A fiber optic bundle connector, ferrule, and fiber optic bundle

Abstract

The application discloses a fiber bundle connector, a ferrule and a fiber bundle, and relates to the technical field of optical connectors, and particularly relates to a fiber bundle connector, a ferrule and a fiber bundle. The fiber bundle connector comprises a ferrule with oppositely arranged front and rear end faces, the front end face is used for abutting with the ferrule of a counterpart connector, and the rear end face is used for penetrating into the following fiber bundle; a plurality of fiber bundle holes are arranged in the ferrule and penetrate through the ferrule along the front-rear direction; the inner wall of each fiber bundle hole is provided with two positioning edges, the two positioning edges intersect to form a reference angle; the fiber bundle is composed of a plurality of densely arranged optical fibers, the outer contour of the fiber bundle abuts against the two positioning edges, so that the fiber bundle is positioned at the reference angle; wherein the front end inner contour cross-sectional dimension of the fiber bundle hole is greater than the frontmost end cross-sectional dimension of the fiber bundle, and the two positioning edges and the reference angle are used for realizing accurate positioning of each optical fiber in the fiber bundle.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication technology, and in particular to an optical fiber connector ferrule for multi-core optical fiber bundle mating, a connector including the ferrule, and a multi-core optical fiber bundle preform, especially suitable for high-speed optical interconnect systems based on Micro-LEDs that include the connector. Background Technology

[0002] High-speed optical interconnect solutions based on Micro-LEDs have broad application prospects in scenarios such as data center rack interconnects, high-performance computing (HPC), and chip-to-chip interconnects in artificial intelligence / machine learning (AI / ML) due to their high density, low power consumption, and low latency. Compared to traditional "narrow and fast" laser-based high-speed optical interconnect solutions, Micro-LED-based high-speed optical interconnect solutions adopt a "wide and slow" approach, that is, using a large number of low-rate channels in parallel transmission to achieve the required overall transmission rate. Fiber bundles, as a aggregation of a large number of optical fibers, can provide a large number of transmission channels within a small size, making them suitable as the transmission medium for this solution.

[0003] Currently, some companies have successfully developed and demonstrated high-speed optical interconnect solutions based on Micro-LEDs, from chip to chip. This solution is based on fiber bundles composed of hundreds of optical fibers, with each end coupled to a Micro-LED optical engine on one of the chips. However, when this solution is actually deployed within a data center, various stages, from the inside of the chassis to the panel, from the panel to the rack patch cord, and the patch and cross-connections on the patch panel, all involve the need for interconnection between fiber bundles. Therefore, a fiber bundle-to-fiber bundle interconnect solution is required; otherwise, Micro-LED parallel optical interconnects based on fiber bundles are not feasible in engineering.

[0004] In traditional single-core (FC / SC / LC) or multi-core (MPO / MT) fiber optic connector solutions, the aperture of the fiber optic port is typically designed to be a precise size, only a few hundred nanometers larger than the outer diameter of the fiber, to achieve accurate positioning. However, existing connectors are designed for single fibers or multiple independent fibers with a fixed spacing, and there is no connector structure specifically for direct mating between closely packed fiber bundles. Applying these existing solutions directly to fiber bundle mating presents fundamental difficulties: First, close-packed fiber bundles consist of dozens to hundreds of fibers, each with a diameter tolerance. The outer dimensions of the entire fiber bundle exhibit significant geometric variations, making it impossible to use the same strictly matched aperture scheme as for single fibers. If the aperture is too small, the fiber bundle cannot be inserted; if the aperture is too large, the fiber bundle will experience uncontrollable free positioning deviations within the aperture.

[0005] Second, the cumulative geometric error of the fiber bundle increases with the number of fibers. The diameter deviation of a single fiber, accumulated over dozens of fibers, can cause the dimensional variation of the fiber bundle's outer contour to reach an order of magnitude comparable to or even greater than the diameter of a single fiber. If this level of error is not constrained, the axial offset between corresponding channels in two fiber bundles will far exceed the allowable range for optical coupling, making it impossible to form an effective optical coupling path.

[0006] Therefore, the positioning of fiber bundles within connectors not only affects transmission performance but also directly determines whether this technology can achieve even the most basic engineering connections. Currently, no technology can effectively solve the direct alignment problem between fiber bundles, which constitutes the primary technical bottleneck for the practical application of high-speed parallel optical interconnects based on fiber bundles. There is an urgent need for a connector technology specifically designed for interfacing fiber bundles, capable of precisely positioning each fiber within the bundles at both ends, thereby making parallel optical interconnects based on fiber bundles practically feasible in engineering. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an optical fiber bundle connector, ferrule and optical fiber bundle to achieve reliable and high-precision docking between optical fiber bundles formed by densely packed multiple optical fibers with dimensional tolerances, so as to make the parallel optical interconnect scheme based on optical fiber bundles feasible in engineering.

[0008] To solve the aforementioned technical problems, two mutually restrictive technical challenges need to be overcome simultaneously: first, how to accommodate the external contour dimensional deviations of the fiber bundle caused by the cumulative dimensional tolerances of multiple fibers, ensuring smooth assembly of the fiber bundle; second, how to accurately determine the docking position of each fiber in the fiber bundle after accommodating the dimensional deviations, meeting the accuracy requirements of optical coupling. In existing technologies, these two challenges point to opposite design directions—tolerance requires gaps, and positioning requires tight fits—and therefore cannot be solved simultaneously in a single structure. This invention, through the synergistic mechanism of a "deviation accommodation area" and a "reference angle + positioning edge," achieves a balance between the two in engineering for the first time, filling the technical gap in direct docking between fiber bundles.

[0009] The technical problem of this invention is solved by the following technical solution: In a first aspect, this application provides an optical fiber bundle connector, comprising: The ferrule has a front end face and a rear end face that are arranged opposite to each other. The front end face is used to mate with the ferrule of the mating connector, and the rear end face is used to insert the following optical fiber bundle. The ferrule has a plurality of optical fiber bundle holes, which penetrate the ferrule in the front-to-back direction. The inner wall of each optical fiber bundle hole has two positioning edges, which intersect to form a reference angle. An optical fiber bundle is composed of multiple closely packed optical fibers. The outer contour of the optical fiber bundle abuts against the two positioning edges so that the optical fiber bundle is positioned at the reference angle. The inner contour cross-sectional dimension of the front end of the fiber bundle aperture is larger than the front end cross-sectional dimension of the fiber bundle, and the precise positioning of each fiber in the fiber bundle is achieved through the two positioning edges and the reference angle.

