Anti-resonance hollow-core optical fiber

Abstract

The invention discloses an anti-resonance hollow-core optical fiber, which comprises an outer tube which extends along the axial direction of the center of the optical fiber, and the outer surface of the outer tube forms an optical fiber cladding outer surface; the outer side surfaces of the reinforcing parts are attached to the inner surface of the outer pipe and are uniformly arranged at intervals, and the inner side surfaces face the center direction of the optical fiber; the plurality of anti-resonance units are arranged at intervals of two adjacent reinforcing parts, and the outer surfaces of the anti-resonance units are in contact connection with the two reinforcing parts respectively; the anti-resonance unit is not in contact with the inner surface of the outer tube and is provided with one or more nested tubular units; the hollow fiber core is a hollow cavity defined by the outer surfaces of a plurality of anti-resonance units and extends in the axial direction of the center of the optical fiber; the cladding cavities are hollow cavities defined by the inner surface of the outer pipe, the side walls of every two adjacent reinforcing pieces and the outer surfaces of the anti-resonance units. By designing the structure and layout of the anti-resonance unit, the reinforcing member and the cladding cavity, the balance between low loss and high mechanical strength of the optical fiber is realized so as to meet the application requirements in the fields of communication, energy transfer, sensing and the like.

Description

Technical Field

[0001] The present invention belongs to the field of hollow-core optical fibers, and in particular, relates to an anti-resonant hollow-core optical fiber. Background Art

[0002] When the thickness of the capillary wall of the inner cladding of an anti-resonant hollow-core optical fiber is proportional to the optical wavelength passing through the hollow-core optical fiber, F-P interference occurs, thereby generating an anti-resonant effect, so that the light passing through the optical fiber is constrained to be transmitted in 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 on anti-resonant hollow-core optical fibers. At the same time, anti-resonant hollow-core optical fibers also have characteristics such as a wide transmission window, low non-linearity, low delay, and low thermal sensitivity, demonstrating the great application potential of this new optical fiber technology in fields such as communication, energy transmission, and sensing.

[0003] When anti-resonant hollow-core optical fibers enter practical applications, loss and strength are the indicators that receive much attention. The patent with the application number 201580042024.6 describes the structure of an anti-resonant hollow-core optical fiber and the low-loss performance obtained under its structure, and the tubular units (anti-resonant units) nested inside the optical fiber are attached to the inner wall of the outer tube. The patent with the application number 202380057271.8 describes adding a tubular support between two anti-resonant units so that the anti-resonant units do not contact the inner wall of the outer tube. Neither of these two patents involves a description of how to enhance the strength of the optical fiber, and the patent with the application number 202380057271.8, because of the addition of a tubular structure for supporting the anti-resonant units in the optical fiber cladding, instead results in a reduction in the strength of the anti-resonant hollow-core optical fiber described in the patent with the application number 201580042024.6 when the outer diameter and core diameter of the optical fiber are determined. Similarly, for the patent with the application number 202211271487.8, the purpose is to enhance the strength of the optical fiber to avoid low strength during the wire drawing process and easy wire breakage, but in fact, due to the addition of support rods or tubes for supporting the anti-resonant units, the strength is lower than that of the optical fiber described in the patent with the application number 202380057271.8 when the outer diameter and core diameter of the optical fiber are the same. In addition, loss is a key indicator for optical fibers, and it is still necessary to explore a better structure to further reduce it. Summary of the Invention

[0004] In view of this, in view of the deficiencies of the existing technology, the main purpose of the present invention is to provide an anti-resonant hollow-core optical fiber to reduce the loss of the optical fiber, enhance the strength of the optical fiber, and at the same time maintain good light transmission performance. By designing the structure and layout of the anti-resonant unit, the reinforcing member, and the cladding cavity, a balance between low loss and high mechanical strength of the optical fiber is achieved to meet the application requirements in fields such as communication, energy transmission, and sensing.

