JP2022176676A - Optical fiber connection structure and method of manufacturing optical fiber connection structure - Google Patents

Abstract

To provide an optical fiber connection structure that can suppress variance in coupling loss due to tilting of a fiber end, and a method of manufacturing the optical fiber connection structure that can facilitate an optical axis adjusting process for a core direction by suppressing variance in coupling loss between cores and aligning a fiber end polishing direction.SOLUTION: A state in which optical fiber units 2, 3 are so arranged that most projecting points of inclined end faces 2a, 3a are upper ends 2aa, 3aa with center axes C1, C2 held horizontally is defined as a reference state. In the reference state of the optical fiber units 2, 3, cores 20a, 30a located at uppermost parts and cores 20c, 30c located at lowermost parts among a plurality of cores 20, 30 are arranged on segments L1, L2 connecting upper ends 2aa, 3aa and lower ends 2ab, 3ab of the end faces 2a, 3a of the optical fiber units 2, 3.SELECTED DRAWING: Figure 2

Description

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

As a conventional optical fiber connection structure of this type, the one disclosed in Japanese Patent Application Laid-Open No. 2002-200000 has been proposed. In Patent Document 1, the optical fiber connection structure includes a multi-core fiber and a fiber bundle formed by bonding a plurality of single-core fibers together with an adhesive. are connecting.

Here, the multiple cores arranged in the multi-core fiber and the fiber bundle are generally made of glass. Therefore, in Patent Document 1, in order to reduce Fresnel reflection caused by the difference in refractive index between glass and air on the end faces of the multi-core fiber and the fiber bundle, the end faces of the multi-core fiber and the fiber bundle are arranged with respect to a plane perpendicular to the central axis. is tilted.

Then, the multi-core fiber and the fiber bundle are arranged in a state in which the tilt directions of the end faces are opposite to each other (state in which the tilt directions are different).

JP 2016-061941 A

However, in the above conventional technology, the arrangement state of the multiple cores on the end faces of the multi-core fiber and the fiber bundle is unknown. That is, in the prior art, the orientation of the core arrangement on the end face inclined with respect to the plane perpendicular to the central axis is not strictly defined.

Therefore, depending on the combination of the orientation of the inclined end face and the orientation of the core arrangement, there is a possibility that the amount of defocus may vary. If there is a variation due to defocus, a variation in coupling loss will occur. Therefore, it is desirable that the core orientation and the tilt orientation be made constant.

The present invention has been made in view of the problems of the prior art. An object of the present invention is to provide an optical fiber connection structure capable of suppressing variations in coupling loss caused by inclining fiber ends. Another object of the present invention is to provide a method for manufacturing an optical fiber connection structure, which makes it possible to suppress variations in coupling loss due to oblique polishing of fiber ends, and simplifies the adjustment process for optically coupling cores to each other.

An optical fiber connection structure according to an aspect of the present invention includes a first optical fiber unit in which a plurality of first cores are arranged, and a plurality of second cores arranged so as to correspond to the plurality of first cores, respectively. and a second optical fiber unit, wherein the end face of the first optical fiber unit is inclined with respect to a plane orthogonal to the central axis of the first optical fiber unit, and the second light The end surface of the fiber unit is inclined with respect to a plane perpendicular to the central axis of the second optical fiber unit, and the first optical fiber unit and the second optical fiber unit are separated from each other by the first optical fiber unit. The direction of inclination of the end surface of the optical fiber unit and the direction of inclination of the end surface of the second optical fiber unit are opposite to each other. The uppermost core and the lowermost core among the plurality of first cores are arranged so that the most protruding point of the inclined end face is the upper end, and the core positioned at the uppermost portion and the core positioned at the lowermost portion of the plurality of first cores It is arranged on the line segment connecting the upper end and the lower end of the end face of the first optical fiber unit, and the point where the inclined end face protrudes most while the central axis of the second optical fiber unit is horizontal. the uppermost core and the lowermost core among the plurality of second cores so that the upper end and the lower end of the end face of the second optical fiber unit placed on the connecting line segment.