[0010] In some embodiments, the following technical features are also included: The optical fiber bundle is fixed inside the optical fiber bundle hole by dispensing adhesive.

[0011] In some embodiments, the outer contour shape of the fiber bundle is adapted to the inner contour of the front end of the fiber bundle aperture; the frontmost cross section of the fiber bundle has at least two straight sides, and when the fiber bundle is inserted into the fiber bundle aperture, the two straight sides abut against the two positioning sides respectively, thereby positioning the fiber bundle at the reference angle.

[0012] In some embodiments, each fiber optic bundle aperture has a polygonal front inner contour cross-sectional shape in the region adjacent to the front end face and a rear inner contour cross-sectional shape in the region adjacent to the rear end face. The maximum size of the rear inner contour cross-sectional shape is greater than the maximum size of the front inner contour cross-sectional shape, and the fiber optic bundle aperture gradually tapers from the rear inner contour cross-section to the front inner contour cross-section to form a tapered transition structure.

[0013] In some embodiments, the ferrule is a dual-structure, including at least two fiber optic bundle holes, each of which has its own reference angle.

[0014] In some embodiments, the ferrule has two guide pin holes that extend through the front and rear faces, for achieving precise alignment of the connector during the mating process.

[0015] Secondly, this application provides an optical fiber bundle connector, comprising: The fiber bundle substrate has a front end face and a rear end face that are disposed opposite to each other, wherein the front end face is used to mate with the ferrule of a mating connector; The fiber bundle substrate is provided with a plurality of fiber slots, which penetrate the fiber bundle substrate in the front-to-back direction and have an open structure. The inner wall of each fiber optic slot is provided with two positioning edges, which intersect to form a reference angle, used to define the position of the fiber optic cable within the fiber optic slot. An optical fiber bundle is composed of multiple closely packed optical fibers. The outer contour of the optical fiber bundle abuts against the two positioning edges so that the optical fiber bundle is positioned at the reference angle. The open structure of the fiber optic slot is used to accommodate the size and position deviations of the fiber bundle in the radial direction, and to achieve precise positioning of each fiber in the fiber bundle through the two positioning sides and the reference angle.

[0016] In some embodiments, the fiber bundle is fixed in the fiber groove by dispensing adhesive.

[0017] In some embodiments, the fiber bundle is composed of multiple closely packed optical fibers; the outer contour shape of the fiber bundle is adapted to the inner contour of the front end of the fiber groove; the frontmost cross section of the fiber bundle has at least two straight sides, and when the fiber bundle is installed in the fiber groove, the two straight sides abut against the two positioning sides respectively, thereby positioning the fiber bundle at the reference angle.

[0018] In some embodiments, the fiber bundle substrate is provided with two guide pin holes that penetrate the front end face and the rear end face, for use in achieving precise alignment of the connector during the docking process.

[0019] Thirdly, this application provides a ferrule for fiber optic bundle mating, the ferrule having a front end face and a rear end face disposed opposite to each other, the front end face being used to mate with the ferrule of a mating connector; The ferrule is provided with a plurality of fiber optic bundle holes, which penetrate the ferrule in the front-to-back direction. Each fiber optic bundle aperture has two positioning edges on its inner wall. The two positioning edges intersect to form a reference angle, which is used to define the position of the fiber optic cable within the fiber optic bundle aperture.

[0020] In some embodiments, the ferrule is a dual-structure, including at least two fiber optic bundle holes, each of which has its own reference angle.

[0021] In some embodiments, the ferrule has two guide pin holes that extend through the front and rear faces, for achieving precise alignment of the connector during the mating process.

[0022] In some embodiments, each fiber optic bundle aperture has a polygonal front inner contour cross-sectional shape in the region adjacent to the front end face and a rear inner contour cross-sectional shape in the region adjacent to the rear end face. The maximum size of the rear inner contour cross-sectional shape is greater than the maximum size of the front inner contour cross-sectional shape, and the fiber optic bundle aperture gradually tapers from the rear inner contour cross-section to the front inner contour cross-section to form a tapered transition structure.

[0023] Fourthly, this application provides an optical fiber bundle, which is composed of multiple closely packed optical fibers; the outer contour shape of the optical fiber bundle is adapted to the inner contour of the front end of the optical fiber bundle aperture; the frontmost cross section of the optical fiber bundle has at least two straight edges, which respectively abut against the two positioning edges, thereby positioning the optical fiber bundle at the reference angle.

[0024] In some embodiments, the diameter deviation of the plurality of optical fibers is less than 1 μm.

[0025] In some embodiments, the plurality of optical fibers are fixed together by melting or sintering to form the outer contour.

[0026] In some embodiments, the multiple optical fibers are fixed together by adhesive bonding, and the outer edge of the adhesive layer does not exceed the outer contour of the optical fiber bundle.

[0027] The beneficial effects of this invention compared to the prior art include: In existing technologies, there is no mature solution for direct alignment between fiber bundles. Traditional single-fiber connectors (such as MT / MPO) can only achieve alignment between individual fibers. For fiber bundles composed of dozens to hundreds of closely packed fibers, there is no dedicated connector structure capable of achieving direct and reliable connection between fiber bundles. This technological gap directly restricts the engineering deployment of high-density parallel optical interconnect solutions based on fiber bundles in scenarios such as data centers. This invention provides, for the first time, a connector technology solution specifically designed for direct connection between fiber bundles, reducing the alignment deviation between fiber bundle channels to within 10 μm through the following mechanism: First, this invention provides a defined positioning reference system for the fiber optic bundle by setting a fiber optic bundle aperture with two positioning edges and a reference angle. When the outer contour of the fiber optic bundle abuts against the positioning edge and is positioned at the reference angle, the six-degree-of-freedom free position of the fiber optic bundle in the aperture is transformed into a deterministic position constrained by the two positioning edges, eliminating the free positioning error introduced by the random gap between the fiber optic bundle aperture and the outer contour of the fiber optic bundle. The final alignment accuracy is mainly limited by the geometric cumulative error of the fiber optic bundle itself, rather than the assembly gap between the aperture and the bundle, thus solving the fundamental feasibility problem of fiber optic bundle docking from a physical perspective.

