Optical fiber connection device and optical fiber connection method

Abstract

An optical fiber connection device 1 according to one embodiment comprises: optical fibers 2, 3 that each include an object element to be rotationally aligned at a position shifted from the center, and are arranged such that the respective tip surfaces thereof face each other along an axial direction X in which a central axis extends; an optical fiber holder 4 that holds the optical fiber 2 in a state where a protruding portion 2a including the tip surface 2b of the optical fiber 2 protrudes along the axial direction X; an optical fiber holder 5 that holds the optical fiber 3 in a state where a protruding portion 3a including the tip surface 3b of the optical fiber 3 protrudes along the axial direction X; and a positioning member 6 that holds the protruding portions 2a, 3a and determines the respective positions of the optical fibers 2, 3. The length L1 of the protruding portion 2a of the optical fiber 2 from the optical fiber holder 4 to the tip surface 2b in the axial direction X is shorter than the length L of the positioning member 6 in the axial direction X.

Description

Optical fiber connection device and optical fiber connection method

[0001] This application claims priority to Japanese Patent Application No. 2024-154791, filed September 9, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] Conventionally, optical fiber splicing devices for splicing a pair of optical fibers that require rotational alignment have been known. For example, see Patent Document 1. Such an optical fiber splicing device includes a pair of optical fibers that require rotational alignment, such as multi-core optical fibers, a groove member having grooves for positioning the pair of optical fibers, and a cover member that covers the pair of optical fibers placed in the grooves.

[0003] JP 2013-117664 A

[0004] The optical fiber connection device of the present disclosure includes a first optical fiber and a second optical fiber, each of which includes a target element to be rotationally aligned at a position offset from the center and which are arranged so that their tip surfaces face each other along an axial direction along which a central axis extends, a first optical fiber holder that holds the first optical fiber with a protruding portion including the tip surface of the first optical fiber protruding along the axial direction, a second optical fiber holder that holds the second optical fiber with a protruding portion including the tip surface of the second optical fiber protruding along the axial direction, and a positioning member that holds the protruding portions of the first optical fiber and the second optical fiber and determines the positions of the first optical fiber and the second optical fiber, wherein the length of the protruding portion of the first optical fiber from the first optical fiber holder to the tip surface in the axial direction is shorter than the length of the positioning member in the axial direction.

[0005] FIG. 1 is a plan view of a fiber splicing device according to an embodiment. FIG. 2 is a side view of the optical fiber splicing device of FIG. 1. FIG. 3 is a cross-sectional view of the optical fiber splicing device taken along line III-III in FIG. 1. FIG. 4a is a cross-sectional view of the optical fiber splicing device taken along line IVa-IVa in FIG. 1. FIG. 4b is a cross-sectional view of the optical fiber splicing device taken along line IVb-IVb in FIG. 1. FIG. 5 is a flowchart of an optical fiber splicing method according to an embodiment. FIG. 6 is a plan view showing a step of arranging a first optical fiber in a positioning member. FIG. 7 is a plan view showing a step of arranging a second optical fiber in a positioning member. FIG. 8 is a perspective view showing a step of rotationally aligning the second optical fiber. FIG. 9 is a side view of an optical fiber splicing device according to a comparative example. FIG. 10 is a cross-sectional view of the optical fiber splicing device taken along line X-X in FIG. 9. FIG. 11a is a cross-sectional view of a positioning groove according to a modified example. FIG. 11b is a cross-sectional view of a positioning groove according to a modified example. FIG. 12 is a cross-sectional view of a positioning groove according to a modified example. FIG. 13 is a cross-sectional view of a positioning member according to a modified example. FIG. 14 is a plan view showing an optical fiber splicing device according to a modified example.

[0006] When splicing a pair of optical fibers using the optical fiber splicing device described above, each optical fiber is placed in a groove of a groove member, rotated and aligned, and then a cover member is placed over each optical fiber to splice the tip surfaces of the optical fibers. However, if the optical fibers are misaligned in the groove, for example, the reaction force from the cover member can cause the optical fiber to roll in the groove, resulting in a deviation in the rotation angle of the optical fiber. Such a deviation in the rotation angle can lead to an increase in connection loss when splicing the optical fibers.

[0007] An object of the present disclosure is to provide an optical fiber splicing device and an optical fiber splicing method that can reduce splice loss.

[0008] According to the optical fiber connection device and the optical fiber connection method of the present disclosure, connection loss can be reduced.

[0009] First, the contents of the embodiments of the present disclosure will be listed and described.

[0010] (1) An optical fiber connection device according to an embodiment of the present disclosure includes a first optical fiber and a second optical fiber, each of which includes a target element to be rotationally aligned at a position offset from the center and which are arranged so that their tip surfaces face each other along an axial direction along which a central axis extends, a first optical fiber holder that holds the first optical fiber with a protruding portion including the tip surface of the first optical fiber protruding along the axial direction, a second optical fiber holder that holds the second optical fiber with a protruding portion including the tip surface of the second optical fiber protruding along the axial direction, and a positioning member that holds the protruding portions of the first optical fiber and the second optical fiber and determines the positions of the first optical fiber and the second optical fiber, wherein the length of the protruding portion of the first optical fiber from the first optical fiber holder to the tip surface in the axial direction is shorter than the length of the positioning member in the axial direction.

[0011] The present inventors have investigated factors that cause deviations in the rotation angles of the first optical fiber and the second optical fiber in the positioning member. Here, the first optical fiber will be described as a representative example. As a result of investigating factors that cause deviations in the rotation angle, the inventors have found that the length of the protruding portion of the first optical fiber from the first optical fiber holder has a significant effect on rotation deviation. Deviations in the rotation angle of the first optical fiber occur due to twisting of the first optical fiber. The weaker the rigidity of the first optical fiber, the more likely such twisting occurs. Furthermore, the rigidity of the first optical fiber depends on the length of the protruding portion of the first optical fiber from the first optical fiber holder. In other words, the longer the length of the protruding portion of the first optical fiber, the weaker the rigidity of the first optical fiber, making it more likely to twist and resulting in deviations in the rotation angle of the first optical fiber. The shorter the length of the protruding portion of the first optical fiber, the stronger the rigidity of the first optical fiber, making it more resistant to twisting and less likely to result in deviations in the rotation angle of the first optical fiber. In the above-described optical fiber splicing device, the length of the protruding portion of the first optical fiber is shorter than the length of the positioning member. By shortening the length of the protruding portion of the first optical fiber in this manner, the deviation in the rotation angle of the first optical fiber can be reduced, thereby reducing the connection loss caused by the deviation in the rotation angle.

