JP5019643B2 - Optical fiber end face structure, optical fiber connection structure, optical connector, mechanical splice, and connection method having optical fiber end face structure - Google Patents

Description

  The present invention relates to an optical fiber end face structure, an optical fiber connection structure, an optical connector, a mechanical splice, and a connection method including an optical fiber end face structure.

  Conventionally, when connecting optical fibers, a refractive index matching body is often interposed between the end face of one optical fiber and the end face of the other optical fiber.

  In Patent Document 1 below, the sheet-like adhesive connecting member is moved in the axial direction of the optical fiber while the end face of the optical fiber is pressed against and adhered to the sheet-like adhesive connecting member (refractive index matching body). A method is disclosed in which a part of the sheet-like adhesive connecting member is cut off in a state where it is attached to the end face of the optical fiber, and another optical fiber is connected in a state where the adhesive connecting member is attached to the end face of the optical fiber. . In this method, an adhesive connecting member is sandwiched between the end face of the optical fiber and the end face of another optical fiber connected thereto, and the distance from the center of the core of the optical fiber to the periphery of the adhesive connecting member is increased. It is set to be within a predetermined range.

  Further, in Patent Document 2 below, a solid adhesive connecting member having refractive index matching is closely attached in a single layer state between the end face of the optical fiber and the end face of another optical fiber connected thereto. An intervening structure is disclosed.

  Further, Patent Document 3 below discloses a structure in which a cross-linking curing type refractive index matching body is interposed between an end face of an optical fiber built in a ferrule and an end face of another optical fiber connected to the ferrule. Yes. The cross-linking curable refractive index matching body is formed by applying a cross-linking curable refractive index matching agent to the end face of the optical fiber built in the ferrule and curing it.

JP 2005-274839 A JP 2005-173575 A JP 2007-225722 A

  However, according to Patent Documents 1 to 3, when the end face of another optical fiber is once connected to the end face of the optical fiber and then the other optical fiber is pulled away, a part of the refractive index matching body becomes the end face of the other optical fiber. The amount of the refractive index matching body on the end face of the optical fiber is insufficient. Further, if the dust existing on the outer peripheral side of the refractive index matching body at the end face of the optical fiber moves to the vicinity of the core and reconnects the end faces of other optical fibers, the connection loss may increase.

  In consideration of the above-mentioned fact, the present invention provides an optical fiber end face structure, an optical fiber connection structure, an optical connector, and a mechanical connector that can reconnect another optical fiber to a disconnected optical fiber without increasing the connection loss. It is an object to obtain a connection method having a splice and an optical fiber end face structure.

  In order to achieve the above object, an end face structure of an optical fiber according to the invention of claim 1 is semi-solid at least in the core portion of the end face of the first optical fiber, and the axial direction of the first optical fiber. Is formed in a direction intersecting with the refractive index matching agent to which the end face of the second optical fiber is connected.

  According to the present invention, the semi-solid refractive index matching agent having a cut portion formed in a direction intersecting the axial direction of the first optical fiber is attached to at least the core portion of the end face of the first optical fiber. The end face of the second optical fiber is connected to the end face of the first optical fiber via a refractive index matching agent. After the connection, when the end face of the second optical fiber is pulled away from the end face of the first optical fiber (the connection of the end face of the second optical fiber is released), the refractive index matching agent is cut off by the cut portion, and the cut portion The refractive index matching agent on one side of the first optical fiber adheres to the end face of the second optical fiber, and the cut surface of the cut portion appears in the refractive index matching agent attached to the end face of the first optical fiber. In this state, the end face of the second optical fiber can be reconnected to the end face of the first optical fiber via the refractive index matching agent. At that time, by appropriately setting the position of the cut portion of the refractive index matching agent, it is possible to prevent the amount of the refractive index matching agent attached to the end face of the first optical fiber from being insufficient. In addition, since the cut surface of the cut portion appears in the refractive index matching agent attached to the end face of the first optical fiber, adhesion of dust and the like is prevented, and connection loss occurs when the end face of the second optical fiber is reconnected. An increase in (transmission loss) is suppressed.

  In order to achieve the above object, an optical fiber end face structure according to a second aspect of the present invention is the optical fiber end face structure according to the first aspect, wherein a plurality of the cut portions are formed in the axial direction of the first optical fiber. It is what.

  According to the present invention, a plurality of cut portions are formed in the refractive index matching agent in the axial direction of the first optical fiber, and the second optical fiber is inserted into the end surface of the first optical fiber via the refractive index matching agent. After connecting the end faces, when the end face of the second optical fiber is pulled away from the end face of the first optical fiber, the refractive index matching agent is cut off at one of the plurality of cut portions and attached to the end face of the first optical fiber. A cut surface of the cut portion appears in the refractive index matching agent. Further, when the end face of the second optical fiber is reconnected to the end face of the first optical fiber via the refractive index matching agent, and then the end face of the second optical fiber is pulled away from the end face of the first optical fiber, The refractive index matching agent is cut off by another cut portion, and the cut surface of the cut portion appears in the refractive index matching agent on the end face of the first optical fiber. For this reason, the end face of the second optical fiber can be connected a plurality of times, and the increase in connection loss (transmission loss) during reconnection is suppressed.

  An optical fiber end face structure according to a third aspect of the present invention is the optical fiber end face structure according to the second aspect of the invention, wherein the cut portion is formed so that the depth is deeper in order from the end face of the first optical fiber. is there.

  According to the present invention, when the end face of the second optical fiber connected to the end face of the first optical fiber via the refractive index matching agent is separated, the depth of the cut portion is far from the end face of the first optical fiber. The cut portion is cut in the order of depth, and a cut portion having a shallow depth remains in the refractive index matching agent on the end face of the first optical fiber. Thus, the cut portion of the refractive index matching agent can be efficiently cut away in order from the end face of the first optical fiber, and the end face of the second optical fiber can be connected a plurality of times.