[0028] Building upon this foundation, the present invention addresses the conflicting technical requirements of easy assembly and high-precision positioning within a single structure by establishing a collaborative structure of a "deviation accommodating zone" (formed by the inner contour cross-sectional dimension of the front end of the fiber bundle aperture being larger than the frontmost cross-sectional dimension of the fiber bundle) and a "reference angle and positioning edge." The "deviation accommodating zone" ensures that fiber bundles with large dimensional tolerances can be smoothly and without damage assembled into ferrule holes or slots, resolving the assembly feasibility issue. After assembly, external top pressure pushes the fiber bundle towards the "reference angle," ensuring its outer contour fits tightly against the "positioning edge." This process forcibly eliminates all free gaps introduced by the accommodating zone, transforming the fiber bundle positioning accuracy from relying on uncontrollable aperture-bundle gaps to relying solely on the cumulative error of the fiber bundle along the positioning edge direction and the processing accuracy of the positioning edge, thereby controlling the positioning error to an extremely small micrometer level. This collaborative mechanism of "tolerance first, then elimination" is key to the present invention's ability to simultaneously address the conflicting requirements of easy assembly and high-precision positioning, ultimately achieving reliable and high-precision docking between fiber bundles.

[0029] Secondly, thanks to the aforementioned positioning constraints, the axial offset between corresponding channels in the two fiber bundles is limited to the order of less than 10 μm, meeting the tolerance requirements for parallel optical coupling in multimode fibers. This makes the high-speed parallel optical interconnect scheme based on Micro-LEDs feasible in engineering.

[0030] Third, this invention enables fiber optic bundles to directly interface with other fiber optic bundles in different stages of actual deployment within a data center, such as from inside the chassis to the panel, from the panel to the rack, and from patch cords to patch panels and cross-connections, without the need to prefabricate an entire optical cable for each link, thus providing the capability for modular segmented deployment.

[0031] In addition, some embodiments also have the following beneficial effects: This invention further ensures the stability of the fiber bundle in the hole or slot by using an adhesive fixing method; the tapered transition structure facilitates the insertion of the fiber bundle and guides it to the reference angle; the dual-link structure and guide pin hole design enhance the alignment capability of the connector; the precision manufacturing and fixing method of the fiber bundle ensures the consistency of its outer contour and durability during the assembly process.

[0032] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the dual quadrilateral fiber optic bundle connector in an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of the double quadrilateral fiber optic bundle connector ferrule in an embodiment of the present invention.

[0035] Figure 3 This is a front view of the ferrule of the dual quadrilateral fiber optic bundle connector in an embodiment of the present invention.

[0036] Figure 4 This is a front view of the dual quadrilateral fiber optic bundle connector ferrule in this embodiment of the invention before the fiber optic bundle is assembled.

[0037] Figure 5 This is a schematic diagram of the overall structure of the dual-link hexagonal fiber optic bundle connector in an embodiment of the present invention.

[0038] Figure 6 This is a schematic diagram of the structure of the double-hexagonal fiber bundle connector ferrule in an embodiment of the present invention.

[0039] Figure 7 This is a front view of the double hexagonal fiber optic bundle connector ferrule in an embodiment of the present invention; Figure 8 This is a front view of the dual hexagonal fiber optic bundle connector ferrule in this embodiment of the invention before the fiber optic bundle is assembled.

[0040] Figure 9 This is a schematic diagram of the structure of the hexagonal fiber bundle in an embodiment of the present invention.

[0041] Figure 10a and Figure 10b These are cross-sectional views of two types of fiber optic bundle apertures along the front-to-back direction in embodiments of the present invention.

[0042] Figure 11 This is a front view of the open slotted fiber bundle substrate in an embodiment of the present invention.

[0043] Figure 12 This is a front view of the open slotted fiber bundle substrate in this embodiment of the invention before the fiber bundle is assembled.

[0044] Figure 13 This is a diagram showing the deviation distribution of each optical fiber in the optical fiber bundle in the experimental example of this invention.

[0045] Reference numerals: 1. Filament; 11. Front end face; 12. Guide pin hole; 13. Fiber bundle; 14. Top opening; 15. Fiber bundle hole; 151. Positioning edge; 152. Reference angle; 153. Front end of fiber bundle hole; 154. Rear end of fiber bundle hole; 16. Rear end face; 17. Fiber bundle substrate; 18. Fiber groove; 19. V-groove. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0047] It should be noted that the directional terms such as left, right, up, down, top, and bottom used in this embodiment are only relative concepts or are based on the normal use of the product, and should not be considered restrictive. The materials and suppliers mentioned in this embodiment are merely examples, and any equivalent materials with similar properties can be substituted.

[0048] This invention, based on the design of fiber optic bundle connectors, ferrules, and fiber bundles, achieves precise positioning of the fiber bundle by setting positioning edges and reference angles, thereby reducing docking losses. The following embodiments illustrate specific implementations of two schemes: closed-hole and open-groove.

[0049] Example 1 like Figures 1 to 4 , Figure 10a and Figure 10b As shown, this embodiment provides a dual quadrilateral fiber optic bundle connector, which offers a technical solution for direct connection between fiber bundles, unlike existing single-fiber / multi-fiber connector solutions, making parallel optical interconnect based on densely packed fiber bundles feasible in engineering.

[0050] The connector's dimensions are based on the existing MPO (Multi-fiber Push-On) connector design, including a ferrule 1 and two multi-fiber bundles 13 composed of closely packed multiple optical fibers. The ferrule 1 is integrally molded from a composite material of PPS (Polyphenylene Sulfide) and glass fiber, with an external cuboid shape and dimensions identical to existing MT (Mechanically Transferable) ferrules. The ferrule 1 has a front face 11 and a rear face 16 positioned opposite each other. The front face 11 mates with the ferrule of the mating connector, and the rear face 16 inserts the multi-fiber bundles.

[0051] The ferrule 1 has two fiber optic bundle holes 15, which penetrate the ferrule 1 in the front-to-back direction and are arranged side by side along the width of the ferrule 1 to form a double-connection structure. The ferrule 1 has two guide pin holes 12, located on both sides of the two fiber optic bundle holes 15, and penetrating the front end face 11 and the rear end face 16, for engaging with the guide pins of the mating connector during the docking process to achieve precise alignment of the connector.

