Hollow core fiber ribbon with axial visualizing marks, optical cable and method of manufacturing thereof

Abstract

The application belongs to the field of optical communication and specifically discloses a hollow-core fiber ribbon with axial visualized marking, an optical cable and a preparation method. The fiber ribbon comprises a plurality of hollow-core anti-resonance optical fibers and a ribbon resin. Each hollow-core anti-resonance optical fiber comprises a cladding, a plurality of anti-resonance units and a coating. The plurality of anti-resonance units are distributed inside the cladding. The cladding has a first mark on the outer profile surface. The relative position of the first mark and the plurality of anti-resonance units is consistent in the length direction. The coating has a second mark corresponding to the first mark on the outer profile surface. The two marks are continuously consistent from the beginning to the end in the length direction of the entire hollow-core anti-resonance optical fiber. The application also provides an optical cable comprising the above fiber ribbon and a preparation method of the fiber ribbon. The application overcomes the problem of insufficient accuracy in positioning the hollow-core anti-resonance optical fiber direction by only marking the positioning surface or end face of the optical fiber coating.

Description

Technical Field

[0001] This application belongs to the field of optical communication, and more specifically, relates to a hollow optical fiber ribbon with axial visual markings, an optical cable, and a method for preparing the same. Background Technology

[0002] Antiresonant optical fibers possess numerous advantages, including ultra-low loss, low dispersion, low nonlinearity, and near-light speed of propagation. With the deepening research into hollow-core antiresonant optical fibers based on the antiresonance principle, a rationally designed hollow-core antiresonant optical fiber can effectively reduce transmission loss, demonstrating its potential as an ultra-long-distance communication fiber and its prospects for large-scale application. It is widely recognized as the next-generation fiber for ultra-high capacity, low latency, and high-speed optical communication systems.

[0003] With the rapid increase in data transmission demand, optical cable structures are gradually developing towards higher core counts and higher fiber density. Simultaneously, to better reduce splicing costs and improve efficiency, the preferred structures mostly employ ribbon fiber cables capable of splicing multiple fibers at once. Traditional optical fibers, with their circular cores and claddings, only require core alignment for splicing, resulting in low splicing loss. However, while hollow-core antiresonant fibers possess rotational symmetry, they lack perfect circular symmetry. Therefore, they cannot be freely rotated relative to each other; otherwise, the antiresonant ring and the core region cannot be properly aligned, leading to high splicing loss and even complete loss of light transmission.

[0004] Chinese patent document CN120195823A discloses a hollow-core anti-resonant fiber ribbon and its preparation method. The aim is to maintain the azimuth consistency of the fibers arranged side-by-side in the fiber ribbon by splicing hollow-core anti-resonant fibers with parallel positioning surfaces. This allows each fiber in the fiber ribbon to be matched with the anti-resonant microstructure during fusion splicing, achieving precise end-face matching. This solves the technical problems of difficulty in individually matching the end faces of each fiber in the hollow-core anti-resonant fiber ribbon and the high splicing loss. The consistency of this hollow-core anti-resonant fiber ribbon, which utilizes a non-circular coating for positioning, primarily depends on the stable positional relationship between the non-circular coating and the azimuth angle of the anti-resonant fiber.

[0005] Chinese patent document CN117405355A discloses a method for detecting the end face of hollow-core anti-resonant optical fiber and a marked hollow-core anti-resonant optical fiber. This anti-resonant optical fiber, which achieves end-face asymmetry, is marked by end-face markings. In this scheme, the cladding or the inner side of the cladding is marked; however, these asymmetrical markings are only visible on the end-face image for end-face splicing matching, and there are no identifiable markings on the axial side of the anti-resonant optical fiber. In the large-scale production of optical fiber ribbons and cables, axial continuous production lines are used. End-face markings only match the azimuth angle of the fiber end face with the coating mold at the beginning of production, and cannot guarantee that the optical fiber will not rotate circumferentially during the production of optical cables thousands of meters long. In actual production, the azimuth angle deviation caused by this circumferential rotation severely affects the axial consistency of the optical fiber ribbon. Although the azimuth angles of the coatings on multiple fibers in a single optical fiber ribbon are consistent, the orientation of the microstructure relative to the anti-resonant optical fiber changes along the axial direction for the coating on a single fiber, still failing to solve the problem of inconsistent azimuth angles among multiple fibers in a hollow-core anti-resonant optical fiber ribbon. To put it more simply, if the fiber is long enough, it is easy to ensure the azimuth consistency of the fiber coating. However, the fiber is prone to rotation. When the fiber rotates relative to the fiber coating, ensuring the azimuth consistency of the fiber coating only makes it appear consistent on the surface. Ultimately, it is still necessary to ensure the axial consistency of the microstructure of the anti-resonant fiber.

