A breakage detectable hollow core anti-resonant optical fiber, its production method and optical cable

Abstract

The application discloses a break-point detectable hollow-core anti-resonant optical fiber and a production method and optical cable thereof, and belongs to the technical field of hollow-core optical fibers. The hollow-core anti-resonant optical fiber comprises an anti-resonant unit covered by a cladding, and at least one solid core made of a germanium-doped core is arranged in the cladding. The solid core is uniformly spirally arranged at the periphery of the anti-resonant unit, so that the hollow-core optical fiber meets the application requirements of the anti-resonant effect and has the use function of break-point detection. The break-point detectable hollow-core anti-resonant optical fiber has the advantages of simple structure, convenient production and use, and the ability to meet the anti-resonant effect of the hollow-core optical fiber and realize the break-point detection of the hollow-core optical fiber without affecting the use performance of the anti-resonant effect of the hollow-core optical fiber. The application effectively realizes the application of the conventional break-point detection technology (for example, the OTDR technology) in the hollow-core optical fiber, further improves the convenience and reliability of the application and maintenance of the hollow-core optical fiber, expands the comprehensive performance of the hollow-core optical fiber, and has good practical value.

Description

Technical Field

[0001] This invention belongs to the field of hollow optical fiber technology, specifically relating to a hollow anti-resonant optical fiber with breakpoint detection, its production method, and optical cable. Background Technology

[0002] Hollow-core fiber is a groundbreaking optical waveguide technology. Its core characteristic is that optical signals are primarily transmitted within a core composed of air, rather than the solid glass core of traditional optical fibers. This unique structure allows its operating principle to move beyond traditional "total internal reflection." Instead, it utilizes the precise microstructure of the cladding to confine light within an air channel. This includes photonic bandgap fibers utilizing the photonic bandgap effect and anti-resonant microstructure fibers utilizing the principle of anti-resonant reflection. Hollow-core anti-resonant fibers, benefiting from the faster propagation speed and lower loss of light in air, can significantly reduce signal transmission delay (by approximately 30%) and signal attenuation. Therefore, it is considered a key technological direction for solving bottleneck problems in future high-speed communications and high-power laser transmission.

[0003] In the application of optical fibers, the detection of fiber optic breaks is a crucial aspect of optical cable maintenance. For traditional solid optical fibers, optical time domain reflectometry (OTDR) is typically used for fiber break detection. The working principle of OTDR is similar to "radar" in optical fiber communication. It transmits light pulses into the fiber and captures the backscattered light signals generated by Rayleigh scattering and Fresnel reflection at the fiber core break. Based on the round-trip time difference of the light pulses, the distance to the event point is accurately calculated, thereby enabling the location of faults such as fiber length, attenuation, splice loss, and breaks.

[0004] However, because the core of hollow fiber is air, Fresnel reflection does not occur at the break point due to the refractive index interface. Furthermore, since hollow fiber uses an air core for light guidance, its backscattering is approximately 40 dB lower than that of solid fiber, which is below the detection limit of traditional commercial OTDR technology, making it difficult to meet the requirements for fiber break detection. Even using photon-counting OTDRs or OTDRs with amplifiers, the reliability of the detection results is low due to weak signal strength and excessive noise interference.

[0005] In existing technologies, some research has been conducted to address the aforementioned problems. For example, Chinese patent document CN117572557A proposes an anti-resonant hollow-core optical fiber suitable for long-distance distributed detection. This method involves placing solid-core optical fibers within the cavity region between the anti-resonant layer structural units and evaluating the detection results of hollow-core optical fiber breakage or damage by detecting the fracture or damage of the solid-core optical fiber. While this approach can achieve the application of existing detection technologies in hollow-core optical fibers to a certain extent, it overlooks the fact that solid-core optical fibers are more robust than hollow-core optical fibers. Furthermore, the solid-core optical fibers are located on the inner wall of the hollow-core optical fiber sleeve and are only distributed on one side of the fiber. When the side of the hollow-core optical fiber is locally damaged, the solid-core optical fiber may still remain intact and capable of transmitting light. This leads to an error between the breakage detection results and the actual situation, and cannot fully guarantee the accuracy of the breakage detection results. Summary of the Invention

