JP6642895B2 - Optical fiber connection method and optical fiber connection structure manufacturing method - Google Patents

Description

  The present invention relates to a method for connecting an optical fiber and a method for manufacturing an optical fiber connection structure.

  Fusion methods, mechanical splice methods, and the like are known as methods for connecting optical fibers to extend optical fibers. The mechanical splicing method is a method of connecting optical fibers by aligning the distal end surfaces of optical fibers to be connected to each other and pressing and fixing them using an aligning member (also referred to as a mechanical splice element). The mechanical splicing method is used in many places because it is possible to connect optical fibers in a short time without fusing the optical fibers.

JP 2011-033731A

  When connecting optical fibers to each other, a liquid refractive index matching agent is interposed between the connection portions of the optical fibers (the portion where the end face of one optical fiber and the end face of the other optical fiber abut) to reduce the connection loss. Reductions have been made. However, before the optical fiber is connected, a liquid refractive index matching agent is applied in advance, and when the end of the optical fiber is inserted into the liquid refractive index matching agent, bubbles are taken into the end face of the optical fiber. There is a possibility (see FIG. 5 described later). As a result, air bubbles are trapped in the connection portion of the optical fiber, and the optical connection loss may increase.

  An object of the present invention is to suppress the formation of bubbles on the end face of an optical fiber.

A main invention for solving the above-mentioned problem is an insertion step of inserting a first optical fiber between a base member and a lid member, and an end face of the first optical fiber in an alignment groove of the base member; A connection step of abutting an end face of a second optical fiber different from the first optical fiber, and the base member and the lid member in a state of abutting an end face of a second optical fiber different from the first optical fiber. By pressing, the first optical fiber and the second optical fiber are pressed and fixed by the alignment groove, and a liquid refractive index matching agent is injected into a gap between the base member and the lid member, An injection step of filling a liquid refractive index matching agent between an end face of the first optical fiber and an end face of the second optical fiber, wherein the inserting step and the connecting step include: Base member and said Interposed member has been inserted between the members, wetting member moistened index matching agent in the liquid, together is provided between said cover member and said base member, said aligning In the injection step, the liquid refractive index matching agent is squeezed from the wet member in the pressing step, whereby the liquid index matching agent is squeezed from the wet member. The liquid refractive index matching agent penetrates into a narrow gap side by capillary action, and the liquid refractive index matching agent is injected into a gap between the base member and the lid member, and the first optical fiber An optical fiber connecting method, wherein the liquid refractive index matching agent is filled between an end face and an end face of the second optical fiber.
Other features of the present invention will become apparent from the accompanying drawings and the present specification.

FIG. 1 is a perspective view of the optical fiber connector according to the first embodiment as viewed from above. 2A to 2C are cross-sectional views (planes cut along the line A-A 'in FIG. 1) of the optical fiber connector according to the first embodiment. FIG. 3 is a work flowchart of the optical fiber connection method according to the first embodiment. 4A to 4C are explanatory diagrams of the injection path of the liquid refractive index matching agent C1. 5A and 5B are explanatory diagrams of a comparative example. FIG. 6 is a view of the base member 31 of the second embodiment as viewed from above. 7A and 7B are explanatory diagrams of the optical fiber connection method according to the second embodiment. 8A to 8D are explanatory diagrams showing the functions of the liquid refractive index matching agent C1 and the solid refractive index matching material C2 of the third embodiment. FIG. 9 is an explanatory diagram of the relationship between the hardness and the thickness of the solid refractive index matching material C2 of the third embodiment. FIG. 10 is an explanatory diagram of a method for forming the solid refractive index matching material C2 of the third embodiment. FIG. 11 is a view of the base member 31 of the fourth embodiment as viewed from above. 12A and 12B are explanatory views of the alignment member 30 ″ of the fifth embodiment.

  At least the following matters will be made clear by the description in the present specification and the accompanying drawings.

  An insertion step of inserting a first optical fiber between a base member and a lid member, and an end face of the first optical fiber and a second optical fiber different from the first optical fiber in an alignment groove of the base member. A connecting step of abutting an end face of the fiber, and a state where the end face of a second optical fiber different from the first optical fiber is abutted, the first optical fiber and the cover A pressing step of pressing and fixing the second optical fiber with the centering groove; and injecting a liquid refractive index matching agent into a gap between the base member and the lid member, thereby forming an end face of the first optical fiber and the second optical fiber. An injection step of filling a liquid refractive index matching agent between the optical fiber and the end face of the optical fiber. According to this optical fiber connection method, it is possible to suppress the formation of bubbles on the end face of the optical fiber.

  In the insertion step and the connection step, an insertion member is interposed between the base member and the lid member, and in the pressing step, the insertion member is disposed between the base member and the lid member. It is preferable that the liquid refractive index matching agent is injected into a portion where the insertion member is inserted in the injection step. This prevents the interposition member from hindering the injection of the liquid refractive index matching agent. In addition, when the insertion member is removed, the gap between the base member and the lid member becomes narrow, so that the liquid refractive index matching agent easily penetrates due to a capillary phenomenon.

  In the injecting step, the liquid refractive index matching agent is penetrated to a gap between the base member and the lid member on a side opposite to a side where the liquid refractive index matching agent is injected as viewed from the alignment groove. It is desirable. Thus, even if bubbles are formed on the end face of the optical fiber, the bubbles can be removed.

  It is preferable that the base member and the lid member have a concave portion through which the interposing member is inserted, and in the injecting step, the liquid refractive index matching agent is injected into the concave portion. Thereby, it is possible to suppress the liquid refractive index matching agent from flowing out.

  Preferably, a groove is formed between the alignment groove and the recess. This makes it easier for the liquid refractive index matching agent injected into the concave portion to flow to the alignment groove, so that the liquid refractive index matching agent is easily filled between the end faces of the optical fiber.

  A wetting member moistened with the liquid refractive index matching agent is provided between the base member and the lid member. In the injection step, the liquid refractive index matching agent is removed from the wet member in the pressing step. Is squeezed, the liquid refractive index matching agent is injected into the gap between the base member and the lid member, and the gap between the end face of the first optical fiber and the end face of the second optical fiber is It is desirable to fill a liquid refractive index matching agent. Accordingly, if the pressing step is performed, the injection step is performed, so that the operator does not need to perform the injection step.

  In the insertion step and the connection step, an interposition member is interposed between the base member and the lid member, and the wetting member is disposed on the side of the interposition member when viewed from the alignment groove. It is desirable to have been. This makes it easier to fill the liquid refractive index matching agent between the end faces of the optical fiber.

  It is preferable that the method further includes a solidification step of solidifying the liquid refractive index matching agent after the injection step. Thereby, the optical connection state of the optical fiber can be stabilized.

  A solid refractive index matching material is previously formed on the end face of the second optical fiber, and in the connecting step, the solid fiber index matching material is interposed between the end face of the first optical fiber and the second optical fiber. It is desirable to abut the end face of the fiber. Thereby, the gap between the end faces of the optical fiber can be reduced.

  It is desirable that the solid refractive index matching material has a shape in which a central portion protrudes. This makes it difficult for bubbles to be formed on the optical path.

  The solid refractive index matching material has a thickness and a Shore hardness E of a thickness of 20 μm, a Shore hardness E of 30, a thickness of 20 μm, a Shore hardness of 85, a thickness of 40 μm, and a Shore hardness of E. Is preferably within a range surrounded by four points of 85 points, a thickness of 60 μm, and a Shore hardness E of 30. Thereby, the connection of the optical fiber can be suitably performed.