[0006] Therefore, there is a need to develop a hollow fiber ribbon, optical cable, and its fabrication method with axially visualized markings. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this application is to provide a hollow fiber ribbon, optical cable, and its preparation method with axial visualization markings, aiming to solve the problem that the positioning of hollow anti-resonant optical fibers is not accurate enough when the fiber is positioned by marking the fiber coating positioning surface or fiber end face.

[0008] To achieve the above objectives, in a first aspect, this application provides a hollow fiber ribbon with axially visible markings, comprising:

[0009] Multiple hollow anti-resonant optical fibers with identical end-face structures are provided. Each hollow anti-resonant optical fiber includes a cladding, a plurality of anti-resonant units distributed inside the cladding, and a coating. The outer contour surface of the cladding has a first mark, which is aligned with the relative position of the plurality of anti-resonant units along its length. The coating covers the cladding and has a second mark corresponding to the first mark on its outer contour surface. The first mark and the second mark are continuous along the entire length of the hollow anti-resonant optical fiber.

[0010] Multiple hollow anti-resonant optical fibers are fixed side-by-side in the resin in a specified orientation.

[0011] In the above-described invention, the first mark is located on the outer contour surface of the cladding, and the second mark is located on the coating. Both the first mark on the cladding and the second mark on the coating are continuous along the entire length of the hollow anti-resonant fiber, visible from the outer surface. This significantly differs from existing hollow anti-resonant fiber markings, which are located on the inner surface of the cladding and can only be observed from the end face. The lack of identifiable markings on the axial side of the anti-resonant fiber, only observable on the end face, presents a practical engineering defect. In the large-scale production of fiber ribbons and cables, axially continuous production lines are used. The end-face marking only matches the azimuth angle between the fiber end face and the coating mold at the beginning of production. It cannot track whether the fiber is rotating during the drawing process, and cannot guarantee that the fiber will not rotate circumferentially during the production of fibers thousands of meters long, resulting in a tracking blind zone. In reality, the fiber may twist during drawing, and the end-face marking cannot reflect this twisting. The first mark, continuous along the entire length of the outer cladding, facilitates the reflection of the drawing process and can correspondingly track whether the fiber is twisting. Referring to the second mark on the coating, which is the first mark on the cladding, it can reliably reflect whether twisting occurred during the drawing process. Correspondingly, the first mark is associated with the second mark, and the relationship between the first mark and the anti-resonance unit is fixed. Ultimately, the direction of the anti-resonance unit can be calibrated by the second mark. This calibration is precise and unique, and exists throughout the length direction.

[0012] Furthermore, the first mark and the second mark maintain the same relative position in the length direction throughout, and both the first mark and the second mark maintain the same relative position in the length direction as the plurality of anti-resonant units.

[0013] Furthermore, the first mark is an additive structure, subtractive structure, or color identifier of the glass cladding, wherein the color identifier is a color different from the main body color of the cladding; and / or the second mark is an additive structure, subtractive structure, marking color, or positioning surface structure of the outermost coating, wherein the marking color is a color different from the main body color of the coating. The second mark can be used to disrupt the symmetry of the coating and identify the position of each anti-resonant unit.

[0014] Furthermore, the additive structure is a protruding ridge, the subtractive structure is a groove, the color mark is colored glass, and the marking color is a colored line.

[0015] Furthermore, the positioning surface structure is at least one positioning surface on the outermost coating, and the cross-section of the entire coating has only one axis of symmetry or the cross-section of the entire coating is an asymmetrical structure.

[0016] Furthermore, the first mark is obtained simultaneously during the hollow anti-resonant fiber drawing process, and the second mark is obtained simultaneously during the outermost coating preparation process. The first mark and the second mark are added as the axial length of the cladding and the axial length of the coating increase, respectively.

[0017] Secondly, a hollow fiber ribbon as described above is provided, wherein the hollow fiber ribbon has an externally detectable mark for locating the position of the anti-resonance unit, so that the anti-resonance unit is set in a specified position when the fiber ribbon is made, and the position of the fiber in different fiber ribbons is clear when the fiber ribbon is spliced, so that the whole ribbon can be accurately spliced ​​in one go.

[0018] Thirdly, a method for fabricating a hollow-core optical fiber ribbon with axially visible markings as described above is provided. First, a hollow-core anti-resonant optical fiber is fabricated. The hollow-core anti-resonant optical fiber preform is drawn, and the drawing process naturally accompanies the fabrication of a first marking on the outer contour surface of the cladding. After drawing, during optical fiber coating, a second marking corresponding to the first marking is fabricated using a coating mold. The first marking and the second marking increase continuously and consistently with the increase of the axial length of the cladding and the axial length of the coating, respectively.