A method for manufacturing an optical fiber connection structure according to an aspect of the present invention comprises: a first optical fiber unit in which a plurality of first cores are arranged; and a plurality of second cores corresponding to the plurality of first cores, respectively. and a second optical fiber unit disposed in the optical fiber connection structure. The method for manufacturing an optical fiber splicing structure is such that the end face of the first optical fiber unit and the end face of the second optical fiber unit are inclined with respect to a plane perpendicular to the central axis of each optical fiber unit, a polishing step of polishing the end face of each optical fiber unit; and an alignment step of optically aligning the end face of the first optical fiber unit and the end face of the second optical fiber unit so as to face each other. , the polishing step includes adjusting the arrangement of the plurality of first cores so that the relationship between the inclination direction of the end surface of the first optical fiber unit and the arrangement direction of the plurality of first cores is the same. a core orientation adjusting step of adjusting the arrangement of the plurality of second cores so that the relationship between the inclination direction of the end surface of the second optical fiber unit and the arrangement direction of the plurality of second cores is the same; After performing the core orientation adjustment step and the first core orientation adjustment step, the central axis of the first optical fiber unit is horizontal, and the most protruding point of the inclined end surface is the upper end. In the arranged state, the uppermost core and the lowermost core among the plurality of first cores are arranged on a line connecting the upper end and the lower end of the end surface of the first optical fiber unit. After performing the first polishing step of polishing the end surface of the first optical fiber unit and the second core orientation adjusting step, the center axis of the second optical fiber unit is aligned so as to be horizontal. while the most protruding point of the inclined end face is the upper end, the uppermost core and the lowermost core among the plurality of second cores a second polishing step of polishing the end face of the second optical fiber unit so as to be arranged on a line segment connecting the upper end and the lower end of the end face of the optical fiber unit; By arranging such that the inclination direction of the end face of the first optical fiber unit and the inclination direction of the end face of the second optical fiber unit are opposite to each other, A core orientation alignment step for aligning the orientation, and an optical axis alignment step for aligning the optical axis after performing the core orientation alignment step.

According to the present invention, it is possible to provide an optical fiber connection structure capable of suppressing variations in coupling loss between cores. In addition, it is possible to provide a method of manufacturing an optical fiber splicing structure that can simplify the process of adjusting the optical axis of the core orientation by suppressing variations in coupling loss between cores and aligning the fiber end polishing orientation. .

1 is a side sectional view schematically showing an example of an optical fiber connection structure; FIG. FIG. 4 is a side cross-sectional view schematically showing an arrangement state of a first optical fiber unit and a second optical fiber unit; FIG. 4 is a diagram schematically showing an end face of a first optical fiber unit and an end face of a second optical fiber unit; It is a figure explaining an example of the manufacturing method of an optical fiber connection structure. FIG. 4 is a side view schematically showing an example of a method of inclining the end face of the first optical fiber unit; FIG. 4 is a front view schematically showing an example of a method of inclining the end surface of the first optical fiber unit; FIG. 4B is a bottom view schematically showing an example of a method of inclining the end face of the first optical fiber unit; It is a side sectional view which shows typically an example of the manufacturing method of a 1st fiber collimator. FIG. 4 is a side sectional view schematically showing an example of an adjustment method between the first optical fiber unit and the first lens; FIG. 5 is a side cross-sectional view schematically showing an example of a method for aligning the first fiber collimator and the second fiber collimator; It is a figure explaining other examples of the manufacturing method of an optical fiber connection structure. FIG. 11 is a side view schematically showing another example of a method of inclining the end face of the first optical fiber unit; FIG. 4 is a front view schematically showing another example of a method of inclining the end surface of the first optical fiber unit; FIG. 4B is a bottom view schematically showing another example of a method of inclining the end face of the first optical fiber unit; It is a figure explaining the core pitch and diagonal core pitch in a 1st optical fiber unit. It is a figure explaining the angular deviation of the 1st optical fiber unit about the Z-axis. 4 is a graph showing the relationship between the angular deviation about the Z-axis and the loss rate for each core pitch; 4 is a graph showing the relationship between core pitch and angular deviation about the Z-axis for each loss rate. FIG. 4 is a diagram schematically showing another example of the end surface of the first optical fiber unit;

Hereinafter, the optical fiber connection structure according to this embodiment will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

Also, the following embodiments and modifications thereof include similar components. Therefore, hereinafter, common reference numerals are given to those similar components, and duplicate descriptions are omitted.

Further, in the following embodiments and modifications thereof, the central axis direction of the first optical fiber unit and the second optical fiber unit will be defined as the Z direction (the front-rear direction of the optical fiber connection structure). In addition, the vertical direction (Y direction) of the optical fiber connection structure is defined in a state in which the most protruding points of the end surfaces of the first optical fiber unit and the second optical fiber unit are arranged upward. do. A direction perpendicular to the Z direction and the Y direction is defined as the width direction (X direction) of the optical fiber connection structure.

As shown in FIG. 1, the optical fiber connection structure 1 according to this embodiment includes a first optical fiber unit 2 in which a plurality of first cores 20 are arranged, and a second optical fiber unit 2 in which a plurality of second cores 30 are arranged. and an optical fiber unit 3 of

In this embodiment, as the first optical fiber unit 2, a multi-core fiber coated with one first clad 21 with four first cores 20 spaced apart from each other is exemplified. Thus, by forming the optical fiber connection structure 1 using multi-core fibers, the communication transmission capacity can be further increased. As a result, it is possible to obtain the optical fiber connection structure 1 capable of coping with an increase in communication transmission capacity due to the rapid spread of IoT and video distribution via the Internet. The multi-core fiber is an optical fiber that is expected to be used as a next-generation backbone system and a transmission line in a data center.

