber without the tile-shaped reinforcement a200.

[0052] Example 2:

[0053] This implementation example Figure 4 As shown, the outer tube 101 of the hollow anti-resonant fiber has an outer diameter of 230 μm and an inner diameter of 96 μm, while the hollow core 107 has an outer diameter of 28 μm. The five tile-shaped reinforcing elements b300 have a thickness of 10 μm and a length of 50 μm. The five circular anti-resonant units 302 have outer diameters of 31 μm each, and each circular anti-resonant unit 302 contains a nested tube. The wall thickness of both the outer tube and the inner nested tube of the circular anti-resonant unit 302 is 410 nm. The five low aspect ratio cladding cavities 301 have rectangular cross-sections with a length of 5 μm and a width of 3 μm, resulting in an aspect ratio of 1.67. The ratio of the width of the reinforcing element b300 cross-section to the outer diameter of the circular anti-resonant unit 302 is 0.36. The ratio of the length of the low aspect ratio cladding cavity 301 cross-section to the diameter of the hollow core 107 is 0.18. The ratio of the maximum length of the low aspect ratio cladding cavity 301 cross-section to the outer diameter of the circular anti-resonant unit 302 is 0.16.

[0054] This antiresonant hollow fiber transmits light in the 1300nm-1700nm band, with a confinement loss of approximately 0.5dB / Km@1550nm. The fiber strength is about 5% higher than that of an antiresonant hollow fiber without the tile-shaped reinforcement b300.

[0055] Example 3:

[0056] This implementation example Figure 5As shown, the outer tube 101 of the hollow anti-resonant optical fiber has an outer diameter of 125 μm and an inner diameter of 44 μm, while the hollow core 107 has a diameter of 20 μm. The seven semi-cylindrical reinforcing members 400 have a radius of 6 μm (i.e., a thickness of 6 μm) and a length of 12 μm. The seven sector-shaped anti-resonant units 402 have an outer diameter of 10 μm and contain a nested tube. The wall thickness of both the outer tube and the inner nested tube of the sector-shaped anti-resonant unit 402 is 380 nm. The maximum width of the cross-section of the seven trapezoidal cladding cavities 401 is 5 μm. The ratio of the diameter of the semi-cylindrical reinforcing member 400 to the outer diameter of the sector-shaped anti-resonant unit 402 is 0.6. The ratio of the maximum width of the trapezoidal cladding cavity 401 to the diameter of the hollow core 107 is 0.25, and the ratio of the maximum width of the trapezoidal cladding cavity 401 to the outer diameter of the sector-shaped anti-resonant unit 402 is 0.5.

[0057] This antiresonant hollow fiber transmits visible light in the 480nm-580nm band, with a confinement loss of approximately 2dB / Km@532nm. The fiber strength is about 3% higher than that of an antiresonant hollow fiber without the semi-cylindrical reinforcement 400.

[0058] The hollow core 107 of the anti-resonant hollow optical fiber is capable of propagating light with one or more wavelengths from 300nm to 3000nm, wherein the wavelength width is not less than 20nm.

[0059] In all the foregoing embodiments, the outer tube 101, reinforcing member 102, and anti-resonance unit 103 of the anti-resonance hollow optical fiber are all made of quartz glass, and the refractive index of the glass is at least 1.37. In actual production, quartz glass with a refractive index of 1.44 is selected. The plurality of anti-resonance units 103 are spaced apart from each other, and the shortest interval between two adjacent anti-resonance units 103 is between 2um and 5um, preferably 3um.

[0060] The anti-resonant hollow fiber in this invention coordinates the reduction of fiber loss and the enhancement of fiber strength by adjusting the structural shape and size of the reinforcing member 102 and the cladding cavity 106, so as to meet different application requirements.

[0061] The key design focus of this invention is that, compared to existing technologies, one of its advantages and benefits lies in the presence of the cladding cavity in the anti-resonant hollow fiber. This reduces the field strength of the core mode at the outer tube location, suppresses mode coupling, and thus reduces fiber loss. The suppression of coupling theory is considered an important explanation for the light guiding mechanism of hollow anti-resonant fibers. A hollow anti-resonant fiber is a combination of waveguide structures supporting different modes; the waveguide includes a hollow core, a cladding anti-resonant unit, and an outermost outer tube. When the core mode propagates alongside lossy anti-resonant unit modes and outer tube modes, the core mode will couple with these modes, resulting in additional loss. The additional loss α caused by the core mode being coupled with other modes is calculated using the following formula:

[0062] ;

[0063] in the formula α l The loss coefficients for the anti-resonant unit mode and the outer tube mode; Δ β k,l This is the difference in propagation constants between the core and cladding modes; κ k,l This is the coupling coefficient or overlap integral between the corresponding mode fields. Therefore, the additional core-mode loss caused by the coupling between the core mode and all cladding and outer tube modes can be calculated and summed to obtain the total core-coupled additional loss. This formula provides strong support for understanding the loss mechanism of hollow fibers and optimizing their structure. From the formula, it can be seen that when the coupling coefficient between the core mode and the outer tube mode is large, the additional core loss caused by mode coupling is greater. The coupling coefficient is mainly related to the mode field distribution of the core mode at the outer tube position. The smaller the core mode field strength at the outer tube position, the smaller the coupling coefficient, and thus the smaller the core mode loss.

