JP2017138364A - Optical connector, manufacturing method of optical connector, and optical connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical connector which attains compaction of a double-end plug type optical connector and suppression of residual air bubbles in an adhesive for fixing an optical fiber insides.SOLUTION: A manufacturing method of an optical connector comprising plugs in both ends includes: a step for preparing a cylindrical member 10 including a through-hole penetrating an axial direction and an adhesive injection passage 12 extending in a radial direction and having an opening on an outer peripheral surface; an insertion step for coaxially inserting two ferrules 20 to openings in both ends of the through-hole; an injection step for injecting an adhesive from the opening of the adhesive injection passage 12 and filling the inside of the through-hole and the inside of optical fiber insertion holes of the two ferrules 20 with the adhesive; and an insertion step for inserting one optical fiber 30 through the optical fiber insertion holes of the two ferrules 20.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical connector having optical plugs at both ends, an optical connector manufacturing method, and an optical connection structure including the optical connector.

  2. Description of the Related Art Conventionally, an optical connector (optical connector) has been used to easily connect and disconnect between optical fibers or between optical fibers and optical elements. One type of optical connector is a plug-type optical connector that incorporates an optical fiber (see, for example, FIG. 16 of Patent Document 1 (Japanese Patent Laid-Open No. 9-90166)).

JP-A-9-90166 JP 2002-350676 A

  As a plug at both ends, an optical connector in which plugs at both ends as shown in FIG. 16 of Patent Document 1 are connected with an optical fiber is generally used. However, it is desired to make such an optical connector compact. Yes. The optical connector is not limited to the purpose of simply performing optical connection, and various functions are provided by incorporating various optical fibers in accordance with the purpose and using the characteristics of the optical fiber to change the optical path. Also used for. As such utilization, utilization for the purpose of reducing speckle noise of a laser display, for example, is being studied.

  If bubbles exist in the adhesive that fixes the optical fiber inside the optical connector, the bubbles repeatedly expand / contract due to repeated heat reception during use, and there is a risk of damage to the optical fiber. In addition, the manufacture of such an optical connector includes a step of inserting an optical fiber into a precise capillary tube and fixing it with an adhesive. In this process, after the adhesive is injected into the inner hole having an inner diameter slightly larger than that of the optical fiber, the adhesive is uniformly filled so that no bubbles are generated in the gap between the inner hole and the optical fiber while the optical fiber is inserted. There is a problem that this difficult work is required and the cost becomes high.

As one solution to such a problem, Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-350676) discloses a method of forming a softened glass or crystallized glass, which is then split and connected to an optical connector. A long capillary tube is obtained from which a plurality of short capillaries constituting an optical device with a fiber are obtained. A technique has been proposed in which a hole is filled with an adhesive, a long optical fiber from which a coating has been removed from the flare portion is inserted, and then the adhesive is cured to fix the optical fiber to the long capillary.
However, depending on the specific structure of the optical connector, the method described in Patent Document 2 may not be applicable.

  As seen in the example of Patent Document 2, the technique of inserting and bonding an optical fiber to a housing (generally called a ferrule) used to align the cores of the end faces when connecting optical fibers is an optical This is one of the important elements in connector assembly technology. Generally, ferrules for optical connectors include metals, resins, glass, and ceramics, but zirconia ceramics dominate because of the comprehensive improvement in accuracy, workability, and strength with the spread of communications. . One of the small holes (125 to 126 μm) is opened on the taper, from which an adhesive is injected, and a thin optical fiber (thickness 125 + 1 / -0 μm) is inserted.

However, when the fiber insertion opening ends are tapered at both ends of the ferrule, there are the following problems. That is, the tip of the ferrule is generally optically polished to transmit an optical signal with low loss. In particular, in the communication field, precise specifications for optical polishing to a spherical shape (PC (Physical Contact JIS C 5970)) are required. If there is an adhesive around the fiber on the end face, the adhesive is softer than the ferrule material (generally made of zirconia), so it will be scraped off, making it difficult for the optical fiber to meet the standards (standards 1-3 listed below). .