[0005] To achieve the above object, the present invention adopts the following technical solutions: An anti-resonant hollow fiber, comprising: An outer tube extending along the central axis of the fiber, and the outer surface thereof forms the outer surface of the fiber cladding; A plurality of reinforcing members, the outer side surfaces of which are attached to the inner surface of the outer tube, are evenly spaced along the circumferential direction of the outer tube, and the inner side surfaces face the center direction of the fiber; A plurality of anti-resonant units disposed at intervals between two adjacent reinforcing members, and the outer surfaces thereof are respectively in contact connection 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, a hollow cavity formed by the outer surfaces of a plurality of anti-resonant units, extending along the central axis of the fiber; A plurality of cladding cavities, hollow cavities formed by the inner surface of the outer tube, the side walls of two adjacent reinforcing members and the outer surface of the anti-resonant unit.

[0006] As a preferred solution: the plurality of anti-resonant units are spaced from each other, and the shortest distance between two adjacent anti-resonant units is 2 μm - 5 μm.

[0007] As a preferred solution: the plurality of anti-resonant units are distributed in the radial direction of the fiber, and point contact or line contact is formed between the outer surface of the anti-resonant unit and the outer surfaces of two adjacent reinforcing members.

[0008] As a preferred solution: the reinforcing member is of a solid structure, and the cross section is in the shape of a tile or a semi-cylindrical shape.

[0009] As a preferred solution: the cross section of the reinforcing member is in the shape of a tile.

[0010] As a preferred solution: the cross section of the tubular unit of the anti-resonant unit is circular, elliptical or oval, and the wall thickness of a single tubular unit is 100 nm - 1800 nm.

[0011] As a preferred solution: the cross-sectional area A jecket of the outer tube and the cross-sectional area A reforcement of the reinforcing member together are approximately equal to the physical cross-sectional area of the effective glass material of the hollow fiber, and the following formula is obtained: F max = σ ⋅ A effective ≈ σ ⋅ (A jecket + A reforcement ) ; Wherein: F max : the maximum tensile strength of the fiber, unit: N; A effective : the actual effective cross-sectional area of the fiber, unit: m²; A jecket: Cross-sectional area of ​​the optical fiber outer tube, unit: m²; A reforcement : The sum of the cross-sectional areas of all optical fiber reinforcement components, unit: m².

[0012] As a preferred solution: the line between the connection points of the reinforcement and the anti-resonance unit does not exceed the line between the widest points of the anti-resonance unit perpendicular to the radial direction of the optical fiber along the radial direction of the optical fiber; and the ratio of the line distance between the connection points of the reinforcement and the anti-resonance unit to the line distance between the widest points of the anti-resonance unit is ≤0.8.

[0013] As a preferred solution: when the cross section of the cladding cavity is rectangular, its aspect ratio is 0.2-5; when it is an irregular shape, the ratio of the maximum length of the cross section of the cladding cavity to the diameter of the hollow fiber core is 0.1-0.95.

[0014] As a preferred solution: the outer tube, the reinforcement, and the anti-resonance unit are made of glass with a refractive index ≥ 1.37.

[0015] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that: First, the loss is reduced. The existence of the cladding cavity of the antiresonant hollow-core optical fiber reduces the field strength of the core mode at the outer tube position, suppresses mode coupling, and thus reduces the loss of the optical fiber. In a hollow-core antiresonant optical fiber, when the core mode propagates together with the lossy antiresonant unit mode and the outer tube mode, it will couple with these modes, resulting in additional losses. In the present invention, an additional cavity portion is added between the antiresonant units and the outer tube to form a cladding cavity. When the outer diameter and core diameter of the optical fiber are determined, the addition of the cladding cavity will reduce the field strength of the core mode at the outer tube position, suppress mode coupling, and thus reduce the loss of the optical fiber.