[0012] (2) In the optical fiber splicing device described in (1) above, a positioning groove supporting a protruding portion of the first optical fiber may be formed on the surface of the positioning member. The positioning groove may include a pair of positioning groove side surfaces that are inclined so that the distance between them decreases with increasing distance from the surface of the positioning member in a cross section perpendicular to the axial direction. A holder groove supporting the first optical fiber may be formed on the surface of the first optical fiber holder. The holder groove may include a pair of holder groove side surfaces that are inclined so that the distance between them decreases with increasing distance from the surface of the first optical fiber holder in a cross section perpendicular to the axial direction. The angle formed by the pair of positioning groove side surfaces may be smaller than the angle formed by the pair of holder groove side surfaces. By reducing the angle formed by the pair of positioning groove side surfaces in this manner, it is possible to reduce deviation of the first optical fiber from the center position of the positioning groove when placing the first optical fiber in the positioning groove. This makes it less likely for the first optical fiber to roll in the positioning groove, thereby effectively reducing deviation in the rotation angle caused by rolling of the first optical fiber.

[0013] (3) In the optical fiber splicing device described in (1) above, a positioning groove supporting a protruding portion of the first optical fiber may be formed on the surface of the positioning member. The positioning groove may have a pair of positioning groove side surfaces that are formed perpendicular to the surface of the positioning member in a cross section perpendicular to the axial direction and that face each other with the protruding portion of the first optical fiber sandwiched therebetween. In this case, the range in which the first optical fiber can move can be easily limited by adjusting the spacing between the pair of positioning groove side surfaces. This makes it difficult for the first optical fiber to roll in the positioning groove, thereby easily reducing deviation in the rotation angle due to rolling of the first optical fiber.

[0014] (4) In the optical fiber splicing device described in (3) above, the positioning groove may have a groove bottom surface connecting the pair of positioning groove side surfaces at a position recessed relative to the surface of the positioning member. The groove bottom surface may extend along the surface between the pair of positioning groove side surfaces, or may be in contact with the protruding portion of the first optical fiber. When the positioning groove has such a groove bottom surface, rolling of the first optical fiber in the positioning groove can be made less likely to occur when the first optical fiber is placed on the groove bottom surface, thereby effectively reducing deviation in the rotation angle due to rolling of the first optical fiber.

[0015] (5) In the optical fiber splicing device described in any one of (1) to (4) above, a positioning groove for supporting a protruding portion of the first optical fiber may be formed on the surface of the positioning member. The center axis of the first optical fiber may be positioned protruding from the surface of the positioning member in a direction normal to the surface of the positioning member, in a direction opposite to the positioning groove. In this case, the size of the positioning groove for the first optical fiber can be reduced. Accordingly, the area in which the first optical fiber can roll on the inner surface of the positioning groove can be reduced. This makes it more difficult for the first optical fiber to roll in the positioning groove, thereby effectively reducing deviation in the rotation angle due to rolling of the first optical fiber.

[0016] (6) In the optical fiber splicing device described in (1) above, the positioning member may have a through hole into which the protruding portions of the first optical fiber and the second optical fiber are inserted. The inner diameter of the through hole may be larger than the outer diameter of the protruding portion of the first optical fiber. In this case, friction between the inner surface of the through hole and the first optical fiber can be reduced when the first optical fiber is inserted into the through hole. As a result, unintentional rotation of the first optical fiber due to friction can be prevented. Therefore, deviation in the rotation angle caused by rolling of the first optical fiber can be effectively reduced.

[0017] (7) In the optical fiber connection device described in any one of (1) to (6) above, the first optical fiber may have a coated portion in which the glass fiber is covered with a resin coating and an exposed portion including a tip surface in which the glass fiber is exposed from the resin coating. The protruding portion of the first optical fiber may have both an exposed portion and a coated portion. In this case, the coating portion can increase the rigidity of the protruding portion of the first optical fiber. This can make the protruding portion of the first optical fiber more resistant to twisting, thereby making it less likely that the rotation angle of the first optical fiber will shift.

[0018] (8) In the optical fiber connection device described in any one of (1) to (6) above, the first optical fiber may have a coated portion in which the glass fiber is covered with a resin coating and an exposed portion including a tip surface where the glass fiber is exposed from the resin coating. The protruding portion of the first optical fiber may include only the exposed portion of the coated portion. In this case, the glass fiber can be accurately placed on the positioning member, thereby reducing the likelihood of the glass fiber being misaligned from its appropriate position on the positioning member. This makes it less likely for the first optical fiber to roll in the positioning groove, thereby effectively reducing deviation in the rotation angle due to rolling of the first optical fiber.

[0019] (9) An optical fiber connection method according to an embodiment of the present disclosure is an optical fiber connection method using the optical fiber connection device described in any one of (1) to (8) above. The optical fiber connection method includes the steps of: arranging a protruding portion of a first optical fiber in a positioning member; arranging a protruding portion of a second optical fiber in the positioning member; rotating and aligning only the second optical fiber of the first optical fiber and the second optical fiber with the protruding portions of the first optical fiber and the second optical fiber positioned in the positioning member; and splicing a distal end face of the second optical fiber to a distal end face of the first optical fiber.

[0020] In the above-described optical fiber splicing device, the protruding portion of the first optical fiber has high rigidity, making it less likely to twist and less likely to rotate out of alignment. Therefore, when the rotationally aligned protruding portion of the first optical fiber is placed in the positioning member, the rotational position of the target element of the first optical fiber to be rotationally aligned is stable. Therefore, in the above-described optical fiber splicing method, only the second optical fiber is rotationally aligned while the protruding portion of the second optical fiber is placed in the positioning member. In this case, the target element of the second optical fiber can be accurately aligned with respect to the target element of the first optical fiber whose rotational position is stable. When only the second optical fiber is rotationally aligned, the time required for rotational alignment of the first optical fiber and the second optical fiber can be shortened compared to when both the first optical fiber and the second optical fiber are rotationally aligned while the protruding portions of the first optical fiber and the second optical fiber are placed in the positioning member, thereby shortening the manufacturing time.

[0021] [Details of the embodiments of the present disclosure] Specific examples of an optical fiber connection device and an optical fiber connection method according to embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the following description, the same elements in the drawings will be given the same reference numerals, and duplicate descriptions will be omitted as appropriate.

[0022] Fig. 1 is a plan view of the optical fiber connection device 1. Fig. 2 is a side view of the optical fiber connection device 1. The optical fiber connection device 1 is, for example, a fusion splicer that connects two optical fibers 2 and 3 to each other. The optical fiber connection device 1 is not limited to a fusion splicer as long as it is a device that connects the two optical fibers 2 and 3 to each other, and may be a mechanical splice connection element that mechanically splices the two optical fibers 2 and 3 to each other, or an optical fiber inspection device that connects the two optical fibers 2 and 3 to each other and inspects the optical characteristics of each of the optical fibers 2 and 3.

[0023] As shown in Figures 1 and 2, the optical fiber connection device 1 includes, for example, an optical fiber 2 (first optical fiber), an optical fiber 3 (second optical fiber), an optical fiber holder 4 (first optical fiber holder), an optical fiber holder 5 (second optical fiber holder), a positioning member 6, and a cover member 7.