[0006] In view of one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides a hollow anti-resonant optical fiber with breakpoint detection, its production method and optical cable, which can realize OTDR detection of optical fiber breakpoints while meeting the requirements of hollow anti-resonant optical fiber installation, thereby improving the maintenance convenience and reliability of hollow anti-resonant optical fiber.

[0007] To achieve the above objectives, one aspect of the present invention provides a hollow anti-resonant optical fiber with breakpoint detection, comprising an anti-resonant unit composed of multiple capillary glass tubes and a cladding disposed around the outer periphery of the anti-resonant unit.

[0008] The cladding contains at least one solid fiber core for fiber break detection.

[0009] The solid fiber core is a germanium-doped fiber core, which is arranged in a spiral shape on the outside of the anti-resonance unit.

[0010] As a further improvement of the present invention, in the germanium-doped fiber core, the relative refractive index difference between the germanium-doped fiber core and the cladding is not less than 2.0%.

[0011] As a further improvement of the present invention, the germanium-doped fiber core is configured to meet single-mode transmission requirements;

[0012] and / or

[0013] The solid fiber cores in the cladding are multiple fibers arranged at equal intervals in a circumferential direction; more preferably, there are 2 to 4 fibers.

[0014] and / or

[0015] The helical pitch of the germanium-doped fiber core is 5mm to 20mm.

[0016] As a further improvement of the present invention, the outer diameter of the solid fiber core is 2μm~3μm; the wall thickness of the cladding is 40μm~80μm;

[0017] and / or

[0018] The solid fiber core is located on the side of the cladding away from the anti-resonant unit.

[0019] As a further improvement of the present invention, the cladding includes an inner cladding located on the inside and an outer cladding located on the outside, and the germanium-doped fiber core is located in the outer cladding.

[0020] As a further improvement of the present invention, the germanium-doped fiber core is located at the center of the outer cladding layer in the thickness direction, and the ratio between the wall thickness of the outer cladding layer and the wall thickness of the inner cladding layer is 3:1 to 1:7.

[0021] Another aspect of the present invention provides a method for producing hollow-core anti-resonant optical fiber, for producing the aforementioned breakpoint-detectable hollow-core anti-resonant optical fiber, comprising the following processes:

[0022] (1) Select the first quartz liner tube, and according to the design parameters of the solid fiber core, open the embedding hole in the wall thickness area of ​​the first quartz liner tube, and embed the germanium-doped quartz rod in the embedding hole to make the outer sleeve.

[0023] (2) Select the second quartz liner and, according to the design parameters of the anti-resonance unit, make an anti-resonance core rod inside the second quartz liner to make the inner rod body;

[0024] (3) The inner rod is embedded and assembled in the outer sleeve to form a hollow anti-resonant optical fiber preform that is coaxial inside and out and separate from each other.

[0025] (4) Assemble the hollow anti-resonant fiber preform onto the rotating drawing tower; wherein, the tail end of the inner rod is fixedly connected, and the outer sleeve is assembled onto the rotating mechanism;

[0026] (5) The hollow anti-resonant fiber is drawn, and the inner rod is drawn and the outer sleeve is rotated and drawn at the same time, so that the outer periphery of the inner fiber drawn by the inner rod can be formed by the outer fiber drawn by the rotation of the outer sleeve, and finally a hollow anti-resonant fiber with a cladding covering the anti-resonant unit and a spiral solid fiber core is provided in the cladding.

[0027] As a further improvement of the present invention, when selecting the second quartz liner in process (2), its outer diameter is controlled. Smaller than the inner diameter of the first quartz liner ,and , The following relationship must be satisfied:

[0028] .