  An insertion step of inserting a first optical fiber between a base member and a lid member, and an end face of the first optical fiber and a second optical fiber different from the first optical fiber in an alignment groove of the base member. A connecting step of abutting an end face of the fiber, and a state where the end face of a second optical fiber different from the first optical fiber is abutted, the first optical fiber and the cover A pressing step of pressing and fixing the second optical fiber with the centering groove; and injecting a liquid refractive index matching agent into a gap between the base member and the lid member, thereby forming an end face of the first optical fiber and the second optical fiber. A method of manufacturing an optical fiber connection structure having a filling step of filling a liquid refractive index matching agent with an end face of an optical fiber is clarified. Thereby, an optical fiber connection structure with reduced optical connection loss can be manufactured.

=== First Embodiment ===
<Basic configuration of optical fiber connector>
Hereinafter, the basic configuration of the optical fiber connector according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a perspective view of the optical fiber connector according to the first embodiment as viewed from above. 2A to 2C are cross-sectional views of the optical fiber connector according to the first embodiment (a surface cut along a line A-A 'in FIG. 1). FIG. 2A shows a state in which the insertion member F is inserted from the insertion recess 30B, and FIGS. 2B and 2C show a state in which the insertion member F is removed from the insertion recess 30B. In the drawings, the X axis, the Y axis, and the Z axis indicate directions in each drawing to clarify the positional relationship between the members, and the axes are orthogonal to each other. The X axis is a direction parallel to the optical axis direction of the optical fiber 10. The Y axis is a direction parallel to the removal direction of the insertion member F. The Z axis is a direction orthogonal to the X axis and the Y axis. In the following description, the side of the insertion-side optical fiber 11 as viewed from the built-in side optical fiber 10 in the X-axis direction (the direction of the arrow of the X-axis shown in FIG. 1) may be referred to as “front”. Further, the Y axis may be expressed as “lateral direction”. Further, the side of the lid member 32 viewed from the base member 31 in the Z-axis direction (the direction of the arrow of the Z-axis shown in FIG. 1) may be expressed as “upper”.

  The optical fiber connector is a connector for optically connecting optical fibers. The optical fiber connector according to the first embodiment is a connector used for a field-assembled optical connector that connects optical fibers by a mechanical splice method. Specifically, the optical fiber connector according to the first embodiment includes an optical fiber 10, a ferrule 20, and an alignment member 30. The optical fiber connector connects the optical fiber 10 incorporated in the ferrule 20 to another optical fiber 11 by an alignment member 30 provided in front of the ferrule 20. Then, the optical fiber connector keeps the connection state by pressing and fixing the optical fibers 10 and 11 in a connected state.

  The optical fiber connection structure is a structure in which optical fibers are optically connected using an optical fiber connector. In the first embodiment, the optical fibers 10 and 11 are optically connected by the centering member 30, whereby the optical fiber connection structure is configured (manufactured).

  The optical fibers 10 and 11 are one optical fiber to be connected and another optical fiber. One optical fiber 10 has a rear end built in and fixed to the ferrule 20 and a front end extending into the alignment groove 30 </ b> A of the alignment member 30. One end face (front end face) of the optical fiber 10 is disposed at a substantially intermediate position (hereinafter, referred to as a “connection position T”) in the longitudinal direction of the alignment groove 30 </ b> A of the alignment member 30. The other end face (rear end face) of the optical fiber 10 is arranged so as to be exposed from the rear end face of the ferrule 20. In FIG. 1, the dotted line represents the optical fiber 10, and the dashed line represents the alignment groove 30A.

  The other optical fiber 11 is an optical fiber inserted into the alignment groove 30 </ b> A of the alignment member 30 from the direction (front) opposite to the built-in side optical fiber 10 (hereinafter, the optical fiber 10 and the optical fiber 11). Are referred to as “built-in side optical fiber 10” and “insertion side optical fiber 11”, respectively. Then, the end face of the optical fiber 11 on the insertion side is inserted up to the connection position T, and connected so as to abut the end face of the optical fiber 10 on the built-in side.

  The coating film of the optical fiber 11 at the tip portion (end face) is removed. The end faces of the optical fibers 10 and 11 have a planar shape cut out perpendicularly to the axial direction. Since the end face of the optical fiber 10 on the built-in side is cut at the manufacturing factory of the optical fiber connector, it is in a mirror state perpendicular to the optical axis with high precision. On the other hand, since the end face of the optical fiber 11 on the insertion side is cut out by an optical fiber cutter at the site where the optical fiber is connected, there is a possibility that the end face has minute irregularities.

  The optical fibers 10 and 11 may be in any state such as an optical fiber, an optical fiber core, an optical fiber cord, or a single optical fiber cable as long as the end faces are exposed so as to be connectable. Is also good. Further, the shape of the end faces of the optical fibers 10 and 11 may be a planar shape cut out in an inclined direction with respect to the axial direction. Further, the end faces of the optical fibers 10 and 11 may be subjected to a polishing treatment such as PC polishing. Further, an optical fiber in which holes are formed in a cladding layer may be used. Further, the material constituting the optical fibers 10 and 11 may be any material such as a quartz-based or plastic-based material. Also, the refractive indexes of the optical fibers 10 and 11 may be different from each other as long as they do not affect the connection characteristics.

  The ferrule 20 is a member for holding and fixing the optical fiber 10 on the built-in side. The ferrule 20 is fixed to the centering member 30. The ferrule 20 is, for example, a single-core SC optical connector (JIS C5973) or an FC optical connector (JIS C5970). If a plurality of optical fibers 10 are to be connected simultaneously, a multi-core MT optical connector or the like can be used. The ferrule 20 connects the rear end face of the built-in optical fiber 10 to an optical fiber built in another ferrule (not shown) by PC.

  The alignment member 30 is a member for connecting the optical fibers so that the optical axes coincide with each other, and pressing and fixing the optical fibers. The alignment member 30 includes a base member 31, lid members 32 and 33, and a clamp spring. The alignment member 30 forms an alignment groove 30A, an insertion recess 30B, a gap 30C, and a gap 30D according to the shapes of the base member 31, the lid members 32 and 33. The centering member 30 is configured such that the optical fibers 10 and 11 supported in the centering groove 30A of the base member 31 are covered with cover members 32 and 33, and are pressed and fixed by a clamp spring 34.

  The base member 31 is a member that supports the optical fibers 10 and 11. The base member 31 has a flat upper surface and faces the lower surfaces of the lid members 32 and 33. A V-shaped groove parallel to the X-axis direction is formed on the upper surface of the base member 31, and the V-shaped groove constitutes the alignment groove 30A. A concave insertion recess 30B having a concave shape is formed on the upper surface of the base member 31 (see FIG. 2). The base member 31 is connected to the ferrule 20 along the longitudinal direction.

  The lid members 32 and 33 are provided so as to cover the alignment groove 30A of the base member 31 from above, and are members that press and fix the optical fibers 10 and 11 to the alignment groove 30A. The lower surfaces of the lid members 32 and 33 are flat surfaces, and face the upper surface of the base member 31. The lower surfaces of the lid members 32 and 33 come into contact with the optical fibers arranged in the alignment grooves 30A, and press the optical fibers 10 and 11 against the alignment grooves 30A. The base member 31 and the lid members 32 and 33 of the centering member 30 may be made of any material such as a plastic material and a metal material.

  The clamp spring 34 is a spring member that presses the base member 31 and the lid members 32 and 33 so as to sandwich the same from above and below. More specifically, the clamp spring 34 is provided so as to sandwich the base member 31 and the lid members 32 and 33 from above and below from below the base member 31 to above the lid members 32 and 33. The clamp spring 34 maintains the base member 31 and the lid members 32 and 33 in a state where pressing force is exerted from above and below. Thus, when the insertion member F is removed from the insertion concave portion 30B, the optical fibers 10 and 11 are pressed and fixed to the lower surfaces of the lid members 32 and 33 and the wall surface of the alignment groove 30A.