Standard 1: radius of curvature of fiber end face 5-30mmR
Standard 2: Fiber pull-in amount + 0.01 / -0.005μm with respect to the imaginary spherical surface of the fiber
Standard 3: Apex deviation (deviation amount from spherical fiber center) 0-50μm

  Accordingly, the present invention should solve the downsizing of the plug-type optical connector and the suppression of bubbles remaining in the adhesive for fixing the optical fiber inside the optical connector. Let it be an issue. Further, one of the further problems to be solved by the present invention is to improve the coaxiality as the connection performance. Another object of the present invention is to reduce the amount of adhesive around the fiber on the ferrule end face.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has come up with the following aspects of the present invention.
That is, the manufacturing method of the optical connector provided with plugs at both ends of the cylindrical member according to the first aspect of the present invention has a through-hole penetrating in the axial direction and an opening in the outer peripheral surface of the cylindrical member extending in the radial direction. A step of preparing a cylindrical member having an adhesive injection passage, an insertion step of inserting two ferrules coaxially into the openings at both ends of the through-hole, and an adhesive from the opening of the adhesive injection passage An injection step of filling the inside of the through hole and the inside of the optical fiber insertion hole of the two ferrules with an adhesive, and inserting one optical fiber into the optical fiber insertion hole of the two ferrules An insertion process.

  According to the manufacturing method of the above aspect, two ferrules can be respectively inserted from both ends of the cylindrical member, and an optical connector having an optical plug at both ends can be manufactured. Therefore, the total length of the optical connector is shortened as much as possible. Can be handled easily. Further, by performing the injection step, the inside of the optical connector, particularly the inside of the optical fiber insertion hole of the ferrule is filled with the adhesive, and a state of leaking a little outside the holes at both ferrule ends is obtained. After that, when performing the insertion process, the optical fiber end can be applied to the adhesive that has leaked a little at the end of the ferrule, and the air can be inserted while preventing air bubbles from entering. Since the adhesive is pushed out from the opening, no air is accompanied by the optical fiber and does not enter the optical fiber insertion hole. Thereby, the optical fiber can be prevented from being damaged due to repeated heat reception.

Further, according to the second aspect of the present invention, the through hole is located between the two fitting insertion hole portions into which the two ferrules are fitted and the two fitting insertion hole portions and communicates with the adhesive injection passage. The through hole is formed so as to have an intermediate hole portion, and the inner diameter of the intermediate hole portion is made smaller than the inner diameter of the fitting insertion hole portion. By doing in this way, the quantity of the adhesive agent to be used can be reduced.
Further, according to the third aspect of the present invention, the space between the insertion hole portion and the intermediate hole portion is tapered. By doing so, it becomes easy to expel the air in the through hole to the outside.

Moreover, according to the 4th aspect of this invention, the opening vicinity part of the optical fiber penetration hole in the fitting insertion side edge part of a ferrule is made into a taper shape. This facilitates the operation of inserting the optical fiber into the optical fiber insertion hole.
Further, according to the fifth aspect of the present invention, the inner diameter of the vicinity of the opening of the optical fiber insertion hole at the end portion on the side opposite to the insertion side of the ferrule is made constant in the axial direction. Thereby, compared with the conventional structure which makes the said opening vicinity part taper shape, the quantity of the adhesive agent of the optical fiber periphery of a ferrule end surface can be reduced.
According to the sixth aspect of the present invention, a portion of the adhesive injection passage near the opening is stepped. According to this, the tip of the adhesive injection nozzle can be brought into contact with the stepped portion of the adhesive injection passage.

  An optical connector according to a seventh aspect of the present invention includes a through-hole penetrating in the axial direction, a cylindrical member provided with an adhesive injection passage extending in the radial direction and having an opening on the outer peripheral surface of the cylindrical member, and a through-hole Ferrules inserted into the openings at both ends of the holes, optical fibers inserted into the optical fiber insertion holes of the ferrules, adhesive injection passages, portions where no ferrule is inserted in the through holes, and optical fiber insertions And an adhesive that fills the holes. The optical connector having such a configuration can make the entire length as short as possible, and the handling thereof becomes simple. Moreover, since it can be suitably manufactured by the manufacturing method according to the first aspect of the present invention described above, the same effects as the manufacturing method according to the first aspect are exhibited.