[0016] Second, adjust the fiber mode. The existence of the antiresonant hollow-core fiber cladding cavity provides an additional way to adjust the fiber mode. The traditional antiresonant hollow-core fiber structure adjusts the high-order mode suppression ratio of the optical fiber by adjusting the size of the gap between the outer ring and the inner ring (or middle ring) of the antiresonant unit to achieve single-mode transmission. In addition to the above method, the hollow-core antiresonant optical fiber described in the present invention can also improve the high-order mode suppression ratio by adjusting the shape and size of the cladding cavity so that it is not much different from the effective refractive index of the high-order mode in the core, and coupling the high-order mode into the cladding for loss, so as to keep the optical fiber in single-mode transmission as much as possible. In particular, by adjusting the ratio of the maximum length of the cladding cavity cross-section to the diameter of the hollow core, the size of the high-order mode suppression ratio can be adjusted, thereby controlling the mode of the transmitted light in the hollow core.

[0017] Third, improve the strength of the optical fiber. The multiple reinforcements in the antiresonant hollow-core optical fiber increase the cross-sectional area of ​​the antiresonant hollow-core optical fiber, thereby improving the strength of the optical fiber and facilitating manufacturing and application. When the outer diameter and core diameter of the optical fiber are determined, increasing the sum of the cross-sectional areas of the reinforcements can improve the strength of the optical fiber. Because the reinforcement is set between the two antiresonant units, there is little light leakage in the direction of its position. The presence of the reinforcement not only enhances the strength of the optical fiber, but also does not affect the loss of the optical fiber.

[0018] In order to more clearly illustrate the structural features and effects of the present invention, it is described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the cross-section structure of the anti-resonant hollow-core optical fiber of the present invention; Figure 2 Schematic diagram of the relationship between light leakage direction and light loss in hollow-core antiresonant optical fiber; Figure 3 It is a schematic diagram of the structural cross-section of the anti-resonant hollow-core optical fiber according to the first embodiment of the present invention; Figure 4 It is a schematic diagram of the structural cross-section of the anti-resonant hollow-core optical fiber of the second embodiment of the present invention; Figure 5 It is a schematic diagram of the structural cross-section of the anti-resonant hollow-core optical fiber according to the third embodiment of the present invention.

[0020] Description of the accompanying drawings: 100, antiresonant hollow core optical fiber; 101, outer tube; 102, reinforcement; 103, antiresonant unit; 104, first nested tube; 105, second nested tube; 106, cladding cavity; 107, hollow core; 200, reinforcement a; 201, high aspect ratio cladding cavity; 202, semicircular antiresonant unit; 300, reinforcement b; 301, low aspect ratio cladding cavity; 302, circular antiresonant unit; 400, semi-cylindrical reinforcement; 401, trapezoidal cladding cavity; 402, fan-shaped antiresonant unit. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the structural features and functions of the present invention, the technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the accompanying drawings; it is obvious that the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0022] Specifically, Figure 1As shown, based on the above problems existing in the prior art, an anti-resonant hollow fiber 100 is provided in an embodiment of the present invention. The anti-resonant hollow fiber 100 has the characteristics of low loss and high strength, and includes: An outer tube 101 that extends along the central axis of the fiber, and its outer surface forms the outer surface of the cladding of the anti-resonant hollow fiber.

[0023] A plurality of reinforcing members 102 are of solid structure, and their cross-sections are preferably in the shape of tiles; the outer surfaces of the reinforcing members 102 are attached to the inner surface of the outer tube 101 and are arranged at equal intervals in the circumferential direction of the outer tube 101, and the inner surfaces of the reinforcing members 102 face the center of the fiber.