[0029] As a further improvement of the present invention, in process (5), the rotation speed of the outer sleeve during wire drawing is controlled to be 1 rpm to 5 rpm.

[0030] In another aspect, the present invention provides a hollow anti-resonant optical fiber cable comprising at least one hollow anti-resonant optical fiber prepared by the method for producing the hollow anti-resonant optical fiber.

[0031] As a further improvement of the present invention, the hollow anti-resonant optical fiber cable is a hybrid optical cable formed by mixing hollow optical fiber cable and solid optical fiber cable.

[0032] The hollow fiber optic cable includes at least one hollow anti-resonant fiber; the solid fiber optic cable includes at least one solid fiber unit, the solid fiber unit includes a loose tube and multiple solid fibers wrapped by the loose tube, and the specifications of the solid fibers are G.652D, G.654E or G.655.

[0033] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0034] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include:

[0035] The present invention relates to a hollow-core anti-resonant optical fiber with breakpoint detection capability, comprising an anti-resonant unit clad in a cladding layer, and at least one solid fiber core with a germanium-doped core disposed within the cladding layer. By utilizing the uniform spiral arrangement of the solid fiber core around the anti-resonant unit, the hollow-core optical fiber not only meets the application requirements of the anti-resonance effect but also possesses the function of breakpoint detection, effectively realizing the application of conventional breakpoint detection technology in hollow-core optical fibers and improving the overall performance of hollow-core optical fibers.

[0036] The hollow anti-resonant optical fiber with breakpoint detection in this invention has a simple structure and is convenient to produce and use. It can satisfy the anti-resonance effect of hollow optical fiber and realize the breakpoint detection of hollow optical fiber without affecting the anti-resonance performance of hollow optical fiber. It effectively realizes the application of conventional breakpoint detection technology (such as OTDR technology) in hollow optical fiber, further improving the convenience and reliability of hollow optical fiber application and maintenance, and has good practical value. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the end face structure of a hollow anti-resonant optical fiber with breakpoint detection in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the outer sleeve structure of the core rod used to prepare hollow anti-resonant optical fiber in an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the inner rod structure of the core rod used to prepare hollow anti-resonant optical fiber in an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of a core rod structure composed of an outer sleeve and an inner rod body in an embodiment of the present invention;

[0042] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically:

[0043] 1. Anti-resonant unit; 2. Cladding; 3. Solid fiber core; 4. Coating; 5. Outer sleeve; 6. Inner rod;

[0044] 101. Capillary glass tube; 201. Inner cladding; 202. Outer cladding; 501. First quartz liner; 502. Germanium-doped quartz rod; 601. Second quartz liner; 602. Anti-resonance glass tube. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0046] In the description of this invention, it should be understood that, unless otherwise expressly specified and limited, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0047] Furthermore, unless otherwise expressly defined, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0050] Below, for reference Figures 1-4 This invention describes a hollow anti-resonant optical fiber with breakpoint detection according to a preferred embodiment of the invention, a method for manufacturing the same, and an optical cable containing the hollow anti-resonant optical fiber.

[0051] As one aspect of the present invention, a hollow anti-resonant optical fiber with breakpoint detection is provided, the structure of which is as follows: Figure 1 As shown, the structure includes an anti-resonance unit 1 composed of multiple capillary glass tubes 101 and a cladding 2 covering the outer periphery of the anti-resonance unit 1. By utilizing the corresponding arrangement of each capillary glass tube 101 in the anti-resonance unit 1 within the cavity of the cladding 2, the hollow optical fiber exhibits an anti-resonance effect, thus meeting the requirements for the installation of a hollow anti-resonance optical fiber.

[0052] Meanwhile, at least one solid fiber core 3 for fiber break detection is provided in the cladding 2; the solid fiber core 3 is further specifically a germanium-doped fiber core, which is arranged in a spiral form on the outside of the anti-resonance unit 1.