  An optical fiber end face structure according to a fourth aspect of the present invention is the optical fiber end face structure according to any one of the first to third aspects, wherein the cut portion is formed at a portion excluding the extension region of the core portion. It is what.

  According to the present invention, the cut portion of the refractive index matching agent is formed in a portion excluding the extended region of the core portion of the first optical fiber, and it is possible to more reliably suppress an increase in connection loss. .

  An optical fiber end face structure according to a fifth aspect of the present invention is the optical fiber end face structure according to any one of the first to fourth aspects, wherein the cut portion is formed in a V-shaped cross section along the axial direction. It is what has been.

  According to the present invention, the cut portion of the refractive index matching agent has a V-shaped groove in cross section along the axial direction. For example, the cut portion can be formed using a mold. This improves the accuracy of the shape and depth of the cut portion.

  An optical fiber end face structure according to a sixth aspect of the present invention is the optical fiber end face structure according to any one of the first to fifth aspects, wherein the second end face of the first optical fiber is interposed via the refractive index matching agent. When the end face of each of the optical fibers is abutted and connected, the refractive index matching agent is inserted between the end face of the first optical fiber and the end face of the second optical fiber. The size and hardness of the second optical fiber do not protrude from the outer peripheral surface.

  According to the present invention, by appropriately setting the size and hardness of the refractive index matching agent, the end face of the second optical fiber is abutted against the end face of the first optical fiber via the refractive index matching agent. In this case, the refractive index matching agent does not protrude from the outer surface of the first optical fiber or the second optical fiber from between the end surface of the first optical fiber and the end surface of the second optical fiber. For this reason, when the refractive index matching agent protrudes from the outer peripheral surface of the first optical fiber or the second optical fiber, it is prevented that a force is applied to the first optical fiber or the second optical fiber. Occurrence of an axial deviation at the time of connecting the fiber and the second optical fiber is suppressed. Further, dust is prevented from adhering to the refractive index matching agent protruding from the outer peripheral surface of the first optical fiber or the second optical fiber.

  An optical fiber end face structure according to a seventh aspect of the present invention is the optical fiber end face structure according to any one of the first to sixth aspects, wherein the refractive index matching agent is a silicone resin.

  According to the present invention, the refractive index matching agent is a silicone resin, and the silicone resin is interposed between the end surface of the first optical fiber and the end surface of the second optical fiber. Air or the like is unlikely to enter between the end face and the end face of the second optical fiber, and the connection loss is more reliably suppressed.

  On the other hand, in order to achieve the above object, an optical fiber connection structure according to an invention of claim 8 is a first light having the optical fiber end face structure according to any one of claims 1 to 7. A second optical fiber in which holes are formed is connected to the end face of the fiber.

  According to the present invention, a refractive index matching agent is interposed between the end face of the first optical fiber and the end face of the second optical fiber even when holes are formed in the end face of the second optical fiber. Can be connected. Also, when the second optical fiber is pulled away from the end face of the first optical fiber, the refractive index matching agent is cut off by the notch, so that the refractive index matching agent attached to the end face of the first optical fiber The end face of the second optical fiber can be reconnected. At that time, it is possible to prevent dust and the like from adhering to the refractive index matching agent on the end face of the first optical fiber, and to suppress an increase in connection loss (transmission loss).

  On the other hand, in order to achieve the above object, an optical connector according to a ninth aspect of the present invention is a first optical fiber in which the optical fiber end face structure according to any one of the first to seventh aspects is formed. Is a built-in optical fiber built in the ferrule, and the end face of the built-in optical fiber and the end face of the second optical fiber are connected.

  According to the present invention, the first optical fiber in which the optical fiber end surface structure according to any one of claims 1 to 7 is formed is a built-in optical fiber built in a ferrule, and the built-in optical fiber After the end surface of the second optical fiber is connected to the end surface of the second optical fiber via the refractive index matching agent, the refractive index matching agent is cut off at the cut portion when the end surface of the second optical fiber is pulled away from the end surface of the built-in optical fiber. Therefore, the end face of the second optical fiber can be reconnected through the refractive index matching agent attached to the end face of the built-in optical fiber. At that time, it is possible to prevent dust and the like from adhering to the refractive index matching agent on the end face of the built-in optical fiber, and to suppress an increase in connection loss (transmission loss).

  On the other hand, in order to achieve the above object, a mechanical splice according to the invention of claim 10 is the first optical fiber having the optical fiber end face structure according to any one of claims 1 to 7. The end face of the second optical fiber is connected to the end face.

  According to the present invention, the second optical fiber is provided on the end face of the first optical fiber having the optical fiber end face structure according to any one of claims 1 to 7 via the refractive index matching agent. After connecting the end faces, when the end face of the second optical fiber is pulled away from the end face of the first optical fiber, the refractive index matching agent is cut off by the notch, so that the refraction attached to the end face of the first optical fiber. The end face of the second optical fiber can be reconnected via the rate matching agent. At that time, it is possible to prevent dust and the like from adhering to the refractive index matching agent on the end face of the first optical fiber, and to suppress an increase in connection loss (transmission loss).

  On the other hand, in order to achieve the above object, a connection method according to an eleventh aspect of the present invention is the first optical fiber having the optical fiber end face structure according to any one of the first to seventh aspects. A connection method for connecting a second optical fiber, the step of abutting the end face of the second optical fiber against the refractive index matching agent attached to the end face of the first optical fiber; and A step of separating an end face of the second optical fiber from an end face of the first optical fiber, and cutting off the refractive index matching agent at the cut portion; and the refractive index matching agent attached to the end face of the first optical fiber. And reconnecting the end face of the second optical fiber against the cut surface.