  The aligning groove 30A connects the pair of optical fibers 10 and 11 from the front-back direction (± X direction) of the aligning member 30 and connects the optical fibers 10 and 11 so that the optical axes coincide with each other. This is a guide groove to be made. The alignment groove 30 </ b> A is formed linearly on the upper surface of the base member 31 so as to penetrate from one side surface to the opposite side surface. A built-in optical fiber 10 extending from the ferrule 20 is inserted and fixed to one end side (−X side) of the alignment groove 30A, and the other end side (+ X side) of the alignment groove 30A is The optical fiber 11 on the insertion side can be inserted.

  The alignment groove 30A is formed as a V groove. However, the cross-sectional shape of the alignment groove 30A may be a shape other than the V-shape, and may be, for example, a rectangular shape or a U-shape. Alternatively, a concave portion or a convex portion may be formed on the lid members 32, 33, and the concave portions or the convex portions of the lid members 32, 33 may be fitted into the alignment grooves 30A of the base member 31.

  The insertion recess 30B is a groove for inserting the insertion member F and forming a space between the alignment groove 30A and the lid members 32 and 33 (see FIGS. 2A and 2B). The insertion recess 30 </ b> B is formed by a concave shape at the lateral end (+ Y direction) of the upper surface of the base member 31 and a concave shape at the lateral end (+ Y direction) of the lower surfaces of the lid members 32 and 33. Have been. However, the insertion recess 30 </ b> B may be formed on one of the upper surface of the base member 31 and the lower surfaces of the lid members 32 and 33. Further, the insertion member F may be inserted between the upper surface of the base member 31 and the lid members 32 and 33 without forming the insertion concave portion 30B.

  The insertion member F is a member that is inserted into the insertion recess 30B. The insertion portion of the insertion member F has a shape that fits into the insertion recess 30B, and can be inserted into the insertion recess 30B. In a state where the insertion member F is inserted into the insertion concave portion 30B, the space between the base member 31 and the lid members 32 and 33 is pushed open against the urging force of the clamp spring 34, and the alignment groove 30A is formed. The optical fiber 11 on the insertion side is maintained in a state where it can be inserted (FIG. 2A). After the insertion side optical fiber 11 is inserted into the alignment groove 30A in a state where the insertion member F is inserted into the insertion concave portion 30B, and after the insertion side optical fiber 11 and the built-in side fiber 10 are connected, When the insertion member F is removed from the insertion concave portion 30B (FIG. 2B), the optical fibers 10, 11 are pressed and fixed between the alignment groove 30A of the base member 31 and the lower surfaces of the lid members 32, 33. .

  As shown in FIGS. 2A to 2C, gaps 30C and 30D are formed between the upper surface of the base member 31 and the lower surfaces of the lid members 32 and 33. Here, a reference numeral 30C is assigned to a gap on the side of the insertion recess 30B as viewed from the alignment groove 30A, and a reference numeral 30D is assigned to a gap on the opposite side. As shown in FIG. 2A, when the insertion member F is inserted into the insertion concave portion 30B, the gaps 30C and 30D are expanded to be relatively wide. When the insertion member F is removed from the insertion concave portion 30B, the gaps 30C and 30D become narrow as shown in FIGS. 2B and 2C. When the insertion member F is removed from the insertion concave portion 30B, the lower surfaces of the lid members 32 and 33 come into contact with the optical fibers 10 and 11, so that the upper surface of the base member 31 and the lower surfaces of the lid members 32 and 33 are in contact with each other. Slight gaps 30C and 30D are formed between them.

  The gap 30C is a gap between the upper surface of the base member 31 and the lower surfaces of the lid members 32 and 33, and is a gap on the side of the insertion recess 30B when viewed from the alignment groove 30A. The gap 30C is a gap narrower than the insertion recess 30B, and communicates with the alignment groove 30A from the insertion recess 30B. The gap 30C is a gap for injecting the liquid refractive index matching agent C1 into the connection position T between the optical fibers 10 and 11 (see FIG. 2C). In other words, the gap 30C allows the liquid refractive index matching agent C1 to be injected into the connection position of the optical fibers 10, 11 in a state where the optical fibers 10, 11 are pressed and fixed in the alignment grooves 30A. When the liquid refractive index matching agent C1 is injected from the insertion concave portion 30B, it penetrates into the gap 30C by capillary action and is injected into the connection portion between the optical fibers 10 and 11.

  The gap 30D is a gap between the upper surface of the base member 31 and the lower surfaces of the lid members 32 and 33, and is a gap on the side opposite to the insertion recess 30B when viewed from the alignment groove 30A. The gap 30D is a gap narrower than the insertion recess 30B. The gap 30D communicates with the alignment groove 30A. The gap 30D is a gap for draining the liquid refractive index matching agent C1 from the connection position T of the optical fibers 10 and 11 (see FIG. 2C). In other words, the gap 30D allows a part of the liquid refractive index matching agent C1 introduced into the alignment groove 30A from the gap 30C to be drained (the details will be described later with reference to FIG. 4C).

<Optical fiber connection method>
Next, with reference to FIGS. 3 to 5, details of a method of connecting an optical fiber (a method of manufacturing an optical fiber connection structure) according to the first embodiment will be described.

  FIG. 3 is a work flowchart of the optical fiber connection method according to the first embodiment. The optical fiber connection process of the first embodiment includes, in chronological order, a preparation step S1, an insertion step S2, a connection step S3, a pressing step S4, an injection step S5, and a solidification step S6. Here, the preparation step S1, the insertion step S2, the connection step S3, the pressing step S4, and the injection step S5 are steps performed by an operator, and the solidification step S6 is a time-consuming operation that does not require an This is a process performed over time. Then, in the injection step S5, while the optical fibers 10 and 11 are pressed and fixed, a liquid refractive index matching agent C1 is made to penetrate the connection portions of the optical fibers 10 and 11 so that the optical connection between the optical fibers 10 and 11 is performed. The loss can be reduced (see FIG. 4).

  The preparation step S1 is a step of preparing the optical fiber connector shown in FIG. As shown in FIGS. 1 and 2A, the alignment member 30 of the prepared optical fiber connector has the insertion member F inserted into the insertion concave portion 30B. In the preparation step S1, pre-processing of the optical fiber 11 on the insertion side shown in FIG. 1 is also performed. As a pretreatment of the optical fiber 11, a step of removing the coating film at the tip portion of the optical fiber 11 to extract the bare optical fiber, and using an optical fiber cutter, the initial optical fiber 11 is cleaved into the cleaved optical fiber 11. A step of making a scratch and a step of cutting the optical fiber 11 at a location where the initial cleavage for the cleavage is made using an optical fiber cutter are performed. The reason why the optical fiber 11 on the insertion side is cut is to adjust the optical fiber 11 to a required length and to expose a flat surface without contamination on the end face of the optical fiber 11. However, an end face cut out using an optical fiber cutter may have fine irregularities when viewed microscopically.

  The insertion step S2 is a step of inserting the optical fiber 11 on the insertion side into the alignment groove 30A of the alignment member 30. Since the insertion member F is inserted into the insertion recess 30B of the alignment member 30, the insertion-side optical fiber 11 can be inserted into the alignment groove 30A (see FIG. 2A).

  The connection step S3 is a step of abutting the end face of the optical fiber 11 on the insertion side with the end face of the optical fiber 10 on the built-in side arranged in the alignment groove 30A. When the insertion-side optical fiber 11 is inserted into the alignment groove 30 </ b> A, and the end surface of the insertion-side optical fiber 11 abuts against the end surface of the built-in side optical fiber 10, the insertion-side optical fiber 11 is located in front of the alignment member 30. Will bend. For this reason, if the operator inserts the insertion-side optical fiber 11 into the alignment groove 30A until the insertion-side optical fiber 11 bends in front of the alignment member 30, the end surface of the insertion-side optical fiber 11 becomes the built-in side. Of the optical fiber 10 of FIG. When the end faces of the optical fibers 10 and 11 abut each other, a slight gap is formed between the end faces of the optical fibers 10 and 11 because the end face of the optical fiber 11 on the insertion side is rough.

