Fiber bundle ferrule manufacturing method, fiber bundle ferrule, and optical switch

Abstract

A fiber bundle ferrule manufacturing method comprising: removing a coating of a ribbon cable in which a plurality of optical fibers have been fixed; and inserting and fixing at least a portion of the ribbon cable into a ferrule in a state in which said portion has been wound into a cylindrical shape.

Description

Method for manufacturing fiber bundle type ferrule, fiber bundle type ferrule, and optical switch

[0001] The present disclosure relates to a method for manufacturing a fiber bundle type ferrule, a fiber bundle type ferrule, and an optical switch.

[0002] For all-optical switches that switch the optical path while keeping the light as light, various methods have been proposed as shown in Non-Patent Document 1. Among these, the fiber optic type mechanical optical switch that controls the butt joint between optical fibers or optical connectors with a robot arm, motor, etc. is inferior to other methods in terms of slow switching speed, but has many advantages over other methods in terms of low loss, low wavelength dependence, multi-portability, and having a self-holding function that maintains the switching state when the power supply is lost. As a typical structure, for example, there are a method of parallel moving a stage using an optical fiber V-groove, a method of selectively coupling to a plurality of optical fibers that are emitted from an incident optical fiber by parallel moving or changing the angle of a mirror or prism, and a method of connecting a jumper cable with an optical connector using a robot arm.

[0003] On the other hand, in the optical fiber path of the access network, by arranging an optical switch at an outdoor node in the middle, it is possible to effectively utilize the optical fiber from the transmission device to the node part. Therefore, an optical fiber type mechanical optical switch (Non-Patent Document 2) assumed for outdoor installation has been proposed. In particular, a fiber bundle type ferrule rotation optical switch (Patent Document 1, Non-Patent Document 3) with improved optical characteristics by optimizing the ferrule end face shape has been proposed.

[0004] International Publication No. 2024 / 013820

[0005] M. Stepanovsky, “A Comparative Review of MEMS-Based Optical Cross-Connects for All-Optical Networks From the Past to the Present Day,” IEEE Communications Surveys & Tutorials, vol. 21, no. 3, pp. 2928-2946, 2019. C. Fukai, Y. Abe, T. Uematsu, I. Ogushi, K. Katayama, “Multi-Core Fiber Rotated Optical Switch,” Optical Fiber Technology, vol. 81, 103470, December, 2023. C. Fukai, T. Uematsu, R. Koyama, I. Ogushi, K. Katayama, “Broadband Transmission Opto-mechanical Switch Based on Cylindrical Ferrule Rotation Switching using Fiber Bundle Inserted in Ferrule, “Optical Fiber Communication Conference 2024, W2A23, 2024.

[0006] Patent Document 1 and Non-Patent Document 3 describe the process of fabricating a fiber bundle type ferrule rotary optical switch. This involves bundling individual optical fibers to create a bundle type ferrule, and then verifying the ports by passing light through them after fabrication. However, verifying the ports by passing light through them after fabrication requires connecting a light source and a light receiver to each port. Therefore, in optical switches with multiple ports, the verification process becomes increasingly complicated as the number of ports increases.

[0007] Furthermore, human error can lead to incorrect port identification, resulting in misconnections.

[0008] This disclosure has been made in view of the above-mentioned problems. The purpose of this disclosure is to provide a method for manufacturing a fiber bundle type ferrule that allows for easy identification of optical fibers without the need for light transmission verification, a fiber bundle type ferrule, and an optical switch.

[0009] To solve the above-mentioned problems, one aspect of the present disclosure is a method for manufacturing a fiber bundle type ferrule, comprising removing the coating from a ribbon core on which a plurality of optical fibers are fixed, and inserting and fixing at least a portion of the ribbon core in a cylindrical shape into a ferrule.

[0010] One aspect of the present disclosure is a fiber bundle ferrule comprising: a fiber bundle in which at least a portion of a ribbon core on which a plurality of optical fibers are fixed is wound in a cylindrical shape; and a ferrule into which the fiber bundle is inserted, wherein a portion of the coating of the ribbon core is removed obliquely with respect to the longitudinal direction of the ribbon core.

[0011] According to this disclosure, it is possible to provide a method for manufacturing a fiber bundle type ferrule that allows for easy identification of optical fibers without performing light transmission verification, a fiber bundle type ferrule, and an optical switch.