  According to the present invention, the end face of the second optical fiber is abutted and connected to the refractive index matching agent attached to the end face of the first optical fiber. Thereafter, the end face of the second optical fiber is pulled away from the end face of the first optical fiber, and the refractive index matching agent is cut off at the cut portion. As a result, the refractive index matching agent on one side of the cut portion adheres to the end surface of the second optical fiber, and the cut surface of the cut portion appears in the refractive index matching agent attached to the end surface of the first optical fiber. In this state, the end surface of the second optical fiber is abutted against the cut surface of the refractive index matching agent attached to the end surface of the first optical fiber, and reconnected. At that time, since a cut surface appears in the refractive index matching agent attached to the end face of the first optical fiber, adhesion of dust and the like is prevented, and connection loss (transmission loss) is caused when the end face of the second optical fiber is reconnected. ) Can be suppressed.

  According to the present invention, the end face of the second optical fiber can be reconnected to the end face of the first optical fiber that has been once disconnected without increasing the connection loss.

It is sectional drawing which shows the optical connector to which the optical fiber end surface structure which concerns on 1st Embodiment of this invention was applied. FIG. 2 is a partially enlarged perspective view showing an end face of an optical fiber built in the optical connector shown in FIG. 1 and an end face of another optical fiber connected to the end face. FIG. 3 is a partially enlarged side view showing a state in which another optical fiber is connected to the optical fiber built in the optical connector shown in FIG. 1. It is a partial expanded side view which shows the process of canceling | releasing connection of another optical fiber with respect to the optical fiber incorporated in the optical connector shown in FIG. FIG. 2 is a partially enlarged perspective view showing an end face of an optical fiber built in the optical connector shown in FIG. 1 and an end face of another optical fiber connected to the end face. It is a partial expansion perspective view which shows the end surface of the optical fiber incorporated in the optical connector to which the optical fiber end surface structure concerning 2nd Embodiment of this invention was applied, and the end surface of the other optical fiber connected to this. It is a partial expansion perspective view which shows the end surface of the optical fiber incorporated in the optical connector to which the optical fiber end surface structure concerning 3rd Embodiment of this invention was applied, and the end surface of the other optical fiber connected to this. FIG. 6B is a partially enlarged side view showing a state in which another optical fiber is connected to the optical fiber built in the optical connector shown in FIG. 6A. It is a partial expanded side view which shows the state which connected the other optical fiber to the optical fiber incorporated in the optical connector with which the optical fiber end surface structure concerning 4th Embodiment of this invention was applied. It is a partial expansion perspective view which shows the process of connecting another optical fiber to the built-in optical fiber of a comparative example. It is a partial expanded side view which shows the process of connecting another optical fiber to the built-in optical fiber of a comparative example. It is a partial expanded side view which shows the state which connected the other optical fiber to the built-in optical fiber of a comparative example. It is a partial expanded side view which shows the state which canceled the connection of the other optical fiber with respect to the built-in optical fiber of a comparative example. It is a disassembled perspective view which shows the mechanical splice to which the optical fiber end surface structure concerning 5th Embodiment of this invention was applied. It is a partial expanded sectional view which shows the process of setting a refractive index matching agent to the board | substrate of the mechanical splice shown to FIG. 10A. It is a perspective view which shows the refractive index matching agent set to the board | substrate of the mechanical splice shown to FIG. 10A. It is a perspective view which shows the process of connecting another optical fiber to an optical fiber using the mechanical splice shown to FIG. 10A. It is a partial expanded side view which shows the state which connected the other optical fiber to the optical fiber using the mechanical splice shown to FIG. 10A. It is a perspective view which shows the state which connected the other optical fiber to the optical fiber using the mechanical splice shown to FIG. 10A.

  A first embodiment of an optical connector to which the optical fiber end face structure of the present invention is applied will be described below with reference to FIGS.

  FIG. 1 shows the overall configuration of the field assembly type optical connector 10. FIG. 2A is a perspective view showing the end face of the optical fiber built in the optical connector 10 and the vicinity of the end face of another optical fiber connected to the end face. FIG. 2B shows a state in which another optical fiber is connected to the optical fiber built into the optical connector 10. As shown in FIG. 1, the optical connector 10 includes a fiber fixing portion 20 for positioning and fixing an optical fiber 40 as a second optical fiber, a lid member 14 that covers the upper side of the fiber fixing portion 20, and a lid. And a clamp member 16 that presses the member 14 toward the fiber fixing portion 20 by a spring force.

  The substrate 12 includes a fiber fixing portion 20 against which the optical fiber 40 is pressed by the lid member 14, a substantially cylindrical ferrule 24 inserted into a cylindrical flange portion 22 fixed to one end side of the fiber fixing portion 20, and It has. The fiber fixing portion 20 has a substantially rectangular cross section in a direction orthogonal to the longitudinal direction, and includes a planar upper surface portion 20A along the longitudinal direction. In the upper surface portion 20A, a shallow groove portion 20B and a groove portion 20C that is deeper and wider than the groove portion 20B are formed continuously along the longitudinal direction. The grooves 20B and 20C have a substantially V-shaped cross section in a direction orthogonal to the longitudinal direction.

  An optical fiber 26 as a first optical fiber is built in the core portion of the ferrule 24, and an end portion 26 </ b> A of the optical fiber 26 protrudes from the flange portion 22 side of the ferrule 24. The optical fiber 26 protruding from the flange portion 22 side is inserted into the groove portion 20 </ b> B of the fiber fixing portion 20.

  The optical fiber 40 includes a covering portion 40B in which the periphery of the bare optical fiber 40A is covered with a resin or the like on the rear end side in the longitudinal direction of the bare optical fiber 40A disposed in the core portion. The bare optical fiber 40 </ b> A of the optical fiber 40 is held in the groove portion 20 </ b> B of the fiber fixing portion 20, and the covering portion 40 </ b> B of the optical fiber 40 is held in the groove portion 20 </ b> C of the fiber fixing portion 20.