[0053] Since the direction of optical fiber breakage is usually radial from the outside to the inside, by placing the solid fiber core 3 for detection inside the cladding 2 rather than in the cavity surrounded by the cladding 2, the solid fiber core 3 is located in the "first-breaking component" when the anti-resonant optical fiber breaks. This avoids the risk that the capillary glass tube 101 breaks before the solid fiber core 3, thus ensuring the accuracy of hollow fiber breakage detection.

[0054] By utilizing the solid fiber core 3 within the cladding 2, an optical waveguide structure is formed between the germanium-doped fiber core and the quartz cladding 2, providing conditions for fiber break detection (especially OTDR technology detection). Furthermore, the helical arrangement of the germanium-doped fiber core allows the optical waveguide structure used for detection to be uniformly distributed circumferentially on the outer wall of the anti-resonant fiber. This ensures that when the anti-resonant fiber breaks, the germanium-doped fiber core is accurately located by break detection technology, thus meeting the break detection requirements of anti-resonant fibers.

[0055] Furthermore, the transmission performance of anti-resonant optical fibers is determined by their end-face structure. Although the end-face structures of existing anti-resonant optical fibers exhibit rotational symmetry, they are mostly not perfectly circumferentially symmetrical. In such cases, if the germanium-doped fiber core in the anti-resonant end-face structure is arranged in a spiral configuration, it will inevitably affect the transmission performance of the anti-resonant optical fiber. Therefore, in the preferred embodiment of this invention, the germanium-doped fiber core is placed in the annular cladding 2. By utilizing the perfect circumferential symmetry of the annular structure, the influence on the anti-resonant end-face structure is avoided while ensuring the spiral arrangement of the detection optical waveguide, thus guaranteeing the transmission performance of the anti-resonant optical fiber.

[0056] Meanwhile, the reason for selecting the solid fiber core 3 as a germanium-doped fiber core is mainly because the softening point temperature of the germanium-doped fiber core (about 1600°C) is close to that of the pure quartz cladding 2 (about 1700°C), which can effectively reduce the interfacial stress during drawing and avoid delamination, thereby ensuring the accuracy of the solid fiber core 3 in the cladding 2.

[0057] The helical structure of germanium-doped fiber core is equivalent to a bent optical fiber. If the helical pitch is too small, the germanium-doped fiber core will be bent too much, resulting in high optical signal loss during operation and reducing the signal-to-noise ratio during OTDR testing. If the helical pitch is too large, the optical waveguide structure will be sparse on the outer periphery of the hollow fiber, which will weaken the structural advantages of the solid fiber core with a 3-helix arrangement. Based on the above technical considerations, the helical pitch of germanium-doped fiber core should be 5mm to 20mm.

[0058] Based on this, in order to ensure the uniformity of the distribution of solid fiber cores 3 around the anti-resonant unit 1 while maintaining the detection distance, in the preferred embodiment, multiple solid fiber cores 3 are arranged at equal intervals in the circumferential direction within the cladding 2. Increasing the number of solid fiber cores 3 alleviates the bending of the optical waveguide and avoids crosstalk caused by excessively dense solid fiber cores 3 during testing. Therefore, in actual setup, the number of solid fiber cores is 2 to 4; for example... Figure 1 The four shown.

[0059] Furthermore, in the germanium-doped fiber core, the relative refractive index difference between the germanium-doped fiber core and the cladding... Not less than 2.0%.

[0060] It should be noted that "relative refractive index difference" "It characterizes the degree of change in the refractive index of a substance relative to pure silicon dioxide, and is expressed by the formula: Calculate; where, The refractive index at the germanium-doped fiber core; is the refractive index of pure silicon dioxide.

[0061] By using a germanium-doped fiber core with a high concentration of doping, its refractive index is significantly increased, and a high contrast is formed between it and the pure quartz cladding 2, which enhances the OTDR backscattering signal during subsequent break point detection, thereby improving the break point detection sensitivity of the anti-resonant fiber.