[0024] The central axis AX2 of the optical fiber 2 extends along the axial direction X. The central axis AX3 of the optical fiber 3 extends along the axial direction X. The optical fibers 2 and 3 are arranged such that the tip surfaces 2b and 3b of the optical fibers 2 and 3 face each other along the axial direction X.

[0025] The optical fibers 2 and 3 are optical fibers that require rotational alignment. The optical fibers 2 and 3 that require rotational alignment include a target element that is the target of rotational alignment at a position shifted from the central axis. The optical fibers 2 and 3 are, for example, multicore fibers, polarization-maintaining fibers, and hollow-core fibers. In this embodiment, the optical fibers 2 and 3 are described as multicore fibers. In this case, the optical fiber 2 includes, as target elements, multiple cores 22 surrounded by a cladding 21. As an example, in FIG. 4a, the number of cores 22 is two. The cores 22 are exposed from the cladding 21 at the tip surface 2b and are arranged in positions facing each other across the central axis AX2 of the optical fiber 2. The optical fibers 2 and 3 may include, as target elements, markers that indicate the rotational positions of the cores 22.

[0026] The optical fiber 3 includes, as target elements, a plurality of cores 32 surrounded by a cladding 31. As an example, in FIG. 4b, the number of cores 22 is two. The two cores 32 of the optical fiber 3 are arranged to correspond to the two cores 22 of the optical fiber 2, respectively. The cores 32 are exposed from the cladding 31 at the tip end face 3b, and are arranged at positions facing each other across the central axis AX3 of the optical fiber 3. When the tip end face 3b of the optical fiber 3 is connected to the tip end face 2b of the optical fiber 2, the cores 32 of the optical fiber 3 overlap with the cores 22 of the optical fiber 2.

[0027] When the optical fibers 2 and 3 are polarization-maintaining portions, the optical fibers 2 and 3 may include, as target elements, a pair of stress-applying portions formed at positions sandwiching the core. When the optical fibers 2 and 3 are hollow-core fibers, the optical fibers 2 and 3 may include, as target elements, a plurality of air holes surrounding a through hole formed at the center of each optical fiber.

[0028] The optical fiber 2 includes an exposed portion 2c and a coating portion 2d. The exposed portion 2c is a portion of the optical fiber 2 where the glass fiber is exposed from the resin coating. The exposed portion 2c includes a tip surface 2b of the optical fiber 2. The coating portion 2d is a portion of the optical fiber 2 where the glass fiber is covered with a resin coating. The optical fiber 3 includes an exposed portion 3c and a coating portion 3d. The exposed portion 3c is a portion of the optical fiber 3 where the glass fiber is exposed from the resin coating. The exposed portion 3c includes a tip surface 3b of the optical fiber 3. The coating portion 3d is a portion of the optical fiber 3 where the glass fiber is covered with a resin coating.

[0029] The optical fiber holder 4 holds the optical fiber 2. The optical fiber holder 4 is, for example, a rectangular parallelepiped member. The optical fiber holder 4 extends along the axial direction X and the width direction Y and has a thickness in the height direction Z. The width direction Y intersects with the axial direction X, and in one example, is perpendicular to it. The height direction Z intersects with the axial direction X and the width direction Y, and in one example, is perpendicular to it. The optical fiber holder 4 holds the optical fiber 2 in a state where a portion of the optical fiber 2 protrudes along the axial direction X. The optical fiber 2 has a protruding portion 2a protruding from the optical fiber holder 4. The protruding portion 2a includes a tip surface 2b of the optical fiber 2. The protruding portion 2a is a portion of the optical fiber 2 located between the front end surface 4S and the tip surface 2b. The front end surface 4S is an end face of the optical fiber holder 4 and faces the positioning member 6 along the axial direction X.

[0030] The protruding portion 2a of the optical fiber 2 includes only the exposed portion 2c of the exposed portion 2c and the coated portion 2d. That is, the entire protruding portion 2a is included in the exposed portion 2c. The portion of the optical fiber 2 protruding from the optical fiber holder 4, opposite to the protruding portion 2a, is included in the coated portion 2d. The optical fiber holder 4 may hold the exposed portion 2c, the coated portion 2d, or both the exposed portion 2c and the coated portion 2d.

[0031] The optical fiber holder 5 holds the optical fiber 3. The optical fiber holder 5 has, for example, the same shape as the optical fiber holder 4. The optical fiber holder 5 holds the optical fiber 3 with a portion of the optical fiber 3 protruding along the axial direction X. The optical fiber 3 has a protruding portion 3a protruding from the optical fiber holder 5. The protruding portion 3a includes a tip surface 3b of the optical fiber 3. The protruding portion 3a is a portion of the optical fiber 3 that is located between the front end surface 5S and the tip surface 3b. The front end surface 5S is an end surface of the optical fiber holder 5 and faces the positioning member 6.

[0032] The protruding portion 3a of the optical fiber 3 includes only the exposed portion 3c of the exposed portion 3c and the coated portion 3d. That is, the entire protruding portion 3a is included in the exposed portion 3c. The portion of the optical fiber 3 protruding from the optical fiber holder 5, opposite to the protruding portion 3a, is included in the coated portion 3d. The optical fiber holder 5 may hold the exposed portion 3c, the coated portion 3d, or both the exposed portion 3c and the coated portion 3d.

[0033] The positioning member 6 determines the positions of the optical fiber 2 and the optical fiber 3. More specifically, the positioning member 6 holds the optical fibers 2 and 3, thereby defining the position of the tip surface 2b of the optical fiber 2 in the width direction Y and the height direction Z, and the position of the tip surface 3b of the optical fiber 3 in the width direction Y and the height direction Z. The positioning member 6 is disposed between the optical fiber 2 and the optical fiber 3 in the axial direction X. The optical fibers 2 and 3 are disposed in the positioning member 6 so that the tip surfaces 2b and 3b face each other along the axial direction X.

[0034] The positioning member 6 is, for example, a rectangular parallelepiped member. The longitudinal direction of the positioning member 6 coincides with the axial direction X. As shown in FIG. 2 , the length L of the positioning member 6 along the axial direction X is the length from end face 6S1 to end face 6S2 along the axial direction X. The end face 6S1 is an end face of the positioning member 6 and faces the front end face 4S of the optical fiber holder 4 along the axial direction X. The end face 6S2 is an end face of the positioning member 6 and faces the front end face 5S of the optical fiber holder 5 along the axial direction X. The length of the positioning member 6 along the axial direction X is longer than the length of the positioning member 6 along the width direction Y.