  The lid member 14 holds the optical fiber 40 inserted into the groove portions 20B and 20C of the fiber fixing portion 20. The lid member 14 has a substantially rectangular cross section in a direction orthogonal to the longitudinal direction, and a planar lower surface portion 14A is formed along the longitudinal direction. It arrange | positions so that 14 A of lower surface parts of the cover member 14 and 20 A of upper surface parts of the fiber fixing | fixed part 20 may face | abut.

  The clamp member 16 has a substantially U-shaped cross section in a direction perpendicular to the longitudinal direction. The clamp member 16 sandwiches the lid member 14 and the fiber fixing portion 20, whereby the lid member 14 is fixed to the fiber fixing portion 20. It is the structure which presses by spring force toward.

  As shown in FIG. 2A, the optical fiber 26 (first optical fiber) is formed in a substantially cylindrical shape, and includes an axial core portion 27A and a cladding 27B around the core portion 27A. Yes. A semi-solid (so-called gel-like) refractive index matching agent 30 is attached to the center portion including the core portion 27A on the end face 26B at the tip end in the axial direction of the optical fiber 26. The refractive index matching agent 30 is attached to a rectangular region in the central portion excluding the edge of the end face 26 </ b> B of the optical fiber 26.

  The bare optical fiber 40A of the optical fiber 40 (second optical fiber) is formed in a substantially cylindrical shape, and includes an axial core part 41A and a clad 41B around the core part 41A. A refractive index matching agent is not applied to the end face 40C at the tip in the axial direction of the bare optical fiber 40A of the optical fiber 40.

  The refractive index matching agent 30 is formed in a block shape, and two cut portions 32 are formed in a direction orthogonal to the axial direction of the optical fiber 26, that is, substantially parallel to the end face 26 </ b> B of the optical fiber 26. One end side of the two cut portions 32 is formed halfway through the refractive index matching agent 30 and does not penetrate to the side surface portion of the refractive index matching agent 30, and the side surface portion of the refractive index matching agent 30 is continuous in the longitudinal direction. ing.

  As shown in FIG. 2B, when the optical fiber 40 is connected to the optical fiber 26, the end face 40C of the optical fiber 40 is connected via the refractive index matching agent 30 attached to the end face 26B of the optical fiber 26. . The refractive index matching agent 30 is interposed between the end face 26B of the optical fiber 26 and the end face 40C of the optical fiber 40, so that air enters between the end face 26B of the optical fiber 26 and the end face 40C of the optical fiber 40. Fresnel reflection caused by the above is avoided and connection loss (transmission loss) is reduced. When the end face 40C of the optical fiber 40 is abutted and connected to the end face 26B of the optical fiber 26 via the refractive index matching agent 30, the refractive index matching agent 30 is formed between the end face 26B of the optical fiber 26 and the end face 40C of the optical fiber 40. The attachment position, size, and hardness of the refractive index matching agent 30 are set so as not to protrude from the gap to the outer peripheral surface of the optical fiber 26 or the outer peripheral surface of the optical fiber 40.

  As a method for producing the refractive index matching agent 30, first, a mold is produced, and a material is poured into the mold and solidified into a semi-solid form, thereby producing a block-like refractive index matching agent. Thereafter, by processing the refractive index matching agent with a laser, a plurality of planar cut portions 32 are formed in a direction orthogonal to the surface of the refractive index matching agent, and the refractive index matching agent 30 is completed. In the present embodiment, the size of the refractive index matching agent 30 is a cube having a side of about 50 μm. The refractive index matching agent 30 is attached to the central portion including the core portion 27A of the end face 26B of the optical fiber 26 using a microscope. At that time, the refractive index matching agent 30 is attached so that the cut portion 32 is substantially parallel to the end face 26B of the optical fiber 26.

  As a material for the refractive index matching agent 30, silicone resin, acrylate resin, polyurethane resin, or the like is used. Further, a refractive index adjusting agent such as fluorine may be added for adjusting the refractive index. The penetration (JIS K 2235 wax penetration test method) which is an index of the hardness of the refractive index matching agent 30 is preferably 55 to 110 degrees. Here, the penetration is a numerical value representing the hardness of a flexible body such as asphalt, wax, grease, etc., and refers to the distance at which the measuring needle penetrates into the substance by a constant gravity for a certain time.

  In this embodiment, an opt seal (product name: manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the material of the refractive index matching agent 30. Opto-seal is a grease-like oil compound that has high transparency close to that of quartz glass. The refractive index is 1.47, which is similar to the refractive index of the optical fibers 26 and 40, and the thickness of the oil compound is 10 mm. Visible light (400 to 700 nm) transmittance is 90% or more.

  Next, operations and effects of the optical connector 10 to which the optical fiber end face structure of the present embodiment is applied will be described.

  As shown in FIG. 1, when the optical connector 10 is attached to the optical fiber 40, the optical fiber 40 is inserted into the grooves 20B and 20C of the fiber fixing portion 20 along the axial direction from the bare optical fiber 40A side. It connects with the end surface 26B of the optical fiber 26 arrange | positioned at the groove part 20B of the fixing | fixed part 20. FIG.

  At that time, as shown in FIG. 2A, the end face 26B of the optical fiber 26 is attached with a semi-solid refractive index matching agent 30 at the center including the core 27A, as shown in FIG. 2B. The end face 40C of the bare optical fiber 40A of the optical fiber 40 is abutted and connected to the end face 26B of the optical fiber 26 via the refractive index matching agent 30. Here, “abut” means that an optical fiber to be connected to one optical fiber is abutted against each other with a pressing force that does not cause the optical fiber to bend. By connecting the optical fiber 26 and the optical fiber 40 in this manner, the refractive index matching agent 30 is placed between the end face 26B of the optical fiber 26 and the end face 40C of the optical fiber 40 so that the outer peripheral surface of the optical fiber 26 and the optical fiber 40 can be obtained. It becomes difficult to stick out. As a result, the refractive index matching agent 30 is prevented from being applied to the optical fiber 26 or the optical fiber 40 by protruding from the outer peripheral surfaces of the optical fiber 26 and the optical fiber 40, and the axial deviation between the optical fiber 26 and the optical fiber 40 is prevented. Can be suppressed. Furthermore, since the refractive index matching agent 30 is difficult to protrude from the outer peripheral surfaces of the optical fiber 26 and the optical fiber 40, it is possible to suppress the adhesion of dust.