[0062] In actual setup, the backscattering coefficient of the high germanium-doped fiber core is about 15 dB higher than that of pure silica, which can compensate for the low scattering (-40 dB) of hollow fiber, so that the signal-to-noise ratio during OTDR detection is improved by no less than 10 dB, thereby effectively ensuring the breakpoint detection sensitivity of the anti-resonant fiber.

[0063] More specifically, in the preferred embodiment, the germanium-doped fiber core is configured to satisfy single-mode transmission.

[0064] Based on single-mode transmission conditions: normalized frequency parameters <2.405; combined with the calculation formula for the normalized frequency parameter: In the formula, The core radius; The operating wavelength; Let be the numerical aperture of the optical fiber. We can obtain: At this point, as long as the working wavelength of the detection light satisfies the above relationship, the germanium-doped fiber core can meet the requirements of single-mode transmission.

[0065] In one specific embodiment, the outer diameter of the solid fiber core 3 ( The wavelength is 2μm to 3μm. Based on this, the operating wavelength of the solid fiber core 3 for single-mode transmission can be quickly selected.

[0066] For example, in one specific embodiment, the outer diameter of the solid fiber core 3 is 3 μm, and the numerical aperture of the optical fiber is... The value is 0.22; at this point, a detection light with a working wavelength of 1310nm is selected, and the normalized frequency parameter is calculated as follows:

[0067]

[0068] Clearly, the solid fiber core 3 at this point meets the requirements for single-mode transmission. Furthermore, in the aforementioned embodiment, as long as the operating wavelength of the detection light is greater than 860nm, the single-mode transmission requirements of the solid fiber core 3 can be met. This provides sufficient convenience for selecting the breakpoint detection conditions and simplifies the breakpoint detection process for hollow-core anti-resonant optical fibers.

[0069] The small core diameter design of the solid core 3 (compared to the conventional core outer diameter of 8μm~10μm) ensures that the solid core 3 can be embedded in thin-walled structures (corresponding to a cladding wall thickness typically no greater than 50μm), while also avoiding a significant impact on the optical performance of the hollow fiber due to the solid core 3. Furthermore, the single-mode transmission configuration not only supports long-distance transmission during breakpoint detection but also ensures the stability of the OTDR detection signal.

[0070] Furthermore, in the preferred embodiment, the cladding 2 of the hollow anti-resonant optical fiber has a wall thickness of 40μm~80μm, and is more preferably 60μm.

[0071] Furthermore, when the solid fiber core 3 is provided, it is preferably located on the side of the cladding 2 away from the anti-resonant unit 1.

[0072] More specifically, in actual configuration, the cladding 2 includes an inner cladding 201 located on the inside and an outer cladding 202 located on the outside. In this case, the germanium-doped fiber core is preferably located in the outer cladding 202, and more preferably located at the center of the outer cladding 202 in the thickness direction.

[0073] In a specific example, the germanium-doped fiber core is located at the center of the outer cladding 202.

[0074] More specifically, for the inner cladding 201 and the outer cladding 202, which are separated into inner and outer layers, the wall thicknesses of the two preferably satisfy the following ratio relationship: the ratio between the wall thickness of the outer cladding 202 and the wall thickness of the inner cladding 201 is 3:1 to 1:7.

[0075] It is understandable that the aforementioned size ratio design can be achieved by selecting the pure quartz liner and designing the size of the germanium-doped quartz core rod during the preform manufacturing process, which will not be elaborated here.

[0076] More preferably, for the hollow anti-resonant optical fiber in the preferred embodiment, a coating 4, such as an acrylic resin coating, is further provided on the outer side of its cladding 2. The number of layers can be a single layer or multiple layers, in order to balance the mechanical strength and bending performance of the optical fiber.

[0077] As another aspect of the present invention, a method for producing hollow anti-resonant optical fiber is further provided for producing the aforementioned breakpoint-detectable hollow anti-resonant optical fiber.