[0024] A plurality of anti-resonant units 103 are arranged at the intervals between two adjacent reinforcing members 102, and their outer surfaces are respectively in contact connection with the surfaces of two adjacent reinforcing members 102. The plurality of anti-resonant units 103 are not in contact with the inner surface of the outer tube 101. The anti-resonant units 103 have one or more nested tubular units, such as Figure 1 As shown, the first nested tube 104 and the second nested tube 105 are both tubular units. The plurality of anti-resonant units 103 are distributed in the radial direction of the fiber, and point contact or line contact is formed between the outer surface of the anti-resonant unit 103 and the outer surfaces of two adjacent reinforcing members 102. The cross-section of the tubular unit is circular, elliptical, oval or other shapes with a closed cross-sectional profile, and the wall thickness of a single tubular unit is 100 nm - 1800 nm.

[0025] The connection line a1 - a2 between the connection points of the reinforcing member 102 and the anti-resonant unit 103 does not exceed the connection line b1 - b2 between the widest position points of the anti-resonant unit 103 perpendicular to the radial direction of the fiber along the radial direction of the fiber, as Figure 1 shown; and the ratio of the distance of the connection line a1 - a2 between the connection points of the reinforcing member 102 and the anti-resonant unit 103 to the distance of the connection line b1 - b2 between the widest position points of the anti-resonant unit 103 ≤ 0.8.

[0026] A hollow core 107 is a hollow cavity formed by enclosing the outer surfaces of a plurality of anti-resonant units 103, and it extends along the central axis of the fiber.

[0027] A plurality of cladding cavities 106 are hollow cavities formed by enclosing the inner surface of the outer tube 101, the spaced surfaces (side walls of the reinforcing members 102) between two adjacent reinforcing members 102, and the outer surface of the anti-resonant unit 103. When the cross-section of the cladding cavity 106 is rectangular, the aspect ratio is 0.2 - 5; when it is of an irregular shape, the ratio of the maximum length of the cross-section of the cladding cavity 106 to the diameter of the hollow core 107 is 0.1 - 0.95.

[0028] In the structure of the anti-resonant hollow fiber 100 of this embodiment, by setting multiple cladding cavities 106, the confinement loss of the fiber is reduced, and by adding multiple reinforcing members 102, the strength of the fiber is increased without affecting the fiber loss. Refer to Figure 2 , the relationship between the light leakage direction and the light loss in the hollow anti-resonant fiber, where Figure 2 The upper half is a schematic diagram of the hollow core mode field contour and the leakage loss schematic diagrams in each direction, Figure 2 The lower half is a schematic diagram of the streamline of the Poynting vector, indicating the direction of energy leakage. Light radiates from the center of the hollow core. The direction between two adjacent anti-resonant unit gaps is the low-loss direction, and the direction connecting the center point of the hollow core and the center point of the anti-resonant unit is the high-loss direction. By setting cladding cavities in the high-loss direction, the distance between the hollow core mode and the outer tube mode is increased, thereby reducing the loss. In the low-loss direction, by adding reinforcing members, the loss is not affected, thus achieving the purpose of enhancing the fiber strength without increasing the loss.

[0029] By setting different cladding cavities, reinforcing members, anti-resonant unit structures and their combinations, various indexes such as fiber loss, strength, manufacturing difficulty, and application convenience are balanced, and anti-resonant hollow fibers with different application purposes are designed and manufactured. The following embodiments describe the technical solutions more specifically, clearly and completely.

[0030] Embodiment 1:

[0031] As shown in this embodiment Figure 3 , the outer diameter of the outer tube 101 of the hollow anti-resonant fiber is 125 μm, the inner diameter is 69 μm, and the diameter of the hollow core 107 is 16 μm; the thickness of the four tile-shaped reinforcing members a200 is 10 μm, and the length is 34 μm; the outer diameter of the four semi-circular anti-resonant units 202 is 23.5 μm, and each semi-circular anti-resonant unit 202 has an embedded tube inside, and the wall thickness of the embedded tube and the wall thickness of the outer tube of the semi-circular anti-resonant unit 202 are both 370 nm; four high aspect ratio cladding cavities 201, the cross-section of which is rectangular, the cross-section length is 12 μm, the cross-section width is 3 μm, and the aspect ratio is 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 cross-section length of the high aspect ratio cladding cavity 201 to the diameter of the hollow 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.