[0035] As shown in FIG. 2 , the length L1 of the protruding portion 2a of the optical fiber 2 along the axial direction X is shorter than the length L of the positioning member 6 along the axial direction X. The length L1 is the length from the front end face 4S to the tip face 2b along the axial direction X. The length L1 is, for example, less than 100 mm. The length L1 may be, for example, 40 mm or less, 30 mm or less, or 20 mm or less. The length L1 is equal to or greater than the length L of the positioning member 6 along the axial direction X minus the length L2 of the protruding portion 3a of the optical fiber 3 along the axial direction X. In other words, the sum of the lengths L1 and L2 is equal to or greater than the length L. The length L1 is, for example, equal to or greater than half the length L. The length L1 may be, for example, 50 mm or more, 40 mm or more, 30 mm or more, or 20 mm or more. The length L1 may be, for example, 20 mm or more and 40 mm or less, or 20 mm or more and 30 mm or less.

[0036] The length L2 of the protruding portion 3a of the optical fiber 3 along the axial direction X is shorter than the length L of the positioning member 6 along the axial direction X. The length L2 is the length from the front end face 5S to the tip face 3b along the axial direction X. The length L2 is, for example, less than 100 mm. The length L2 may be, for example, 40 mm or less, 30 mm or less, or 20 mm or less. The length L2 is equal to or greater than the length L of the positioning member 6 along the axial direction X minus the length L1 of the protruding portion 2a of the optical fiber 2 along the axial direction X. The length L2 is, for example, equal to or greater than half the length L. The length L2 may be, for example, 50 mm or more, 40 mm or more, 30 mm or more, or 20 mm or more. The length L2 may be, for example, 20 mm or more and 40 mm or less, or 20 mm or more and 30 mm or less.

[0037] The positioning member 6 has a surface 6a on which the optical fibers 2 and 3 are arranged. The surface 6a is the surface facing the cover member 7. The normal direction of the surface 6a coincides with the height direction Z. The positioning member 6 has a positioning groove 6b formed in the surface 6a. The positioning groove 6b extends along the axial direction X from the end face 6S1 to the end face 6S2. The protruding portion 2a of the optical fiber 2 and the protruding portion 3a of the optical fiber 3 are arranged in the positioning groove 6b. In other words, the positioning groove 6b supports the protruding portions 2a and 3a.

[0038] The lid member 7 covers the positioning member 6. The lid member 7 is, for example, a rectangular parallelepiped member. The length of the lid member 7 along the axial direction X is shorter than the length L of the positioning member 6 along the axial direction X. The thickness of the lid member 7 along the height direction Z is thicker than the thickness of the positioning member 6 along the height direction Z. The lid member 7 is aligned with the positioning member 6 along the height direction Z. The lid member 7 covers the positioning member 6 so as to sandwich the optical fibers 2 and 3 arranged in the positioning grooves 6b. The protruding portions 2a and 3a of the optical fibers 2 and 3 are sandwiched between the positioning member 6 and the lid member 7 and thereby held by the positioning member 6 and the lid member 7.

[0039] FIG. 3 is a cross-sectional view of the optical fiber splicing device 1 taken along line III-III in FIG. 1. The shape of the positioning groove 6b in a cross section perpendicular to the axial direction X is, for example, V-shaped. The positioning groove 6b includes a pair of positioning groove side surfaces 6c. The pair of positioning groove side surfaces 6c face each other along the width direction Y. The pair of positioning groove side surfaces 6c are inclined with respect to both the width direction Y and the height direction Z. Specifically, the pair of positioning groove side surfaces 6c are inclined so that the distance between them along the width direction Y becomes narrower as they move away from the surface 6a. The pair of positioning groove side surfaces 6c intersect with each other at the bottom of the positioning groove 6b, forming an angle θ1 at the intersection. The angle θ1 is, for example, greater than 0° and equal to or less than 120°. The pair of positioning groove side surfaces 6c do not necessarily need to intersect with each other. For example, a bottom surface connected to each of the pair of positioning groove side surfaces 6c may be provided between the pair of positioning groove side surfaces 6c.

[0040] The width of the positioning groove 6b on the surface 6a along the width direction Y is, for example, shorter than the outer diameters of the optical fibers 2 and 3. The central axis AX2 of the optical fiber 2 is disposed at a position protruding in the height direction Z from the surface 6a of the positioning member 6 in the opposite direction from the positioning groove 6b. That is, in the height direction Z, the surface 6a is located between the central axis AX2 and the positioning groove 6b. The protrusion amount d of the optical fiber 2 from the surface 6a is, for example, 1 / 3 or more of the outer diameter of the optical fiber 2. The protrusion amount d is the distance along the height direction Z from the surface 6a to the upper end of the optical fiber 2. The upper end of the optical fiber 2 refers to the portion of the optical fiber 2 that is farthest from the surface 6a in the height direction Z. The protrusion amount d may be, for example, 1 / 2 or more of the outer diameter of the optical fiber 2, or 2 / 3 or more of the outer diameter of the optical fiber 2. The central axis AX3 of the optical fiber 3 is disposed at a position protruding in the height direction Z from the surface 6a in the opposite direction from the positioning groove 6b. The amount of protrusion of the optical fiber 3 from the surface 6 a is, for example, the same as the amount of protrusion d of the optical fiber 2 .

[0041] Figure 4a is a cross-sectional view of the optical fiber connection device 1 taken along line IVa-IVa in Figure 1. The optical fiber holder 4 has, for example, a support member 41 and a cover member 42. The support member 41 is a member that supports the optical fiber 2. The cover member 42 covers the support member 41. The cover member 42 is aligned with the support member 41 in the height direction Z.

[0042] The support member 41 has a holder groove 4b formed on a surface 4a of the support member 41. The holder groove 4b supports the optical fiber 2. The shape of the holder groove 4b in a cross section perpendicular to the axial direction X is, for example, V-shaped. The holder groove 4b includes a pair of holder groove side surfaces 4c. The pair of holder groove side surfaces 4c face each other along the width direction Y.

[0043] The pair of holder groove side surfaces 4c are inclined with respect to both the width direction Y and the height direction Z. Specifically, the pair of holder groove side surfaces 4c are inclined so that the distance between them becomes narrower as they move away from the surface 4a. The pair of holder groove side surfaces 4c intersect with each other at the bottom of the holder groove 4b, and form an angle θ2 at the intersecting portion. The pair of holder groove side surfaces 4c do not necessarily have to intersect with each other. For example, a bottom surface connected to each of the pair of holder groove side surfaces 4c may be provided between the pair of holder groove side surfaces 4c. The angle θ2 formed by the pair of holder groove side surfaces 4c is greater than the angle θ1 formed by the pair of positioning groove side surfaces 6c. The angle θ2 is, for example, greater than 120°.

[0044] Figure 4b is a cross-sectional view of the optical fiber connection device 1 taken along line IVb-IVb in Figure 1. The optical fiber holder 5 has, for example, a support member 51 and a cover member 52. The support member 51 is a member that supports the optical fiber 3. The cover member 52 covers the support member 51. The cover member 52 is aligned with the support member 51 in the height direction Z.