[0019] Multiple hollow anti-resonant optical fibers are arranged side by side, with the axial visual markings of these fibers positioned in a specified orientation relative to the fiber ribbon's arrangement direction.

[0020] A photocurable resin is coated on the outside of the multiple hollow anti-resonant optical fibers arranged side by side and then cured to form a resin-coated structure, thereby fixing the position of the multiple hollow anti-resonant optical fibers.

[0021] Furthermore, in the step of preparing hollow anti-resonant optical fiber: the first mark on the outer contour surface of the cladding is monitored by a visual monitoring device, and axially aligned with the second mark on the newly prepared optical fiber length portion. The coating mold is adjusted by axial rotation in real time, or the newly drawn fiber without coating is adjusted by axial rotation in real time, so as to ensure that the positions of the second mark and the first mark are synchronized in real time.

[0022] Furthermore, in the step of fabricating hollow anti-resonant optical fiber, after machining the hollow anti-resonant optical fiber preform to obtain a subtractive prestructure, fiber drawing is performed; alternatively, an additive prestructure / colored glass preform is combined with the hollow anti-resonant optical fiber preform and then drawn together. During the fiber drawing process, the subtractive prestructure, additive prestructure, or colored glass preform naturally form the first mark on the outer contour surface of the cladding.

[0023] When coating the optical fiber after drawing, a second mark is prepared on the outer coating by means of the coating mold corresponding to the structure. The coating mold corresponding to the structure is a local radially outward protrusion, a radially inward depression, or the shape of the mold outlet cross section.

[0024] Furthermore, in the step of preparing hollow anti-resonant optical fiber: axial cutting is performed on the hollow anti-resonant optical fiber preform to obtain a groove as a subtractive prestructure, followed by drawing; or, a long glass rod is combined as an additive prestructure on the hollow anti-resonant optical fiber preform to form a whole, followed by merging and drawing to obtain a protruding ridge; or, a striped glass preform is combined on the hollow anti-resonant optical fiber preform to form a whole, followed by merging and drawing to obtain a striped glass mark that is fused into the cladding component.

[0025] Furthermore, in the step of preparing hollow anti-resonant optical fiber, a suitable tension state is maintained during fiber drawing, specifically a low tension state, such as a tension of 20-50g, so as to simultaneously ensure the structural integrity of the inner side of the cladding and that the first mark on the outer contour surface of the cladding is not blurred or disappears, but can be clearly present.

[0026] Meanwhile, axial circumferential heating is used during wire drawing to ensure uniform temperature and reduce surface tension differences caused by thermal stress.

[0027] The drawing speed is controlled below 500m / min, and the drawing temperature is 1900℃~2200℃.

[0028] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art:

[0029] (1) In this invention, the azimuth angle of each optical fiber in the optical fiber strip is directly determined by the first mark of the cladding. The positional relationship between the second mark of the coating and the first mark of the cladding is always corresponding. The second mark is continuously present in the entire length direction of the optical fiber. The second mark and the anti-resonance unit of the optical fiber are uniquely determined and correspond to each other. There is no ambiguity in the prior art where the initial end face mark of the optical fiber corresponds to the anti-resonance unit in the optical fiber over several kilometers. In this invention, the second mark of the coating can accurately calibrate the anti-resonance unit in real time, and the consistency of the azimuth of each optical fiber is guaranteed.

[0030] (2) In this invention, when the fiber ribbon is fused, it is only necessary to align the fiber ribbon for fusion, without stripping a long single fiber for single fiber end face alignment and fusion, which greatly improves the fusion efficiency. At the same time, it will not cause the fiber ribbon to have inconsistent azimuth angles, resulting in excessive loss or non-connection of some fibers after fusion.

[0031] (3) In the method for preparing hollow fiber ribbon in this invention, the drawing process is naturally accompanied by the preparation of the first mark on the outer contour surface of the cladding. The cladding and anti-resonance unit are fixed components of the optical fiber. The orientation of the first mark and the anti-resonance unit is always fixed. When the optical fiber is coated after drawing, a second mark corresponding to the first mark is prepared by the coating mold. The first mark and the second mark increase continuously and consistently with the increase of the axial length of the cladding and the axial length of the outermost coating, respectively, which always ensures that the relationship between the second mark and the first mark is fixed, real-time and accurate.

[0032] (4) In the method for preparing hollow fiber ribbon in this invention, the second mark on the newly prepared fiber length portion is monitored by a visual monitoring device, and the coating mold is adjusted by axial rotation in real time or the new fiber without coating is adjusted by axial rotation in real time. This ensures that the positions of the second mark and the first mark are synchronized in real time, and the relationship between the second mark, the first mark and the anti-resonance unit orientation is fixed accurately and in real time, thus ensuring the accuracy of the anti-resonance unit orientation by the second mark. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a hollow fiber ribbon cross-section structure with axial visual markings provided in Embodiment 1 of this application, wherein the first and second markings are both raised ridges.