[0032] This anti-resonant hollow fiber transmits light in the 1100 nm - 1500 nm band. At 1310 nm, its confinement loss is about 0.4 dB / Km. Through numerical calculation, the strength of the fiber is increased by nearly 10% compared with the anti-resonant hollow fiber without the tile-shaped reinforcing member a200.

[0033] Example 2:

[0034] As shown in this example, Figure 4 the outer diameter of the outer tube 101 of the hollow anti-resonant fiber is 230 um, the inner diameter is 96 um, and the outer diameter of the hollow core 107 is 28 um; the thickness of the five tile-shaped reinforcements b300 is 10 um, and the length is 50 um; the outer diameters of the five circular anti-resonant units 302 are 31 um respectively. Each circular anti-resonant unit 302 contains an embedded tube. The wall thickness of the outer tube of the circular anti-resonant unit 302 and the wall thickness of the internal embedded tube are both 410 nm; the cross-section of the five low aspect ratio cladding cavities 301 is rectangular, with a length of 5 um, a width of 3 um, and an aspect ratio of 1.67. The ratio of the width of the cross-section of the reinforcement b300 to the outer diameter of the circular anti-resonant unit 302 is 0.36. The ratio of the length of the cross-section of the low aspect ratio cladding cavity 301 to the diameter of the hollow core 107 is 0.18. The ratio of the maximum length of the cross-section of the low aspect ratio cladding cavity 301 to the outer diameter of the circular anti-resonant unit 302 is 0.16.

[0035] This anti-resonant hollow fiber transmits light in the 1300 nm - 1700 nm band, with a confinement loss of about 0.5 dB / Km@1550 nm. The strength ratio of the fiber is about 5% higher than that of the anti-resonant hollow fiber without the tile-shaped reinforcement b300.

[0036] Example 3:

[0037] As shown in this example, Figure 5 the outer diameter of the outer tube 101 of the hollow anti-resonant fiber is 125 um, the inner diameter is 44 um, and the diameter of the hollow core 107 is 20 um; the radius of the seven semi-cylindrical reinforcements 400 is 6 um, that is, the thickness is 6 um, and the length is 12 um; the outer diameter of the seven sector-shaped anti-resonant units 402 is 10 um, and each contains an embedded tube. The wall thickness of the outer tube of the sector-shaped anti-resonant unit 402 and the wall thickness of the internal embedded tube are both 380 nm; the maximum width of the cross-section of the seven trapezoidal cladding cavities 401 is 5 um. The ratio of the diameter of the cross-section of the semi-cylindrical reinforcement 400 to the outer diameter of the sector-shaped anti-resonant unit 402 is 0.6. The ratio of the maximum width of the cross-section of the trapezoidal cladding cavity 401 to the diameter of the hollow core 107 is 0.25. The ratio of the maximum width of the cross-section of the trapezoidal cladding cavity 401 to the outer diameter of the sector-shaped anti-resonant unit 402 is 0.5.

[0038] This anti-resonant hollow fiber transmits visible light in the 480 nm - 580 nm band, with a confinement loss of about 2 dB / Km@532 nm. The strength ratio of the fiber is about 3% higher than that of the anti-resonant hollow fiber without the semi-cylindrical reinforcement 400.

[0039] Light with one or several wavelength bands in the range of 300 nm to 3000 nm can propagate in the hollow core 107 of the anti-resonant hollow-core fiber, and the bandwidth of the wavelength band is not less than 20 nm.

[0040] In all of the foregoing embodiments, the outer tube 101, the reinforcing member 102, and the anti-resonant unit 103 of the anti-resonant hollow-core 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-resonant units 103 are spaced apart from each other, and the shortest spacing distance between two adjacent anti-resonant units 103 is between 2 μm and 5 μm, preferably 3 μm.