It is the general-view figure and sectional drawing of the example of the optical connector manufactured by the manufacturing method of this invention. It is a figure for demonstrating the general flow of the manufacturing method of this invention. It is a figure for demonstrating a part of manufacturing method of this invention. It is the schematic which shows the optical connection structure using the optical connector manufactured by the manufacturing method of this invention. It is a figure which shows another example of the optical connector manufactured by the manufacturing method of this invention.

  Hereinafter, an example of an optical connector according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1A is a schematic view of a double-ended plug type optical connector 1 as an example of the optical connector according to this embodiment, and FIG. 1B is a longitudinal sectional view of the optical connector 1. The optical connector 1 of this embodiment is a double-ended plug type optical connector 1 used for optical connection between an optical plug and an optical receptacle and optical connection between optical plugs. As shown in FIGS. 1A and 1B, the optical connector 1 is an internal cavity made of a metal having high thermal conductivity such as copper, brass (brass), aluminum, stainless steel, or a resin with little thermal deformation. A cylindrical member 10 having light, and two ferrules 20 that are inserted concentrically with the cylindrical member 10 at both ends of the cylindrical member 10, and light that is inserted and fixed by bonding through the optical fiber insertion holes 21 of the two ferrules 20. The fiber 30, the plug frame 40 that is concentrically attached and fixed to the outer periphery of the cylindrical member 10, and the nut 50 that is loosely fitted to the outer periphery of the plug frame 40. The inner cavity of the cylindrical member 10 and the periphery of the optical fiber 30 inside the optical fiber insertion hole 21 of the ferrule 20 are filled with a cured adhesive 60. Note that the ferrule 20 is a member in which the cores of the end faces are aligned via a housing having an interrupt parallel to an axis called a split sleeve when an optical fiber is connected. The plug frame 40 of the present embodiment is a component including one of optical reference surfaces that is attached so as to cover the ferrule 20.

  The internal cavity of the cylindrical member 10 includes an axial cavity 11 extending in the axial direction, and an adhesive injection passage 12 extending radially in the vicinity of the axial center of the cylindrical member 10 and connecting the outer peripheral surface and the axial cavity 11. It consists of. With the transition portion 111 where the inner diameter of the axial cavity 11 changes in a tapered shape as a boundary, the diameter of the center side portion (intermediate hole portion) is relatively small, and the diameters of both end portions (insertion hole portions) are relatively small. It is getting bigger. The two ferrules 20 are inserted into both end portions (insertion hole portions) of the axial cavity 11 without gaps, and each end face on the insertion side of each ferrule 20 faces the axial cavity 11 or the transition portion 111. . The ends opposite to the insertion side of the two ferrules 20 protrude from both ends of the cylindrical member 10. The opening of the optical fiber insertion hole 21 in the end surface on the fitting insertion side of each ferrule 20 is conical. The adhesive injection passage 12 of the cylindrical member 10 has a step portion 13.

Next, with reference to FIG. 1 and FIG. 2, a schematic flow of a method for manufacturing the optical connector 1 according to the present embodiment will be described.
First, as shown in FIG. 2A, a solid cylindrical member 10 ′ made of metal having high thermal conductivity such as copper, brass (brass), aluminum, stainless steel or the like is prepared. Next, as shown in FIG. 2 (B), the inside of the columnar member 10 ′ is cut with a drill or the like to form the axial cavity 11, the adhesive injection passage 12, and the step portion 13, and the cylindrical member 10 And The manufacturing method of the cylindrical member 10 is not limited to this. For example, when the cylindrical member 10 is made of resin, an appropriate method may be selected according to the material, such as injection molding or manufacturing the cylindrical member 10 itself by a 3D printer.
Next, as shown in FIG. 2C, the two ferrules 20 are respectively inserted into the large-diameter portions (insertion hole portions) of the axial cavity 11 from both ends of the cylindrical member 10.