On the other hand, after the optical fiber 40 is connected to the optical fiber 26, when the condition of the connection occurs due to inspection or the like and the connection of the optical fiber 40 is performed again, as shown in FIG. 26 is pulled apart in the axial direction indicated by the arrow to disconnect the optical fiber 40. At that time, the refractive index matching agent 30 is cut off by one of the cut portions 32, and the first film 30A on one side of the cut portion 32 adheres to the end surface 40C of the optical fiber 40 and adheres to the end surface 26B of the optical fiber 26. The surface 30C of the second film 30B on the other side of the notch 32 appears in the refractive index matching agent 30 (see FIG. 4). Since the surface 30C (cut surface) of the second film 30B of the refractive index matching agent 30 appears, adhesion of dust 36 and the like is prevented.
At this time, the adhesive force between the second coating 30B and the end face 40C of the optical fiber 40 is adjusted to be larger than the adhesive strength between the first coating 30A and the second coating 30B of the cut portion 32 of the refractive index matching agent 30. is doing.

  Since the first film 30A of the refractive index matching agent 30 is adhered to the end face 40C of the optical fiber 40, the end face 40C of the optical fiber 40 is cleaned and dried before the optical fiber 40 is reconnected. Thereafter, as shown in FIG. 1, the optical fiber 40 is inserted again into the grooves 20 </ b> B and 20 </ b> C of the fiber fixing portion 20 of the optical connector 10 along the axial direction from the bare optical fiber 40 </ b> A side. Then, as shown in FIG. 4, the end face 40 </ b> C of the optical fiber 40 is reconnected through the second coating 30 </ b> B of the refractive index matching agent 30 on the end face 26 </ b> B of the optical fiber 26. At this time, since the surface 30C of the second coating 30B on the other side of the cut portion 32 appears in the refractive index matching agent 30 attached to the end face 26B of the optical fiber 26, there is no adhesion of dust or the like. In addition, by appropriately setting the position of the cut portion 32, it is possible to prevent the amount of the refractive index matching agent 30 adhering to the end face 26B of the optical fiber 26 from being insufficient. For this reason, when the end face 40C of the optical fiber 40 is reconnected to the end face 26B of the optical fiber 26 via the refractive index matching agent 30, an increase in connection loss (transmission loss) is suppressed, and stable optical characteristics can be obtained. .

  Since the refractive index matching agent 30 has the notch 32, the optical fiber 40 can be disconnected from the optical fiber 26 and the optical fiber 40 can be connected again. That is, when the connection of the optical fiber 40 is released, the refractive index matching agent 30 is cut by the cut portion 32, and the second film 30 </ b> B on one side of the cut portion 32 adheres to the end face 40 </ b> C of the optical fiber 40. The surface (cut surface) of the third film 30D of the refractive index matching agent 30 appears on the end face 26B. For this reason, adhesion of dust or the like to the surface of the third coating 30D of the refractive index matching agent 30 is prevented. Further, by appropriately setting the position of the cut portion 32, it is possible to prevent the amount of the refractive index matching agent 30 adhering to the end face 26B of the optical fiber 26 from being insufficient, and the end face 26B of the optical fiber 26. In addition, the end face 40C of the optical fiber 40 can be reconnected through the refractive index matching agent 30.

  8A to 8C show the end face structure of the optical fiber 200 of the comparative example. As shown in FIGS. 8A and 8B, the refractive index matching agent 230 is attached in a convex curved surface over almost the entire end surface 200 </ b> A of the optical fiber 200. In this configuration, as shown in FIG. 8C, when the end face 202A of the optical fiber 202 is abutted against the end face 200A of the optical fiber 200 via the refractive index matching agent 230, the refractive index matching agent 230 becomes the end face 200A of the optical fiber 200. And the end face 202 </ b> A of the optical fiber 202, it protrudes to the outer peripheral surface side of the optical fiber 200 and the optical fiber 202, and dust easily adheres (it becomes easy to take in dust).

  Further, when the end face 202A of the optical fiber 202 is disconnected from the end face 200A of the optical fiber 200, a part of the refractive index matching agent 230 adheres to the end face 202A of the optical fiber 202, and as shown in FIG. The amount of the refractive index matching agent 230 adhering to the end surface 200A of the 200 decreases, and the amount of the refractive index matching agent 230 may be insufficient when the end surface 202A of the optical fiber 202 is reconnected. Further, when the dust 36 existing on the outer peripheral side of the end surface 200A of the optical fiber 200 moves to the vicinity of the core portion 27A of the end surface 200A of the optical fiber 200 and the optical fiber 40 is reconnected, the connection loss ( Transmission loss) may increase.

  On the other hand, in the present embodiment, when the connection of the end face 40C of the optical fiber 40 to the end face 26B of the optical fiber 26 is released, the refractive index matching agent 30 is cut off by the notch 32 and a new surface appears. Even if the optical fiber 40 is reconnected to the optical fiber 26 via the refractive index matching agent 30, an increase in connection loss can be suppressed. In addition, since a plurality of (two in this embodiment) cut portions 32 are formed in the refractive index matching agent 30, after the optical fiber 40 is once disconnected from the optical fiber 26, the optical fiber 40 is connected to the optical fiber 26. Can be connected multiple times (in this embodiment, twice).

