Optical fiber unit, optical connector, and method for manufacturing optical fiber unit

Abstract

To provide an optical fiber unit, an optical connector, and a method for manufacturing the optical fiber unit that enable suppression of influence of etching on an unintended portion.SOLUTION: An optical fiber unit comprises: an optical fiber provided with a glass part and a coating covering a part of the glass part; and a protection resin covering a part of the optical fiber. The glass part has a bare part extending from the coating, and the bare part has: a large-diameter part a diameter of which is equal to that of the portion covered with the coating in the glass part; a small-diameter part a diameter of which is smaller than that of the large-diameter part; and a tapered part which is positioned between the small-diameter part and the large-diameter part, and a diameter of which varies along a lengthwise direction of the glass part. The protection resin covers an end of the coating and the large-diameter part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical fiber unit, an optical connector, and a method for manufacturing an optical fiber unit. [Background technology]

[0002] Conventionally, optical fibers have been known that include a glass portion and a coating that covers a portion of the glass portion, and the glass portion has a bare portion extending from the coating. Patent Document 1 discloses a technique for reducing the diameter of an optical fiber by immersing the bare portion of the optical fiber in an etching solution and dissolving it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-27135 Summary of the Invention [Problem to be solved by the invention]

[0004] The bare portion that is not immersed in the etching solution is exposed to the etching gas generated by the evaporation of the etching solution, which can lead to unintended narrowing of the bare portion, thereby reducing the strength of the optical fiber in the unintended portion.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide an optical fiber unit, an optical connector, and a method for manufacturing an optical fiber unit that can prevent unintended parts from being affected by etching. [Means for solving the problem]

[0006] In order to solve the above problem, the optical fiber unit according to aspect 1 of the present invention comprises an optical fiber having a glass portion and a coating covering a portion of the glass portion, and a protective resin covering a portion of the optical fiber, wherein the glass portion has a bare portion extending from the coating, and the bare portion has a large diameter portion having the same diameter as the portion of the glass portion covered by the coating, a small diameter portion having a diameter smaller than the large diameter portion, and a tapered portion located between the small diameter portion and the large diameter portion and having a diameter that changes along the longitudinal direction of the glass portion, and the protective resin covers the end of the coating and the large diameter portion.

[0007] A second aspect of the present invention is the optical fiber unit of the first aspect, wherein the protective resin has resistance to hydrofluoric acid.

[0008] A third aspect of the present invention is the optical fiber unit of the first or second aspect, wherein the tapered portion is formed adjacent to the protective resin in the longitudinal direction.

[0009] In addition, an optical connector according to aspect 4 of the present invention comprises an optical fiber unit according to any one of aspects 1 to 3, a ferrule having a fiber hole through which the small diameter portion is inserted, and an adhesive for fixing the small diameter portion to the ferrule.

[0010] A fifth aspect of the present invention is the optical connector of the fourth aspect, wherein the protective resin is disposed inside the ferrule.

[0011] A sixth aspect of the present invention is the optical connector of the fourth or fifth aspect, wherein the optical fiber unit comprises a plurality of optical fibers including the optical fiber, and the plurality of optical fibers are bundled together by the protective resin.

[0012] In addition, a manufacturing method for an optical fiber unit according to aspect 7 of the present invention includes preparing an optical fiber having a glass portion and a coating, providing a protective resin so as to cover at least the end of the coating, and etching at least a portion of the glass portion that is not covered by the coating and the protective resin, thereby forming a small diameter portion and a tapered portion. [Effects of the Invention]

[0013] According to the above aspects of the present invention, it is possible to provide an optical fiber unit, an optical connector, and a method for manufacturing an optical fiber unit that can prevent unintended portions from being affected by etching. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a perspective view of an optical connector according to an embodiment; [Figure 2] 1 is a cross-sectional view of an optical connector according to an embodiment. [Figure 3] 1A to 1C are diagrams illustrating a method for manufacturing an optical connector according to an embodiment. [Figure 4] 10A to 10C are diagrams illustrating a method for manufacturing an optical connector according to a modified example of an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] An optical fiber unit, an optical connector, and a method for manufacturing an optical fiber unit according to an embodiment will be described below with reference to the drawings. As shown in Fig. 1, the optical connector 1 includes an optical fiber unit 2, a ferrule 20, and an adhesive 30. As shown in Fig. 2, the optical fiber unit 2 includes a plurality of optical fibers 10 and a protective resin 40. In this embodiment, the number of optical fibers 10 is four. However, the number of optical fibers 10 can be changed as appropriate.