[0012] Figure 1 is a perspective view showing an example of a fiber bundle type ferrule rotary optical switch according to Embodiment 1. Figure 2 is a perspective view showing an example of a tape core wire according to Embodiment 1. Figure 3 is a perspective view showing an example of the tape core wire with the coating removed according to Embodiment 1. Figure 4 is a diagram showing an example of a cross-section of the tape core wire according to Embodiment 1. Figure 5 is a perspective view showing an example of the tape core wire in a wound state according to Embodiment 1. Figure 6 is a diagram showing an example of the bundled fiber end face according to Embodiment 1. Figure 7 is a perspective view showing an example of a fiber bundle type ferrule made from the tape core wire according to Embodiment 1. Figure 8 is a diagram showing another example of the bundled fiber end face according to Embodiment 1. Figure 9 is a diagram showing another example of the bundled fiber end face according to Embodiment 1. Figure 10 is a perspective view showing an example of an intermittently bonded tape core wire according to Embodiment 1. Figure 11 is a diagram showing an example of the tape core wire with the coating removed according to Embodiment 2. Figure 12 is a diagram showing an example of the tape core wire with the coating removed diagonally in a wound state according to Embodiment 2. Figure 13 is a diagram showing an example of a ferrule structure according to Embodiment 2. Figure 14 is a diagram showing an example of the bundled fibers inserted into the ferrule according to Embodiment 2. Figure 15 shows another example of the bundled fibers according to Embodiment 2 inserted into a ferrule.

[0013] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments shown below. These embodiments are merely illustrative, and this disclosure can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. In this specification and in the drawings, components with the same reference numerals refer to the same components.

[0014] (Embodiment 1) Figure 1 is a perspective view showing an example of the structure of a fiber bundle type ferrule rotating optical switch (hereinafter also referred to as "optical switch") according to this embodiment. The optical switch can be used, for example, to switch the path of an optical line using single-mode optical fiber in an optical fiber network.

[0015] The illustrated optical switch comprises a fixed-side ferrule 12, a rotating-side ferrule 14, a sleeve 13, and a flange 15.

[0016] In the optical switch, the fixed ferrule 12 and the rotating ferrule 14 are inserted into the sleeve 13, and the rotating ferrule 14 is rotated. This switches the connection state of the optical fibers 10 inserted and fixed to the respective ferrules 12 and 14, thereby allowing the optical switch to perform path switching. The optical switch may also be equipped with a rotation mechanism (not shown) for rotating the rotating ferrule 14. For example, a gear or a motor can be used for the rotation mechanism.

[0017] In each ferrule 12 and 14, the optical fibers 10 are bundled together, and the bundled optical fibers 10 are inserted into a fiber hole (not shown) located in the center of the ferrules 12 and 14 and fixed with adhesive. Here, the optical fibers 10 not used for path switching become dummy fibers 11. Depending on the number of fibers bundled or the position of the fiber core, a dummy fiber 11 may also be placed in the center. The central dummy fiber 11 may be a core, and is not limited to the examples given here, as long as it is a shape that allows for the manufacture of a fiber bundle type ferrule.

[0018] The fiber bundle type ferrule of this embodiment comprises a fiber bundle in which at least a portion of a ribbon core 16 on which a plurality of optical fibers 10 are fixed is wound into a cylindrical shape, and a ferrule 14 into which the fiber bundle is inserted. The optical switch of this embodiment is a fiber bundle type ferrule rotary optical switch using the fiber bundle type ferrule.

[0019] Figure 2 is a perspective view showing an example of a ribbon fiber according to this embodiment. The ribbon fiber 16 is formed by bonding and fixing multiple optical fibers 10, each covered with a covering material, side by side (parallel to side). Figure 2 shows an example of a ribbon fiber with eight optical fibers, but the number of optical fibers in a ribbon fiber is not limited to eight. Generally, ribbon fibers used in optical communications have 2, 4, 8, or 12 fibers. Furthermore, the number of optical fibers used in this embodiment may be any number that allows for the manufacture of an optical switch, and is not limited to the examples given here.

[0020] Figure 3 is a perspective view showing an example of the state of removing the coating from a ribbon fiber according to this embodiment. The coating 18 is removed from a ribbon fiber 16 on which a plurality of optical fibers 10 are fixed. The coating 18 (coating material) of the ribbon fiber 16 can be removed from a portion of the coating 18 of each optical fiber 10 by, for example, using a hot stripper to heat the coating 18 (coating material), and then inserting a blade in a state where only the coating 18 can be cut and tearing it off. In the illustrated example, the coating is removed from one end portion of the ribbon fiber 16.