  Next, an optical connector to which the optical fiber end face structure according to the second embodiment of the present invention is applied will be described. In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 5, the end face 26B of the optical fiber 26 built in the fiber fixing portion (see FIG. 1) of the optical connector is replaced with the refractive index matching agent 30 of the first embodiment. A block-shaped refractive index matching agent 50 having a plurality of (two in the present embodiment) cut portions 52 is attached. The cut portions 52 are provided so as to penetrate through the four side surfaces (upper, lower, left and right side portions in FIG. 5) of the refractive index matching agent 50 substantially parallel to the end surface 26B of the optical fiber 26.

  In such a configuration, when the end face 40C of the optical fiber 40 is disconnected after the end face 40C of the optical fiber 40 is connected via the refractive index matching agent 50 attached to the end face 26B of the optical fiber 26, the refractive index is reduced. The matching agent 50 is cut off by one of the cut portions 52, and the surface of the second coating 50B of the refractive index matching agent 50 appears on the end face 26B of the optical fiber 26. At that time, the notch 52 is provided so as to penetrate through the four side surfaces of the refractive index matching agent 50, and when the end face 40 </ b> C of the optical fiber 40 is disconnected, the refractive index matching agent 50 is notched 52. The surface of the second film 50B of the refractive index matching agent 50 is more reliably exposed to the end face 26B of the optical fiber 26. For this reason, there is no adhesion of dust or the like to the second film 50B of the refractive index matching agent 50, and connection is made when the end face 40C of the optical fiber 40 is reconnected to the end face 26B of the optical fiber 26 via the refractive index matching agent 50. Increase in loss is suppressed, and stable optical characteristics can be obtained.

  Next, an optical connector to which the optical fiber end face structure of the third embodiment of the present invention is applied will be described. In addition, the same code | symbol is attached | subjected to the member same as 1st and 2nd embodiment, and the overlapping description is abbreviate | omitted.

  In this embodiment, as shown in FIGS. 6A and 6B, the end face 26B of the optical fiber 26 built in the fiber fixing portion (see FIG. 1) of the optical connector is provided on the refractive index matching agent 30 of the first embodiment. Instead of the above, a block-shaped refractive index matching agent 60 is attached. One refractive index matching agent 60 is provided on each side surface portion 60A (upper and lower side surface portions 60A in FIG. 6A) along the axial direction of the optical fiber 26 in a direction perpendicular to the axial direction of the optical fiber 26. The notch part 62 is provided. The cut portion 62 is formed in a substantially V-shaped cross section along the axial direction, and is provided in a direction along the end face 26 </ b> B of the optical fiber 26.

  In this refractive index matching agent 60, when the refractive index matching agent 60 is attached to the central portion including the core portion 27 </ b> A of the end face 26 </ b> B of the optical fiber 26, the cut portions 62 on both sides of the side surface portion 60 </ b> A are the core portions of the optical fiber 26. It is provided so as to be a portion excluding the region on the extended line of 27A. In the present embodiment, for example, the diameter of the core portion 27A is set to about 10 μm, and the distance D between the deep portions of the cut portions 62 on both sides of the side surface portion 60A is set to about 20 μm.

  The refractive index matching agent 60 can be formed by pouring and hardening a material such as silicone resin into a mold having a substantially V-shaped groove. When the notch 62 is formed by pouring a material into the mold, the depth and shape of the notch 62 can be formed with higher precision than when the notch is formed by laser processing.

  In such a configuration, when the end face 40C of the optical fiber 40 is disconnected after the end face 40C of the optical fiber 40 is connected via the refractive index matching agent 60 attached to the end face 26B of the optical fiber 26, the refractive index is reduced. The matching agent 60 is cut along the cut portions 62 on both sides of the side surface portion 60 </ b> A, and one side of the refractive index matching agent 60 adheres to the end surface 40 </ b> C of the optical fiber 40 and the refractive index adheres to the end surface 26 </ b> B of the optical fiber 26. A cut surface of the cut portion 62 appears in the matching agent 60. For this reason, there is no adhesion of dust or the like to the cut surface of the refractive index matching agent 60, and connection loss is reduced when the end face 40C of the optical fiber 40 is reconnected to the end face 26B of the optical fiber 26 via the refractive index matching agent 60. The increase is suppressed and stable optical characteristics can be obtained.

  In addition, since the cut portion 62 of the refractive index matching agent 60 is formed at a portion other than the region on the extension line of the core portion 27A of the optical fiber 26, the end face 26B of the optical fiber 26 is interposed via the refractive index matching agent 60. When the end face 40 </ b> C of the optical fiber 40 is connected, it is possible to suppress an increase in connection loss due to the cut portion 62.

  Next, an optical connector to which the optical fiber end face structure according to the fourth embodiment of the present invention is applied will be described. In addition, the same code | symbol is attached | subjected to the member same as 1st-3rd embodiment, and the overlapping description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 7, the end face 26B of the optical fiber 26 built in the fiber fixing portion (see FIG. 1) of the optical connector is replaced with the refractive index matching agent 30 of the first embodiment. Thus, a block-shaped refractive index matching agent 70 is attached. The refractive index matching agent 70 is formed on the side surface portions 70A (upper and lower side surface portions 70A in FIG. 7) on both sides along the axial direction of the optical fiber 26 in a direction perpendicular to the axial direction of the optical fiber 26, ie, the optical fiber. A plurality of (three in this embodiment) cut portions 71, 72, 73 are provided along the end face 26 </ b> B of 26. The cut portions 71, 72, 73 are formed in a substantially V-shaped cross section along the axial direction, and are formed so that the depth increases as the distance from the end face 26 </ b> B of the optical fiber 26 increases. That is, the depths of the notches 72 and 73 far from the end face 26B of the optical fiber 26 are formed so as to be gradually deeper than the notches 71 near the end face 26B of the optical fiber 26.