[0016] The ferrule 20 has a connection end face 20a, a fiber hole 21, an injection hole 22, two positioning holes 23, and an introduction hole 24 (see FIG. 2). The connection end face 20a is the surface that abuts against another connector or the like when the optical connector 1 is connected to another connector or the like. The fiber hole 21 and the two positioning holes 23 open to the connection end face 20a. The optical connector 1 of this embodiment is a female side, and the relative positions of the optical connector 1 and the other connector are determined by inserting a positioning pin of the other connector into the positioning hole 23. However, the optical connector 1 may also be a male side. In other words, the optical connector 1 may have a positioning pin. Furthermore, the positioning pin and the two positioning holes 23 may be omitted as long as the connection state with the other connector can be maintained appropriately.

[0017] (direction definition) In this specification, the direction in which the optical fiber 10 or the fiber hole 21 extends is referred to as the Z direction, axial direction, or longitudinal direction Z. In other words, the longitudinal direction Z coincides with the longitudinal direction of the optical fiber 10 inserted into the fiber hole 21. A direction perpendicular to the longitudinal direction Z is referred to as the first direction X. The first direction X is also the direction in which the two positioning holes 23 are aligned. A direction perpendicular to both the longitudinal direction Z and the first direction X is referred to as the second direction Y. The direction from the rear end face of the ferrule 20 toward the connection end face 20a along the longitudinal direction Z is referred to as the +Z direction, forward, or tip side. The direction opposite to the +Z direction is referred to as the -Z direction, rear, or base end side.

[0018] At the connection end face 20a, the fiber hole 21 is arranged so as to be sandwiched between two positioning holes 23. The injection hole 22 opens at one end face of the ferrule 20 facing the second direction Y. The injection hole 22 communicates with the internal space of the ferrule 20 and the fiber hole 21. The introduction hole 24 is located rearward of the fiber hole 21. The introduction hole 24 communicates with the fiber hole 21. The introduction hole 24 opens at the rear end face of the ferrule 20. The multiple optical fibers 10 are inserted into the fiber hole 21 through the introduction hole 24.

[0019] The ferrule 20 is made of a material such as resin, ceramic, etc. Examples of resin include epoxy, PPS, PEEK, and PEI. Examples of ceramic include zirconia.

[0020] As shown in FIG. 2, each optical fiber 10 has a glass portion G and a coating 12. The glass portion G is made of, for example, silica glass. Although detailed illustration is omitted, the glass portion G has a core and a cladding. The cladding is disposed so as to surround the core. The refractive index of the cladding is lower than the refractive index of the core. Therefore, the optical fiber 10 can confine light within the core.

[0021] The coating 12 partially covers the glass portion G and serves to protect the glass portion G. For example, the material of the coating 12 is a UV-curable resin. At the front end of each optical fiber 10, the coating 12 is not provided, and the glass portion G is exposed. In other words, the glass portion G has a bare portion 11 extending from the coating 12. The bare portion 11 is inserted into the fiber hole 21 of the ferrule 20.

[0022] The bare portion 11 has a small diameter portion 11a, a large diameter portion 11b, and a tapered portion 11c. The large diameter portion 11b has the same diameter as the portion of the glass portion G covered with the coating 12. The outer diameter of the small diameter portion 11a is smaller than the outer diameter of the large diameter portion 11b. The small diameter portion 11a is located on the tip side of the bare portion 11. The large diameter portion 11b is located on the base end side of the bare portion 11. The tapered portion 11c is located between the small diameter portion 11a and the large diameter portion 11b. The outer diameter of the tapered portion 11c gradually decreases toward the front. In other words, the outer diameter of the tapered portion 11c is a portion where the outer diameter changes from the outer diameter of the large diameter portion 11b to the outer diameter of the small diameter portion 11a. In this embodiment, the four small diameter portions 11a of the four optical fibers 10 are inserted into one fiber hole 21 of the ferrule 20. The large diameter portion 11b is covered with a protective resin 40. The small diameter portion 11a and the tapered portion 11c are located closer to the tip side than the protective resin 40. The tapered portion 11c is disposed adjacent to the protective resin 40 in the longitudinal direction Z.