[0034] Figure 2 This is a schematic diagram of a hollow fiber ribbon cross-section structure with axial visual markings provided in Embodiment 2 of this application. The first marking is a groove, and the second marking is a coating positioning surface structure. In this embodiment, the positioning surface structure includes a pair of parallel planes, which are connected by a plane and an arc-shaped surface, respectively.

[0035] Figure 3 This is a schematic diagram of a hollow fiber ribbon cross-section structure with axial visualization markings provided in Embodiment 3 of this application. The first marking is also a groove, and the second marking is a coating positioning surface structure. In this embodiment, the cross-section of the positioning surface structure is octagonal, and the octagon has only one axis of symmetry along the center, and only one unique axis of symmetry.

[0036] Figure 4 This is a schematic diagram of a hollow fiber ribbon cross-section structure with axial visualization markings provided in Embodiment 4 of this application. The first marking is colored glass, and the second marking is a coating positioning surface structure. The coating positioning surface structure in this embodiment is the same as that in Embodiment 2.

[0037] Figure 5 This is an axial view of an anti-resonant optical fiber with axial visualization markings provided in an embodiment of this application.

[0038] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0039] 1 is the first mark, 2 is the second mark, 3 is the anti-resonance unit, 4 is the cladding, 5 is the coating, 6 is the resin, and 7 is the positioning surface. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0042] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, endpoint values ​​of various ranges, endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention. Process parameters in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0043] The embodiments of this application are described below with reference to the accompanying drawings.

[0044] Example 1

[0045] See Figure 1 This embodiment provides a hollow fiber ribbon with axially visible markings. In its cross-sectional view, the outermost layer is a parallel resin 6. In this embodiment, four hollow anti-resonant fibers are fixed side-by-side in the parallel resin at a specified orientation. The four hollow anti-resonant fibers have different orientations, with adjacent anti-resonant fibers differing by 180°. The first mark 1 on the cladding is a raised ridge, and the coating 5 has a corresponding second mark 2, which is also a raised ridge. The raised ridges on the coating 5 and the raised ridges on the cladding 4 are stacked. Inside the cladding, there is an anti-resonant unit 3, and the hollow cavity formed by the anti-resonant unit 3 is the fiber core.

[0046] The method for preparing the hollow fiber ribbon in this embodiment is as follows:

[0047] (1) Preparation of hollow anti-resonant optical fiber. Specifically, a glass rod is fused onto a hollow anti-resonant optical fiber preform as an additive prestructure, forming a whole. Then, a merging and drawing process is performed. During the drawing process, the glass rod, acting as the additive prestructure, naturally forms a raised ridge on the outer contour surface of the cladding, which is the first mark 1. When preparing the optical fiber coating after drawing, the inner side of the inlet and outlet molds of the coating mold is designed with local radial outward protrusions to form the second mark. The protrusion of the inlet mold controls the first mark 1 of the cladding to be introduced into the mold along the direction set by the mold, and the protrusion of the outlet mold ensures that the second mark of the coating is generated along the specified direction. Precise positioning of the inlet and outlet molds ensures the relative positions of the first mark 1 and the second mark 2. The width of the first mark 1 on the outer circular contour surface of the cladding is approximately 50 μm, and its height is 15 μm.

[0048] The fiber drawing process and the coating preparation process are sequential, with coating preparation taking place shortly after fiber drawing on the same production line. A high-speed camera monitors the second mark 2 on the newly prepared fiber length and compares it axially with the first mark 1 on the cladding outer contour surface, which is also monitored by the high-speed camera. If a deviation in the relative axial positions of the first mark 1 and the second mark 2 is detected, the newly drawn fiber without coating is rotated and adjusted in real time to ensure that the position of the first mark 1 on the newly drawn fiber corresponds to the location where the second mark 2 is prepared by the coating mold. This ensures that the positions of the second mark 2 and the first mark 1 are synchronized in real time.

[0049] Maintaining a suitable tension during wire drawing ensures the structural integrity of the inner cladding layer and prevents the first mark 1 on the outer contour surface of the cladding layer from becoming blurred or disappearing. Specifically, this suitable tension refers to low tension, between 20-40g. Simultaneously, axial circumferential heating is employed during wire drawing to ensure uniform temperature control, thereby reducing surface tension differences caused by thermal stress. The wire drawing speed is controlled at 100m / min, and the wire drawing temperature is between 1900-2200℃.