  In such a configuration, when the end face 40C of the optical fiber 40 is disconnected after the end face 40C of the optical fiber 40 is connected through the refractive index matching agent 70 attached to the end face 26B of the optical fiber 26, the refractive index is reduced. The matching agent 70 is cut along the deepest cut portion 73, and one side of the refractive index matching agent 70 is attached to the end face 40C of the optical fiber 40, and the refractive index matching is attached to the end face 26B of the optical fiber 26. A cut surface of the cut portion 73 appears in the agent 70. For this reason, there is no adhesion of dust or the like to the cut surface of the refractive index matching agent 70, and connection loss is reduced when the end face 40C of the optical fiber 40 is reconnected to the end face 26B of the optical fiber 26 via the refractive index matching agent 70. The increase is suppressed and stable optical characteristics can be obtained.

  Further, when the end face 40C of the optical fiber 40 is reconnected to the end face 26B of the optical fiber 26 via the refractive index matching agent 70, and then the connection of the end face 40C of the optical fiber 40 is released, the refractive index matching agent 70 is notched. The cut surface of the cut portion 72 appears in the refractive index matching agent 70 that is cut along the cut portion 72 having the deepest depth next to the portion 73 and adhered to the end surface 26B of the optical fiber 26. In this way, by forming the cut portions 73, 72, 71 having a deeper depth in order from the end face 26B of the optical fiber 26, when the connection of the end face 40C of the optical fiber 40 is released, the cuts are made in the order of the deeper depth. Since the portions 73, 72, 71 are cut, the cut portions 73, 72, 71 can be efficiently cut and the end face 40C of the optical fiber 40 can be connected a plurality of times (three times in the present embodiment).

  Next, a mechanical splice to which the optical fiber end face structure of the fifth embodiment of the present invention is applied will be described. In addition, the same code | symbol is attached | subjected to the member same as 1st-4th embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 10A, the mechanical splice 80 includes a rectangular substrate 82 and a rectangular lid member 84. In the upper surface portion 20A of the substrate 82, a shallow groove portion 20B is formed at the center in the longitudinal direction, and a groove portion 20C that is deeper and wider than the groove portion 20B is formed on both sides in the longitudinal direction of the groove portion 20B. A groove 86 in which the refractive index matching agent 90 is disposed is formed in the longitudinal intermediate portion of the groove 20B of the substrate 82. An optical fiber 88 as a first optical fiber is inserted from one end in the longitudinal direction of the substrate 82 and attached to the refractive index matching agent 90, and as a second optical fiber from the other end in the longitudinal direction of the substrate 82. The optical fiber 40 is inserted and connected to the optical fiber 88 via the refractive index matching agent 90.

  The optical fiber 88 is provided with a coating portion 88B on the outer periphery of the bare optical fiber 88A disposed in the core portion, and the bare optical fiber 88A is exposed at the axial end portion of the optical fiber 88. When the optical fiber 88 and the optical fiber 40 are connected, the respective bare optical fibers 88A and 40A are held in the groove portions 20B of the substrate 82, and the respective covering portions 88B and 40B are groove portions on both sides in the longitudinal direction of the substrate 82. Held at 20C.

  Although not shown, the mechanical splice 80 includes a clamp member that sandwiches the substrate 82 and the lid member 84, and the optical fiber 88 and the optical fiber 40 are moved into the groove 20B and the groove 20C by the lid member 84 by the spring force of the clamp member. It is pressed and gripped.

  As shown in FIGS. 10B, 11 and 12B, the refractive index matching agent 90 has light on the side surface portions 90A (upper and lower side surface portions 90A in FIG. 10B) on both sides along the axial direction of the optical fiber 88. A plurality of (two in this embodiment) cut portions 91 and 92 are provided in a direction orthogonal to the axial direction of the fiber 88, that is, along the end face 88C of the optical fiber 88. The cut portions 91 and 92 have a substantially V-shaped cross section along the longitudinal direction. Further, between the cut portion 91 and the cut portion 92 of one side surface portion 90A (lower side surface portion 90A in FIG. 10B), it engages with a concave engagement portion 86A formed in the groove 86 of the substrate 82. A protruding portion 94 is provided. The protruding portion 94 has a trapezoidal shape formed continuously with the wall surfaces of the cut portions 91 and 92, and the engaging portion 86A is a trapezoidal groove with which the protruding portion 94 is engaged. The refractive index matching agent 90 is made of a semi-solid (so-called gel) material, and a silicone resin is used in this embodiment.

  In this mechanical splice 80, first, the refractive index matching agent 90 is fitted into the groove 86 formed in the longitudinal direction intermediate portion of the groove portion 20B of the substrate 82, and the refractive index matching agent 90 is inserted into the engaging portion 86A formed in the groove 86. The protrusion 94 is engaged. In this state, as shown in FIGS. 12A and 12B, the optical fiber 88 is inserted into the grooves 20B and 20C from one longitudinal end of the substrate 82, and the refractive index matching agent 90 is attached to the end face 88C of the optical fiber 88. . At this time, the refractive index matching agent 90 is attached to the region including the core portion 27 </ b> A of the end face 88 </ b> C of the optical fiber 88.

  12A and 12B, the optical fiber 40 is inserted into the grooves 20B and 20C from the other end in the longitudinal direction of the substrate 82, and light is transmitted through the refractive index matching agent 90 to the end face 88C of the optical fiber 88. The end face 40C of the fiber 40 is abutted. In this state, as shown in FIG. 13, the upper portion of the substrate 82 is covered with a lid member 84, and the substrate 82 and the lid member 84 are sandwiched by a clamp member (not shown), whereby the lid member is applied by the spring force of the clamp member. At 84, the optical fiber 88 and the optical fiber 40 are pressed and fixed to the grooves 20B and 20C.