[0023] The small diameter portion 11a and the tapered portion 11c are formed by thinning the end of the bare portion 11, which has a constant outer diameter (the same outer diameter as the large diameter portion 11b) in the longitudinal direction Z, by etching. Specifically, the diameter of the end of the bare portion 11 is thinned by immersing it in an etching solution and dissolving it. For example, hydrofluoric acid or buffered hydrofluoric acid (BHF) is used as the etching solution.

[0024] The adhesive 30 functions to fix the optical fiber 10 to the ferrule 20. When the optical connector 1 is assembled, the adhesive 30 is injected into the ferrule 20 through the injection hole 22. The injected adhesive 30 also penetrates into the fiber hole 21.

[0025] The adhesive 30 is made of a material that has high adhesiveness to the optical fiber 10 and the ferrule 20. For example, a thermosetting resin or a UV-curable resin may be used as the adhesive 30. The adhesive 30 may also be an epoxy-based, acrylic-based, or urethane-based resin.

[0026] The protective resin 40 is provided so as to cover the end of the coating 12 and the large diameter portion 11b. In this embodiment, the protective resin 40 is provided so as to cover the entire large diameter portion 11b. The protective resin 40 is disposed inside the ferrule 20. The protective resin 40 serves to protect the end of the coating 12 and the large diameter portion 11b from the etching solution. The protective resin 40 is also formed so as to cover the four optical fibers 10 collectively. That is, the four optical fibers 10 are bundled together by the protective resin 40.

[0027] The protective resin 40 is made of a material that is resistant to the etching solution. When hydrofluoric acid or buffered hydrofluoric acid (BHF) is used as the etching solution, the protective resin 40 is made of a material that is resistant to hydrofluoric acid. The protective resin 40 is made of a material with poor gas permeability. The water vapor permeability of the protective resin 40 is smaller than that of the coating 12. For example, the water vapor permeability of the protective resin 40 is preferably 400 cc / m 2 -24h / atm (40℃, 90%RH) or less. For example, a thermosetting resin or a UV-curable resin may be used as the protective resin 40. The protective resin 40 may be an epoxy-based, acrylic-based, or urethane-based resin.

[0028] As described above, the small diameter portion 11a and the tapered portion 11c are formed by immersing the end of the bare portion 11 in an etching solution and dissolving it. Here, gas generated by vaporization of the etching solution (hereinafter also referred to as etching gas) floats above the liquid surface of the etching solution. In the past, the portion of the bare portion that was not immersed in the etching solution was exposed to the etching gas, which could result in unintended portions of the bare portion being thinned in diameter. In this case, the strength of the optical fiber in the unintended portions would be reduced. Furthermore, the diameter precision of the bare portion would be reduced. Furthermore, if a gap occurs between the bare portion and the coating due to exposure to etching gas, the adhesive cannot penetrate into the gap, which may reduce the strength of the fixation of the optical fiber to the ferrule. Furthermore, if the coating is immersed in an etching solution, the coating may dissolve or decompose in the etching solution, generating impurities that may adhere to the optical fiber and contaminate or corrode the optical fiber in downstream processes or products, causing failure of the optical connector.

[0029] In this embodiment, the protective resin 40 is arranged to cover the portion of the bare portion 11 where it is not desired to reduce the diameter (i.e., the large diameter portion 11b), thereby preventing the etching gas from reducing the diameter of unintended portions of the bare portion 11. Furthermore, the protective resin 40 is made of a material with poor gas permeability, making it difficult for the etching gas to pass through. As a comparative example, focusing on the water vapor permeability, the water vapor permeability of the protective resin 40 is lower than that of the coating 12. Compared to the coating 12, the protective resin 40 prevents the etching gas from reaching the bare portion 11. As described above, by providing the protective resin 40, it is possible to suppress a decrease in the strength of the optical fiber 10. In addition, it is possible to suppress a decrease in the diameter accuracy of the bare portion 11.