[0052] Each fiber optic bundle aperture 15 has a front inner profile cross-sectional shape in the region adjacent to the front end face 11 and a rear inner profile cross-sectional shape in the region adjacent to the rear end face 16. The front inner profile cross-sectional shape of the fiber optic bundle aperture 15 is polygonal (quadrilateral in this embodiment), and its shape is adapted to the quadrilateral outer profile of the multi-core fiber bundle to be accommodated.

[0053] In one embodiment, the complete structure of the fiber optic bundle aperture 15 from its front end 153 to its rear end 154 is as follows: Figure 10b As shown, the maximum size of the rear inner contour section is greater than the maximum size of the front inner contour section, and the fiber bundle aperture 15 smoothly tapers from the shape of the rear inner contour section to the shape of the front inner contour section, forming a tapered transition structure that facilitates the introduction of the fiber bundle 13.

[0054] In another implementation, such as Figure 10a As shown, the fiber optic bundle aperture 15 adopts a structure with consistent front and rear dimensions.

[0055] Each fiber optic bundle aperture 15 has two positioning edges 151 on its inner wall in the area of ​​the front end face 11 and adjacent to the front end face 11. These two positioning edges 151 extend in the front-rear direction and intersect to form a 90° reference angle. Preferably, this reference angle is a bottom corner (e.g., the lower left corner) of the fiber optic bundle aperture 15. By applying pressure from above and the side, the fiber optic bundle 13 is stably pressed against this corner, achieving bidirectional constraint and positioning of the fiber optic bundle. The outer contour of the fiber optic bundle 13 abuts against the two positioning edges 151, positioning the fiber optic bundle 13 at the reference angle 152. The cross-sectional dimension of the inner contour of the front end of the fiber optic bundle aperture is larger than the cross-sectional dimension of the front end of the fiber optic bundle 13, and precise positioning of each fiber in the fiber optic bundle 13 is achieved through the two positioning edges 151 and the reference angle 152. This effect is achieved based on the synergistic mechanism of "deviation tolerance" and "precise positioning" in this embodiment. Specifically, the interference fit design creates a "deviation accommodating area" between the inner wall of the fiber bundle aperture 15 and the outer contour of the fiber bundle 13. This area accommodates dimensional deviations in the outer contour of the fiber bundle 13 itself (including accumulated tolerances in single fiber diameters and positional errors introduced by the fiber arrangement process) and the clearance required for insertion and assembly. This ensures that the fiber bundle 13 can smoothly insert into the fiber bundle aperture 15 without damaging the fiber. The reference angle 152 allows the "precision positioning area" (i.e., the two positioning edges) to eliminate all accommodated macroscopic deviations at once, achieving a complete fit between the outer contour of the fiber bundle 13 and the positioning edges. While ensuring smooth insertion of the fiber bundle 13, the interference fit, through externally applied top pressure, presses the fiber bundle 13 towards the reference angle 152 during assembly, thereby completely eliminating any free clearance introduced by the interference fit.

[0056] During the design phase, the interference fit between the inner profile cross-sectional dimension of the front end and the outermost cross-sectional dimension of the fiber bundle should be greater than the maximum expected deviation of the outer profile dimension of the fiber bundle. This maximum expected deviation can be calculated by geometrically summing the maximum diameter tolerance of each individual fiber, the close-packed structure, and the number of fibers. Simultaneously, the interference fit should not be too large; the upper limit should be that during assembly and pressurization, the fiber bundle can be reliably pushed into the reference angle without internal fiber buckling or misalignment. In this embodiment, the interference fit (on one side) is preferably on the order of 1 / 5 to 1 / 2 of the fiber diameter, sufficient to accommodate all dimensional deviations and ensure smooth assembly.

[0057] The key to this embodiment lies in the fact that, through the reference angle 152 and the positioning edge 151 structure, the positioning accuracy of the fiber bundle 13 after assembly depends primarily on two factors: first, the inherent cumulative error of the fiber bundle 13 itself, which originates from the cumulative diameter deviation of each individual fiber along the positioning edge direction, approximately ±0.5μm × the number of fibers arranged in a single layer along the positioning edge 151 direction (15 fibers in this embodiment, with a cumulative error of approximately ±7.5μm); second, the processing accuracy of the positioning edge 151, which can be controlled within ±1μm. Therefore, the overall positioning error of the fiber bundle 13 can be controlled within approximately ±10μm, limiting the axial offset between corresponding channels in the two fiber bundles 13 to within the allowable range of optical coupling, thus solving the fundamental feasibility problem of fiber bundle docking from a physical perspective.

[0058] Each multi-core fiber bundle 13 consists of multiple closely packed optical fibers with a quadrilateral cross-section. The multiple optical fibers are arranged in alternating rows of 15 and 14 fibers, for a total of 21 rows. A single multi-core fiber bundle 13 can hold a total of 305 optical fibers.

[0059] Multiple optical fibers are fixed together by adhesive bonding, and the outer edge of the adhesive layer does not exceed the outer contour of the multi-core optical fiber bundle 13.

[0060] During assembly, the ferrule 1 is first fixed. Two multi-core fiber bundles 13 are then inserted into their corresponding fiber bundle apertures 15 from the rear end face of the ferrule 1, with the front end of each fiber bundle 13 protruding forward a predetermined length beyond the front end face of the ferrule. The tapered transition structure of the fiber bundle aperture provides coarse guidance to each fiber bundle during insertion, directing it from the larger rear end section to near the front end section, allowing each fiber bundle to enter the adjacent region of its corresponding reference angle.

[0061] Subsequently, pressure is applied to the fiber bundles 13 in the two fiber bundle apertures 15 from both sides towards the center, forcing the outer contours of each fiber bundle 13 to abut against the positioning edge 151 inside its respective fiber bundle aperture 15, achieving lateral positioning. Next, top pressure is applied downwards from above the two fiber bundles 13, pressing both fiber bundles 13 simultaneously against the positioning edge 151 at the bottom of their respective fiber bundle apertures 15, achieving longitudinal positioning. Thus, the outer contours of each fiber bundle 13 simultaneously abut against the two positioning edges 151 and are positioned at the reference angle 152 formed by the intersection of the two positioning edges 151, completing precise positioning.