  Next, as shown in FIG. 2 (D), the adhesive injection nozzle 100 is pressed against the step portion 13 of the adhesive injection passage 12 to inject adhesive 60 ′ before curing, and the adhesive 60 ′ is adhesive. The injection path 12, the axial cavity 11, and the ferrule 20 are filled into the optical fiber insertion hole 21, and the adhesive 60 ′ is discharged from both ends of the optical fiber insertion hole 21. The flow direction of the adhesive 60 ′ is schematically shown by arrows in the drawing. Thus, by continuing injection and discharge of the adhesive 60 'for a predetermined time, the optical fiber insertion hole 21 is caused to flow from the air existing in the axial cavity 11 and the optical fiber insertion hole 21 by the flow of the adhesive 60'. Extrude completely through the openings on both ends. As the adhesive 60 ', a two-pack type epoxy resin (manufactured by Epoxy Technologies, Inc.) is often used, but an organic adhesive such as a light-transmitting adhesive or an inorganic adhesive may be used. Any adhesive may be used as long as the bonding operation can be performed.

  By doing so, the inside of the optical fiber insertion hole 21 is filled with the adhesive 60 ′, and the adhesive 60 ′ leaks slightly outside the holes at the ends of both ferrules 20. After the extrusion of air and before the adhesive 60 ′ is cured, as shown in FIG. 2 (E), the optical fiber 30 is inserted from the end face side of the anti-fitting insertion side of one of the ferrules 20. A common optical fiber 30 is inserted into the optical fiber insertion hole 21 of the ferrule 20. At this time, the end of the optical fiber 30 can be applied to the adhesive 60 ′ that has slightly leaked at the end of the ferrule 20, and can be inserted while preventing bubbles from entering. The inner diameter of the end opening of the optical fiber insertion hole 21 on the side where the optical fiber 30 is inserted is constant in the axial direction and is not tapered. As a method for inserting the optical fiber 30 into such a non-tapered end opening, for example, the method shown in FIG. 3 can be employed. That is, hold the hand slightly above the end of the optical fiber 30 (you may wear a thin glove), and tilt the optical fiber 30 diagonally as shown in FIG. Trace 20 end faces. When the optical fiber 30 is caught by the edge of the optical fiber insertion hole 21 (FIG. 3B), the optical fiber insertion hole is pressed as shown in FIG. 3C while pressing the optical fiber 30 against the edge of the optical fiber insertion hole 21. The optical fiber 30 is inserted straight into 21.

When the optical fiber 30 is inserted, the adhesive 60 ′ in the optical fiber insertion hole 21 overflows from the opening at both ends of the optical fiber insertion hole 12. This is because the resistance that the adhesive in the optical fiber insertion hole 21 moves toward the center of the cylindrical member 10 and overflows from the adhesive injection passage 12 with the insertion of the optical fiber 30 is reduced in the optical fiber insertion hole 21. This is because it is larger than the resistance of being pushed out from the opening on both ends. In order to ensure such an action, the adhesive injection flow path 12 is preferably closed. The diameter of the intermediate hole portion of the axial cavity 11 is preferably larger than the diameter of the adhesive injection passage 12 and the diameter of the optical fiber insertion hole 21.
The overflow of the adhesive 60 ′ from the openings on both ends of the optical fiber insertion hole 12 indicates that the air is not inserted into the optical fiber insertion hole 21 due to the insertion of the optical fiber 30.
After the adhesive 60 is cured, as shown in FIG. 2F, both sides of the optical fiber 30 are cut in accordance with the end face of the ferrule 20, and the end face of the ferrule 20 is polished.
Next, the optical connector 1 shown in FIG. 1 is obtained by extrapolating the two plug frames 40 each having the nut 50 loosely fitted from both ends of the cylindrical member 10 and fixing them with an adhesive 70 or the like.