[0045] The support member 51 has a holder groove 5b formed on a surface 5a of the support member 51. The holder groove 5b supports the optical fiber 3. The shape of the holder groove 5b in a cross section perpendicular to the axial direction X is, for example, V-shaped. The holder groove 5b includes a pair of holder groove side surfaces 5c. The pair of holder groove side surfaces 5c face each other along the width direction Y.

[0046] The pair of holder groove side surfaces 5c are inclined with respect to both the width direction Y and the height direction Z. Specifically, the pair of holder groove side surfaces 5c are inclined so that the distance between them becomes narrower as they move away from the surface 5a. The pair of holder groove side surfaces 5c intersect with each other at the bottom of the holder groove 5b, forming an angle θ2 at the intersection. The pair of holder groove side surfaces 5c do not necessarily have to intersect with each other. For example, a bottom surface connected to each of the pair of holder groove side surfaces 5c may be provided between the pair of holder groove side surfaces 5c. The angle θ2 formed by the pair of holder groove side surfaces 5c is the same as the angle θ2 formed by the pair of holder groove side surfaces 4c. Therefore, the angle θ2 is greater than the angle θ1 formed by the pair of positioning groove side surfaces 6c. The angle θ2 is, for example, greater than 120°.

[0047] An optical fiber splicing method according to this embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart of the optical fiber splicing method according to this embodiment. The optical fiber splicing method according to this embodiment is carried out using an optical fiber splicing device 1.

[0048] First, the optical fiber 2 is held in the optical fiber holder 4 with the length of the protruding portion 2a of the optical fiber 2 adjusted along the axial direction X (step S11). For example, the length L1 of the protruding portion 2a along the axial direction X is made shorter than the length L of the positioning member 6 along the axial direction X. The optical fiber 3 is held in the optical fiber holder 5 with the length of the protruding portion 3a of the optical fiber 3 adjusted along the axial direction X (step S11). For example, the length L2 of the protruding portion 3a along the axial direction X is made shorter than the length L of the positioning member 6 along the axial direction X.

[0049] Next, the optical fiber 2 is placed on the positioning member 6 (step S12), as shown in Fig. 6. Fig. 6 is a plan view showing the process of placing the optical fiber 2 on the positioning member 6. The optical fiber 2 is placed on the positioning member 6 so that the protruding portion 2a of the optical fiber 2 is supported by the positioning groove 6b. The protruding portion 2a is placed on the positioning member 6 after being rotated and aligned by, for example, a rotary alignment machine.

[0050] Next, the optical fiber 3 is placed on the positioning member 6 (step S13), as shown in Fig. 7. Fig. 7 is a plan view showing the process of placing the optical fiber 3 on the positioning member 6. The optical fiber 3 is placed on the positioning member 6 so that the protruding portion 3a of the optical fiber 3 is supported by the positioning groove 6b. The protruding portion 3a is placed on the positioning member 6 after being rotationally aligned by, for example, a rotary alignment machine.

[0051] Next, the optical fiber 3 is rotationally aligned as shown in Figure 8 (step S14). Figure 8 is a perspective view showing the process of rotationally aligning the optical fiber 3. First, the position of the core 22 of the protruding portion 2a of the optical fiber 2 placed in the positioning groove 6b is confirmed. Then, with the protruding portion 3a of the optical fiber 3 placed in the positioning member 6, only the optical fiber 3 of the optical fibers 2 and 3 is rotationally aligned. At this time, the optical fiber 2 placed in the positioning member 6 is not rotationally aligned.

[0052] Next, the tip surface 3b of the optical fiber 3 is connected to the tip surface 2b of the optical fiber 2 (step S15). For example, the tip surface 3b of the optical fiber 3 is fusion-spliced ​​to the tip surface 2b of the optical fiber 2. Next, the lid member 7 is placed over the positioning member 6 (step S16). The optical fibers 2, 3 are held by being sandwiched between the positioning member 6 and the lid member 7. The optical fibers 2, 3 may be mechanically spliced ​​instead of being fusion-spliced. That is, the positions of the optical fibers 2, 3 may be fixed by being sandwiched between the positioning member 6 and the lid member 7 without being fusion-spliced, or the optical fibers 2, 3 may be optically coupled.

[0053] The effects obtained by the optical fiber splicing device 1 and the optical fiber splicing method according to the present embodiment will be described below, along with the problems of the comparative example. The effects will be described below focusing on the optical fiber 2, but the same effects as those of the optical fiber 2 can also be obtained with the optical fiber 3.

[0054] Fig. 9 shows an optical fiber connection device 100 according to a comparative example. Fig. 10 is a cross-sectional view of the optical fiber connection device 100 taken along line X-X in Fig. 9. The optical fiber connection device 100 according to the comparative example includes an optical fiber 102, an optical fiber 103, an optical fiber holder 104, an optical fiber holder 105, a positioning member 106, and a cover member 107.

[0055] The optical fiber 102 differs from the above-described optical fiber 2 in that the length L101 of the protruding portion 102a along the axial direction X is longer than the length L100 of the positioning member 106 along the axial direction X. The length L101 is, for example, longer than 100 mm. The optical fiber holder 104 holds the optical fiber 102. The optical fiber 103 differs from the above-described optical fiber 3 in that the length L102 of the protruding portion 103a along the axial direction X is longer than the length L100 of the positioning member 106 along the axial direction X. The length L102 is, for example, longer than 100 mm. The optical fiber holder 105 holds the optical fiber 103. The length L100 of the positioning member 106 is the same as the length L of the positioning member 6.

[0056] 10 , the positioning member 106 has a positioning groove 106b formed in a surface 106a. The pair of inclined surfaces forming the positioning groove 106b form an angle θ3. The angle θ3 is greater than the angle θ1. The cover member 107 is a member that holds the optical fibers 102, 103 by sandwiching the optical fibers 102, 103 between itself and the positioning member 106.

[0057] In the optical fiber connection device 100 according to the comparative example, the length L101 of the protruding portion 102a of the optical fiber 102 along the axial direction X is longer than the length L100 of the positioning member 106 along the axial direction X, so the rigidity of the protruding portion 102a is weak. Therefore, the protruding portion 102a is prone to twisting, which may result in the protruding portion 102a itself unintentionally rotating. Because the rigidity of the protruding portion 102a is weak, the optical fiber 102 is prone to bending, which may result in the central axis AX102 of the optical fiber 102 being positioned off-center from the positioning groove 106b, as shown in FIG. 10 . If the cover member 107 is then placed over the optical fiber 102 in this state, the optical fiber 102 may roll in the positioning groove 106b. This may result in a deviation in the rotation angle of the optical fiber 102. Because the angle θ3 formed by the pair of inclined surfaces forming the positioning groove 106b is large, the optical fiber 102 may be positioned off-center from the positioning groove 106b. This may result in a deviation in the rotation angle of the optical fiber 102. The optical fiber 103 has the same problems as the optical fiber 102 described above for the same reasons.