[0041] In the anti-resonant hollow-core fiber of the present invention, by adjusting the structural shapes and dimensions of the reinforcing member 102 and the cladding cavity 106, the fiber loss is coordinated to be reduced and the fiber strength is enhanced to meet different application requirements.

[0042] The design focus of the present invention is that, compared with the prior art, one of the advantages and benefits brought by the present invention is the existence of the cladding cavity of the anti-resonant hollow-core fiber, which reduces the field strength of the core mode at the position of the outer tube, suppresses mode coupling, and thus reduces the loss of the fiber. The suppression coupling theory is considered to be an important explanation for the light guiding mechanism of the hollow-core anti-resonant fiber. The hollow-core anti-resonant fiber is a combination of waveguide structures supporting different modes; the waveguide includes a hollow core, a cladding anti-resonant unit, and the outermost outer tube. When the core mode propagates together with the lossy anti-resonant unit mode and the outer tube mode, the core mode will couple with these modes, resulting in additional losses. The additional loss α of the core mode caused by coupling with other modes is calculated according to the following formula: ; In the formula α l is the loss coefficient of the anti-resonant unit mode and the outer tube mode; Δ β k,l is the difference in propagation constants between the core and the cladding modes; κ k,l is the coupling coefficient or overlap integral between their corresponding mode fields. Therefore, the additional loss of the core mode caused by coupling with all cladding modes and outer tube modes can be calculated and added up to obtain the total additional loss of core coupling. This formula provides strong support for understanding the loss mechanism of the hollow fiber and optimizing the structure of the hollow fiber; from the above formula, it can be seen that when the coupling coefficient between the core mode and the outer tube mode is large, the additional loss of the core caused by mode coupling is greater. The coupling coefficient is mainly related to the mode field distribution of the core mode at the position of the outer tube. The smaller the field strength of the core mode at the position of the outer tube, the smaller the coupling coefficient, and thus the smaller the loss of the core mode.

[0043] In a hollow anti-resonant fiber, adopting a multi-layer anti-resonant structure and a large inner diameter of the outer tube will effectively attenuate the field strength of the core mode, suppress the coupling between the core mode and the outer tube mode, and thus reduce the loss of the core mode. Therefore, adding an additional cavity part between multiple anti-resonant units 103 and the outer tube 101 forms a cladding cavity 106. When the outer diameter and core diameter of the fiber are determined, increasing the cladding cavity 106 will reduce the field strength of the core mode at the position of the outer tube, suppress the mode coupling, and thus reduce the loss of the fiber. Therefore, the cladding cavity 106 formed by enclosing multiple reinforcing members 102, the outer tube 101, and multiple anti-resonant units 103 further reduces the loss of the anti-resonant hollow fiber.

[0044] Compared with the existing technology, the second advantage and benefit of the present invention is that the existence of the cladding cavity 106 of the anti-resonant hollow fiber additionally provides a way to adjust the fiber mode. For example, the traditional anti-resonant hollow fiber structure adjusts the suppression ratio of the high-order mode of the fiber by adjusting the size of the gap between the outer ring and the inner ring (or middle ring) of the anti-resonant unit to achieve single-mode transmission. In addition to the above method, the hollow anti-resonant fiber described in the present invention can also adjust the shape and size of the cladding cavity 106 so that it has little difference from the effective refractive index of the high-order mode in the core, couple the high-order mode into the cladding and lose it, to improve the high-order mode suppression ratio, and thus make the fiber maintain single-mode transmission as much as possible. In particular, a simpler method can be adopted to adjust the suppression ratio of the high-order mode by adjusting the ratio of the maximum length of the cross-section of the cladding cavity 106 to the diameter of the hollow core 107, so as to control the mode of the light transmitted in the hollow core 107.