[0078] Specifically, the preferred method for producing hollow antiresonant optical fiber includes the following processes:

[0079] (1) Select the first quartz liner 501, and according to the design parameters of the solid fiber core 3, open an embedding hole in the wall thickness area of ​​the first quartz liner 501, and embed a germanium-doped quartz rod 502 in the embedding hole to make it as shown in the figure. Figure 2 The outer sleeve 5 shown in the figure;

[0080] Specifically, during the fabrication of the outer sleeve 5, the preferred design parameters of the solid fiber core 3 include the ratio between the outer diameter of the solid fiber core 3 and the wall thickness of the outer cladding 202, and the placement position of the solid fiber core 3 in the direction of the wall thickness of the outer cladding 202.

[0081] Of course, for the germanium-doped quartz rod 502, its outer diameter needs to correspond to the wall thickness of the first quartz liner 501 during manufacturing, that is, to the design ratio between the outer diameter of the solid fiber core 3 and the wall thickness of the outer cladding 202. At the same time, the molar concentration of germanium doping in the design of the solid fiber core 3 also needs to be considered, which will not be elaborated here.

[0082] (2) Select the second quartz liner 601, and according to the design parameters of the anti-resonance unit 1, fabricate an anti-resonance core rod inside the second quartz liner 601, as shown in the figure. Figure 3 The inner rod 6 shown in the figure;

[0083] It should be noted that the technology for fabricating the anti-resonant core rod based on the anti-resonant glass tube 602 is a known prior art and is not the core design of this invention, so it will not be elaborated here.

[0084] Meanwhile, the selection of the second quartz liner 601 is based on the wall thickness ratio between the inner cladding 201 and the outer cladding 202, as well as the wall thickness of the first quartz liner 501.

[0085] More specifically, in actual installation, the wall thickness of the first quartz liner 501 is 5mm to 10mm, and the wall thickness of the second quartz liner 601 is 0.2mm to 1mm. Furthermore, the wall thickness of the glass tube forming the anti-resonance unit 1 is preferably 0.1mm to 0.5mm.

[0086] (3) The inner rod 6 is embedded and assembled in the outer sleeve 5 to form a hollow anti-resonant optical fiber preform that is coaxial inside and out and separate from each other.

[0087] (4) Assemble the hollow anti-resonant optical fiber preform onto the rotating drawing tower; wherein, the tail end of the inner rod 6 is fixedly connected, and the outer sleeve 5 is assembled onto the rotating mechanism.

[0088] When assembling hollow anti-resonant optical fiber preforms, the coaxiality between the inner rod body 6 and the outer sleeve 5 must be fully considered to avoid errors during subsequent fiber drawing.

[0089] (5) The hollow anti-resonant fiber is drawn, and the inner rod 6 and the outer sleeve 5 are drawn simultaneously, so that the outer periphery of the inner fiber drawn by the inner rod 6 can be simultaneously formed by the outer fiber drawn by the outer sleeve 5. Finally, a hollow anti-resonant fiber is obtained, in which the anti-resonant unit 1 is covered by the cladding 2 and a spiral solid fiber core 3 is provided in the cladding 2. Figure 1 As shown in the image.

[0090] Furthermore, since the outer sleeve 5 needs to be rotated throughout the wire drawing process while the inner rod 6 remains stationary, a certain gap needs to be maintained between the inner rod 6 and the outer sleeve 5. Figure 4 The gap W shown in the figure.

[0091] In practical applications, the gap design between the inner rod 6 and the outer sleeve 5 significantly impacts the difficulty and quality of hollow anti-resonant fiber drawing. If the gap is too small, high precision is required in the assembly and control of the preform on the drawing tower. Extremely high coaxiality between the inner rod 6 and the outer sleeve 5 during assembly and rotational drawing is essential; otherwise, contact friction will occur, affecting the reliability of fiber drawing. Conversely, if the gap is too large, it may affect the uniformity of the cladding 2 after cooling, resulting in obvious inner and outer cladding boundaries, or even introducing microscopic gaps, thus impacting the performance of the hollow anti-resonant fiber.