[0062] The ferrule has a top opening 14, which communicates with the fiber bundle aperture 15. This opening is used to inject adhesive during assembly to secure the fiber bundles. While maintaining pressure at each top, each fiber bundle 13 is fixed into its corresponding fiber bundle aperture 15 via dispensing adhesive at the top opening 14. After the adhesive cures, the pressure is released, completing the assembly.

[0063] The diameter deviation of multiple optical fibers is less than 1 μm. In this embodiment, the outer diameter of a single optical fiber is 50 μm.

[0064] Example 2 like Figures 5 to 8 As shown, this embodiment provides a dual-hexagonal fiber optic bundle connector. This embodiment offers a technical solution for direct connection between fiber bundles, different from existing single-fiber / multi-fiber connector solutions, making parallel optical interconnects based on hexagonal close-packed fiber bundles feasible in engineering.

[0065] The connector includes a ferrule 1 and two multi-core fiber bundles 13 composed of multiple closely packed optical fibers. The ferrule 1 is integrally molded from a composite material of PPS and glass fiber, and has an external cuboid shape. The ferrule 1 has a front end face 11 and a rear end face 16 arranged opposite to each other. The front end face 11 is used to mate with the ferrule 1 of the mating connector, and the rear end face 16 is used to insert the multi-core fiber bundles 13.

[0066] The ferrule 1 has two fiber optic bundle holes 15, which penetrate the ferrule 1 in the front-to-back direction and are arranged side by side along the width of the ferrule 1 to form a double-connection structure. The ferrule 1 has two guide pin holes 12, located on both sides of the two fiber optic bundle holes 15, and penetrating the front end face 11 and the rear end face 16, for engaging with the guide pins of the mating connector during the docking process to achieve precise alignment of the connector.

[0067] Each fiber optic aperture 15 has a front inner profile cross-sectional shape in the region adjacent to the front end face and a rear inner profile cross-section in the region adjacent to the rear end face, wherein the maximum size of the rear inner profile cross-section is greater than the maximum size of the front inner profile cross-section shape. (Refer to...) Figure 10b The positioning edge 151 exists for a certain length near the front end, and the front and rear ends of the fiber optic bundle aperture 15 transition smoothly. Specifically, the fiber optic bundle aperture 15 smoothly tapers from the inner contour cross-sectional shape of the rear end to the inner contour cross-sectional shape of the front end, forming a tapered transition structure that facilitates the introduction of the fiber optic bundle. The inner contour cross-sectional shape of the front end is a regular hexagon.

[0068] The inner wall of each fiber optic bundle aperture 15 is provided with two positioning edges 151 in the area of ​​the front end face 11 and adjacent to the front end face 11. The two positioning edges 151 extend in the front-rear direction and intersect to form a reference angle 152. The reference angle 152 is 120°.

[0069] The outer contour of the fiber bundle 13 abuts against the two positioning edges 151, so that the fiber bundle 13 is positioned at the reference angle 152. The front end inner contour cross-sectional dimension of the fiber bundle aperture 15 is larger than the front end cross-sectional dimension of the fiber bundle, and the two positioning edges 151 and the reference angle 152 achieve precise positioning of each fiber in the fiber bundle 13. This embodiment is also based on the synergistic mechanism of "deviation tolerance" and "precise positioning": the dimensional interference forms a deviation tolerance area between the inner wall of the fiber bundle aperture 15 and the outer contour of the fiber bundle 13, which is used to accommodate the dimensional deviation of the outer contour of the fiber bundle 13 itself and the insertion gap allowance, ensuring smooth insertion without damaging the fiber; then, from above the fiber bundle 13, a directional top pressure is applied along the bisector of the reference angle 152, so that the top pressure acts on the adjacent outer contour surfaces of the fiber bundle 13 at the same time, pressing the fiber bundle 13 into the 120° reference angle 152 formed by the two positioning edges 151. The precise positioning area formed by the two positioning edges 151 eliminates all the accommodated macroscopic deviations at once, realizing the full fit between the outer contour of the fiber bundle and the two positioning edges.

[0070] The key to this embodiment lies in the fact that, through the aforementioned reference angle and positioning edge structure, the positioning accuracy of the fiber bundle after assembly depends primarily on two factors: first, the inherent cumulative error of the fiber bundle itself, which originates from the cumulative diameter deviation of each individual fiber along the positioning edge direction, on the order of ±0.5μm × the number of fibers arranged in a single layer along the positioning edge direction (in this embodiment, the longest is 19 fibers, with a cumulative error of approximately ±9.5μm); second, the processing accuracy of the positioning edge, which can be controlled within ±1μm. Therefore, the overall positioning error of the fiber bundle can be controlled within approximately ±10μm, limiting the axial offset between corresponding channels in the two fiber bundles to within the allowable range of optical coupling, thus physically solving the fundamental feasibility problem of fiber bundle docking.

[0071] Each multi-core fiber bundle consists of multiple closely packed fibers with a hexagonal cross-section. The fibers are arranged in a hexagonal pattern, forming 10 loops, with 10 fibers on the outermost side of each side. A single multi-core fiber bundle contains a total of 271 fibers. The fibers are fixed together by adhesive, with the outer edge of the adhesive layer not exceeding the outer contour of the multi-core fiber bundle.

[0072] During assembly, the ferrule 1 is first fixed. Two multi-core fiber bundles 13 are then inserted into their corresponding fiber bundle apertures 15 from the rear end face 16 of the ferrule 1, with the front end of each fiber bundle 13 protruding forward beyond the front end face 11 of the ferrule 1 by a predetermined length. The tapered transition structure of the fiber bundle aperture 15 provides coarse guidance to each fiber bundle 13 during insertion, guiding it from the larger rear end section to near the front end section, allowing each fiber bundle 13 to enter the adjacent region of the corresponding reference angle 152.

[0073] Subsequently, directional top pressure is applied along the bisector of the reference angle 152 to press each fiber bundle 13 into the 120° reference angle formed by the two positioning edges 151, so that the outer contour of the fiber bundle simultaneously abuts against the two positioning edges, thus completing the precise positioning.