  The pressing step S4 is a step of pressing and fixing the connected optical fibers 10 and 11 to the alignment groove 30A to maintain the connection state. The pressing step S4 is, specifically, a step of removing the insertion member F from the insertion recess 30B of the alignment member 30. As a result, the clamp spring 34 presses the base member 31 and the lid members 32 and 33 so as to sandwich them from above and below, and presses and fixes the connected optical fibers 10 and 11 to the alignment groove 30A. When the insertion member F is removed from the insertion recess 30B, the gaps 30C and 30D become narrow as shown in FIGS. 2B and 2C.

  The injection step S5 is a step of injecting the liquid refractive index matching agent C1 into the connection position T between the optical fibers 10 and 11. At this time, when the operator injects the liquid refractive index matching agent C1 from the insertion concave portion 30 from which the insertion member F has been removed (see FIG. 2C), the liquid refractive index matching agent C1 is inserted through the gap 30C. And the liquid refractive index matching agent C1 is introduced into the connection position T of the optical fibers 10 and 11 in the alignment groove 30A. Then, the liquid refractive index matching agent C1 penetrates into a minute gap between the end faces of the optical fibers 10 and 11 by a capillary phenomenon.

  5A and 5B are explanatory diagrams of a comparative example. In the comparative example, before the optical fiber is connected, the liquid refractive index matching agent is injected beforehand, and the end of the optical fiber on the insertion side is inserted into the liquid injected refractive index matching agent beforehand. I have. FIG. 5A shows a state in which a liquid refractive index matching agent Z1 is injected before the optical fiber Z2 is inserted. FIG. 5B shows a state in which a bubble Z3 is taken into the end face of the optical fiber Z2 when the optical fiber Z2 is inserted. Conventionally, when optical fibers are connected to each other, a liquid refractive index matching agent is injected in advance into the alignment groove, and in this state, the optical fiber is inserted into the liquid refractive index matching agent, and another optical fiber is inserted. There has been a method of connecting a fiber with a liquid refractive index matching agent between the fiber and the fiber. However, in the case of using this method, as shown in FIG. 5B, when the end of the optical fiber is inserted into the liquid refractive index matching agent, bubbles are taken in (entrained) on the end face of the optical fiber. There was something. As a result, bubbles are included in the connection portion of the optical fiber, and the bubbles increase the optical connection loss. In addition, when this method is used, when the end of the optical fiber is inserted into the liquid refractive index matching agent, there is a possibility that dust may enter the connection portion of the optical fiber.

  Therefore, in this embodiment, instead of inserting the ends of the optical fibers into a liquid refractive index matching agent that has been injected in advance as in the comparative example, the optical fibers 10 and 11 are brought into contact with each other. , 11 are filled with a liquid refractive index matching agent. Thereby, the introduction of air bubbles into the connection portion of the optical fibers 10 and 11 can be suppressed.

  4A to 4C are explanatory diagrams of the injection path of the liquid refractive index matching agent C1. 4A to 4C show the state of penetration of the liquid refractive index matching agent C1 below the lid member 32. The right figures in each figure show the state of penetration of the liquid refractive index matching agent C1 at the end face of the optical fiber.

  As shown in FIG. 4A, when the liquid refractive index matching agent C1 is injected into the interposition concave portion 30B, the gap between the upper surface of the base member 31 and the lower surface of the lid member 32 flows from the interposition concave portion 30B. Penetrate 30C. Since the gap 30C is a gap narrower than the interposing concave portion 30B, the liquid refractive index matching agent C1 easily permeates into the gap 30C by capillary action.

  In the present embodiment, after the insertion member F is removed, the liquid refractive index matching agent is injected into the portion (the insertion concave portion 30B) where the insertion member F was inserted. For this reason, the insertion member F does not hinder the injection of the liquid refractive index matching agent C1. Further, since the insertion member F is removed from the insertion concave portion 30B to make the gap between the base member 31 and the cover member 32 narrow, the liquid refractive index matching agent C1 is injected. Is easy to penetrate.

  In the present embodiment, a liquid refractive index matching agent is injected into the insertion concave portion 30B for inserting the insertion member F. Therefore, when the liquid refractive index matching agent is injected, the liquid refractive index matching agent C1 can be prevented from flowing out, and the outer peripheral surface of the alignment member 30 can be prevented from being stained with the liquid refractive index matching agent C1. it can.

  As shown in FIG. 4B, the liquid refractive index matching agent C1 further penetrates through the gap 30C and penetrates between the end faces of the optical fibers 10 and 11. Since the end faces of the optical fibers 10 and 11 are butted in the connection step S3 described above, the gap between the end faces of the optical fibers 10 and 11 is extremely small. The liquid refractive index matching agent C1 penetrates into the gap. As a result, gas (bubbles) is unlikely to be formed between the end faces of the optical fibers 10 and 11.

As shown in FIG. 4C, the liquid refractive index matching agent C1 penetrates deeper than the alignment groove 30A, and penetrates into the gap 30D between the upper surface of the base member 31 and the lower surface of the lid member 32. The gap 30D is a gap narrower than the insertion recess 30B, and the liquid refractive index matching agent C1 penetrates into the gap 30D by capillary action.
Further, in the present embodiment, the liquid refractive index matching agent C1 penetrates into the gap 30D by capillary action, so that the liquid refractive index matching agent C1 is supplied to the gap 30D from between the end faces of the optical fibers 10 and 11. Will be. In other words, even after the liquid refractive index matching agent C1 is filled between the end faces of the optical fibers 10 and 11, the liquid refractive index matching agent C1 penetrates into the gap 30D due to the capillary phenomenon, and thus the optical fibers 10, 11 , The liquid refractive index matching agent C1 continues to flow between the end faces. Accordingly, even if gas remains between the end faces of the optical fibers 10 and 11 at the stage of FIG. 4B and bubbles are formed on the end faces of the optical fibers, as shown in FIG. Penetrates into the gap 30D, the bubbles on the end face of the optical fiber flow to the back together with the liquid refractive index matching agent C1, so that the bubbles on the end face of the optical fiber can be removed.

  The solidification step S6 is a step of solidifying the liquid refractive index matching agent C1. By solidifying the liquid refractive index matching agent C1, deterioration of the liquid refractive index matching agent C1 can be suppressed, and the optical connection state of the optical fibers 10 and 11 can be stabilized. In the present embodiment, for example, a volatile material is used as the liquid refractive index matching agent C1. For this reason, the liquid refractive index matching agent C1 is solidified by evaporating the solvent after a certain period of time from the injection, so that the solidification work by the operator is unnecessary.

  By the way, if the liquid refractive index matching agent is injected from the product shipping stage of the optical fiber connector (for example, in the case of the comparative example), the liquid refractive index matching agent solidifies before connecting the optical fiber. Is not allowed, it is necessary to employ a liquid index matching agent which does not solidify. On the other hand, in the present embodiment, since the liquid refractive index matching agent is filled between the end faces of the optical fibers 10 and 11 after the optical fibers 10 and 11 are abutted, for example, solidification such as a volatile material is performed. Possible liquid refractive index matching agents can be employed.

<Characteristics of refractive index matching agent>
More specific characteristics of the above-mentioned liquid refractive index matching agent C1 will be described.

  As described above, the liquid refractive index matching agent C1 is a member that is injected into the connection portion after the optical fibers 10 and 11 are connected, and fills the minute gap generated in the connection portion between the optical fibers 10 and 11. Then, the liquid refractive index matching agent C1 is fixed to the connection portion between the optical fibers 10 and 11, and performs the refractive index matching of the connection portion between the optical fibers 10 and 11.