The first clad 21 can be made flexible using a material such as glass, and has a cord shape elongated in the Z direction (front-rear direction). On the other hand, the first core 20 can be formed to be flexible using a material such as glass, for example, and is elongated in the Z direction (front-rear direction). are placed in

Furthermore, in the present embodiment, the first clad 21 and the four first cores 20 are formed to have a circular cross-sectional shape cut along a plane perpendicular to the central axis C1.

The four first cores 20 are arranged at regular intervals on a circle around the central axis C1 of the first optical fiber unit 2 (see FIG. 3).

Here, in this embodiment, numbers are given to the four first cores 20 . Specifically, in the state shown in FIG. 3, the first core 20 positioned at the center and upper side in the X direction (width direction) is designated as the first core No. 1 20a. Further, in the state shown in FIG. 3, the first core No. 20b, the first core No. 3 20c, and the first core No. 4 20d are arranged clockwise starting from the first core No. 1 20a. It should be noted that the above numbers are given for convenience and are not specified by standardization or the like. Therefore, the assignment of numbers to the four first cores 20 can be set randomly.

Furthermore, in the present embodiment, the end face 2a on one side in the Z direction (front-rear direction) of the first optical fiber unit 2 is inclined with respect to the plane orthogonal to the central axis C1 of the first optical fiber unit 2. there is By doing so, Fresnel reflection caused by the difference in refractive index between the glass (first core 20) of the end surface 2a of the first optical fiber unit 2 and the air can be more reliably reduced.

The end face 2a inclined with respect to the plane perpendicular to the central axis C1 can be formed by polishing the end of the first optical fiber unit 2. As shown in FIG. By polishing the end portion of the first optical fiber unit 2 in this way to form the end face 2a inclined with respect to the plane perpendicular to the central axis C1, the end face 2a can be easily and reliably polished. It can be a flat inclined surface. As a result, Fresnel reflection caused by the difference in refractive index between the glass (first core 20) of the end surface 2a of the first optical fiber unit 2 and the air can be more reliably reduced.

Furthermore, in this embodiment, when the end face 2a of the first optical fiber unit 2 is tilted, the tilt direction of the end face 2a and the arrangement direction of the four first cores 20 are made to have the same relationship.

Specifically, when the inclination direction of the end face 2a is the lower side in the vertical direction (Y direction) and one side in the front-to-rear direction (Z direction), the first core No. 1 20a and the first core No. 3 20c They are arranged in the vertical direction (Y direction).

In this embodiment, the first core No. 1 20a and the first core No. 3 20c are two vertices located on the diagonal when a square is drawn with the four first cores 20 as vertices. Also, this diagonal line is a line segment passing through the central axis C1 of the first optical fiber unit 2 .

Thus, in this embodiment, in the reference state of the first optical fiber unit 2, the first core No. 1 is placed on the line segment L1 connecting the upper end 2aa and the lower end 2ab of the end surface 2a of the first optical fiber unit 2. 20a and the first core No. 3 20c are arranged. Here, the reference state of the first optical fiber unit 2 means that the central axis C1 of the first optical fiber unit 2 is horizontal, and the most protruding point of the inclined end surface 2a is the upper end 2aa. It is the state of being arranged like this. Further, the first core No. 1 20 a is the first core 20 positioned at the top among the four first cores 20 in the reference state of the first optical fiber unit 2 . The first core No. 3 20c is the first core 20 located at the lowest position among the four first cores 20 in the reference state of the first optical fiber unit 2 . At this time, the first core No. 2 20b and the first core No. 4 20d are arranged in the standard state of the first optical fiber unit 2, respectively, at the central portion in the vertical direction (Y direction) of the end surface 2a. That is, the first core No. 2 20 b and the first core No. 4 20 d are arranged on a horizontal line passing through the central axis C 1 of the first optical fiber unit 2 in the reference state of the first optical fiber unit 2 .

Further, in the present embodiment, as described above, the first clad 21 is formed to have a circular cross-sectional shape taken along a plane perpendicular to the central axis C1. That is, the end face 2a of the first optical fiber unit 2 has a circular profile when viewed along the central axis C1. Therefore, the end face 2a inclined with respect to the plane orthogonal to the central axis C1 has an elliptical shape. A line segment L1 connecting the upper end 2aa and the lower end 2ab coincides with the long axis of the elliptical end face 2a, and a horizontal line passing through the central axis C1 of the first optical fiber unit 2 is the elliptical end face 2a. aligned with the short axis.

Moreover, in this embodiment, as the second optical fiber unit 3, a bundle of four single-mode fibers in which one second core 30 is coated with one second clad 31 is exemplified.