[0058] In contrast, in the optical fiber splicing device 1 according to this embodiment, the length of the protruding portion 2a of the optical fiber 2 along the axial direction X is shorter than the length of the positioning member 6 along the axial direction X. The shorter the length of the protruding portion 2a of the optical fiber 2, the stronger the rigidity of the optical fiber 2, making the optical fiber 2 more resistant to twisting and less likely to cause deviation in the rotation angle of the optical fiber 2. Therefore, by shortening the length of the protruding portion 2a of the optical fiber 2 in this manner, it is possible to reduce deviation in the rotation angle of the optical fiber 2, thereby reducing connection loss caused by deviation in the rotation angle.

[0059] A positioning groove 6b that supports the protruding portion 2a of the optical fiber 2 is formed on the surface 6a of the positioning member 6. The positioning groove 6b includes a pair of positioning groove side surfaces 6c that are inclined so that the distance between them becomes narrower as they move away from the surface 6a of the positioning member 6 in a cross section perpendicular to the axial direction X. A holder groove 4b that supports the optical fiber 2 is formed on the surface 4a of the optical fiber holder 4. The holder groove 4b includes a pair of holder groove side surfaces 4c that are inclined so that the distance between them becomes narrower as they move away from the surface 4a of the optical fiber holder 4 in a cross section perpendicular to the axial direction X. The angle θ1 formed by the pair of positioning groove side surfaces 6c is smaller than the angle θ2 formed by the pair of holder groove side surfaces 4c.

[0060] In the optical fiber connection device 1, the angle θ1 formed by the pair of positioning groove side surfaces 6c is small, so the optical fiber 2 is easily positioned at the center of the positioning groove 6b when placed in the positioning groove 6b. In this state, even if the cover member 7 is placed over the positioning member 6, the optical fiber 2 is less likely to move, making it less likely for rotational deviation of the optical fiber 2 to occur. By reducing the angle θ1 formed by the pair of positioning groove side surfaces 6c in this way, it is possible to reduce deviation of the optical fiber 2 from the center position of the positioning groove 6b when placing the optical fiber 2 in the positioning groove 6b. This makes it less likely for the optical fiber 2 to roll in the positioning groove 6b, effectively reducing deviation in the rotation angle due to rolling of the optical fiber 2.

[0061] A positioning groove 6b that supports the protruding portion 2a of the optical fiber 2 is formed on the surface 6a of the positioning member 6. The center axis AX2 of the optical fiber 2 is disposed at a position that protrudes from the surface 6a of the positioning member 6 in the direction normal to the surface 6a of the positioning member 6, in the opposite direction to the positioning groove 6b. In this case, the size of the positioning groove 6b relative to the optical fiber 2 can be reduced. Accordingly, the area in which the optical fiber 2 can roll on the positioning groove side surface 6c of the positioning groove 6b can be reduced. This makes it more difficult for the optical fiber 2 to roll in the positioning groove 6b, thereby effectively reducing deviation in the rotation angle due to rolling of the optical fiber 2.

[0062] The optical fiber 2 has a coated portion 2d in which the glass fiber is covered with a resin coating, and an exposed portion 2c including a tip surface where the glass fiber is exposed from the resin coating. The protruding portion 2a of the optical fiber 2 includes only the exposed portion 2c of the coated portion 2d and the exposed portion 2c. In this case, the exposed portion 2c where the glass fiber is exposed can be accurately placed on the positioning member 6, thereby reducing the likelihood of the optical fiber 2 being positioned in an appropriate position on the positioning member 6. This makes it less likely for the optical fiber 2 to roll in the positioning groove 6b, effectively reducing deviations in the rotation angle due to the rolling of the optical fiber 2.

[0063] In the optical fiber splicing device 1, the protruding portion 2 a of the optical fiber 2 has high rigidity, making it less likely to twist, and rotational misalignment of the protruding portion 2 a of the optical fiber 2 is less likely to occur. Therefore, when the rotationally aligned protruding portion 2 a of the optical fiber 2 is placed in the positioning member 6, the rotational position of the core 22 of the optical fiber 2, which is the target of rotational alignment, is stabilized. Therefore, in the optical fiber splicing method according to this embodiment, only the optical fiber 3 is rotationally aligned with the protruding portion 3 a of the optical fiber 3 placed in the positioning member 6. In this case, the core 32 of the optical fiber 3 can be accurately aligned with the core 22 of the optical fiber 2, whose rotational position is stable. When only the optical fiber 3 is rotationally aligned, the time required for rotational alignment of the optical fibers 2 and 3 can be shortened compared to when both the optical fibers 2 and 3 are rotationally aligned with the protruding portions 2 a and 3 a placed in the positioning member 6, thereby shortening the manufacturing time.

[0064] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the claims.

[0065] 11a and 11b are cross-sectional views of positioning grooves 6d and 6e provided in an optical fiber connection device according to a modified example. The optical fiber connection device according to the modified example includes a positioning member 6A or a positioning member 6B instead of the above-described positioning member 6. In the positioning members 6A and 6B, the shape of the positioning grooves 6d and 6e in a cross section perpendicular to the axial direction X is different from the shape of the positioning groove 6b of the above-described positioning member 6.

[0066] In the positioning member 6A shown in Fig. 11a, the shape of the positioning groove 6d in a cross section perpendicular to the axial direction X is U-shaped. The positioning groove 6d has a pair of positioning groove side surfaces 6f that face each other. The pair of positioning groove side surfaces 6f are formed perpendicular to the surface 6a of the positioning member 6A in a cross section perpendicular to the axial direction X of the positioning groove 6d. The pair of positioning groove side surfaces 6f extend from the surface 6a along the height direction Z. The pair of positioning groove side surfaces 6f sandwich the protruding portion 2a of the optical fiber 2 and the protruding portion 3a of the optical fiber 3 in the width direction Y.

[0067] The positioning groove 6d has a groove bottom surface 6g that connects a pair of positioning groove side surfaces 6f at a position recessed relative to the surface 6a of the positioning member 6A. The groove bottom surface 6g is curved in the height direction Z so as to move away from the cover member 7. The curvature of the groove bottom surface 6g is smaller than the curvature of the outer shape of the optical fiber 2. The groove bottom surface 6g is in contact with the protruding portion 2a of the optical fiber 2 and supports the protruding portion 2a. The groove bottom surface 6g is in contact with the protruding portion 3a of the optical fiber 3 and supports the protruding portion 3a.

[0068] In the positioning member 6B shown in Figure 11b, the shape of the positioning groove 6e in a cross section perpendicular to the axial direction X is rectangular. The positioning groove 6e has a pair of positioning groove side surfaces 6h. The pair of positioning groove side surfaces 6h are formed perpendicular to the surface 6a of the positioning member 6B in a cross section perpendicular to the axial direction X of the positioning groove 6e. The pair of positioning groove side surfaces 6h extend from the surface 6a along the height direction Z. The pair of positioning groove side surfaces 6h sandwich the protruding portion 2a and the protruding portion 3a in the width direction Y.