  The liquid refractive index matching agent C1 is more preferably an acrylic or silicone polymer material, for example, from the viewpoint of adhesion to an optical fiber and environmental resistance. However, polymer materials such as epoxy, vinyl, rubber, urethane, methacryl, nylon, bisphenol, diol, polyimide, fluorinated epoxy, and fluorinated acrylic can be used. Further, a combination of these polymer materials or a combination of these polymer materials with other materials may be used. Further, a material obtained by adding a cross-linking agent, an additive, or a softening agent to the above material may be used. In addition, the polymer materials listed above have wettability to glass (optical fibers 10 and 11), and are injected into the connection portions of the optical fibers 10 and 11 by capillary action in the injection step S5. .

  Also, it is preferable that the liquid refractive index matching agent C1 is formed so that the viscosity at the time of injection is 300 mPa · s or less. By setting the viscosity at the time of injection to 300 mPa · s or less, it is possible to easily penetrate into minute gaps generated at the connection portions of the optical fibers 10 and 11 by capillary action. The viscosity can be adjusted, for example, by adding an additive (a plasticizer or a lubricant) to the refractive index matching agent. In addition, it can also be carried out by emulsifying a resin having refractive index matching with water.

  Further, it is desirable that the liquid refractive index matching agent C1 be solidified after the injection and be a material fixed to the connection portion of the optical fibers 10 and 11. As a result, the connection portion (between the end faces) of the optical fibers 10 and 11 is stably maintained, and a good connection state can be maintained for a long time. As a property for solidifying after injection, a resin that cures by reacting with air or moisture, a volatile material, an ultraviolet curable resin, a thermoplastic resin, a thermosetting resin, or the like can be given. Note that any of the above-described polymer materials can have any of these characteristics by selecting a solvent or the like, and can also function as an adhesive. However, when the liquid refractive index matching agent C1 is kept in a stable state by surface tension, it is not always necessary to solidify the liquid crystal refractive index matching agent C1.

  In addition, the refractive index of the liquid refractive index matching agent C1 is set to have a difference in refractive index between the optical fibers 10 and 11 within ± 0.1 to avoid Fresnel reflection on the end faces of the optical fibers 10 and 11. More preferably, the refractive index is adjusted so as to be within ± 0.05. When the refractive indexes of the optical fibers 10 and 11 to be connected are different from each other, the difference between the refractive index of the liquid refractive index matching agent C1 and the average value of the refractive indexes of the optical fibers 10 and 11 to be connected is ±. It is desirable to set it within 0.1. The refractive index of the refractive index matching agent can be adjusted by changing the components and the composition ratio to be contained in the refractive index matching agent. For example, the refractive index can be adjusted by mixing a low refractive index epoxy or acrylic polymer material and a high refractive index vinyl polymer material, and adjusting the composition ratio. The refractive index can also be adjusted by changing the sulfur content and the fluorine content of the epoxy polymer material.

  As described above, according to the optical fiber connection method of the present embodiment, after the end faces of the optical fibers 10 and 11 are butted against each other, the liquid refractive index matching agent C1 is inserted into the gap (gap 30C) between the base member 31 and the lid member 32. To fill a liquid refractive index matching agent between the end faces of the optical fibers 10 and 11 (see FIGS. 4A to 4C). For this reason, according to the optical fiber connection method of the present embodiment, bubbles are not taken into the end face of the optical fiber 11 unlike the comparative example (see FIG. 5B). In the optical fiber connecting method according to the present embodiment, the liquid refractive index matching agent C1 penetrates into a very small gap between the end faces of the optical fibers 10 and 11 by capillary action. Is easily filled with the liquid refractive index matching agent C1, and bubbles are not easily formed on the end face of the optical fiber.

  Further, according to the optical fiber connection method of the present embodiment, in the injection step S5, the gap 30D (the gap opposite to the side where the liquid refractive index matching agent is injected when viewed from the alignment groove 30A) is filled with the liquid. The refractive index matching agent is permeated (see FIG. 4C). Thus, even after the liquid refractive index matching agent C1 is filled between the end faces of the optical fibers 10 and 11, the liquid refractive index matching agent C1 continues to flow between the end faces of the optical fibers 10 and 11. Therefore, even if bubbles are formed on the end face of the optical fiber, the bubbles can be removed.

  Further, according to the present embodiment, the optical fibers 10 and 11 are optically connected by the centering member 30 of the optical fiber connector to constitute (manufacture) the optical fiber connection structure. According to such a method for manufacturing an optical fiber connection structure, since an air bubble is not easily formed on the end face of the optical fiber, an optical fiber connection structure with reduced optical connection loss can be manufactured.

(Modification)
After optically connecting the optical fibers 10 and 11 using the optical fiber connector (aligning member 30) as described above, the connection portion between the optical fibers 10 and 11 is caused by the aging of the liquid refractive index matching agent C1 or the like. In some cases, a gap is generated, and the optical connection loss may gradually increase. In such a case, the gap can be filled by re-injecting the liquid refractive index matching agent C1 into the connection portion between the optical fibers 10 and 11. The method of re-injecting the liquid refractive index matching agent C1 is the same as in the above embodiment. That is, when the operator injects the liquid refractive index matching agent C1 from the insertion concave portion 30, the liquid refractive index matching agent C1 penetrates the inside through the gap 30C, and the optical fiber in the alignment groove 30A. The liquid crystal refractive index matching agent C1 is filled in the gap between the end faces of the optical fibers 10 and 11 (the gap generated at the connection portion between the optical fibers 10 and 11 due to the deterioration of the liquid refractive index matching agent C1 with time). Thereby, the optical connection loss can be recovered. At this time, the liquid refractive index matching agent C1 may be injected while measuring the optical connection loss.

=== Second Embodiment ===
FIG. 6 is a view of the base member 31 of the second embodiment as viewed from above. 7A and 7B are explanatory diagrams of the optical fiber connection method according to the second embodiment. As in the first embodiment, an alignment groove 31 is formed on the upper surface of the base member 31. An accommodation groove 312 is formed on the upper surface of the base member 31 according to the second embodiment. A string-shaped wetting member 35 is accommodated in the accommodation groove 312, and the wetting member 35 is moistened with the liquid refractive index matching agent C1.

  The accommodation groove 312 is a groove for accommodating the wet member 35 and is a groove parallel to the alignment groove 31. The housing groove 312 is formed at least in the vicinity of the end face of the optical fiber 10 on the internal side. Therefore, the wetting member 35 wetted with the liquid refractive index matching agent C1 is also disposed near the end face of the optical fiber 10 on the visceral side. The accommodation groove 312 has, for example, a rectangular shape with a width of about 0.5 to 1.0 mm and a length of about 3 mm when viewed from above. The depth of the accommodation groove 312 is smaller than the diameter of the wetting member 35. Here, the wetting member 35 has a diameter of about 1.0 mm, and the depth of the accommodation groove 312 is about 0.8 mm. For this reason, the wetting member 35 is accommodated in the accommodating portion while at least a part thereof is projected from the accommodating groove 312 (see FIG. 7A). That is, a part of the wet member 35 protruding from the accommodation groove 312 is disposed in the gap between the base member 31 and the lid member 32 (see FIG. 7A).