[0092] In the preferred embodiment, considering the influence of various factors, when selecting the second quartz liner 601 in the aforementioned process (2), its outer diameter is controlled. Smaller than the inner diameter of the first quartz liner 501 ,and , The following relationship must be satisfied:

[0093] .

[0094] As an example, after the hollow anti-resonant optical fiber preform is coaxially assembled, the gap between the inner wall of the outer sleeve 5 and the outer wall of the inner rod 6 is preferably no more than 0.5 mm.

[0095] More preferably, in the aforementioned process (5), the rotation speed of the outer sleeve 5 during wire drawing is controlled to be 1 rpm to 5 rpm.

[0096] Based on the aforementioned production method design, the drawing production of hollow anti-resonant optical fiber can be accurately completed, resulting in hollow optical fiber that satisfies both the anti-resonance effect and the requirements for breakpoint detection.

[0097] Based on this, a preferred embodiment of the present invention further proposes a hollow anti-resonant optical fiber cable, which contains at least one hollow anti-resonant optical fiber prepared by the aforementioned hollow anti-resonant optical fiber production method.

[0098] More preferably, according to the needs of actual applications, the aforementioned hollow-core anti-resonant optical fiber cable is a hybrid optical cable formed by mixing hollow-core optical fiber cables and solid-core optical fiber cables. The hollow-core optical fiber cable includes at least one of the aforementioned hollow-core anti-resonant optical fibers. The solid-core optical fiber cable includes at least one solid-core optical fiber unit, and the solid-core optical fiber unit includes a loose tube and multiple solid-core optical fibers wrapped by the loose tube. More specifically, the specifications of the solid-core optical fibers are G.652D, G.654E, or G.655.

[0099] During the laying and use of the aforementioned hollow-core anti-resonant optical fiber cable, when there is a need to detect breaks in the hollow-core optical fiber, the detection can be completed based on the following process:

[0100] The hollow fiber is connected to the OTDR testing equipment, and the solid fiber core 3 in the cladding 2 is illuminated to detect the location of any abnormality or break in the solid fiber core 3. The ratio between the length of the abnormal location and the total length of the solid fiber core 3 is calculated, and the actual location of the break on the hollow anti-resonant fiber is calculated based on this ratio, thereby realizing the detection of break on the hollow anti-resonant fiber.

[0101] Obviously, based on the calculation of the ratio of the detected breakpoint length of solid fiber core 3 to the total length of solid fiber core 3, the length difference caused by the spiral arrangement of solid fiber core 3 (the length difference between solid fiber core 3 and the actual length of optical fiber) is simplified, the breakpoint location determination process during breakpoint detection is simplified, the amount of calculation is saved and the accuracy of abnormal location detection is improved.

[0102] The hollow anti-resonant optical fiber with breakpoint detection in this invention has a simple structure and is convenient to produce and use. It can satisfy the anti-resonance effect of hollow optical fiber and realize the breakpoint detection of hollow optical fiber without affecting the anti-resonance performance of hollow optical fiber. It effectively realizes the application of conventional breakpoint detection technology (such as OTDR technology) in hollow optical fiber, further improving the convenience and reliability of hollow optical fiber application and maintenance, and has good practical value.

[0103] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hollow anti-resonant optical fiber with breakpoint detection, comprising an anti-resonant unit composed of multiple capillary glass tubes and a cladding layer surrounding the anti-resonant unit; characterized in that, The cladding contains at least one solid fiber core for fiber break detection. The solid fiber core is a germanium-doped fiber core, which is arranged in a spiral shape on the outside of the anti-resonance unit.