[0021] After removing the coating, the ends of each optical fiber 10 in the ribbon fiber 16 may be cut. Specifically, after removing the coating, the ends of the optical fibers 10 on the side where the coating was removed may be cut using, for example, a fiber cutter. This makes it possible to produce a ribbon fiber 16 with uniform fiber end faces. It is necessary to align the longitudinal fiber end faces at the ferrule end faces of the ferrules 12 and 14, but expensive microscopes and depth gauges are required to align the fiber end faces of each optical fiber 10 with high precision. If the positions are aligned by visual inspection, some variation may occur, and the optical characteristics such as connection loss and return loss of the optical switch may not meet the required conditions, resulting in a low yield.

[0022] In this embodiment, after removing the coating 18, the ends of each optical fiber 10 of the ribbon core 16 are cut together (all at once) using a fiber cutter or the like. This makes it easy to align the fiber end faces of each optical fiber 10.

[0023] Figure 4 shows an example of a cross-section of the ribbon fiber 16 according to this embodiment. Figure 4 shows an example of an 8-core ribbon fiber. Here, for example, the ports of the optical fiber 10 are identified as F1 to F8 from left to right. Figure 4 shows a cross-sectional view of the ribbon fiber 16 in the portion where the insulation has not been removed, cut by a plane perpendicular to the longitudinal direction.

[0024] Figure 5 is a perspective view showing an example of the tape core wire 16 in a wound state according to this embodiment. At least a portion of the tape core wire 16 is wound into a cylindrical shape and inserted into the ferrule 17 for fixation. Alternatively, the tape core wire 16 with the coating 18 removed may be wound around the dummy fiber 11, the core rod 11, or another portion of the tape core wire 16.

[0025] In the illustrated example, the eight-core tape fiber 16 is wound around the central dummy fiber 11 or core rod 11. By winding in this manner, as shown in Figure 6, a fiber bundle can be created in which F1 to F8 are arranged in order counterclockwise at the fiber end face of the tape fiber 16. This fiber bundle is then inserted into the rotating ferrule 14 and fixed in place by adhesive.

[0026] As a result, as shown in Figure 7, the optical fibers 10 of the ribbon fiber 16 are arranged circumferentially within the ferrule 14, and outside the ferrule 14, the optical fibers 10 are arranged in a single row in order. In other words, in the portion of the ribbon fiber 16 not inserted into the ferrule 14, the optical fibers 10 arranged circumferentially within the ferrule 14 can be arranged in a single row in the order F1 to F8. This makes it possible to manufacture a fiber bundle type ferrule 14 that facilitates the identification of ports (optical fibers 10).

[0027] Furthermore, by incorporating a rotating mechanism (not shown), such as a gear and motor, a fixed-side ferrule 12, a sleeve 13, and a flange 15 into the ferrule 14, it is possible to manufacture a fiber bundle type ferrule rotary optical switch.

[0028] Although Figure 6 shows the optical fibers 10 F1 to F8 arranged counterclockwise, a fiber bundle type ferrule 14 may also be manufactured with the optical fibers 10 F1 to F8 arranged clockwise. Furthermore, in addition to 8-core ribbon fiber, a fiber bundle type ferrule may also be manufactured by winding a 4-core ribbon fiber, for example, as shown in Figure 8. In this case, dummy fibers and cores are not required.

[0029] Furthermore, as shown in Figure 9, for example, a tape core with a number of cores other than that of a typical tape core (in the illustrated example, a 7-core tape core) may be wound. In the illustrated tape core 16, the remaining optical fibers 10 (F2-F7) are wound in a cylindrical shape so as to surround a portion of the optical fiber (F1) of the tape core 16. In this case, for example, an intermittently bonded tape core 16 may be used as the tape core 16. By using an intermittently bonded tape core 16 as shown in Figure 10, it is possible to easily produce a 7-core tape core by cutting off one core from an 8-core tape core 16. The intermittently bonded tape core 16 has a structure in which two adjacent optical fibers 10 are intermittently connected in the longitudinal direction by adhesive 17 (adhesive part), and single-core parts and adhesive parts are periodically arranged. By using an intermittently bonded tape core 16, it is possible to easily wind a tape core 16 with a common number of cores such as 4 or 8.

[0030] The ribbon fiber 16 can be any ribbon fiber 10 (optical fiber cores) arranged side by side with their coverings attached and glued together, such as a single-core separated ribbon fiber or a ribbon fiber made by a single-core assembly machine, and is not limited to the examples given herein.