The second clad 31 can be made flexible using a material such as glass, and has a cord shape elongated in the Z direction (front-rear direction). On the other hand, the second core 30 can be formed to have flexibility using a material such as glass, for example, and is elongated in the Z direction (front-rear direction). are placed in

Furthermore, in the present embodiment, the second clad 31 and the second core 30 are formed to have a circular cross-sectional shape taken along a plane perpendicular to the central axis C2.

The four single-mode fibers are bundled such that the four second cores 30 correspond to the four first cores 20 one-to-one. The second optical fiber unit 3 having four second cores 30 is formed by fixing the four single-mode fibers bundled with an adhesive or the like.

Furthermore, in the present embodiment, the four second cores 30 are also arranged at regular intervals on the circumference around the central axis C2 of the second optical fiber unit 3 (see FIG. 3).

Here, in this embodiment, the four second cores 30 are also numbered. Specifically, in the state shown in FIG. 3, the second core 30 located at the center and upper side in the X direction (width direction) is the second core No. 1 30a. In the state shown in FIG. 3, the second core No. 30b, the second core No. 3 30c, and the second core No. 4 30d are arranged counterclockwise from the second core No. 1 30a. It should be noted that the above numbers are also given for convenience, and are not specified by standardization or the like. Therefore, the assignment of numbers to the four second cores 30 can also be set randomly. At this time, it is preferable to assign the same number as the number assigned to the corresponding first core 20 .

Furthermore, in the present embodiment, the end face 3a on one side in the Z direction (front-rear direction) of the second optical fiber unit 3 is inclined with respect to the plane perpendicular to the central axis C2 of the second optical fiber unit 3. there is By doing so, Fresnel reflection caused by the difference in refractive index between the glass (second core 30) of the end face 3a of the second optical fiber unit 3 and the air can be more reliably reduced.

The end face 3a inclined with respect to the plane perpendicular to the central axis C2 can also be formed by polishing the end of the second optical fiber unit 3. FIG.

Furthermore, in this embodiment, even when the end surface 3a of the second optical fiber unit 3 is inclined, the inclination direction of the end surface 3a and the arrangement direction of the four second cores 30 are made to have the same relationship.

Specifically, when the inclination direction of the end surface 3a is set to the lower side in the vertical direction (Y direction) and to one side in the front-to-rear direction (Z direction), the second core No. 1 30a and the second core No. 3 30c They are arranged in the vertical direction (Y direction).

In the present embodiment, the second core No. 1 30a and the second core No. 3 30c are two vertices located on the diagonal when a square is drawn with the four second cores 30 as vertices. Also, this diagonal line is a line segment passing through the central axis C2 of the second optical fiber unit 3 .

Thus, in this embodiment, in the reference state of the second optical fiber unit 3, the second core No. 1 is placed on the line segment L2 connecting the upper end 3aa and the lower end 3ab of the end face 3a of the second optical fiber unit 3. 30a and the second core No. 3 30c are arranged. Here, the reference state of the second optical fiber unit 3 means that the central axis C2 of the second optical fiber unit 3 is horizontal, and the most protruding point of the inclined end surface 3a is the upper end 3aa. It is the state of being arranged like this. Further, the second core No. 1 30 a is the second core 30 located at the top among the four second cores 30 in the standard state of the second optical fiber unit 3 . The second core No. 3 30 c is the second core 30 located at the bottom among the four second cores 30 in the standard state of the second optical fiber unit 3 . At this time, the second core No. 2 30b and the second core No. 4 30d are arranged in the standard state of the second optical fiber unit 3 at the central portion in the vertical direction (Y direction) of the end surface 3a. That is, the second core No. 2 30 b and the second core No. 4 30 d are arranged on a horizontal line passing through the central axis C 2 of the second optical fiber unit 3 in the reference state of the second optical fiber unit 3 .

The optical fiber connection structure 1 is formed by optically coupling the first optical fiber unit 2 and the second optical fiber unit 3 configured as described above.

In order to realize an optical communication system using multi-core fibers, a fan-in/fan-out (FIFO) device is required to connect each core of the multi-core fiber and the core of the existing single-mode fiber. Is required. In this embodiment, as the optical fiber connection structure 1, a connection structure formed when manufacturing a fan-in/fan-out (FIFO) device is exemplified.

By the way, one of connection methods for optically coupling the first optical fiber unit 2 and the second optical fiber unit 3 is a spatial coupling type connection method using a lens. Also, as one means of the spatial coupling type connection system using lenses, there is a structure in which two single lenses are used to optically couple the propagation core of a multi-core fiber and a bundle of a plurality of single mode fibers.