[0045] Compared with the existing technology, the third advantage and benefit of the present invention is that by adjusting the width and thickness of the reinforcement 102, when the outer diameter and core diameter of the optical fiber are determined, a higher optical fiber strength can be achieved than the antiresonant hollow core optical fiber of the structure described in the patent application number 201580042024.6, while not affecting the loss of the optical fiber. In the manufacturing process of the antiresonant hollow core optical fiber, it is required to keep the internal microstructure of the optical fiber unchanged in the length direction, so as to reduce the structural loss. Therefore, it is necessary to maintain high tension and continuous drawing without breaking the wire during the drawing process. The enhancement of the optical fiber strength is conducive to achieving this goal. In addition, in the application process of the optical fiber, the high optical fiber strength helps to prevent it from breaking during the process of stripping the coating, cutting, welding, cabling, installation and use. Therefore, enhancing the optical fiber strength is a very valuable effort. The strength of the optical fiber generally refers to the mechanical tensile strength, which is related to the cross-sectional area of ​​the optical fiber. For the antiresonant hollow core optical fiber, its cross-sectional area needs to exclude the hollow area and only calculate the cross-sectional area occupied by the glass material. Compared with the hollow core optical fiber and the solid core optical fiber of the same outer diameter, the strength of the hollow core optical fiber must be weaker than that of the solid core optical fiber. The mechanical tensile strength of optical fiber is mainly determined by the material fracture strength σ (unit: Pa) and the effective glass material physical cross-sectional area A of the hollow core optical fiber. effective (Unit: m²). Because the wall thickness of the glass tube in which the antiresonance unit is embedded in the antiresonance hollow core fiber is very thin, generally in the order of microns or submicrons, and the wall thickness of the outer tube 101 is generally in the order of tens of microns, in comparison, the actual cross-sectional area of ​​the antiresonance unit 103 is very small and can be ignored, and the contribution it can provide to the fiber strength is also very small. Therefore, the cross-sectional area A of the outer tube 101 is jecket and the cross-sectional area A of the reinforcement member 102 reforcement The sum is approximately equal to the effective glass material physical cross-sectional area of ​​the hollow core optical fiber, from which the following formula is obtained: F max =σ⋅A effective ≈σ⋅(A jecket +A reforcement ) in: F max : Maximum tensile strength of optical fiber (unit: N); A effective : Actual effective cross-sectional area of ​​the optical fiber (unit: m²); A jecket : Cross-sectional area of ​​the optical fiber outer tube (unit: m²); A reforcement : The sum of the cross-sectional areas of all optical fiber reinforcement components (unit: m²); From the above formula, it can be concluded that increasing the outer diameter of the optical fiber can directly increase the tensile strength of the optical fiber, i.e. A jecketIt will increase, but the flexibility will be sacrificed. For example, when the diameter exceeds 1 mm, the stiffness is high, resulting in a large bending diameter required for the optical fiber to be used. Therefore, to meet the requirements of practical applications, the outer diameter of the optical fiber cannot be too large. For example, optical fibers with a 125-μm cladding diameter are commonly used in communication. Therefore, when the outer diameter of the optical fiber is determined, the sum of the cross-sectional areas A of the reinforcing members 102 can be increased reforcement to improve the strength of the optical fiber. For example, the reinforcing member 102 adopts a solid material structure, and its width and thickness are increased to make A reforcement as large as possible.

[0046] Since the reinforcing member 102 is placed between the two anti-resonant units 103, there is very little light leakage in its position direction. The presence of the reinforcing member 102 not only enhances the strength of the optical fiber but also has no impact on the loss of the optical fiber.

[0047] The design of the hollow-core optical fiber needs to consider various factors such as the outer diameter, loss, mode field, mode, strength, manufacturing convenience, and application convenience. These factors restrict each other and are the result of compromise and comprehensive consideration. In short, the multiple reinforcing members 102 in the anti-resonant hollow-core optical fiber increase the cross-sectional area of the anti-resonant hollow-core optical fiber. When the outer diameter of the optical fiber is limited, it can improve the strength of the optical fiber and facilitate manufacturing and application.