[0064] In hollow-core antiresonant optical fibers, the use of a multilayer antiresonant structure and a large outer tube inner diameter effectively attenuates the field strength of the core mode and suppresses the coupling between the core mode and the outer tube mode, thereby reducing the core mode loss. Therefore, adding an additional cavity between multiple antiresonant units 103 and the outer tube 101 forms a cladding cavity 106. Given a fixed fiber outer diameter and core diameter, adding the cladding cavity 106 reduces the field strength of the core mode at the outer tube location, suppressing mode coupling and thus reducing fiber loss. Therefore, the cladding cavity 106 formed by multiple reinforcement members 102, the outer tube 101, and multiple antiresonant units 103 further reduces the loss of the antiresonant hollow-core optical fiber.

[0065] Compared with existing technologies, the second advantage and benefit of this invention lies in the fact that the presence of the anti-resonant hollow fiber cladding cavity 106 provides an additional way to adjust the fiber mode. For example, traditional anti-resonant hollow fiber structures adjust the high-order mode suppression ratio of the fiber by adjusting the size of the gap between the outer and inner (or middle) rings of the anti-resonant unit, enabling single-mode transmission. However, the hollow anti-resonant fiber described in this invention, in addition to employing the above method, can also improve the high-order mode suppression ratio by adjusting the shape and size of the cladding cavity 106 to make it similar to the effective refractive index of the high-order modes in the fiber core, thus coupling the high-order modes into the cladding and causing them to be lost, thereby maintaining single-mode transmission as much as possible. In particular, a simpler method can be used: by adjusting the ratio of the maximum length of the cladding cavity 106 cross-section to the diameter of the hollow fiber core 107, the high-order mode suppression ratio can be adjusted, thereby controlling the mode of light transmitted in the hollow fiber core 107.

[0066] Compared with existing technologies, the third advantage and benefit of this invention lies in the fact that, by adjusting the width and thickness of the reinforcing member 102, a higher fiber strength than that described in the anti-resonant hollow-core fiber of patent application number 201580042024.6 can be achieved without affecting fiber loss, given a fixed outer and core diameter of the fiber. During the manufacturing process of anti-resonant hollow-core fiber, it is required to maintain the internal microstructure of the fiber along its length to reduce structural loss. Therefore, high tension and continuous drawing without breakage are necessary during the fiber drawing process, and enhancing fiber strength is beneficial to achieving this goal. Furthermore, in the application of optical fibers, high fiber strength helps prevent breakage during coating removal, cutting, splicing, cabling, installation, and use. Therefore, enhancing fiber strength is a very valuable effort. The strength of an optical fiber generally refers to its mechanical tensile strength, which is related to the cross-sectional area. For anti-resonant hollow-core fiber, the cross-sectional area needs to exclude the hollow region and only calculate the cross-sectional area occupied by the glass material. Compared with solid fiber of the same outer diameter, the strength of hollow-core fiber is always weaker. The mechanical tensile strength of optical fiber is mainly determined by the material's breaking strength σ (unit: Pa) and the effective physical cross-sectional area A of the glass material in the hollow fiber. effective (Unit: m²) This is determined because the wall thickness of the glass tube nested within the anti-resonant unit in the anti-resonant hollow fiber is very thin, typically on the order of micrometers or submicrometers, while the wall thickness of the outer tube 101 is typically on the order of tens of micrometers. In comparison, the actual cross-sectional area of ​​the anti-resonant unit 103 is negligible and contributes very little to the fiber strength. Therefore, the cross-sectional area A of the outer tube 101... jecket and the cross-sectional area A of the reinforcing member 102 reforcement The sum of these is approximately equal to the effective physical cross-sectional area of ​​the glass material in the hollow optical fiber, from which the following formula is derived:

[0067] F max =σ⋅A effective ≈σ⋅(A jecket +A reforcement )

[0068] in:

[0069] F max Maximum tensile strength of optical fiber (unit: N);

[0070] A effective : Actual effective cross-sectional area of ​​optical fiber (unit: m²).

[0071] A jecket Cross-sectional area of ​​the fiber optic outer tube (unit: m²);

[0072] A reforcement The sum of the cross-sectional areas of all fiber reinforcement components (unit: m²).