[0030] Furthermore, by providing the protective resin 40, it is possible to prevent the etching gas from causing a gap between the bare portion 11 and the coating 12. Therefore, it is possible to prevent a decrease in the fixing strength of the optical fiber 10 to the ferrule 20. Furthermore, because the end of the coating 12 is covered with the protective resin 40, the coating 12 can be prevented from being immersed in the etching solution. Because the protective resin 40 is made of a material that is resistant to the etching solution, even when the protective resin 40 is immersed in the etching solution, the protective resin 40 is prevented from being eluted into the etching solution or from being decomposed in the etching solution. This prevents impurities from being generated in the etching solution, and prevents impurities generated in the etching solution from adhering to the optical fiber 10 and contaminating or corroding the optical fiber 10.

[0031] An example of a method for manufacturing the optical fiber unit 2 and the optical connector 1 will be described with reference to FIG.

[0032] First, a plurality of optical fibers 10 are prepared, each having a coating 12. As shown in Fig. 3(a), the coating 12 is partially removed from each of the plurality of optical fibers 10 to expose the glass portion G. That is, a certain length of the coating 12 necessary for etching is removed from the tip of the optical fiber 10, in which the coating 12 covers the entire glass portion G. The portion of the glass portion G from which the coating 12 has been removed becomes the bare portion 11.

[0033] Next, as shown in FIG. 3(b), a protective resin 40 is provided so as to cover at least the end of the coating 12. The protective resin 40 is formed so as to cover the end of the coating 12 of the plurality of optical fibers 10. For example, a plurality of optical fibers 10 are bundled together. Then, the resin that will become the protective resin 40 is applied to the end of the coating 12 of the bundled optical fibers 10 and the base end side of the bare portion 11 (i.e., the portion that will become the large diameter portion 11b), and is cured. This forms the protective resin 40 that covers the end of the coating 12 of the plurality of optical fibers 10 and the base end side of the bare portion 11.

[0034] Next, as shown in FIGS. 3(c) and (d), at least a portion of the exposed portion of the bare portion 11 that is not covered with the protective resin 40 (i.e., the portion of the glass portion G that is not covered with the coating 12 and the protective resin 40) is etched to form the small diameter portion 11a and the tapered portion 11c. Specifically, as shown in FIG. 3(c), at least a portion of the exposed portion of the bare portion 11 is immersed in an etching solution L, and the etching solution L is used to dissolve the portion and reduce its diameter. At this time, the outer diameters of the small diameter portion 11a and the tapered portion 11c can be adjusted by varying the time for which the bare portion 11 is immersed in the etching solution L for each position in the longitudinal direction Z. In this way, the optical fiber unit 2 is manufactured.

[0035] Note that the portion of the bare portion 11 that is not covered with the protective resin 40 is thinned by exposure to the etching gas even if it is not immersed in the etching liquid L. In this embodiment, the tapered portion 11c also includes such a portion that is not immersed in the etching liquid L but is thinned by exposure to the etching gas. The tapered portion 11c is formed on the base end side of the exposed portion of the bare portion 11, and is adjacent in the longitudinal direction Z to the portion of the bare portion 11 that is covered with the protective resin 40.

[0036] 3(e), the small diameter portions 11a of the bare portions 11 are inserted into the fiber holes 21 of the ferrule 20. Next, a resin that will become the adhesive 30 is injected through the injection hole 22, and the resin is cured. As a result, the optical fiber 10 is fixed to the ferrule 20.

[0037] In the above manufacturing method, the protective resin 40 is formed so as to cover the ends of the coatings 12 of the multiple optical fibers 10. In this case, the protective resin 40 also functions to increase the rigidity by bundling the optical fibers 10. However, the protective resin 40 may be formed individually for each optical fiber 10.