In this embodiment, as the optical fiber connection structure 1, a structure is adopted in which two single lenses are used to optically couple a propagation core of a multi-core fiber and a bundle of a plurality of single mode fibers. By doing so, the coupling tolerance in the X and Y directions (vertical and horizontal directions) in the first core 20 and the second core 30 is greater than in the case where the end faces of the optical fibers need to be brought into close contact with each other. It is loose and allows the coupling loss to stabilize.

That is, in this embodiment, the optical fiber splicing structure 1 includes the first lens 212a optically coupled to the end surface 2a of the first optical fiber unit 2 and the end surface 3a of the second optical fiber unit 3. and a second lens 312a coupled to. In this embodiment, aspherical lenses are used as the first lens 212a and the second lens 312a.

The first lens 212a and the second lens 312a are optically coupled to each other.

Specifically, by inserting and fixing the first optical fiber unit 2 in the collimator pipe 210 holding the first lens 212a, the end face 2a of the first optical fiber unit 2 and the first lens 212a are optically separated. forming a first fiber collimator 200 which is symmetrically coupled.

At this time, since the first optical fiber unit 2 has flexibility, the first optical fiber unit 2 is inserted into a cylindrical first ferrule 22 made of ceramic or metal and fixed by adhesion. It is inserted into the collimator pipe 210 in a folded state. In this embodiment, the first ferrule 22 is fixed to the side where the end surface 2a of the first optical fiber unit 2 is formed.

Furthermore, in this embodiment, the collimator pipe 210 includes a cylindrical main body 211 into which the first optical fiber unit 2 is inserted, and a lens holding cylinder 212 that holds the first lens 212a. The collimator pipe 210 with the first lens 212a is formed by fixing the lens holding cylinder 212 holding the first lens 212a and the tubular main body 211 together.

Note that the first ferrule 22 (first optical fiber unit 2) and the cylindrical body portion 211 are fixed after the first optical fiber unit 2 is manufactured.

Similarly, by inserting and fixing the second optical fiber unit 3 in the collimator pipe 310 holding the second lens 312a, the end surface 3a of the second optical fiber unit 3 and the second lens 312a are optically separated. A combined second fiber collimator 300 is formed.

At this time, since the second optical fiber unit 3 also has flexibility, the second optical fiber unit 3 is inserted into the cylindrical second ferrule 32 made of ceramic or metal and fixed by adhesion. It is inserted into the collimator pipe 310 in a folded state. In this embodiment, the second ferrule 32 is fixed to the side where the end surface 3a of the second optical fiber unit 3 is formed.

Furthermore, in this embodiment, the collimator pipe 310 includes a cylindrical main body portion 311 into which the second optical fiber unit 3 is inserted, and a lens holding cylinder 312 that holds the second lens 312a. The optical fiber connection structure 1 is formed by optically coupling the first lens 212a and the second lens 312a to each other. In addition, in this embodiment, the optical fiber connection structure 1 in which the first fiber collimator 200 and the second fiber collimator 300 are fixed by the cylindrical adapter 41 and the fixing ring 42 is illustrated.

In the first optical fiber unit 2 and the second optical fiber unit 3, the inclination direction of the end surface 2a of the first optical fiber unit 2 and the inclination direction of the end surface 3a of the second optical fiber unit 3 are opposite to each other. are arranged in the same direction. That is, the inclination direction of the end face 2a is the lower side in the vertical direction (Y direction) and one side in the front-rear direction (Z direction), while the inclination direction of the end face 3a is the lower side in the vertical direction (Y direction) and the front-rear direction (Z direction). direction).

Also, the first optical fiber unit 2 and the second optical fiber unit 3 are arranged in a state in which the central axis C1 of the first optical fiber unit 2 and the central axis C2 of the second optical fiber unit 3 are aligned. are arranged (see Fig. 2).

Next, an example of a method for manufacturing the optical fiber splicing structure 1 according to this embodiment will be described with reference to FIGS. 4 to 10. FIG.

5 to 7 show an example of a method of polishing the end surface 2a of the first optical fiber unit 2, but the end surface 3a of the second optical fiber unit 3 can also be polished by the same method. can.

Moreover, although FIG. 8 shows an example of a method of manufacturing the first fiber collimator 200, the second fiber collimator 300 can also be manufactured by a similar method.

FIG. 9 shows an example of the adjustment method between the first optical fiber unit 2 and the first lens 212a, but the adjustment method between the second optical fiber unit 3 and the second lens 312a is similar. can be done with

The optical fiber connection structure 1 according to this embodiment can be manufactured through the steps shown in FIG.

First, the end portion of the first optical fiber unit 2 is tilted so that the end surface 2a of the first optical fiber unit 2 becomes an inclined surface with respect to a plane orthogonal to the central axis C1 of the first optical fiber unit 2. 2a is polished (fiber processed end surface polishing step: polishing step).