[0048] The above description is only a preferred embodiment of the present invention and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An anti-resonant hollow-core optical fiber, characterized in that, Comprising: An outer tube, extending along the central axis of the optical fiber, and the outer surface thereof forms the outer surface of the optical fiber cladding; A plurality of reinforcing members, the outer side surfaces of which are attached to the inner surface of the outer tube, are arranged at equal intervals along the circumferential direction of the outer tube, and the inner side surfaces face the direction of the optical fiber center; A plurality of anti-resonant units, disposed at the intervals between two adjacent reinforcing members, and the outer surfaces thereof are respectively in contact connection with the two reinforcing members; the anti-resonant units do not contact the inner surface of the outer tube and have one or more nested tubular units; A hollow core, a hollow cavity formed by surrounding the outer surfaces of a plurality of anti-resonant units, extending along the central axis of the optical fiber; A plurality of cladding cavities, hollow cavities formed by the inner surface of the outer tube, the side walls of two adjacent reinforcing members and the outer surface of the anti-resonant unit.

2. The anti-resonant hollow optical fiber according to claim 1, characterized in that: The plurality of anti-resonant units are spaced apart from each other, and the shortest spacing distance between two adjacent anti-resonant units is 2 μm - 5 μm.

3. The anti-resonant hollow optical fiber according to claim 1, characterized in that: The plurality of anti-resonant units are distributed in the radial direction of the optical fiber, and point contact or line contact is formed between the outer surface of the anti-resonant unit and the outer surfaces of two adjacent reinforcing members.

4. The anti-resonant hollow-core optical fiber according to claim 1, characterized in that: The reinforcing member is of a solid structure, and the cross section is in the shape of a tile or a semi-cylindrical shape.

5. The anti-resonant hollow optical fiber according to claim 1, characterized in that: The cross section of the reinforcing member is in the shape of a tile.

6. The anti-resonant hollow optical fiber according to claim 1, characterized in that: The cross section of the tubular unit of the anti-resonant unit is circular, elliptical or oval, and the wall thickness of a single tubular unit is 100 nm - 1800 nm.

7. The anti-resonant hollow-core optical fiber according to claim 1, characterized in that: The cross-sectional area A of the outer tube jecket and the cross-sectional area A of the reinforcement reforcement The sum is approximately equal to the physical cross-sectional area of the effective glass material of the hollow optical fiber, and the following formula is obtained: F max = σ ⋅ A effective ≈ σ ⋅ (A jecket + A reforcement ) Wherein: F max : Maximum tensile strength of the optical fiber, unit: N; A effective : The actual effective cross-sectional area of the optical fiber, unit: m²; A jecket : Cross-sectional area of the outer tube of the optical fiber, unit: m²; A reforcement : The sum of the cross-sectional areas of all the strength members of the optical fiber, unit: m².

8. The anti-resonant hollow optical fiber according to claim 1, characterized in that: The connection line between the connection points of the reinforcing member and the anti-resonant unit does not exceed the connection line between the widest position points of the anti-resonant unit perpendicular to the radial direction of the optical fiber along the radial direction of the optical fiber; and the ratio of the connection line distance between the connection points of the reinforcing member and the anti-resonant unit to the connection line distance between the widest position points of the anti-resonant unit ≤ 0.

8.

9. The anti-resonant hollow-core optical fiber according to claim 1, characterized in that: When the cross section of the cladding cavity is rectangular, the aspect ratio is 0.2 - 5; when it is an irregular shape, 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.

10. The anti-resonant hollow-core optical fiber according to claim 1, characterized in that: The outer tube, the reinforcing member and the anti-resonant unit are made of glass with a refractive index ≥ 1.37.

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