[0050] (2) Arrangement steps of multiple hollow anti-resonant optical fibers. Four hollow anti-resonant optical fibers are arranged side by side. The axial visual mark of the four hollow anti-resonant optical fibers arranged side by side is in a specified position relative to the arrangement direction of the optical fiber strip, that is, the orientation of adjacent anti-resonant optical fibers differs by 180°.

[0051] (3) Resin filling and curing. A photocurable resin is coated onto the outer side of the multiple hollow anti-resonant optical fibers arranged side-by-side and then cured to form a transparent layer with resin 6, thus fixing the position of the multiple hollow anti-resonant optical fibers. In this embodiment, the resin is polyacrylic acid resin, and the curing process is ultraviolet curing.

[0052] Example 2

[0053] See Figure 2 , Figure 2 This is a schematic diagram of a hollow fiber ribbon cross-section structure with axially visible markings provided in Embodiment 2 of this application. The first marking 1 is a groove on the cladding 4, and the second marking 2 is a coating positioning surface structure. In this embodiment, the positioning surface 7 structure includes a pair of parallel planes, connected by a plane and an arc-shaped surface, respectively. Its cross-section is similar to the cross-section of a long loaf of toast.

[0054] Depend on Figure 2 It is known that the outermost layer is a parallel resin 6. In this embodiment, four hollow anti-resonant optical fibers are fixed side by side in the parallel resin 6 with the same orientation, and all anti-resonant optical fibers have the same orientation. The first mark 1 on the cladding is a recessed groove, and the coating 5 has a positioning surface 7. The positioning surface 7 is unique and distinguishable on the cross-section of the hollow anti-resonant optical fiber, and can clearly distinguish the positioning surface from the non-positioning surface, ensuring the uniqueness of the marked second mark 2. The positioning surface 7 on the outer contour surface of the coating 5 forms the second mark 2. There are multiple anti-resonant units 3 inside the cladding, and the hollow cavity formed by the multiple anti-resonant units 3 is the optical fiber core.

[0055] The method for preparing the hollow fiber ribbon in this embodiment is as follows:

[0056] (1) Preparation of hollow anti-resonant fiber. Specifically, the hollow anti-resonant fiber preform is cut along the axial direction to obtain an axial groove, and the hollow anti-resonant fiber preform with the axial groove is drawn. The width of the first mark 1 on the outer circumference of the cladding is about 60 μm, and the groove depth is 15 μm. During the drawing process, the groove, as a subtractive prestructure, naturally forms an axial groove on the outer contour surface of the cladding, which is the first mark 1. When the fiber is coated after drawing, the corresponding second mark 2 is prepared by the cross-sectional shape of the mold exit on the coating mold. The inner side of the inlet mold of the coating mold is designed with a local radial inward protrusion. The protrusion of the inlet mold can match the first mark 1 of the cladding and guide it into the mold along the direction set by the mold. By designing the cross-section of the outlet mold, the outer contour surface of the coating is matched. After the coating passes through the outlet of the mold, it is naturally molded into the cross-sectional shape of the outlet mold to obtain the corresponding outer contour surface of the coating. By accurately matching the inlet and outlet of the coating mold, the relative positions of the first mark 1 and the second mark 2 can be guaranteed.

[0057] The wire drawing process and the coating preparation process are sequential, with the coating being prepared shortly after wire drawing on the same production line. A high-speed camera monitors the first mark 1 on the outer contour surface of the cladding. When a deviation in the axial relative position of the first mark 1 and the second mark 2 is detected, the newly drawn wire, which has not yet been coated, is adjusted axially in real time to ensure that the position of the first mark 1 on the new wire corresponds to the position of the coating mold. This ensures that the positions of the second mark 2 and the first mark 1 are synchronized in real time.

[0058] Maintaining a suitable tension during wire drawing ensures the structural integrity of the inner cladding layer and prevents the first mark 1 on the outer contour surface of the cladding layer from becoming blurred or disappearing. This suitable tension specifically refers to a low tension state, approximately 20-40g. Simultaneously, axial circumferential resistance wire rotation heating is employed during wire drawing to ensure uniform temperature control, thereby reducing surface tension differences caused by thermal stress. The wire drawing speed is controlled at 100m / min, and the wire drawing temperature is 1900-2200℃.

[0059] (2) Arrangement steps of multiple hollow anti-resonant optical fibers. Four hollow anti-resonant optical fibers are arranged side by side, and the axial visual markings of the four hollow anti-resonant optical fibers arranged side by side are in the same direction relative to the fiber ribbon.

[0060] (3) Resin filling and curing. A photocurable resin is coated onto the outer side of the multiple hollow anti-resonant optical fibers arranged side-by-side and then cured to form a transparent layer with resin 6, thus fixing the position of the multiple hollow anti-resonant optical fibers. In this embodiment, the resin is polyacrylic acid resin, and the curing process is ultraviolet curing.