  Also in the second embodiment, the insertion-side optical fiber 11 is inserted into the alignment groove 30A of the alignment member 30 (insertion step S2), and the end face of the insertion-side optical fiber 11 is connected to the end face of the built-in side optical fiber 10. After butting (after the connection step S3), the interposition member F is removed from the insertion recess 30B of the alignment member 30, and the connected optical fibers 10, 11 are pressed and fixed to the alignment groove 30A (pressing step S4). . In the second embodiment, when the insertion member F is removed, the gap between the base member 31 and the lid member 32 is reduced, and the wet member 35 protruding from the housing groove 312 is pressed from the lid member 32 (see FIG. 7B). ). Since the liquid refractive index matching agent C1 is wetted in advance by the wet member 35, when the wet member 35 is pressed from the lid member 32, the liquid refractive index matching agent C1 is squeezed out of the wet member 35, and The liquid refractive index matching agent C1 is injected into the connection position of the optical fibers 10 and 11 (see FIG. 7B: injection step). Therefore, in the second embodiment, even if the operator does not inject the liquid refractive index matching agent C1 as in the first embodiment, if the pressing step is performed, the liquid is inserted into the gap between the base member 31 and the lid member 32. The liquid crystal refractive index matching agent C1 can be filled between the end faces of the optical fibers 10 and 11 by injecting the refractive index matching agent C1.

  The accommodation groove 312 and the wetting member 35 are desirably arranged on the side where the insertion member F is inserted when viewed from the alignment groove 30A. Thereby, the liquid refractive index matching agent C1 squeezed from the wetting member 35 penetrates into the narrow gap side (the left side in FIG. 7B) by capillary action, and the liquid refractive index matching agent C1 becomes optical fibers 10 and 11. Is easily injected into the connection position.

  Further, it is desirable that the gap between the base member 31 and the lid member 32 in a state where the interposition member F is interposed (see FIG. 7A) is smaller than the outer diameter of the wetting member 35. Thereby, it is possible to prevent the wetting member 35 from falling out of the accommodation groove 312. In addition, in order to further prevent the wetting member 35 from falling off, it is preferable that a non-slip is formed in the housing groove 312. For example, in the present embodiment, a plurality of protrusions 312A (non-slip portions) are formed on the bottom surface of the accommodation groove 312, and the protrusions 312A are cut into the wetting member 35 to prevent the wetting member 35 from falling off. are doing.

  In the present embodiment, the wetting member wetted with the liquid refractive index matching agent has a string shape. However, the wetting member may be, for example, a rectangular parallelepiped sponge member. Further, the wet member 35 may be arranged on the side of the lid member 32 instead of the side of the base member 31. Further, the wetting member 35 may be disposed between the base member 31 and the lid member 32 even if it is not housed in the housing groove 312.

=== Third Embodiment ===
The third embodiment is different from the first embodiment in that a solid refractive index matching material C2 is interposed at the connection portion between the optical fibers 10 and 11. The configuration of the optical fiber connector (aligning member 30) and the optical fiber connection process (preparation step S1, insertion step S2, connection step S3, pressing step S4, injection step S5, solidification step S6) are described in The description is omitted because it is common to the first embodiment.

  8A to 8D are explanatory diagrams showing the functions of the liquid refractive index matching agent C1 and the solid refractive index matching material C2 of the third embodiment. Here, FIG. 8A shows the insertion step S2. FIG. 8B shows the connecting step S3. FIG. 8C shows the implantation step S5. FIG. 8D shows the solidification step S6.

  In the third embodiment, a film-like solid refractive index matching material C2 is previously attached to the end face of the optical fiber 10 on the built-in side (FIG. 8A). When the optical fiber 11 on the insertion side is inserted, the end face of the optical fiber 11 on the insertion side comes into contact with the solid refractive index matching material C2, and the optical fibers 10 and 11 are connected via the solid refractive index matching material C2. (FIG. 8B). The solid refractive index matching material C2 acts as a stress relieving material when the optical fiber 11 on the insertion side is inserted, and reduces the impact force on the end face of the optical fiber 10 on the built-in side. When the end face of the optical fiber 11 on the insertion side comes into contact with the solid refractive index matching material C2, the solid refractive index matching material C2 is deformed so as to follow the shape of the end face of the optical fiber 11, and Adhere to the end face. Even if there are minute irregularities on the end face of the optical fiber 11 on the insertion side, the solid refractive index matching material C2 is deformed in accordance with the irregularities, so that the solid refractive index matching material C2 and the end face of the optical fiber 11 are not deformed. There is almost no gap (gas) between them. In the present embodiment, since the solid refractive index matching material C2 has a partial spherical shape with a protruding central portion, the solid refractive index matching material C2 is mainly formed in the central region (core region) of the end face of the optical fiber 11. (The layer 11a or the mode field diameter portion). In the present embodiment, the outer peripheral regions (cladding layers 10b and 11b) of the end faces of the optical fibers 10 and 11 are not in contact with each other by the solid refractive index matching material C2.

  Thereafter, in the pressing step S4, the insertion member F is removed from the insertion recess 30B of the alignment member 30 (see FIG. 2B), and the optical fibers 10 and 11 are aligned with the alignment grooves 30A by the lid members 32 and 33. Pressed and fixed inside.

  In the injection step S5, when the liquid refractive index matching agent C1 is injected from the insertion concave portion 30 from which the insertion member F is removed (see FIG. 2C), the liquid refractive index matching agent C1 is inserted through the gap 30C. And the gap between the end faces of the optical fibers 10 and 11 connected via the solid refractive index matching material C2 is filled with the liquid refractive index matching agent C1 (FIG. 8C). In other words, the gap between the solid refractive index matching material C2 attached to the end face of the optical fiber 10 on the built-in side and the end face of the optical fiber 11 on the insertion side is filled with a liquid refractive index matching agent C1. At this time, even if there is a gap (gas) between the solid refractive index matching material C2 and the end face of the optical fiber 11 on the insertion side (particularly, the end face of the core layer 11a), a liquid refractive index matching agent is formed in this gap. Since C1 is filled, formation of bubbles on the end faces of the optical fibers 10 and 11 can be suppressed. Since the gap between the solid refractive index matching material C2 and the end face of the optical fiber 11 on the insertion side is minute, the liquid refractive index matching agent C1 easily penetrates into the gap due to capillary action. Further, since the gap between the solid refractive index matching material C2 and the end face of the optical fiber 11 on the insertion side is very small, once the liquid refractive index matching material C1 is filled, the liquid refractive index matching material C1 becomes the surface. It is easy to be fixed in the gap by the tension.

  After the injection step S5 (see FIG. 8C), the liquid refractive index matching agent C1 is solidified in the solidification step S6 (FIG. 8D). In the present embodiment, each of the liquid refractive index matching agent C1 and the solid refractive index matching material C2 functions as a refractive index matching agent in a connection portion of the optical fibers 10 and 11, thereby improving connection characteristics.

<Characteristics of refractive index matching material>
Here, more specific characteristics of the above-described refractive index matching material will be described. As the liquid refractive index matching agent C1, those having the same materials and characteristics as those described in the first embodiment can be used.

  The solid refractive index matching material C2 is a member that deforms along the shape of the end faces of the optical fibers 10 and 11 when the optical fibers 10 and 11 are abutted with each other, and reduces a gap at a connection portion of the optical fibers 10 and 11. It is. The solid refractive index matching material C2 has a refractive index matching property (close to the refractive index) with the optical fibers 10 and 11 to be connected, like the liquid refractive index matching material C1, and improves connection characteristics. Let it.

  As the solid refractive index matching material C2, a solid material (having a large viscosity) similar to the liquid refractive index matching agent C1 described above can be used. Specifically, the solid refractive index matching material C2 is desirably an acrylic or silicone polymer material from the viewpoint of adhesiveness to an optical fiber and environmental resistance, and other epoxy, vinyl, and rubber materials. A high molecular material such as a system, a urethane system, a methacryl system, a nylon system, a bisphenol system, a diol system, a polyimide system, a fluorinated epoxy system, a fluorinated acrylic system, or a combination thereof can also be used. Further, the solid refractive index matching material C2 and the liquid refractive index matching agent C1 may be made of different materials or may be made of the same material as long as they can fulfill the respective functions described above. . In order to enhance the wettability, the surface may be activated by subjecting the solid refractive index matching material C2 to UV irradiation, plasma treatment, or the like.