[0074] The ferrule has a top opening 14, which communicates with the fiber bundle aperture 15. This opening is used to inject adhesive during assembly to fix the fiber bundles. While maintaining pressure at each top, each fiber bundle is fixed into its corresponding fiber bundle aperture via dispensing adhesive at the top opening 14. After the adhesive cures, the pressure is released, completing the assembly. The assembled hexagonal fiber bundle has the shape shown below. Figure 9 As shown.

[0075] The diameter deviation of multiple optical fibers is less than 1 μm. In this embodiment, the outer diameter of a single optical fiber is 50 μm.

[0076] Example 3 like Figure 11 and Figure 12 As shown, this embodiment provides an open slot type fiber optic bundle connector, which offers a technical solution for direct connection between fiber bundles, unlike existing single-fiber / multi-fiber connector solutions, making parallel optical interconnect based on densely packed fiber bundles feasible in engineering.

[0077] The connector includes a fiber optic bundle substrate 17 and one or more multi-core fiber optic bundles 13 (four fiber optic bundles in this embodiment) composed of multiple closely packed optical fibers. The fiber optic bundle substrate is integrally molded from a PPS and glass fiber composite material, and its external outline is cuboid. The fiber optic bundle substrate 17 has a front end face 11 and a rear end face 16 disposed opposite to each other, and the front end face 11 is used for mating with the mating connector.

[0078] The fiber optic bundle substrate 17 has a fiber optic groove 18 that extends through the substrate 17 in the front-to-back direction. The depth h of the fiber optic groove 18 is 1 mm, and its top has an open structure. The fiber optic bundle substrate 17 has two guide pin holes 12, located on both sides of the fiber optic groove 18, and extending through the front end face 11 and the rear end face 16, for precise alignment of the connector during the mating process.

[0079] The fiber optic groove 18 has a front inner contour section in the region adjacent to the front end face 11 and a rear inner contour section in the region adjacent to the rear end face. The inner wall of the fiber optic groove 18 is provided with two positioning edges 151 in the region of the front end face 11 and the region adjacent to the front end face 11. The two positioning edges 151 extend in the front-rear direction and intersect to form a reference angle 152.

[0080] The bottom of the fiber optic slot 18 is provided with a positioning structure, which consists of multiple V-shaped slots 19 extending in the front-to-back direction. The two inclined surfaces of each V-shaped slot 19 intersect to form a reference angle 120° 152. The pitch L1 of the V-shaped slots 19 is adapted to the lateral dimension of the multi-core fiber bundle to be accommodated. In this embodiment, L1 is 0.9 mm, and the total width L2 formed by the four V-shaped slots 19 is 3.6 mm.

[0081] The fiber bundle 13 is composed of multiple closely packed optical fibers with a hexagonal cross-section. The fibers are arranged in a hexagonal pattern, with 10 fibers on the outermost side of each side. A single multi-core fiber bundle 13 accommodates a total of 271 fibers, with an outer contour dimension of approximately 0.85mm × 1mm. The fibers are fixed together by adhesive bonding, with the outer edge of the adhesive layer not exceeding the outer contour of the multi-core fiber bundle.

[0082] The fiber bundle 13 is placed within the fiber groove 18 through the open structure, with its outer contour abutting against the two positioning edges 151, so that the fiber bundle 13 is positioned at the reference angle 152. The open structure of the fiber groove 18 is used to accommodate dimensional and positional deviations of the fiber bundle 13 in the radial direction, and to achieve precise positioning of each fiber in the fiber bundle 13 through the two positioning edges 151 and the reference angle 152.

[0083] This embodiment achieves high-performance docking through a coordinated "open tolerance" and "precise positioning" mechanism. The open structure forms a "deviation accommodating zone," significantly reducing assembly difficulty, allowing the fiber bundle to be inserted radially rather than axially, and accommodating larger dimensional fluctuations. Subsequently, by applying pressure, the fiber bundle is pushed to the reference angle, causing the "precise positioning zone" (i.e., the two positioning edges) to eliminate all accommodated deviations at once, achieving final precise positioning of the fiber bundle. This solution combines the ease of assembly of an open structure with the high precision advantages of a closed structure.

[0084] During assembly, the fiber optic bundle substrate 17 is first fixed, and the multi-core fiber optic bundle 13 is radially placed into the fiber optic slot 18 through the open structure. Then, a directional top pressure is applied from above the fiber optic bundle 13 along the bisector of the reference angle 152, so that the directional top pressure acts simultaneously on the adjacent outer contour surfaces of the fiber optic bundle 13, pressing the fiber optic bundle 13 into the 120° reference angle formed by the two positioning edges 151, so that the straight edge of the outer contour at the front end of the fiber optic bundle 13 abuts against the two positioning edges 151. While maintaining this pressure, the fiber optic bundle 13 is fixed in the fiber optic slot by dispensing adhesive, and the pressure is removed after the adhesive has cured.

[0085] The diameter deviation of multiple optical fibers is less than 1 μm. In this embodiment, the outer diameter of a single optical fiber is 50 μm.

[0086] Example 4 This embodiment provides a ferrule for fiber optic bundle docking, which offers a ferrule structure that directly docks fiber optic bundles, unlike existing single-fiber / multi-fiber ferrule solutions, making parallel optical interconnects based on densely packed fiber optic bundles feasible in engineering.

[0087] The insert is integrally molded from a PPS and glass fiber composite material, with an external cuboid shape. The insert has a front end face and a rear end face that are positioned opposite each other, and the front end face is used to mate with the insert of the mating connector.

[0088] The ferrule has two fiber optic bundle holes that extend through the ferrule in the front-to-back direction and are arranged side-by-side along the width of the ferrule, forming a double-connection structure. The ferrule also has two guide pin holes located on either side of the two fiber optic bundle holes, extending through the front and rear faces, for precise alignment of the connector during the mating process.

[0089] Each fiber optic bundle aperture has a front inner contour cross-sectional shape in the region adjacent to the front end face and a rear inner contour cross-sectional shape in the region adjacent to the rear end face. The maximum size of the rear inner contour cross-sectional shape is larger than the maximum size of the front inner contour cross-sectional shape. The fiber optic bundle aperture smoothly tapers from the rear inner contour cross-sectional shape to the front inner contour cross-sectional shape, forming a tapered transition structure. The front inner contour cross-sectional shape is polygonal, and its shape is adapted to the outer contour of the multi-core fiber bundle to be accommodated, such as any one of quadrilateral, hexagonal, or triangular shapes.