[0061] Example 3

[0062] See figure. Figure 3 This is a schematic diagram of the cross-sectional structure of a hollow fiber ribbon with axially visible markings provided in Embodiment 3 of this application. The first mark 1 is also a groove, similar to the first mark 1 in Embodiment 2. The second mark 2 is a positioning surface on the coating 5. The difference between this embodiment and Embodiment 2 is that in this embodiment, the cross-section of the positioning surface 7 is octagonal. This octagon has only one axis of symmetry along its center, and only one unique axis of symmetry. That is, the cross-section of the coating is octagonal, and the coating consists of eight faces connected by edges, among which a pair of parallel faces can serve as the positioning surface 7. Everything else is the same as in Embodiment 2.

[0063] Example 4

[0064] See Figure 4 This embodiment provides a hollow fiber ribbon with axially visible markings. In its cross-sectional view, the outermost layer is a parallel resin 6. In this embodiment, four hollow anti-resonant fibers are fixed side-by-side in the parallel resin 6 with the same orientation. The first mark 1 on the cladding is colored glass, and the second mark 2 on the coating 5 is the same as in embodiment 2. An anti-resonant unit 3 is provided inside the cladding, and the hollow cavity formed by the anti-resonant unit 3 is the fiber core.

[0065] The method for preparing the hollow fiber ribbon in this embodiment is as follows:

[0066] (1) Steps for preparing hollow anti-resonant optical fiber. A striped glass rod is used as a striped glass preform and is bonded to a hollow anti-resonant optical fiber preform to form a whole. Then, the fiber is drawn together to obtain the striped glass markings that are fused into the cladding components.

[0067] When coating the optical fiber after drawing, the cross-section of the coating mold exit and the cross-section of the coating outer contour are the same as in Example 2.

[0068] By monitoring the first mark 1 on the outer contour surface of the cladding with a high-speed camera, when a deviation is found in the axial relative position of the first mark 1 and the second mark 2, the new wire without coating is adjusted by axial rotation in real time so that the position of the first mark 1 on the new wire corresponds to the position of the coating mold.

[0069] Maintaining a suitable tension during wire drawing ensures the structural integrity of the inner cladding layer and prevents the first mark 1 on the outer contour surface of the cladding layer from becoming blurred or disappearing. This suitable tension specifically refers to low tension, such as 30-50g. Simultaneously, axial circumferential heating is employed during wire drawing to ensure uniform temperature control, thereby reducing surface tension differences caused by thermal stress. The wire drawing speed is controlled at 300 m / min, and the wire drawing temperature is 1900-2200℃.

[0070] (2) Arrangement steps of multiple hollow anti-resonant optical fibers. Four hollow anti-resonant optical fibers are arranged side by side, and the axial visual markings of the four hollow anti-resonant optical fibers arranged side by side are in the same direction relative to the fiber ribbon.

[0071] (3) Resin filling and curing. A photocurable resin is coated onto the outer side of the multiple hollow anti-resonant optical fibers arranged side-by-side and then cured to form a transparent layer with resin 6, thus fixing the position of the multiple hollow anti-resonant optical fibers. In this embodiment, the resin is polyacrylic acid resin, and the curing process is ultraviolet curing.

[0072] Figure 5 This is an axial view of an anti-resonant optical fiber with an axial visualization mark provided in an embodiment of this application. As can be seen from the figure, the second mark 2 exists continuously along the axial direction of the optical fiber from beginning to end.

[0073] It should be noted that by changing the shape of the cross-section of the coating mold outlet, more types of second marks 2 can be prepared, such as C-shaped, racetrack-shaped, or other positioning surface structures that can uniquely correspond to the first mark 1. Essentially, the second mark 2 is uniquely corresponding to and positioned by the first mark 1, and during the production process, it is ensured that the second mark 2 corresponds to the first mark 1 in real time and uniquely, and is continuously marked and displayed along the axial length direction. During fiber ribbon production, the position of the anti-resonant unit can be reflected by the position of the second mark 2. Based on this, multiple hollow anti-resonant fibers are arranged and encapsulated and cured with transparent resin to obtain a hollow fiber ribbon with axially visible markings.