[0069] The positioning groove 6e has a groove bottom surface 6j connecting the pair of positioning groove side surfaces 6h at a position recessed with respect to the surface 6a of the positioning member 6. The groove bottom surface 6j extends in the width direction Y along the surface 6a between the pair of positioning groove side surfaces 6h. The groove bottom surface 6j is, for example, parallel to the surface 6a. The groove bottom surface 6j is in contact with the protruding portion 2a of the optical fiber 2 and supports the protruding portion 2a. The groove bottom surface 6j is in contact with the protruding portion 3a of the optical fiber 3 and supports the protruding portion 3a.

[0070] A positioning groove 6d is formed on the surface 6a of the positioning member 6A to support the protruding portion 2a of the optical fiber 2. A positioning groove 6e is formed on the surface 6a of the positioning member 6B to support the protruding portion 2a of the optical fiber 2. In a cross section perpendicular to the axial direction X, the positioning groove 6d has a pair of positioning groove side surfaces 6f that are formed perpendicular to the surface 6a of the positioning member 6A and face each other across the protruding portion 2a of the optical fiber 2. In a cross section perpendicular to the axial direction X, the positioning groove 6e has a pair of positioning groove side surfaces 6h that are formed perpendicular to the surface 6a of the positioning member 6B and face each other across the protruding portion 2a of the optical fiber 2. In this case, the range in which the optical fiber 2 can move can be easily limited by adjusting the respective spacing between the pair of positioning groove side surfaces 6f, 6h. This makes it easy to prevent the optical fiber 2 from rolling in the positioning grooves 6d, 6e, thereby easily reducing deviations in the rotation angle due to rolling of the optical fiber 2. The same effect as described above can also be achieved for the optical fiber 3.

[0071] The positioning groove 6e of the positioning member 6B has a groove bottom surface 6j that connects the pair of positioning groove side surfaces 6h at a position recessed relative to the surface 6a of the positioning member 6B. The groove bottom surface 6j extends in a direction along the surface 6a between the pair of positioning groove side surfaces 6h and contacts the protruding portion 2a of the optical fiber 2. When the positioning groove 6e has such a groove bottom surface 6j, rolling of the optical fiber 2 in the positioning groove 6e can be made less likely to occur when the optical fiber 2 is placed on the groove bottom surface 6j, thereby effectively reducing deviation in the rotation angle due to rolling of the optical fiber 2. The same effect as described above can also be obtained for the optical fiber 3.

[0072] FIG. 12 is a cross-sectional view of a positioning groove 6k provided in an optical fiber splicing device according to a modified example. The optical fiber splicing device according to the modified example includes a positioning member 6C instead of the positioning member 6. The positioning member 6C differs from the positioning member 6 described above in that it includes a positioning groove 6k instead of the positioning groove 6b. The shape of the positioning groove 6k in a cross section perpendicular to the axial direction X is V-shaped. The positioning groove 6k differs from the positioning groove 6b in that its depth is deeper than that of the positioning groove 6b. The center axis AX2 of the optical fiber 2 is positioned so as not to protrude from the surface 6a of the positioning member 6C in the height direction Z. In other words, the center axis AX2 of the optical fiber 2 is positioned inside the positioning groove 6k. The upper end of the optical fiber 2 protrudes slightly from the surface 6a in the height direction Z. The protrusion amount dA of the optical fiber 2 from the surface 6a may be ⅓ or more of the outer diameter of the optical fiber 2. In other words, a portion of the optical fiber 2 extending ⅓ or more of the outer diameter from the upper end thereof may be located opposite the positioning groove 6b with respect to the surface 6a. The protrusion amount L3 may be equal to or less than one-third of the outer diameter of the optical fiber 2.

[0073] The width of the positioning groove 6k along the width direction Y on the surface 6a is smaller than the outer diameter of each of the optical fibers 2 and 3. This allows the optical fibers 2 and 3 to be inserted into the positioning groove 6k from the opening of the positioning groove 6k in the height direction Z. The interior of the positioning groove 6k is an area sandwiched between a pair of positioning groove side surfaces 6m. The optical fiber 2 contacts each of the pair of positioning groove side surfaces 6m inside the positioning groove 6k and is sandwiched between the pair of positioning groove side surfaces 6m.

[0074] 13 is a cross-sectional view of a positioning member 6D included in an optical fiber splicing device according to a modified example. The optical fiber splicing device according to the modified example includes a positioning member 6D instead of the positioning member 6. The positioning member 6D differs from the positioning member 6 in that it has a through hole 6n instead of a positioning groove 6b. The through hole 6n penetrates the positioning member 6D along the axial direction X. More specifically, the through hole 6n extends along the axial direction X from the end face 6S1 to the end face 6S2. The protruding portion 2a of the optical fiber 2 is inserted into the through hole 6n. The protruding portion 3a of the optical fiber 3 is inserted into the through hole 6n. The inner diameter d2 of the through hole 6n is larger than the outer diameter d1 of the optical fiber 2. The inner diameter d2 of the through hole 6n is larger than the outer diameter of the optical fiber 3. The difference between the inner diameter d2 and the outer diameter d1 is, for example, 3 μm.

[0075] The positioning member 6D has a through hole 6n into which the protruding portion 2a of the optical fiber 2 and the protruding portion 3a of the optical fiber 3 are inserted. The inner diameter d2 of the through hole 6n is larger than the outer diameter d1 of the protruding portion 2a of the optical fiber 2. In this case, when the optical fiber 2 is inserted into the through hole 6n, friction between the inner surface of the through hole 6n and the optical fiber 2 can be reduced. As a result, unintentional rotation of the optical fiber 2 due to friction can be prevented. Therefore, deviation in the rotation angle caused by rolling of the optical fiber 2 can be effectively reduced. The same effect as described above can be obtained for the optical fiber 3.

[0076] Fig. 14 is a plan view showing an optical fiber connection device 1A according to a modified example. As shown in Fig. 13, the optical fiber connection device 1A differs from the above-described optical fiber connection device 1 in that it has optical fibers 2A and 3A instead of the optical fibers 2 and 3. The protruding portion 2a of the optical fiber 2A has both an exposed portion 2c and a coated portion 2d. The protruding portion 3a of the optical fiber 3A has both an exposed portion 3c and a coated portion 3d. The optical fiber holder 4 holds the coated portion 2d of the optical fiber 2A and the coated portion 3d of the optical fiber 3A.

[0077] In the optical fiber connection device 1A, as described above, the protruding portion 2a of the optical fiber 2A has both the exposed portion 2c and the coated portion 2d. In this case, the coated portion 2d can increase the rigidity of the protruding portion 2a of the optical fiber 2A. This makes the protruding portion 2a of the optical fiber 2A resistant to twisting, making it less likely that the rotation angle of the optical fiber 2A will shift. The same effect as described above can be obtained for the optical fiber 3A.