[0090] Each fiber optic bundle aperture has two positioning edges on its inner wall within the area of ​​the front end face and adjacent to the front end face. These two positioning edges extend in the front-rear direction and intersect to form a reference angle. The angle of this reference angle matches the corresponding interior angle of the outer contour of the fiber optic bundle to be accommodated, for example, 90° (quadrilateral fiber optic bundle) or 120° (hexagonal fiber optic bundle). It is understood that the angle of the reference angle is not limited to the above examples and can also be 60° (triangular fiber optic bundle) or any other acute or obtuse angle (i.e., greater than 0° and less than 180°), as long as it matches the corresponding interior angle of the outer contour of the fiber optic bundle and can constrain the position of the fiber optic bundle through the two positioning edges. The outer contour of the fiber optic bundle abuts against the two positioning edges to position the fiber optic bundle at the reference angle. The cross-sectional dimension of the inner contour of the front end of the fiber optic bundle aperture is larger than the cross-sectional dimension of the frontmost end of the fiber optic bundle, and the two positioning edges and the reference angle achieve precise positioning of each fiber in the fiber optic bundle.

[0091] The key design feature of this embodiment lies in the synergistic mechanism of "deviation tolerance" and "precise positioning": the tapered transition structure provides deviation tolerance, while the two positioning edges and the reference angle together constitute the precise positioning reference. This structure ensures that when the fiber bundle is inserted and pushed to the reference angle, all its positional degrees of freedom are constrained, thereby achieving precise alignment of each fiber in the fiber bundle. Its positioning accuracy mainly depends on the inherent cumulative error of the fiber bundle itself and the processing accuracy of the positioning edges. As described in embodiments 1 to 3 above, the overall positioning error can be controlled within approximately ±10μm, limiting the axial offset between corresponding channels in the two fiber bundles to within the allowable range of optical coupling, thus solving the basic feasibility problem of fiber bundle docking from a physical perspective.

[0092] As a variant of this embodiment, the ferrule may also have only one fiber bundle hole and a corresponding reference angle, forming a single-hole ferrule. In this case, the ferrule may have two guide pin holes or no guide pin holes. This single-hole ferrule is used for one-to-one fiber bundle mating with the single-hole ferrule of the mating connector.

[0093] Example 5 This embodiment provides a multi-core fiber bundle. The multi-core fiber bundle consists of multiple closely packed optical fibers. The diameter deviation of the multiple optical fibers is less than 1 μm, and the close packing forms an outer contour structure with at least two straight sides, such as a quadrilateral, hexagonal, or triangular structure. The shape of the outer contour is configured to match the polygonal front end inner contour cross-section of the fiber bundle aperture or fiber slot as described in Embodiments 1-4.

[0094] The multiple optical fibers are fixed together by adhesive bonding, with the outer edge of the adhesive layer not exceeding the outer contour of the multi-core optical fiber bundle, to ensure the accuracy and consistency of its outer contour size and shape, thereby achieving precise positioning when matched with the positioning edge and reference angle.

[0095] The advantage of the fiber bundle in this embodiment lies in the fact that, by using a fiber bundle with a precise geometric outer contour, it provides the prerequisite for the coordinated mechanism of "deviation tolerance" and "precise positioning" described in embodiments 1 to 4 above. On the one hand, when the fiber bundle is inserted into or placed into the ferrule, its outer contour dimensions determine the required interference fit; on the other hand, when the fiber bundle is pushed to the reference angle, a surface contact is formed between the straight edge of the outer contour and the positioning edge of the ferrule, and the positioning accuracy depends only on the geometric accuracy of the outer contour itself, rather than the assembly gap between the hole and the bundle. As described in the previous embodiments, this positioning accuracy is mainly limited by the inherent cumulative error of the fiber bundle itself along the arrangement direction, plus the processing accuracy of the positioning edge, and the overall error can be controlled within approximately ±10μm, so that the axial offset between corresponding channels in the two fiber bundles is limited within the allowable range of optical coupling.

[0096] In this embodiment, the outer diameter of a single optical fiber is 50 μm.

[0097] As a variation of this embodiment, the multiple optical fibers can also be fixed together by melting or sintering to form an integral optical fiber bundle preform with a stable outer contour. Furthermore, the multiple optical fibers can also be fixed together by other methods, such as laser splicing, ultrasonic welding, or mechanical clamping, as long as the multiple optical fibers can be densely packed to form an optical fiber bundle with a stable outer contour.

[0098] Experimental Example To verify the positioning accuracy of the fiber optic bundle connector provided in this embodiment of the invention, the following experimental scheme was used to test the double quadrilateral fiber optic bundle connector described in this embodiment of the invention.

[0099] Take a sample of an optical fiber bundle connector assembled according to the embodiment of the present invention. In this experimental example, the optical fiber bundle consists of 413 closely packed optical fibers, each with an outer diameter of 50 μm, arranged in alternating rows of 17 and 16 fibers, for a total of 25 rows, forming a quadrilateral outer contour. The reference angle is 90°.

[0100] A high-precision microscopic imaging system is used to image the end face of the fiber bundle and the guide pin holes within the fiber bundle aperture from the front end direction. A positioning coordinate system is established with the center of the two guide pin holes as a reference, and the reference position that each fiber in the fiber bundle should be in is drawn based on this coordinate system. Then, the offset of the center position of each fiber relative to the reference position is measured, and this offset is the positioning deviation of each fiber.

[0101] Statistical analysis was performed on the measurement data of all 413 optical fibers, and the results are shown in Table 1.

[0102] Table 1 The sum of the percentages for each interval is 100%, and the deviations of all 413 optical fibers are included in the statistics. The deviation distribution of each optical fiber is as follows: Figure 13 As shown, the horizontal axis represents the deviation range in micrometers (μm), and the vertical axis represents the percentage of fibers in each range out of the total number of fibers. Experimental results show that, using the fiber bundle connector described in this embodiment, the positioning deviation of all 413 fibers relative to the reference angle is below 4.45 μm, and the deviation distribution exhibits a typical normal distribution, concentrated around the average value of 2.13 μm. Specifically, more than 50% of the fiber deviations fall within the range of 1.0~2.5 μm, and approximately 85% of the fiber deviations are below 3.5 μm.