  Also, the refractive index matching of the solid refractive index matching material C2 is, like the liquid refractive index matching agent C1, such that the difference in refractive index between the optical fibers 10 and 11 is within ± 0.1, more preferably ± 0. .05 or less.

  FIG. 9 is an explanatory diagram of the relationship between the hardness and the thickness of the solid refractive index matching material C2 of the third embodiment. The horizontal axis represents the thickness of the solid refractive index matching material C1, and the vertical axis represents Shore hardness E (JIS K6253). As described below, as the solid refractive index matching material C2, those having the hardness and thickness corresponding to the R1 region and the R2 region (region surrounded by a thick line) in FIG. 9 can be preferably used.

  In the region R3 (the region where the Shore hardness E is lower than 30), the hardness is too low, so that the impact relaxation effect due to the abutment of the optical fiber 11 cannot be sufficiently obtained. However, even when the solid refractive index matching material C2 in the region R3 is used, the impact due to the abutment of the optical fiber 11 can be reduced as compared with the case where the solid refractive index matching material C2 is not provided.

  In the region R4 (region where the Shore hardness E is larger than 85), the hardness is too high, and the follow-up deformation to the unevenness of the end face of the optical fiber 11 on the insertion side becomes insufficient. However, even when the solid refractive index matching material C2 in the region R4 is used, the gap between the end faces of the optical fibers 10 and 11 can be made finer than when no solid refractive index matching material C2 is used. The liquid refractive index matching agent C1 easily penetrates into the gap due to capillary action.

  In the region R5 (the region having a thickness smaller than 20 μm), the impact relaxation effect due to the abutment of the optical fiber 11 cannot be sufficiently obtained because the thickness is too thin. However, even when the solid refractive index matching material C2 in the region R5 is used, the impact due to the abutment of the optical fiber 11 can be reduced as compared with the case where the solid refractive index matching material C2 is not provided.

  In the region R6 (the region having a thickness larger than 60 μm), the position of the end portion of the optical fiber 11 is difficult to be stabilized because the thickness is too large, and the alignment accuracy may be reduced. Also, in the region R7 (the region on the side where the thickness is larger than the straight line LP connecting the point P1 and the point P2), the position of the end of the optical fiber 11 becomes difficult to stabilize, and there is a possibility that the alignment accuracy may decrease. is there. However, even when the solid refractive index matching material C2 in the region R6 and the region R7 is used, the gap between the end faces of the optical fibers 10 and 11 is made finer than when the solid refractive index matching material C2 is not provided. As a result, the liquid crystal refractive index matching agent C1 easily penetrates into the gap due to capillary action.

  Therefore, the region R1 and the region R2 have appropriate hardness and thickness of the solid refractive index matching material C2. That is, the solid refractive index matching material C2 is (thickness 20 μm, Shore hardness E: 30), (thickness 20 μm, Shore hardness E: 85), (thickness 40 μm, Shore hardness E: 85), (thickness Those having a range surrounded by four points of 60 μm and Shore hardness E: 30) can be suitably used.

  The solid refractive index matching material C2 in the region R2 can be suitably used when the optical fiber 11 on the insertion side is a holey optical fiber (for example, hole-assisted fiber: HAF). When the optical fiber 11 on the insertion side is an optical fiber with a hole, a hole is opened at the end face, and the solid refractive index matching material C2 enters the hole, so that light on the insertion side with respect to the optical fiber 10 on the built-in side. The position of the fiber 11 is stabilized, and the alignment accuracy is stabilized. If the hardness of the solid refractive index matching material C2 is too low, the position of the optical fiber 11 on the insertion side is not stable even if the solid refractive index matching material C2 enters the holes, and if the hardness is too high, It becomes difficult for the solid refractive index matching material C2 to enter the holes. Therefore, when the optical fiber 11 on the insertion side is an optical fiber with a hole, the solid refractive index matching material C2 in the region R2 can be suitably used.

  The solid refractive index matching material C2 preferably has a partial spherical shape protruding toward the distal end so that a top is formed on the extension of the optical axis of the optical fiber 10 on the built-in side (see FIG. 8A). ). Since the center of the solid refractive index matching material C2 has a shape protruding so that the top is located on the optical axis of the optical fiber, the solid refractive index matching material C2 and the central region of the end face of the optical fiber 11 on the insertion side are formed. (The core layer 11a or the mode field diameter portion), and bubbles are less likely to be formed on the optical axis. In addition, since the outer peripheral regions (cladding layers 10b and 11b) of the end faces of the optical fibers 10 and 11 can be brought into contact with each other, the edge protruding sharply at the outer peripheral portion of the end face of the optical fiber 11 cut by the optical fiber cutter can be obtained. Even in the case where the optical fiber is formed, it is possible to prevent the edge of the optical fiber from being displaced by the edge at the time of abutting, and to suppress the possibility of damaging the other end of the optical fiber. However, the shape of the solid refractive index matching material C2 may be formed in a uniform film thickness instead of the partial spherical shape.

FIG. 10 is an explanatory diagram of a method for forming the solid refractive index matching material C2 of the third embodiment. The step of forming the solid refractive index matching material C2 is not performed at the connection site of the optical fiber, but is performed at a manufacturing factory of the optical fiber connector.
As shown in the drawing, a liquid refractive index matching agent is attached to the end of the built-in side optical fiber 10 before being housed in the centering member 30, and the liquid state refractive index matching agent is solidified. A partial refractive index matching material C2 having a partially spherical shape can be formed at the end of the solid-state imaging device 10. When bubbles are taken into the end face of the optical fiber 10 as shown in FIG. 5B (comparative example) when the liquid refractive index matching agent is adhered to the end of the optical fiber 10, such a defect is caused. It is preferable that the optical fiber 10 is eliminated in a quality inspection process or the like, and an optical fiber connector is manufactured using only the optical fiber 10 having a normal solid refractive index matching material C2 without bubbles. Alternatively, a voltage may be applied between the optical fiber 10 and the liquid refractive index matching agent to electrostatically adsorb a droplet made of the liquid refractive index matching agent to the end of the built-in optical fiber 10. The method of forming the solid refractive index matching material C2 may be another method, for example, a coating method (printing, spraying electrostatic coating, etc.), a vapor deposition method (chemical vapor deposition, physical vapor deposition, etc.), a film May be used.

  As described above, according to the optical fiber connection method (the method for manufacturing an optical fiber connection structure) of the present embodiment, the gap between the end faces of the optical fibers 10 and 11 can be reduced by the solid refractive index matching material C2. The refractive index matching agent C1 easily penetrates between the end faces of the optical fibers 10 and 11 due to the capillary phenomenon.

=== Fourth Embodiment ===
The method of connecting an optical fiber (the method of manufacturing an optical fiber connection structure) described in the above embodiment can be used for an optical fiber connector (alignment member 30) in various modes.

  FIG. 11 is a view of the base member 31 of the fourth embodiment as viewed from above.