Specifically, the polishing jig 50 is used to polish the end of the first optical fiber unit 2 . At this time, since the first optical fiber unit 2 is fibrous and flexible, it may be bent during the polishing of the end portion, making it impossible to polish the end face uniformly. Therefore, the side where the end face 2a of the first optical fiber unit 2 is formed is fixed by bonding to the first ferrule 22, and the end face of the first optical fiber unit 2 is polished together with the first ferrule 22. FIG.

Further, in this embodiment, the polishing jig 50 includes a body portion 51 having a V-shaped groove 51a formed therein in which the first optical fiber unit 2 adhered and fixed to the first ferrule 22 is placed. . Further, the polishing jig 50 rotates the first optical fiber unit 2 around the central axis C1 in a state where the first optical fiber unit 2 adhesively fixed to the first ferrule 22 is placed in the groove 51a. A holding plate 52 is provided to hold down so as not to put it away.

The V-shaped groove 51a is angled in advance so that when the first optical fiber unit 2 adhered and fixed to the first ferrule 22 is placed in the groove 51a, the first optical fiber unit The angle between the central axis C1 of 2 and the horizontal plane is an angle θ. This angle θ can be, for example, 76 degrees to 84 degrees.

After setting the first optical fiber unit 2 adhesively fixed to the first ferrule 22 on the polishing jig 50 and before polishing the end surface, the arrangement direction of the four first cores 20 is determined using a microscope or the like. (Confirm the core orientation). In this method of confirming the orientation of the core, for example, the crosshairs R of a microscope or the like and the reference planes P1 and P2 of the polishing jig 50 are used to adjust the arrangement direction of the four first cores 20 so that they are aligned in a predetermined direction. be able to. In this embodiment, the method shown in FIG. 7 is exemplified. In FIG. 7, the first core No. 1 20a is observed using a crosshair R of a microscope or the like, and the first core No. 20a is positioned so that the reference plane P2 extending in the horizontal direction passes through the maximum diameter of the first core No. 1 20a. By rotating the optical fiber unit 2, the arrangement direction of the four first cores 20 is adjusted.

Next, the first fiber collimator 200 is manufactured using the first optical fiber unit 2 having the end surface 2a inclined so that the relationship between the inclination direction of the end surface 2a and the arrangement direction of the first cores 20 is the same ( fiber collimator manufacturing process).

Specifically, first, the first optical fiber unit 2 is inserted into the collimator pipe 210 holding the first lens 212a. Then, while the first optical fiber unit 2 is inserted into the collimator pipe 210, the first optical fiber unit 2 is relatively moved in the front-rear direction (direction of arrow A in FIGS. 8 and 9). By doing so, the distance between the first optical fiber unit 2 and the first lens 212a is adjusted so that the focal position is optimized.

In this embodiment, as described above, the end surface 2a is an inclined surface that is inclined with respect to the plane orthogonal to the central axis C1 of the first optical fiber unit 2. As shown in FIG. Therefore, a difference occurs in the focal length between each first core 20 and the first lens 212a. Therefore, in this embodiment, the focus distances of all the first cores 20 are averaged. Specifically, as shown in FIG. 9, light emitted from one first core 20 of the first optical fiber unit 2 is passed through the first lens 212a to be a collimated beam. By arranging the total reflection mirror 60 at the position of the beam waist A1 and maximally coupling it to the first cores 20 located diagonally, the difference in distance between the two first cores 20 and the first lens 212a is averaged. We are making it possible to Here, in this embodiment, in the reference state of the first optical fiber unit 2, the first core No. 1 20a is placed on the line segment L1 connecting the upper end 2aa and the lower end 2ab of the end surface 2a of the first optical fiber unit 2. and the first core No. 3 20c are arranged. Therefore, in this embodiment, the first core No. 1 20a and the first core No. 3 20c are the combination with the largest core-lens distance difference. Therefore, the first core No. 1 20a is used as one first core 20, the first core No. 3 20c is used as the first core 20 located diagonally, and the maximum coupling is performed between these two first cores 20. I have to. By doing so, all core-lens distances are averaged. At this time, the core-to-lens distances of the first core No. 2 20b and the first core No. 4 20d are just between the first core No. 20a and the first core No. 3 20c, resulting in an average distance.

Then, after adjusting the distance between the first optical fiber unit 2 and the first lens 212a, the first ferrule 22 (the first optical fiber unit 2) and the cylindrical body portion 211 are fixed. By carrying out like this, the 1st fiber collimator 200 is manufactured. Note that once the fiber collimator is configured, it will be housed inside the lens and the metal pipe, so it will not be possible to observe the core orientation thereafter.

Next, the first fiber collimator 200 and the second fiber collimator 300 are opposed to perform optical alignment (collimator facing system alignment process: alignment process).