[0073] From the formula above, we can deduce that increasing the outer diameter of the optical fiber directly increases its tensile strength, A. jecket Increasing the diameter sacrifices flexibility; for example, a diameter exceeding 1mm results in high stiffness, requiring a large bending diameter for the fiber. Therefore, to meet practical application requirements, the outer diameter of the fiber cannot be too large; for instance, fibers with a cladding diameter of 125µm are commonly used in communications. Thus, given a fixed outer diameter, the sum A of the cross-sectional areas of the reinforcing members 102 can be increased. reforcement To improve fiber strength, for example, the reinforcement 102 can be made of solid material, increasing its width and thickness, so that A reforcement Make it as big as possible.

[0074] Because the reinforcement 102 is placed between the two anti-resonant units 103, there is very little light leakage in its position direction. The presence of the reinforcement 102 not only enhances the strength of the optical fiber, but also does not affect the loss of the optical fiber.

[0075] The design of hollow-core optical fibers requires consideration of various factors, including outer diameter, loss, mode field, mode, strength, ease of manufacturing, and ease of application. These factors are interdependent and represent the result of compromise and comprehensive consideration. In summary, the multiple reinforcing elements 102 in the anti-resonant hollow-core optical fiber increase the cross-sectional area of ​​the fiber, thereby improving its strength and facilitating manufacturing and application when the fiber's outer diameter is limited.

[0076] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A reverse-hemispherical hollow-core optical fiber, characterized by, The application relates to an optical fiber, which comprises the following components: an outer tube extending along the central axis of the optical fiber, the outer surface of which forms the outer surface of the cladding of the optical fiber; a plurality of reinforcing members, the outer surfaces of which are attached to the inner surface of the outer tube and are uniformly arranged along the circumferential direction of the outer tube, and the inner surfaces of which face the central direction of the optical fiber; a plurality of anti-resonant units arranged at the intervals between two adjacent reinforcing members, the outer surfaces of which are respectively connected with the two reinforcing members; the anti-resonant units are not in contact with the inner surface of the outer tube, and have one or more nested tubular units; a hollow core formed by the hollow cavities surrounded by the outer surfaces of the anti-resonant units, which extends along the central axis of the optical fiber; a plurality of cladding cavities formed by the hollow cavities surrounded by the inner surface of the outer tube, the side walls of the two adjacent reinforcing members and the outer surfaces of the anti-resonant units; the plurality of anti-resonant units are spaced from each other, and the shortest interval distance between two adjacent anti-resonant units is 2-5 mu m; the connecting line between the connecting points of the reinforcing members and the anti-resonant units does not exceed the connecting line between the widest position points of the anti-resonant units perpendicular to the radial direction of the optical fiber in the radial direction of the optical fiber; and the ratio of the connecting line distance between the connecting points of the reinforcing members and the anti-resonant units to the connecting line distance between the widest position points of the anti-resonant units is less than or equal to 0.

8.

2. The anti-resonant hollow core optical fiber according to claim 1, characterized in that: the plurality of anti-resonant units are distributed along the radial direction of the optical fiber, and the outer surfaces of the anti-resonant units form point contact or line contact with the outer surfaces of the two adjacent reinforcing members.

3. The anti-resonant hollow core optical fiber of claim 1, characterized in that: the reinforcing members are solid structures, and the cross sections thereof are in the shape of tiles or half cylinders.

4. The anti-resonant hollow core optical fiber of claim 1, characterized in that: the cross sections of the reinforcing members are in the shape of tiles.

5. The anti-resonant hollow core optical fiber according to claim 1, characterized in that: the cross sections of the tubular units of the anti-resonant units are in the shape of circles, ellipses or ovals, and the wall thickness of a single tubular unit is 100-1800 nm.

6. The anti-resonant hollow core optical fiber according to claim 1, characterized in that: The sum of the cross-sectional area A of the outer tube jecket and the cross-sectional area A of the reinforcing member reforcement is approximately equal to the effective glass material physical cross-sectional area of the hollow core optical fiber, from which the following equation results: F max =σ⋅A effective ≈σ⋅(A jecket +A reforcement ); wherein: sigma: material breaking strength, unit: Pa; F max : maximum tensile force of the optical fiber, in N; A effective : actual effective cross-sectional area of the optical fiber, in m²; A jecket : cross-sectional area of the outer tube of the optical fiber, in m²; A reforcement : Sum of all reinforcing elements cross-sectional areas, in m².

7. The anti-resonant hollow core optical fiber according to claim 1, characterized in that: when the cross section of the cladding cavity is in the shape of a rectangle, the length-width ratio thereof is 0.2-5; when the cross section of the cladding cavity is in the shape of an irregular polygon, the ratio of the maximum length of the cross section of the cladding cavity to the diameter of the hollow core is 0.1-0.

95.

8. The anti-resonant hollow core optical fiber according to claim 1, characterized in that: the outer tube, the reinforcing members and the anti-resonant units are made of glass with a refractive index greater than or equal to 1.37.

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