  According to the manufacturing method which concerns on this embodiment mentioned above, the optical connector 1 of the structure which inserts the two ferrules 20 from the both ends of the cylindrical member 10, and equips both ends with an optical plug can be manufactured. Thereby, the full length of the optical connector 1 can be shortened as much as possible, and the handling becomes easy. Further, since air can be prevented from remaining in the adhesive 60 for fixing the optical fiber 30 in the optical connector 1, particularly in the ferrule 20, the optical fiber 30 can be prevented from being damaged due to repeated heat reception. .

Further, by providing the transition portion 111 in which the inner diameter of the axial cavity 11 changes in a tapered shape, it becomes easy to expel the air in the axial cavity 11 to the outside.
In addition, since the opening of the optical fiber insertion hole 21 at the fitting insertion side end face of each ferrule 20 is conical, the operation of inserting the optical fiber 30 into the optical fiber insertion hole 21 is facilitated.
Further, the inner diameter of the vicinity of the opening of the optical fiber insertion hole 21 at the end of the ferrule 20 on the side opposite to the insertion side (that is, the end on the protruding side) is constant in the axial direction. Thereby, the amount of the adhesive 60 around the optical fiber 30 on the end face of the ferrule 20 can be reduced as compared with the conventional configuration in which the vicinity of the opening is tapered.
The adhesive injection passage 12 of the cylindrical member 10 has a step portion 13. Thereby, the tip of the adhesive injection nozzle 100 can be brought into contact with the step portion 13 of the adhesive injection passage 12.

(Usage example of optical connector 1)
Next, as an example of use of the optical connector 1 according to the present embodiment, an optical connection structure in combination with an adapter 200 that holds a zirconia split sleeve 201 is shown in FIG. The adapter of the type that holds the zirconia split sleeve is also used for connecting a general single mode fiber (SMF), and is a known connecting component that can realize excellent connection loss. As shown in FIG. 4, when the optical connector 1 is inserted into the adapter 200, the mechanical reference surface and the optical reference surface come into contact with each other and are fitted together. In the case of a specification in which the ferrule is pushed by a spring, at the time of fitting, the tip of the ferrule 20 of the optical connector 1 is pressed against the ferrule 300 such as a plug to be connected with each other and is pushed in slightly by 0.5 mm. The ferrules are pressed against each other with a force of about 10 N (ferrule pressing force). However, since the thing of this embodiment is a springless specification, this point is different.

  As described above, by using the adapter 200 that holds the zirconia split sleeve 201, the plug frame 40 of the optical connector 1 of the present embodiment is screwed into the adapter 200 and fixed with an adhesive so that the coaxiality is within 1 μm. And was able to. Thus, an optical connection structure with high coaxiality is provided by the optical connector 1 and the adapter 200 holding the split sleeve 201 made of zirconia according to the manufacturing method of the present invention. Since the optical connection structure constituted by the optical connector 1 and the adapter 200 according to the present invention has a small degree of coaxiality (that is, a small shift of the central axis), an insertion loss of 0.5 dB or less can be realized with SMF.

As described above, the compact optical connector 1 of the both-end plug type that can be used for the optical connection between the optical plug and the optical receptacle and the optical connection between the optical plugs has been realized. The optical connector 1 can be handled in the same manner as a general optical fiber cord even in connection to a receptacle and connection between plugs via an adapter.
The optical connector 1 of the present invention is not limited to the one shown in FIG. 1, and the structure can be simplified by eliminating one of the plug frames 40, such as the optical connector 1 ′ shown in FIG. Even in that case, it can be directly fitted to the optical receptacle or optical adapter. The nut 51 on the simplified side of the plug frame 40 of this example is screwed and bonded and fixed to the cylindrical member 10.