In this embodiment, as described above, the relationship between the inclination direction of the end surface 2a of the first optical fiber unit 2 and the arrangement direction of the first cores 20 is made the same for each product. Similarly, the relationship between the inclination direction of the end face 3a of the second optical fiber unit 3 and the arrangement direction of the second cores 30 is the same for each product. In this embodiment, the first optical fiber unit 2 and the second optical fiber unit 3 are separated from each other by the inclination direction of the end face 2a of the first optical fiber unit 2 and the end face 3a of the second optical fiber unit 3 are arranged in such a manner that the directions of inclination thereof are opposite to each other.

Therefore, the core orientations can be roughly aligned simply by visually confirming and setting the first fiber collimator 200 and the second fiber collimator 300 so that the inclination directions (polishing orientations) of the end surfaces 2a and 3a are opposite to each other. state (core orientation alignment process). In this way, when the optical fiber splicing structure 1 is formed, if the core arrangement is roughly aligned at first, alignment work can be performed without taking much time during the subsequent adjustment. In particular, in this embodiment, since the core arrangement and the polishing orientation are known in advance, it is not necessary to confirm the core arrangement that can be observed only with a microscope, so the core arrangement can be easily and quickly aligned. After the cores are roughly aligned, the optical axes are aligned to maximize coupling (the optical axis alignment process is performed), and then the core alignment direction is finely aligned so that each core has the minimum loss. (Core orientation precision alignment process and X, Y, θx, θy optical axis adjustment process).

Thus, if the optical fiber splicing structure 1 is manufactured by the method shown in this embodiment, it is not necessary to confirm the core orientation before the fiber collimator manufacturing process or the collimator facing system alignment process. As a result, it becomes possible to manufacture the optical fiber connection structure 1 (optically connect the first optical fiber unit 2 and the second optical fiber unit 3) with high precision (low loss) and in a short time.

The optical fiber connection structure 1 can also be manufactured by the method shown in FIGS. 11 to 18. FIG.

Another example of the method for manufacturing the optical fiber connection structure 1 will be described below with reference to FIGS. 11 to 18. FIG.

12 to 14 show another example of the method of polishing the end face 2a of the first optical fiber unit 2, the end face 3a of the second optical fiber unit 3 is also polished by the same method. be able to.

The optical fiber connection structure 1 can be manufactured through the steps shown in FIG.

First, the end portion of the first optical fiber unit 2 is tilted so that the end surface 2a of the first optical fiber unit 2 becomes an inclined surface with respect to a plane orthogonal to the central axis C1 of the first optical fiber unit 2. (fiber processing end surface polishing step: polishing step).

This fiber processing end surface polishing step is basically performed by the same method as the method shown in the above embodiment. That is, the end portion of the first optical fiber unit 2 is polished while the first optical fiber unit 2 with the first ferrule 22 is fixed using the polishing jig 50 . The configuration of the polishing jig 50 is the same as that of the polishing jig 50 used in the method shown in the above embodiment.

Here, in the method shown in FIGS. 12 to 14, the rear end portion of the first ferrule 22 is provided with a marking M1 capable of matching the inclination direction of the end face 2a with the core arrangement. By providing such a marking M1 on the first ferrule 22, the polishing direction can be known at the polishing stage. By doing this, even if the polishing direction of the end surface 2a cannot be visually observed from the outside due to the first lens 212a and the collimator pipe 210 when manufacturing the first fiber collimator 200, the marking M1 can be used as a reference in the subsequent process. can be done. When performing the marking forming step of providing the marking M1 on the rear end portion of the first ferrule 22, it is preferable to perform the first optical fiber unit 2 with the first ferrule 22 attached to the polishing jig 50. FIG. By doing so, the marking can be performed more accurately and easily than when the first optical fiber unit 2 with the first ferrule 22 is removed from the polishing jig 50, the microscopic observation is performed, the core orientation is observed, and the marking is performed. be able to put it in.

Next, the first fiber collimator 200 is manufactured using the first optical fiber unit 2 having the end surface 2a inclined so that the relationship between the inclination direction of the end surface 2a and the arrangement direction of the first cores 20 is the same ( fiber collimator manufacturing process).

This fiber collimator manufacturing process is performed by a method similar to the method shown in the above embodiment. That is, the first optical fiber unit 2 is inserted into the collimator pipe 210 holding the first lens 212a. Then, while the first optical fiber unit 2 is inserted into the collimator pipe 210, the first optical fiber unit 2 is relatively moved in the front-rear direction (direction of arrow A in FIGS. 8 and 9). By doing so, the distance between the first optical fiber unit 2 and the first lens 212a is adjusted so that the focal position is optimized.

Then, after adjusting the distance between the first optical fiber unit 2 and the first lens 212a, the first ferrule 22 (the first optical fiber unit 2) and the cylindrical body portion 211 are fixed. By carrying out like this, the 1st fiber collimator 200 is manufactured.

Next, the first fiber collimator 200 and the second fiber collimator 300 are opposed to perform optical alignment (collimator facing system alignment process: alignment process).