[0074] As a supplementary explanation, as stated in patent application CN120195823A: General communication optical fibers possess relatively perfect symmetry, with an end-face structure consisting of nested circular cores and claddings. Regardless of the orientation of the end-faces, the splicing effect is not significantly affected. Therefore, the orientational differences between side-by-side optical fibers are not considered during fiber ribbon fabrication. However, hollow-core antiresonant fibers differ from perfectly symmetrical circular core-cladding fibers. The number and fabrication quality of their microstructures affect their symmetry. Theoretically, hollow-core antiresonant fibers have a rotational symmetry axis, related to the number of their antiresonant units. Furthermore, since it is difficult to ensure that different antiresonant units have identical shape parameters during fabrication, this further deteriorates the symmetry. Therefore, orientation is a significant factor affecting the splicing of antiresonant fibers. Typically, during splicing of hollow-core antiresonant fibers, the orientation of the end-faces on both sides of the fiber needs to be adjusted to ensure proper registration of the hollow-core microstructure units. For hollow-core anti-resonant fiber ribbons, poor orientational consistency between the hollow-core anti-resonant fibers leads to misalignment during ribbon splicing, or even complete failure to achieve proper orientation, resulting in no light transmission after splicing. Therefore, for hollow-core anti-resonant fiber ribbon splicing, consistent orientation of the fiber ribbon relative to the fiber arrangement direction is crucial. This invention first marks the orientation of the hollow-core anti-resonant fibers using positioning surfaces. Registration between these positioning surfaces ensures consistent orientation of multiple fibers within the hollow-core anti-resonant fiber ribbon, enabling ribbon splicing. Patent application CN120195823A merely uses coating positioning surfaces corresponding to the anti-resonant unit positions within the fiber, assuming no fiber twisting during production. This approach has proven inaccurate. This invention improves upon this, featuring markings for the cladding and coating along the fiber's axial length throughout. This correspondence reflects the time dimension, resulting in more accurate markings and ensuring better subsequent ribbon splicing.

[0075] This invention also provides an optical cable comprising the aforementioned fiber ribbons. This fiber ribbon optical cable is a special optical cable structure designed specifically to meet the needs of extremely high fiber density and efficient large-scale splicing. It consists of multiple single optical fibers pre-arranged in parallel and bonded together to form a flat fiber ribbon unit. Each fiber ribbon contains, for example, 4, 6, 8, 12, or even 24 fibers. During production, multiple such fiber ribbons are stacked in a matrix to form a compact, rectangular cross-section fiber ribbon stack. This fiber ribbon stack is precisely placed into a loose tube, which is filled with a special water-blocking compound to completely isolate moisture; this is the "core" of the optical cable. This structure allows hundreds or even thousands of optical fibers to be housed within a relatively small cross-sectional area, maximizing space utilization.

[0076] In practical engineering, the entire loose tube cable core is surrounded and supported by structural tensile components. Typically, a central reinforcement (such as a glass fiber reinforced plastic rod) is placed in or near the center of the cable core to provide the main tensile strength. At the same time, multiple strands of high-strength aramid yarn are tightly wrapped around the perimeter of the loose tube in a twisted manner, forming a distributed tensile layer. This layer can evenly distribute the tensile stress borne by the optical cable during laying and operation, ensuring that the fragile internal fiber ribbon will not experience strain or additional loss due to external forces.

[0077] At the outermost layer, a tightly extruded polyethylene inner sheath secures all internal components, forming a robust first line of defense. For applications with higher requirements, such as direct burial, a layer of plastic-coated threaded steel tape armor is added outside the inner sheath to provide excellent resistance to lateral pressure and protection against rodent bites. Finally, the entire structure is encased in an outermost black high-density polyethylene outer sheath. This sheath possesses excellent resistance to ultraviolet radiation, abrasion, and environmental corrosion, ensuring long-term stable operation of the optical cable under various complex geographical and climatic conditions. Due to its extremely high fiber integration and ease of multi-core one-time splicing, this type of optical cable, composed of fiber ribbons, has become a critical infrastructure in high-capacity communication scenarios such as metropolitan area network backbone lines, data center interconnections, and fiber-to-the-home hub segments.

[0078] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hollow fiber ribbon with axially visible markings, characterized in that, include: Multiple hollow anti-resonant optical fibers with identical end-face structures are provided. Each hollow anti-resonant optical fiber includes a cladding, multiple anti-resonant units distributed inside the cladding, and a coating. A first mark is provided on the outer contour surface of the cladding, and the first mark is aligned with the relative position of the multiple anti-resonant units along its length. The coating covers the cladding and has a second mark corresponding to the first mark on the outer contour surface of the coating. The first mark and the second mark are continuously present along the entire length of the hollow anti-resonant fiber. When the hollow anti-resonant fiber preform is drawn, the drawing process naturally accompanies the preparation of the first mark on the outer contour surface of the cladding. The first mark, which is continuously present along the length of the outer contour surface of the cladding, is used to track whether there is twisting during the drawing process. Multiple hollow anti-resonant optical fibers are fixed side-by-side in the resin in a specified orientation.