[0103] The above measured data effectively verifies the significant effects of the embodiments of the present invention. First, the deviation of all optical fibers is controlled to an extremely small level (below 5μm), which can meet the alignment requirements of each optical fiber in the fiber bundle. Second, the distribution pattern of deviation gradually increasing from the reference angle to the outside confirms the effectiveness of the reference angle as an absolute positioning reference: the optical fiber immediately adjacent to the reference angle achieves extremely high positioning accuracy (deviation close to 0), while the deviation of the outermost optical fiber is only about 4.45μm, which mainly reflects the inherent cumulative error of the fiber bundle itself. It can be seen that the embodiments of the present invention, through the precise positioning structure composed of two positioning edges and the reference angle, successfully eliminate the free positioning error (about ±25μm) of the fiber bundle in the hole, so that the final positioning accuracy is mainly limited by the cumulative error of the fiber bundle itself, realizing precise and controllable positioning of each optical fiber.

[0104] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or purpose, should be considered within the scope of protection of the present invention.

Claims

1. A fiber optic bundle connector, characterized in that, include: The ferrule has a front end face and a rear end face that are arranged opposite to each other. The front end face is used to mate with the ferrule of the mating connector, and the rear end face is used to insert the following optical fiber bundle. The ferrule has a plurality of optical fiber bundle holes, which penetrate the ferrule in the front-to-back direction. The inner wall of each optical fiber bundle hole has two positioning edges, which intersect to form a reference angle. An optical fiber bundle is composed of multiple closely packed optical fibers. The outer contour of the optical fiber bundle abuts against the two positioning edges so that the optical fiber bundle is positioned at the reference angle. The inner contour cross-sectional dimension of the front end of the fiber bundle aperture is larger than the front end cross-sectional dimension of the fiber bundle, and the precise positioning of each fiber in the fiber bundle is achieved through the two positioning edges and the reference angle.

2. The fiber optic bundle connector as described in claim 1, characterized in that, The optical fiber bundle is fixed inside the optical fiber bundle hole by dispensing adhesive.

3. The fiber optic bundle connector according to claim 1, characterized in that, The outer contour of the fiber bundle is adapted to the inner contour of the front end of the fiber bundle aperture; the front end section of the fiber bundle has at least two straight sides. When the fiber bundle is inserted into the fiber bundle aperture, the two straight sides abut against the two positioning sides, thereby positioning the fiber bundle at the reference angle.

4. The fiber optic bundle connector according to claim 1, characterized in that, Each fiber optic aperture has a polygonal front inner contour cross-sectional shape in the region adjacent to the front end face and a rear inner contour cross-sectional shape in the region adjacent to the rear end face. The maximum size of the rear inner contour cross-sectional shape is greater than the maximum size of the front inner contour cross-sectional shape, and the fiber optic aperture gradually tapers from the rear inner contour cross-section to the front inner contour cross-section, forming a tapered transition structure.

5. The fiber optic bundle connector according to claim 1, characterized in that, The ferrule has a dual structure, including at least two fiber optic bundle holes, each of which has its own reference angle.

6. The fiber optic bundle connector as described in claim 1, characterized in that, The ferrule has two guide pin holes that extend through the front and rear faces, enabling precise alignment of the connector during the mating process.

7. A fiber optic bundle connector, characterized in that, include: The fiber bundle substrate has a front end face and a rear end face that are disposed opposite to each other, wherein the front end face is used to mate with the ferrule of a mating connector; The fiber bundle substrate is provided with a plurality of fiber slots, which penetrate the fiber bundle substrate in the front-to-back direction and have an open structure. The inner wall of each fiber optic slot is provided with two positioning edges, which intersect to form a reference angle, used to define the position of the fiber optic cable within the fiber optic slot. An optical fiber bundle is composed of multiple closely packed optical fibers. The outer contour of the optical fiber bundle abuts against the two positioning edges so that the optical fiber bundle is positioned at the reference angle. The open structure of the fiber optic slot is used to accommodate the dimensional and positional deviations of the fiber bundle in the radial direction, and to achieve precise positioning of each fiber in the fiber bundle through the two positioning edges and the reference angle; the fiber bundle is fixed in the fiber optic slot by dispensing adhesive.

8. The fiber optic bundle connector as described in claim 7, characterized in that, The fiber bundle is composed of multiple closely packed optical fibers; the outer contour shape of the fiber bundle is adapted to the inner contour of the front end of the fiber groove; the front end section of the fiber bundle has at least two straight sides, and when the fiber bundle is installed in the fiber groove, the two straight sides abut against the two positioning sides respectively, thereby positioning the fiber bundle at the reference angle.

9. A ferrule for splicing optical fiber bundles, characterized in that: The ferrule has a front end face and a rear end face that are disposed opposite to each other, and the front end face is used to mate with the ferrule of the mating connector; The ferrule is provided with a plurality of fiber optic bundle holes, which penetrate the ferrule in the front-to-back direction. The inner wall of each fiber optic bundle aperture is provided with two positioning edges, which intersect to form a reference angle to define the position of the fiber optic cable within the fiber optic bundle aperture; the ferrule is a dual structure, including at least two fiber optic bundle apertures, each of which is provided with its own reference angle. The ferrule has two guide pin holes that penetrate the front and rear faces, which are used to achieve precise alignment of the connector during the docking process. Each fiber optic aperture has a polygonal front inner contour cross-sectional shape in the region adjacent to the front end face and a rear inner contour cross-sectional shape in the region adjacent to the rear end face. The maximum size of the rear inner contour cross-sectional shape is greater than the maximum size of the front inner contour cross-sectional shape, and the fiber optic aperture gradually tapers from the rear inner contour cross-section to the front inner contour cross-section, forming a tapered transition structure.

10. An optical fiber bundle, characterized in that, The fiber bundle is composed of multiple closely packed optical fibers; the outer contour shape of the fiber bundle is adapted to the inner contour of the front end of the fiber bundle aperture; the frontmost cross section of the fiber bundle has at least two straight edges, which respectively abut against the two positioning edges, thereby positioning the fiber bundle at the reference angle; the diameter deviation of the multiple optical fibers is less than 1 μm; the multiple optical fibers are fixed to each other by melting or sintering to form the outer contour; or, the multiple optical fibers are fixed to each other by adhesive bonding, and the outer edge of the adhesive layer does not exceed the outer contour of the fiber bundle.

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