By using one of the two ferrules with a larger inner diameter (for example, 0.125 mm and 0.220 mm as an example), different types of optical fibers with different thicknesses and types can be fused with commercially available fusion machines. When it is inserted after being connected, the fused part, which is slightly thicker, does not enter the other ferrule hole, and the fused part stops at the intermediate part. Therefore, a double-ended optical connector coupler having a simple structure in which the fused portion does not get in the way can be realized.
In the application of the manufacturing method according to the present invention, the optical fiber can be used in various applications such as communication, medical, semiconductor, analysis, measurement, and industrial equipment because it does not choose any kind of SMF, SIF, GIF, and POF.
According to the manufacturing method of the present invention, it is possible to fuse and incorporate different types and different outer diameter optical fibers.
The manufacturing method according to the present invention can be widely applied to a terminator, a fixed attenuator, an FBG temperature sensor, a strain sensor, a small mode scrambler, and the like.

DESCRIPTION OF SYMBOLS 1, 1 'Optical connector 10 Cylindrical member 20 Ferrule 30 Optical fiber 40 Plug frame 50, 51 Nut 60, 60', 70 Adhesive 200 Adapter

Claims (14)

A method of manufacturing an optical connector comprising plugs at both ends of a cylindrical member,
Preparing the cylindrical member including a through-hole penetrating in the axial direction and an adhesive injection passage extending in a radial direction and having an opening on an outer peripheral surface of the cylindrical member;
An insertion step of coaxially inserting two ferrules into the openings at both ends of the through hole; and
An injection step of injecting an adhesive from the opening of the adhesive injection passage and filling the inside of the through hole and the inside of the optical fiber insertion hole of the two ferrules with the adhesive,
An insertion step of inserting one optical fiber into the optical fiber insertion hole of the two ferrules.   The through hole has two insertion hole portions into which the two ferrules are inserted, and an intermediate hole portion that is located between the two insertion hole portions and communicates with the adhesive injection passage. The manufacturing method according to claim 1, wherein the through hole is formed, and an inner diameter of the intermediate hole portion is smaller than an inner diameter of the fitting insertion hole portion.   The manufacturing method according to claim 2, wherein a gap is formed between the fitting hole portion and the intermediate hole portion.   The manufacturing method as described in any one of Claims 1-3 which makes the opening vicinity part of the said optical fiber penetration hole in the fitting insertion side edge part of the said ferrule taper shape.   The manufacturing method as described in any one of Claims 1-4 which makes constant the internal diameter of the opening vicinity part of the said optical fiber penetration hole in the counter fitting insertion side edge part of the said ferrule to an axial direction.   The manufacturing method according to claim 1, wherein, in the adhesive injection passage, a portion near the opening of the adhesive injection passage is stepped.   The manufacturing method according to claim 1, wherein the adhesive is a two-component epoxy resin, or an organic adhesive or an inorganic adhesive including a light-transmitting adhesive. A through hole penetrating in the axial direction; and the cylindrical member provided with an adhesive injection passage extending in a radial direction and having an opening on an outer peripheral surface of the cylindrical member;
Ferrules inserted into the openings at both ends of the through hole,
An optical fiber inserted into the optical fiber insertion hole of each ferrule;
An adhesive filling the adhesive injection passage, a portion where the ferrule is not inserted in the through hole, and the optical fiber insertion hole;
An optical connector comprising:   The through hole has two insertion hole portions into which the two ferrules are inserted, and an intermediate hole portion that is located between the two insertion hole portions and communicates with the adhesive injection passage. The optical connector according to claim 8, wherein the through hole is formed, and an inner diameter of the intermediate hole portion is smaller than an inner diameter of the fitting insertion hole portion.   The optical connector according to claim 9, wherein a gap is formed between the insertion hole portion and the intermediate hole portion.   The optical connector according to any one of claims 8 to 10, wherein a portion near the opening of the optical fiber insertion hole at the fitting insertion side end of the ferrule is tapered.   The optical connector according to any one of claims 8 to 11, wherein an inner diameter of a portion in the vicinity of the opening of the optical fiber insertion hole at an end of the ferrule opposite to the insertion side is constant in the axial direction.   The optical connector according to any one of claims 8 to 12, wherein, in the adhesive injection passage, a portion near the opening of the adhesive injection passage has a stepped shape. The optical connector according to claim 8, wherein the adhesive is a two-component epoxy resin, or an organic adhesive or an inorganic adhesive including a light-transmitting adhesive.

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