  On the other hand, after connecting the end face 40C of the optical fiber 40 to the end face 88C of the optical fiber 88 via the refractive index matching agent 90, the optical fiber 88 and the optical fiber 40 are moved to both sides in the axial direction to release these connections. Since the protruding portion 94 of the refractive index matching agent 90 is engaged with the engaging portion 86A of the substrate 82, the refractive index matching agent 90 is cut by the notches 91 and 92 and both sides of the refractive index matching agent 90 are light. The fiber 88 adheres to the end face 88C of the fiber 88 and the end face 40C of the optical fiber 40, respectively, and the intermediate part of the refractive index matching agent 90 (part provided with the protruding part 94) remains on the substrate 82. That is, the refractive index matching agent 90 is cut by the cut portions 91 and 92, and cut surfaces of the cut portions 91 and 92 appear on both sides of the intermediate portion of the refractive index matching agent 90.

  After cleaning and drying the end face 88C of the optical fiber 88 and the end face 40C of the optical fiber 40, the optical fiber 88 is inserted into the grooves 20B and 20C from one longitudinal end of the substrate 82, and from the other longitudinal end of the substrate 82. The optical fiber 40 is inserted into the grooves 20B and 20C, and the end face 40C of the optical fiber 40 is reconnected to the end face 88C of the optical fiber 88 via the refractive index matching agent 90. At this time, since the cut surfaces of the cut portions 91 and 92 appear on both sides of the intermediate portion of the refractive index matching agent 90, adhesion of dust and the like is prevented. For this reason, when the end face 40C of the optical fiber 40 is reconnected to the end face 88C of the optical fiber 88 via the refractive index matching agent 90, an increase in connection loss is suppressed, and stable optical characteristics are obtained.

  For simplification of the connection work, the lid member 84 includes a lid that fixes the central portion of the optical fiber 88, a lid that fixes the central portion of the optical fiber 40, and the connecting portions of the optical fibers 88 and 40. A clamp member for individually clamping each lid is prepared. First, the optical fiber 88 is fixed with the lid and the clamp, the optical fiber 40 is connected, and the corresponding lid is provided. It may be fixed by.

  In addition, although 1st Embodiment, 2nd Embodiment, and 4th Embodiment which were mentioned above are examples of an optical connector, even if the structure of the refractive index matching agent provided with the same some notch part is applied to a mechanical splice, Good.

  In the first to fourth embodiments described above, the refractive index matching agent is attached to the central portion including the core portion of the end face of the first optical fiber. However, the present invention is not limited to this. A refractive index matching agent may be attached to the entire end face of the optical fiber.

  In the first to fifth embodiments described above, the type of optical fiber 40 having no holes is used as the second optical fiber connected to the first optical fiber. The same effect can be obtained even if the optical fiber formed with is applied to the above embodiment.

10 optical connector 24 ferrule 26 optical fiber (first optical fiber)
26B End surface 27A Core part 30 Refractive index matching agent 32 Notch part 36 Waste 40 Optical fiber (2nd optical fiber)
40C End face 41A Core portion 50 Refractive index matching agent 52 Cut portion 60 Refractive index matching agent 62 Cut portion 70 Refractive index matching agent 71 Cut portion 72 Cut portion 73 Cut portion 80 Mechanical splice 88 Optical fiber (first optical fiber)
88C End face 90 Refractive index matching agent 91 Cut part 92 Cut part

Claims (11)

  A cut portion is formed in at least the core portion of the end face of the first optical fiber in a semi-solid shape and in a direction intersecting with the axial direction of the first optical fiber, and the end face of the second optical fiber is connected. An optical fiber end face structure to which a refractive index matching agent is attached.   The optical fiber end face structure according to claim 1, wherein a plurality of the cut portions are formed in an axial direction of the first optical fiber.   The optical fiber end surface structure according to claim 2, wherein the cut portion is formed to have a deeper depth in order from the end surface of the first optical fiber.   The optical fiber end face structure according to any one of claims 1 to 3, wherein the cut portion is formed in a portion excluding an extension region of the core portion.   The optical fiber end face structure according to any one of claims 1 to 4, wherein the cut portion is formed in a V-shaped groove in cross section along the axial direction.   When the end surface of the second optical fiber is abutted against and connected to the end surface of the first optical fiber via the refractive index matching agent, the refractive index matching agent is in contact with the end surface of the first optical fiber and the second optical fiber. 6. The size and hardness of the optical fiber according to claim 1, wherein the first optical fiber or the second optical fiber does not protrude from an end surface of the first optical fiber to the outer surface of the first optical fiber. The optical fiber end face structure described.   The optical fiber end face structure according to any one of claims 1 to 6, wherein the refractive index matching agent is a silicone resin.   An optical fiber in which a second optical fiber in which holes are formed is connected to an end face of the first optical fiber having the optical fiber end face structure according to any one of claims 1 to 7. Connection structure.   The first optical fiber on which the optical fiber end face structure according to any one of claims 1 to 7 is formed is a built-in optical fiber built in a ferrule, and the end face of the built-in optical fiber and a second end face An optical connector to which the end face of the optical fiber is connected.   A mechanical splice in which the end face of the second optical fiber is connected to the end face of the first optical fiber having the optical fiber end face structure according to any one of claims 1 to 7. A connection method for connecting a second optical fiber to the first optical fiber having the optical fiber end face structure according to any one of claims 1 to 7, comprising:
Abutting and connecting the end face of the second optical fiber to the refractive index matching agent attached to the end face of the first optical fiber;
Pulling the end face of the second optical fiber away from the end face of the first optical fiber, and cutting off the refractive index matching agent at the cut portion;
Abutting and reconnecting the end surface of the second optical fiber to the cut surface of the refractive index matching agent attached to the end surface of the first optical fiber;
A connection method.

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