[0078] The present disclosure allows for various other modifications. For example, the length L1 of the protruding portion 2a along the axial direction X may be shorter than the length L of the positioning member 6 along the axial direction X. The length L2 of the protruding portion 3a along the axial direction X may be longer than the length L of the positioning member 6 along the axial direction X. Conversely, the length L2 of the protruding portion 3a along the axial direction X may be shorter than the length L of the positioning member 6 along the axial direction X. The length L1 of the protruding portion 2a along the axial direction X may be longer than the length L of the positioning member 6 along the axial direction X. The angle θ1 formed by the pair of positioning groove side surfaces 6c may be greater than or equal to the angle θ2 formed by the pair of holder groove side surfaces 4c.

[0079] In the above-described optical fiber connection method, the optical fiber 2 is placed in the positioning groove 6b first, and then the optical fiber 3 is placed in the positioning groove 6b. The optical fiber 3 may be placed in the positioning groove 6b first, and then the optical fiber 2 may be placed in the positioning groove 6b. Instead of rotationally aligning only the optical fiber 3, only the optical fiber 2 may be rotationally align. Both the optical fibers 2 and 3 may be rotationally align.

[0080] If the optical fiber connection device is an optical fiber inspection device, after connecting the tip end face 3b to the tip end face 2b (step S15), the optical characteristics of the connected optical fibers 2 and 3 may be inspected. More specifically, for example, the connection loss of light at the tip end faces 2b and 3b may be inspected by irradiating light into either the optical fiber 2 or 3.

[0081] The optical fiber holder 4 has a support member 41 and a lid member 42. The optical fiber holder 4 does not have to have the support member 41 and the lid member 42, as long as it can hold the optical fiber 2. That is, the optical fiber holder 4 is not limited to the above-mentioned configuration. The optical fiber holder 5 does not have to have the support member 51 and the lid member 52, as long as it can hold the optical fiber 3. That is, the optical fiber holder 5 is not limited to the above-mentioned configuration.

[0082] DESCRIPTION OF SYMBOLS 1, 1A...Optical fiber connection device 2, 2A...Optical fiber (first optical fiber) 2a...Protruding portion 2b...Tip surface 2c...Exposed portion 2d...Coated portion 3, 3A...Optical fiber (second optical fiber) 3a...Protruding portion 3b...Tip surface 3c...Exposed portion 3d...Coated portion 4...Optical fiber holder (first optical fiber holder) 4a...Surface 4b...Holder groove 4c...Holder groove side surface 4S...Front end surface 5...Optical fiber holder (second optical fiber holder) 5a...Surface 5b...Holder groove 5c...Holder groove side surface 5S...Front end surface 6...Positioning member 6a...Surface 6b, 6d, 6e, 6k...Positioning groove 6c, 6f, 6h, 6m...Positioning groove side surface 6g, 6j...Groove bottom surface 6n...Through hole 6S1, 6S2...End surface 7...Cover member 21...Cladding 22...Core 31...Cladding 32...Core 41...Support member 42...Cover member 51...Support member 52...Cover member AX2, AX3...Central axis d1...Outer diameter d2...Inner diameter L, L1, L2...Length d, dA...Protrusion amount θ1, θ2, θ3...Angle

Claims

1. An optical fiber connection device comprising: a first optical fiber and a second optical fiber, each of which includes a target element to be rotationally aligned at a position offset from the center, and which are arranged so that their tip surfaces face each other along an axial direction in which a central axis extends; a first optical fiber holder that holds the first optical fiber with a protruding portion including the tip surface of the first optical fiber protruding along the axial direction; a second optical fiber holder that holds the second optical fiber with a protruding portion including the tip surface of the second optical fiber protruding along the axial direction; and a positioning member that holds the protruding portions of the first optical fiber and the second optical fiber and determines the positions of the first optical fiber and the second optical fiber, wherein the length of the protruding portion of the first optical fiber from the first optical fiber holder to the tip surface in the axial direction is shorter than the length of the positioning member in the axial direction.

2. An optical fiber connection device as described in claim 1, wherein a positioning groove is formed on the surface of the positioning member to support the protruding portion of the first optical fiber, and the positioning groove includes a pair of positioning groove side surfaces that are inclined so that the spacing between them becomes narrower the further away from the surface of the positioning member in a cross section perpendicular to the axial direction; and a holder groove is formed on the surface of the first optical fiber holder to support the first optical fiber, and the holder groove includes a pair of holder groove side surfaces that are inclined so that the spacing between them becomes narrower the further away from the surface of the first optical fiber holder in a cross section perpendicular to the axial direction; and the angle formed by the pair of positioning groove side surfaces is smaller than the angle formed by the pair of holder groove side surfaces.

3. An optical fiber connection device as described in claim 1, wherein a positioning groove is formed on the surface of the positioning member to support the protruding portion of the first optical fiber, and the positioning groove has a pair of positioning groove side surfaces that are formed perpendicular to the surface of the positioning member in a cross section perpendicular to the axial direction and that face each other with the protruding portion of the first optical fiber in between.

4. An optical fiber connection device as described in claim 3, wherein the positioning groove has a groove bottom surface connecting the pair of positioning groove side surfaces at a position recessed relative to the surface of the positioning member, and the groove bottom surface extends in a direction along the surface between the pair of positioning groove side surfaces and contacts the protruding portion of the first optical fiber.

5. An optical fiber connection device as described in any one of claims 1 to 4, wherein a positioning groove is formed on the surface of the positioning member to support the protruding portion of the first optical fiber, and the central axis of the first optical fiber is positioned in a protruding position opposite to the positioning groove relative to the surface of the positioning member in the normal direction to the surface of the positioning member.

6. The optical fiber connection device according to claim 1, wherein the positioning member has a through hole into which the protruding portions of the first optical fiber and the second optical fiber are inserted, and the inner diameter of the through hole is larger than the outer diameter of the protruding portion of the first optical fiber.

7. An optical fiber connection device as described in any one of claims 1 to 6, wherein the first optical fiber has a coated portion in which the glass fiber is covered with a resin coating, and an exposed portion including the tip surface in which the glass fiber is exposed from the resin coating, and the protruding portion of the first optical fiber has both the exposed portion and the coated portion.

8. An optical fiber connection device as described in any one of claims 1 to 6, wherein the first optical fiber has a coated portion in which the glass fiber is covered with a resin coating, and an exposed portion including the tip surface where the glass fiber is exposed from the resin coating, and the protruding portion of the first optical fiber includes only the exposed portion of the exposed portion and the coated portion.

9. An optical fiber connection method using an optical fiber connection device described in any one of claims 1 to 8, comprising the steps of: placing the protruding portion of the first optical fiber in the positioning member; placing the protruding portion of the second optical fiber in the positioning member; rotating and aligning only the second optical fiber of the first optical fiber and the second optical fiber while the protruding portions of the first optical fiber and the second optical fiber are placed in the positioning member; and connecting the tip surface of the second optical fiber to the tip surface of the first optical fiber.

Images