2. The hollow-core optical fiber ribbon as described in claim 1, characterized in that, The first mark and the second mark are always in the same relative position in the length direction, and both the first mark and the second mark are in the same relative position with the plurality of anti-resonant units in the length direction.

3. The hollow-core optical fiber ribbon as described in claim 1, characterized in that, The first marker is an additive structure, subtractive structure, or color identifier for the cladding, wherein the color identifier is a color different from the main body color of the cladding; and / or The second mark is an additive structure, subtractive structure, marking color, or positioning surface structure of the outermost coating, wherein the marking color is a color different from the main color of the coating.

4. The hollow-core optical fiber ribbon as described in claim 3, characterized in that, The additive structure is a protruding ridge, the subtractive structure is a groove, the color mark is colored glass, and the marking color is a colored line.

5. The hollow fiber ribbon as described in claim 3, characterized in that, The positioning surface structure is at least one positioning surface on the coating.

6. The hollow-core optical fiber ribbon as described in any one of claims 1-5, characterized in that, The first mark is obtained simultaneously during the hollow anti-resonant fiber drawing process, and the second mark is obtained simultaneously during the coating preparation process. The first mark and the second mark are added as the axial length of the cladding and the axial length of the coating increase, respectively.

7. An optical cable, characterized in that, The invention includes the hollow fiber ribbon as described in any one of claims 1 to 6, wherein the hollow fiber ribbon has a visible mark for locating the position of the anti-resonance unit, for setting the anti-resonance unit at a specified position when making the fiber ribbon, and for achieving one-time precise splicing of the entire ribbon during fiber ribbon fusion splicing.

8. A method for preparing a hollow optical fiber ribbon as described in any one of claims 1 to 6, characterized in that, To fabricate a hollow antiresonant optical fiber, the hollow antiresonant optical fiber preform is drawn. During the drawing process, a first mark is naturally created on the outer contour surface of the cladding. After drawing, when coating the fiber, a second mark corresponding to the first mark is created using a coating mold. Both the first and second marks increase continuously and consistently with the increase of the cladding axial length and the coating axial length, respectively. Multiple hollow anti-resonant optical fibers are arranged side by side, with the axial visual markings of the multiple side-by-side hollow anti-resonant optical fibers positioned in a specified orientation relative to the fiber ribbon's arrangement direction. A photocurable resin is coated on the outside of multiple hollow anti-resonant optical fibers arranged side by side and then cured to form a resin-coated structure, thereby fixing the position of the multiple hollow anti-resonant optical fibers.

9. The preparation method according to claim 8, characterized in that, In the step of preparing hollow anti-resonant optical fiber, the first mark on the outer contour surface of the cladding is monitored by a visual monitoring device, and axially aligned with the second mark on the newly prepared optical fiber length portion. The coating mold is adjusted by axial rotation in real time, or the newly drawn fiber without coating is adjusted by axial rotation in real time, so as to ensure that the positions of the second mark and the first mark are synchronized in real time.

10. The preparation method according to claim 9, characterized in that, In the process of fabricating hollow anti-resonant optical fiber, after machining a hollow anti-resonant optical fiber preform to obtain a subtractive prestructure, fiber drawing is performed. Alternatively, an additive prestructure / colored glass preform can be respectively bonded to the hollow anti-resonant optical fiber preform, and then combined and drawn separately. During the fiber drawing process, the subtractive prestructure, additive prestructure, or colored glass preform naturally form the first mark on the outer contour surface of the cladding, respectively. When coating the optical fiber after drawing, a second mark is prepared on the coating by means of the structure corresponding to the coating mold. The structure corresponding to the coating mold is either a local radially outward protrusion, a radially inward depression, or the cross-sectional shape of the mold exit.

11. The preparation method according to claim 10, characterized in that, In the step of preparing the hollow anti-resonant optical fiber: A groove is obtained by axially cutting the hollow anti-resonant optical fiber preform as a subtractive prestructure, followed by fiber drawing. A long glass rod is used as an additive prestructure and bonded to a hollow anti-resonant optical fiber preform to form a whole. Then, a merging and drawing process is performed to obtain protruding ridges, or... The colored glass preform is bonded to the hollow anti-resonant optical fiber preform to form a whole, and then the merging and drawing are performed to obtain the colored glass mark that is fused into the cladding component.

12. The preparation method according to any one of claims 8 to 11, characterized in that, In the process of preparing the hollow-core anti-resonant optical fiber, a set tension is maintained during fiber drawing to simultaneously ensure the structural integrity of the inner cladding and the clear preservation of the first mark on the outer contour surface of the cladding. Meanwhile, axial circumferential heating is used during wire drawing to ensure uniform temperature and reduce surface tension differences caused by thermal stress. The drawing speed is controlled below 500m / min, and the drawing temperature is 1900℃~2200℃.

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