[0031] (Embodiment 2) In this embodiment, the coating 18 of the tape core 16 is removed at an angle with respect to the longitudinal direction of the tape core 16. The fiber bundle type ferrule and optical switch of this embodiment differ from Embodiment 1 in that the coating 18 is removed at an angle, and are otherwise the same as Embodiment 1. That is, the fiber bundle type ferrule of this embodiment comprises a fiber bundle in which at least a portion of the tape core 16 on which a plurality of optical fibers 10 are fixed is wound into a cylindrical shape, and a ferrule 14 into which the fiber bundle is inserted, wherein a portion of the coating of the tape core 16 is removed at an angle with respect to the longitudinal direction of the tape core 16.

[0032] Figure 11 shows an example of the state in which the coating of the tape fiber 16 according to this embodiment has been removed. In the example shown, a seven-core tape fiber 16 is shown. In a normal hot stripper, the blade is set perpendicular to the longitudinal direction of the optical fiber 10, but for example, the blade can also be set at an angle to the longitudinal direction of the optical fiber 10. This allows a portion of the coating 18 to be removed at an angle to the longitudinal direction of the tape fiber 16, and the length of the portion of each optical fiber 10 (fiber core) from which the coating 18 has been removed can be varied.

[0033] Figure 12 shows an example of a tape fiber 16 with the coating 18 removed diagonally according to this embodiment, in a wound state. For example, the tape fiber 16 with the coating 18 removed as shown in Figure 11 is wound as shown in Figure 9. In this case, as shown in Figure 12, the coating 18 of the middle optical fiber 10 (F1) of the wound tape fiber 16 is the longest, and the coating 18 of the outermost optical fiber 10 (F7) is the shortest. In this way, by removing the coating 18 diagonally, the length of the optical fiber 10 of each fiber (the length of the optical fiber 10 in the coating removal portion) is different, making it possible to prevent errors in the winding direction of the optical fiber 10.

[0034] Figure 13 shows an example of a ferrule structure according to this embodiment. A fiber hole 20 is located in the center of the ferrule 14, and the fiber hole 20 has a tapered portion 21 (tapered portion) that is tapered toward the flange 15 side. The tapered portion 21 shown in the figure is inclined such that the diameter of the fiber hole 20 increases toward the end face toward the flange 15 side.

[0035] When inserting the optical fiber 10 (the rolled ribbon core 16) into the ferrule 14, the tapered portion 21 acts as a boundary between the portion of the optical fiber 10 from which the coating 18 has been removed and the portion of the optical fiber 10 with the coating 18 still attached, preventing the portion of the optical fiber 10 with the coating 18 from penetrating the fiber hole 20.

[0036] As shown in Figure 12, the tape core wire 16, which has had its coating 18 removed diagonally and wound, has a smooth boundary between the exposed optical fiber 10 and the coating 18. By inserting such a tape core wire 16 into the ferrule 14, it is possible to prevent a large step from occurring at the boundary between the exposed optical fiber 10 and the coating 18 in the tapered portion 21, as shown in Figure 14.

[0037] The fixed-side ferrule 12 is the same as the ferrule 14 shown in Figures 13 and 14.

[0038] Furthermore, as shown in Figure 15, the fiber end face 22 of the fiber bundle (the rolled ribbon fiber 16) may be positioned inside the ferrule end face 23 of the ferrule 14. Specifically, when cutting the tip of the optical fiber 10 on the side where the coating is to be removed, the cutting length can be adjusted to pull the fiber end face 22 in from the ferrule end face 23, as shown in Figure 15. This also makes it possible to prevent damage to the fiber end face 22 that may occur when switching paths by rotation while the fiber end faces (the fiber end faces of the ferrules 12 and 14) are in close contact with each other.

[0039] Furthermore, a fiber bundle type ferrule may be constructed by applying a refractive index matching material to the fiber end face 22 while the fiber end face 22 is retracted more than the ferrule end face 23. By using a refractive index matching material, it is possible to prevent reflected light that occurs between the fiber end face 22 and the air.

[0040] In addition, even in the case of the fiber bundle type ferrule and optical switch of Embodiment 1, as shown in Figure 15, the fiber end face 22 of the fiber bundle may be positioned inside the ferrule end face 23 of the ferrule 14.

[0041] Furthermore, in the fixed-side ferrule 12, similar to the ferrule 14 shown in Figure 15, the fiber end face may be positioned inside the ferrule end face of ferrule 12. Alternatively, both fiber end faces of ferrules 12 and 14 may be positioned inside the ferrule end faces, or either one of the fiber end faces of ferrules 12 or 14 may be positioned inside the ferrule end face.