Similarly to the base member 31 of the first embodiment, the upper surface of the base member 31 ′ of the fourth embodiment is formed with an alignment groove 30A and an insertion recess 30B. In the fourth embodiment, an injection groove 311 'is formed on the upper surface of the base member 31'. The injection groove 311 ′ is a groove for guiding the liquid refractive index matching agent C1 (see FIG. 2C) injected into the insertion concave portion 30B to the joint portion of the optical fibers 10 and 11. The injection groove 311 'is formed between the alignment groove 30A and the insertion recess 30B, and is formed in a direction parallel to the Y axis. The injection groove 311 ′ is formed to match the position of the front end of the optical fiber 10 on the built-in side (the position of the connection position T). Specifically, the front end of the built-in side optical fiber 10 is located between the front edge and the rear edge in the X-axis direction of the injection groove 311 ′. The depth of the injection groove 311 ′ is smaller than the depth of the insertion recess 30 </ b> B formed on the upper surface of the base member 31. For this reason, the liquid refractive index matching agent C1 injected from the insertion concave portion 30B penetrates the gap 30C between the upper surface of the injection groove 311 ′ and the lower surface of the cover member 32 by capillary action, and the optical fiber 10, 11 is injected into the connection portion. By forming the injection groove 311 ′ on the upper surface of the base member 31, the liquid refractive index matching agent C1 injected into the insertion recess 30 </ b> B easily flows to the joint portion between the optical fibers 10 and 11. In addition, since the injection groove 311 ′ is formed on the upper surface of the base member 31, it becomes easy for the operator to visually recognize the injection position of the liquid refractive index matching agent C1 in the insertion recess 30B.
=== Fifth Embodiment ===

  The method of connecting an optical fiber (the method of manufacturing an optical fiber connection structure) described in the above embodiment can be used for an optical fiber connector (alignment member 30) in various modes.

  12A and 12B are explanatory diagrams of the alignment member 30 ″ of the fifth embodiment. FIG. 12A shows a configuration of the alignment member 30 ″ as viewed from above. FIG. 12B is a side view of the alignment member 30 ″ cut along the line BB ′. The optical fiber connector according to the fifth embodiment is a so-called mechanical splice. In the fifth embodiment, the optical fibers 10 ″ and 11 ″ to be connected are not pre-installed in the alignment member 30 ″, whereas the alignment grooves 30 A ″ are built in the fifth embodiment. Can be inserted from both directions.

  The aligning member 30 "includes a base member 31", three lid members 32 ", and a clamp spring 34". The aligning groove 30A ", An insertion recess 30B ", a gap 30C", and a gap 30D "are formed. The role and function of each member are the same as in the first embodiment.

  The alignment groove 30A "is formed linearly on the upper surface of the base member 31" so as to penetrate from one side to the opposite side so that the optical fibers 10 "and 11" can be inserted from both sides. . Then, the optical fiber 10 "is inserted from one side of the alignment groove 30A" penetrating linearly, and the optical fiber 11 "is inserted from the other side so that the end faces of the optical fibers 10" and 11 "abut. When the optical fibers 10 "and 11" are pressed and fixed in the alignment grooves 30A ", three cover members 32" are covered so as to cover the alignment grooves 30A "of the base member 31". Is mounted, and is clamped from above and below by a clamp spring 34 ″. According to the centering member 30 ", the optical fibers 10" and 11 "that are not built in the ferrule can be connected to each other.

=== Other Embodiments ===
The embodiments described above are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

  In the above-described embodiment, the mode in which the base member 31 and the lid members 32 and 33 are configured as separate members has been described as the configuration of the centering member 30. However, the centering member 30 may have the base member 31 and the lid members 32 and 33 formed integrally. In other words, the base member 31 and the lid members 32 and 33 are names that indicate the role of the members, and may be integrally formed of the same material.

  In the above-described embodiment, the mode in which the clamp spring 34 is used as a configuration for pressing and fixing the optical fiber by the base member 31 and the lid members 32 and 33 has been described. However, the fixing method can be variously modified.

  In the above-described embodiment, the mode in which the pair of optical fibers 10 and 11 is connected has been described. However, not limited to the pair of optical fibers 10 and 11, a plurality of pairs of optical fibers may be connected. In this case, for example, a plurality of alignment grooves 30A for connecting a plurality of pairs of optical fibers are formed in the alignment member, and the end faces of the plurality of pairs of optical fibers are abutted to press the plurality of pairs of optical fibers. A method of injecting a liquid refractive index matching agent C1 in a fixed state can be used. According to this method, it is possible to fill the gap formed in the connection portion of the plurality of pairs of optical fibers with the liquid refractive index matching agent C1 in one process.

10, 11 optical fiber 20, ferrule 30, alignment member 30A, alignment groove 30B, insertion recesses 30C, 30D, gap 31, base member 311 ', injection groove 312, accommodation groove 312A, projections 32, 33 ... Lid member 34. Clamp spring 35. Wetting member F. Intermediate member C1. Liquid refractive index matching agent C2.

Claims (6)

An insertion step of inserting the first optical fiber between the base member and the lid member;
A connection step of abutting an end face of the first optical fiber with an end face of a second optical fiber different from the first optical fiber in the alignment groove of the base member;
In a state where the end face of the second optical fiber different from the first optical fiber is abutted, the first optical fiber and the second optical fiber are separated by the centering groove by the base member and the lid member. A pressing step of pressing and fixing,
Injecting a liquid refractive index matching agent into a gap between the base member and the lid member, and filling a liquid refractive index matching agent between an end face of the first optical fiber and an end face of the second optical fiber. An optical fiber connection method comprising:
In the insertion step and the connection step, an insertion member is inserted between the base member and the lid member,
Wetting member moistened index matching agent in the liquid, along with being provided between the lid member and the base member is disposed on a side of the insertion member when viewed from the alignment groove ,
In the injection step, the liquid refractive index matching agent squeezed from the wetting member in the pressing step causes the liquid refractive index matching agent squeezed from the wetting member to move closer to a narrow gap by capillary action. penetrate into the base member and the refractive index matching agent in the liquid in the gap between the lid member is injected, the liquid between the end face of the end surface and the second optical fiber of the first optical fiber An optical fiber connection method, wherein a refractive index matching agent is filled. The optical fiber connection method according to claim 1 ,
An optical fiber connection method, further comprising a solidification step of solidifying the liquid refractive index matching agent after the injection step. The optical fiber connection method according to claim 1 or 2 ,
A solid refractive index matching material is previously formed on the end face of the second optical fiber,
In the connecting step, an end face of the first optical fiber and an end face of the second optical fiber are abutted via the solid refractive index matching material. The optical fiber connection method according to claim 3 ,
An optical fiber connecting method, wherein the solid refractive index matching material has a shape in which a central portion protrudes. The optical fiber connection method according to claim 3 or 4 ,
The thickness and Shore hardness E of the solid refractive index matching material are
A point with a thickness of 20 μm and a Shore hardness E of 30;
The point whose thickness is 20 μm and Shore hardness E is 85,
40 μm in thickness and 85 in Shore hardness E,
An optical fiber connection method, wherein the thickness is within a range surrounded by four points of 60 μm and 30 points of Shore hardness E. An insertion step of inserting the first optical fiber between the base member and the lid member;
A connecting step of abutting an end face of the first optical fiber with an end face of a second optical fiber different from the first optical fiber in the centering groove of the base member;
In a state where the end face of the second optical fiber different from the first optical fiber is abutted, the first optical fiber and the second optical fiber are separated by the centering groove by the base member and the lid member. A pressing step of pressing and fixing,
Injecting a liquid refractive index matching agent into a gap between the base member and the lid member, and filling a liquid refractive index matching agent between an end face of the first optical fiber and an end face of the second optical fiber. And a method of manufacturing an optical fiber connection structure having a step,
In the insertion step and the connection step, an insertion member is inserted between the base member and the lid member,
Wetting member moistened index matching agent in the liquid, along with being provided between the lid member and the base member is disposed on a side of the insertion member when viewed from the alignment groove ,
In the injection step, the liquid refractive index matching agent squeezed from the wetting member in the pressing step causes the liquid refractive index matching agent squeezed from the wetting member to move closer to a narrow gap by capillary action. penetrate into the base member and the refractive index matching agent in the liquid in the gap between the lid member is injected, the liquid between the end face of the end surface and the second optical fiber of the first optical fiber A method for manufacturing an optical fiber connection structure, characterized by being filled with a refractive index matching agent.

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