[0038] As described above, the optical fiber unit 2 according to this embodiment includes an optical fiber 10 having a glass portion G and a coating 12 that covers a portion of the glass portion G, and a protective resin 40 that covers a portion of the optical fiber 10. The glass portion G has a bare portion 11 extending from the coating 12. The bare portion 11 has a large diameter portion 11b that has the same diameter as the portion of the glass portion G that is covered with the coating 12, a small diameter portion 11a that has a smaller diameter than the large diameter portion 11b, and a tapered portion 11c that is located between the small diameter portion 11a and the large diameter portion 11b and has a diameter that changes along the longitudinal direction of the glass portion G. The protective resin 40 covers the end of the coating 12 and the large diameter portion 11b. In addition, the manufacturing method of the optical fiber unit 2 according to this embodiment includes preparing an optical fiber 10 having a glass portion G and a coating 12, providing a protective resin 40 so as to cover at least the end of the coating 12, and etching at least a portion of the glass portion G that is not covered by the coating 12 and the protective resin 40, thereby forming the small diameter portion 11a and the tapered portion 11c.

[0039] According to the above configuration, it is possible to prevent unintended portions of the optical fiber 10 from being affected by etching, thereby preventing a decrease in the strength of the optical fiber 10.

[0040] Moreover, the protective resin 40 is resistant to hydrofluoric acid. According to the above configuration, when hydrofluoric acid or buffered hydrofluoric acid is used as the etching solution, the protective resin 40 can more reliably protect the end of the coating 12 and the large diameter portion 11b from the etching solution. Furthermore, even when the protective resin 40 is immersed in the etching solution, the protective resin 40 is prevented from dissolving in the etching solution or from being decomposed in the etching solution. Therefore, impurities are prevented from being generated in the etching solution, and the impurities generated in the etching solution are prevented from adhering to the optical fiber 10, thereby contaminating and corroding the optical fiber 10.

[0041] The tapered portion 11c is disposed adjacent to the protective resin 40 in the longitudinal direction Z. According to the above configuration, the tapered portion 11c can be formed at an intended portion of the bare portion 11, which makes it easier to design the optical fiber 10.

[0042] The optical connector 1 according to this embodiment includes an optical fiber unit 2, a ferrule 20 having a fiber hole 21 through which the small diameter portion 11a is inserted, and an adhesive 30 that fixes the small diameter portion 11a to the ferrule 20. The optical fiber unit 2 includes a plurality of optical fibers 10, which are bundled together by a protective resin 40. According to the above configuration, by bundling the optical fibers 10 with the protective resin 40, the rigidity of the optical fibers 10 is improved.

[0043] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0044] For example, as shown in Fig. 4, the optical fiber unit 2 may include only a single optical fiber 10. Even in this case, the optical fiber unit 2 and the optical connector 1 can be manufactured using the same procedures as in the above embodiment.

[0045] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described embodiments and variations may be combined as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0046] 1...optical connector 2...optical fiber unit 10...optical fiber 11...bare portion 11a...small diameter portion 11b...large diameter portion 11c...tapered portion 12...coating 20...ferrule 21...fiber hole 30...adhesive 40...protective resin G...glass portion Z...longitudinal direction

Claims

1. an optical fiber including a glass portion and a coating covering a portion of the glass portion; a protective resin covering a portion of the optical fiber; Equipped with the glass portion has a bare portion extending from the coating; the bare portion has a large diameter portion having the same diameter as the portion of the glass portion covered with the coating, a small diameter portion having a diameter smaller than that of the large diameter portion, and a tapered portion located between the small diameter portion and the large diameter portion and having a diameter that varies along the longitudinal direction of the glass portion, The protective resin covers the end of the coating and the large diameter portion. Fiber optic unit.

2. The protective resin is resistant to hydrofluoric acid.

2. The optical fiber unit according to claim 1.

3. the tapered portion is disposed adjacent to the protective resin in the longitudinal direction.

2. The optical fiber unit according to claim 1.

4. The optical fiber unit according to any one of claims 1 to 3; a ferrule having a fiber hole through which the small diameter portion is inserted; an adhesive that fixes the small diameter portion to the ferrule; An optical connector comprising:

5. The protective resin is disposed inside the ferrule.

5. The optical connector according to claim 4.

6. the optical fiber unit includes a plurality of optical fibers including the optical fiber; The plurality of optical fibers are bundled by the protective resin.

5. The optical connector according to claim 4.

7. providing an optical fiber having a glass portion and a coating; a protective resin is provided so as to cover at least an end portion of the coating; forming a small diameter portion and a tapered portion by etching at least a portion of the glass portion that is not covered with the coating and the protective resin; A method for manufacturing an optical fiber unit.

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