[0042] [Effect of Embodiment] As described in detail above, the method for manufacturing the fiber bundle type ferrule of the present embodiment removes the coating of the tape core wire to which a plurality of optical fibers are fixed, and inserts and fixes at least a part of the tape core wire into the ferrule in a state of being wound into a cylindrical shape.

[0043] Further, the fiber bundle type ferrule of the present embodiment is a fiber bundle type ferrule, and includes a fiber bundle in which at least a part of a tape core wire to which a plurality of optical fibers are fixed is wound into a cylindrical shape, and a ferrule into which the fiber bundle is inserted. Further, the optical switch of the present embodiment is a fiber bundle type ferrule rotary optical switch using the fiber bundle type ferrule.

[0044] Thereby, it is possible to realize a fiber bundle type ferrule and an optical switch using the ferrule that can easily identify ports without performing light transmission confirmation. Specifically, in the present embodiment, by using the tape core wire 16, a fiber bundle to be inserted into the ferrule 14 can be easily manufactured, and the optical fibers 10 (each port in the optical switch) inserted into the ferrule 14 can be easily identified.

[0045] Further, after removing the coating 18, the tip of each optical fiber 10 of the tape core wire 16 may be cut. Thereby, the fiber end face positions in the longitudinal direction of each optical fiber 10 can be aligned, and the lengths and positions of each optical fiber 10 at the fiber end face 22 can be easily controlled without variation, and a fiber bundle type ferrule and an optical switch with good characteristics and high yield can be realized.

[0046] Further, the coating 18 of the tape core wire 16 may be removed obliquely with respect to the longitudinal direction of the tape core wire 16. Thereby, since the lengths of the optical fibers 10 of each core wire (the lengths of the optical fibers 10 in the coating-removed portion) are different, it is possible to prevent an error in the winding direction of the optical fibers 10.

[0047] Further, the fiber end face 22 of the fiber bundle may be disposed inside the ferrule end face 23 of the ferrule 14. Thereby, it is possible to prevent damage to the fiber end face 22 that may occur during path switching by rotating with the fiber end faces of the ferrules 12 and 14 in close contact with each other.

[0048] As described above, the content of the present disclosure has been described in accordance with the embodiments. However, the present disclosure is not limited to these descriptions, and it is obvious to those skilled in the art that various modifications and improvements are possible. It should not be understood that the discussion and drawings forming part of this disclosure limit the present disclosure. Various alternative embodiments, examples, and operation techniques will become apparent to those skilled in the art from this disclosure.

[0049] The present disclosure naturally includes various embodiments and the like not described herein. Therefore, the technical scope of the present disclosure is defined by the invention-specific matters according to the legitimate claims derived from the above description.

[0050] 10 Optical fiber 11 Dummy fiber or mandrel 12 Fixed-side ferrule 13 Sleeve 14 Rotating-side ferrule 15 Flange 16 Tape core wire 17 Adhesive 18 Coating 20 Fiber hole 21 Taper portion 22 Fiber end face 23 Ferrule end face

Claims

1. A method for manufacturing a fiber bundle type ferrule, comprising removing the coating from a ribbon core on which multiple optical fibers are fixed, and inserting and fixing at least a portion of the ribbon core in a cylindrical shape into a ferrule.

2. A method for manufacturing a fiber bundle type ferrule according to claim 1, wherein after removing the coating, the ends of each optical fiber of the ribbon core are cut.

3. The method for manufacturing a fiber bundle type ferrule according to claim 1, wherein the tape core is an intermittently bonded tape core.

4. The method for manufacturing a fiber bundle type ferrule according to claim 1, wherein the coating is removed obliquely with respect to the longitudinal direction of the tape core wire.

5. A method for manufacturing a fiber bundle type ferrule according to claim 1, wherein the tape core from which the coating has been removed is wound around a dummy fiber, a core rod, or another part of the tape core.

6. A fiber bundle type ferrule comprising: a fiber bundle in which at least a portion of a ribbon core on which a plurality of optical fibers are fixed is wound into a cylindrical shape; and a ferrule into which the fiber bundle is inserted, wherein a portion of the coating of the ribbon core is removed obliquely with respect to the longitudinal direction of the ribbon core.

7. The fiber bundle type ferrule according to claim 6, wherein the fiber end face of the fiber bundle is positioned inside the ferrule end face of the ferrule.

8. An optical switch using a fiber bundle type ferrule as described in claim 6 or claim 7.

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