2. The hollow-core anti-resonant optical fiber with breakpoint detection according to claim 1, characterized in that, In the germanium-doped fiber core, the relative refractive index difference between the germanium-doped fiber core and the cladding is not less than 2.0%.

3. The hollow-core anti-resonant optical fiber with breakpoint detection according to claim 2, characterized in that, The germanium-doped fiber core is configured to meet single-mode transmission requirements; and / or The solid fiber cores in the cladding are multiple ones arranged at equal intervals in a circumferential direction; and / or The helical pitch of the germanium-doped fiber core is 5mm to 20mm.

4. The hollow-core anti-resonant optical fiber with breakpoint detection according to any one of claims 1 to 3, characterized in that, The outer diameter of the solid fiber core is 2μm~3μm; the wall thickness of the cladding is 40μm~80μm; and / or The solid fiber core is located on the side of the cladding away from the anti-resonant unit.

5. The hollow-core anti-resonant optical fiber with breakpoint detection according to claim 4, characterized in that, The cladding includes an inner cladding located on the inside and an outer cladding located on the outside, with the germanium-doped fiber core located in the outer cladding.

6. The hollow-core anti-resonant optical fiber with breakpoint detection according to claim 5, characterized in that, The germanium-doped fiber core is located at the center of the outer cladding layer in the thickness direction, and the ratio between the wall thickness of the outer cladding layer and the wall thickness of the inner cladding layer is 1:7 to 3:

1.

7. A method for producing hollow-core anti-resonant optical fiber, used to produce hollow-core anti-resonant optical fiber with breakpoint detection as described in any one of claims 1 to 6, characterized in that, The production method includes the following processes: (1) Select the first quartz liner tube, and according to the design parameters of the solid fiber core, open the embedding hole in the wall thickness area of ​​the first quartz liner tube, and embed the germanium-doped quartz rod in the embedding hole to make the outer sleeve. (2) Select the second quartz liner and, according to the design parameters of the anti-resonance unit, make an anti-resonance core rod inside the second quartz liner to make the inner rod body; (3) The inner rod is embedded and assembled in the outer sleeve to form a hollow anti-resonant optical fiber preform that is coaxial inside and out and separate from each other. (4) Assemble the hollow anti-resonant fiber preform onto the rotating drawing tower; wherein, the tail end of the inner rod is fixedly connected, and the outer sleeve is assembled onto the rotating mechanism; (5) The hollow anti-resonant fiber is drawn, and the inner rod is drawn and the outer sleeve is rotated and drawn at the same time, so that the outer periphery of the inner fiber drawn by the inner rod can be formed by the outer fiber drawn by the rotation of the outer sleeve, and finally a hollow anti-resonant fiber with a cladding covering the anti-resonant unit and a spiral solid fiber core is provided in the cladding.

8. The method for producing hollow anti-resonant optical fiber according to claim 7, characterized in that, When selecting the second quartz liner in process (2), control its outer diameter. Smaller than the inner diameter of the first quartz liner ,and , The following relationship must be satisfied: 。 9. The method for producing hollow anti-resonant optical fiber according to claim 7 or 8, characterized in that, In process (5), the rotation speed of the outer sleeve during wire drawing is controlled to be 1 rpm to 5 rpm.

10. A hollow-core anti-resonant optical fiber cable, characterized in that, The hollow anti-resonant optical fiber cable includes at least one hollow anti-resonant optical fiber prepared by the production method of hollow anti-resonant optical fiber according to any one of claims 7 to 9.

11. The hollow-core anti-resonant optical fiber cable according to claim 10, characterized in that, The hollow anti-resonant optical fiber cable is a hybrid optical cable formed by mixing hollow optical fiber cable and solid optical fiber cable. The hollow fiber optic cable includes at least one hollow anti-resonant fiber; the solid fiber optic cable includes at least one solid fiber unit, the solid fiber unit includes a loose tube and multiple solid fibers wrapped by the loose tube, and the specifications of the solid fibers are G.652D, G.654E or G.655.

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