At this time, the cores are roughly aligned based on the markings M1 provided in the previous step. By doing this, it becomes possible to perform the alignment work of the core orientation without taking much time at the time of subsequent adjustment.

For example, if the first fiber collimator 200 and the second fiber collimator 300 are arranged so that the marking M1 is positioned on the upper side, the tilt directions (polishing directions) of the end surfaces 2a and 3a can be reversed. 11 to 18, the core orientations can be roughly aligned simply by visually confirming and setting the first fiber collimator 200 and the second fiber collimator 300. FIG.

Furthermore, in the method shown in FIGS. 11 to 18, by calculating the relationship between the amount of angular deviation θz about the central axis C1 (about the Z axis) and the amount of loss (increase in loss) before manufacturing, the core pitch d1 The amount of angular deviation θz and the amount of loss with respect to (diagonal core pitch d2) are clarified.

The core pitch d1 is the distance between two cores adjacent in the circumferential direction, as shown in FIG. is the distance between Also, the angular deviation amount θz represents how much the object has rotated around the central axis C1 (around the Z axis) with respect to the reference state (see FIG. 16).

Further, FIG. 17 shows the result of calculating the coupling efficiency at angular pitches of 0.07 deg when the spot size radius is 5.5 μm and the wavelength λ is 1550 nm. Also, FIG. 18 shows an example of the relationship between the amount of loss and the amount of angular deviation θz.

From the graph of FIG. 17, for example, in the case of a core pitch of 40 μm (diagonal core pitch of 56.6 μm), the amount of loss (increase) can be kept within 0.2 dB by defining the deviation between the polishing orientation and the core orientation to 3 degrees or less. It turns out that it is possible. In other words, it can be seen that the loss (increase) amount can be kept within 0.2 dB if the angular deviation between the cores is defined as a relative angle of ±1.5 deg or less.

This process can be adapted to other core pitches, allowing pre-calculated results to be used to define the angular deviation range. Furthermore, by using the results of FIG. 17, the relationship between the core pitch and the angle deviation with respect to the desired loss amount can be obtained as shown in FIG. . As a result, it becomes possible to manufacture the FIFO device more simply and in a short period of time according to the required loss amount (specification) of the FIFO device.

Thus, by using the method shown in FIGS. 11 to 18, for example, the optical fiber splicing structure 1 can be formed within a loss increase amount of 0.2 dB without requiring precise alignment work.

Also, the manufacturing time can be shortened according to the amount of loss (specification) required for the FIFO device. That is, it becomes possible to form the optical fiber connection structure 1 in an appropriate manufacturing time according to the required performance.

As described above, if the optical fiber connection structure 1 is manufactured by the method shown in FIGS. 11 to 18, the core orientation precision alignment process performed by the method shown in the above embodiment can be omitted. As a result, it becomes possible to manufacture the optical fiber connection structure 1 (optically connect the first optical fiber unit 2 and the second optical fiber unit 3) with high precision (low loss) and in a short time.

Alternatively, as shown in FIG. 19, the first optical fiber unit 2 may be a multi-core fiber coated with one first clad 21 with seven first cores 20 spaced apart from each other. is. In FIG. 19 as well, the first clad 21 and the seven first cores 20 are formed to have a circular cross-sectional shape taken along a plane perpendicular to the central axis C1.

One first core 20 is arranged in the center of the seven first cores 20, and the six first cores 20 are arranged on a circumference centered on the central axis C1 of the first optical fiber unit 2. are evenly spaced.

Here, in FIG. 19, the seven first cores 20 are numbered. Specifically, in the state shown in FIG. 19, the first core 20 positioned at the center and upper side in the X direction (width direction) is the first core No. 1 20a. Further, in the state shown in FIG. 19, the first core 20 arranged so as to include the central axis C1 of the first optical fiber unit 2 is designated as the first core No. 2 20b, and the center in the X direction (width direction) and The lower first core 20 is designated as first core No. 3 20c. Then, in the state shown in FIG. 19, the remaining four first cores 20 are rotated counterclockwise starting from the first core No. 1 20a, respectively. The first core is No. 6, 20f and the first core is No. 7, 20g. Note that the above numbers are given so as to match the numbers of the first core 20 positioned at the top and the first core 20 positioned at the bottom in accordance with the above-described embodiment. Assignment of numbers to one core 20 can be set at random.

When the end surface 2a of the first optical fiber unit 2 shown in FIG. 19 is formed as an inclined surface, in the reference state of the first optical fiber unit 2, the first core No. 1 20a, the first core The end face 2a is inclined so that the second core 20b and the first core third 20c are arranged.

In the case of the first optical fiber unit 2 shown in FIG. 19, the second optical fiber unit 3 is a bundle of seven single-mode fibers in which one second core 30 is coated with one second clad 31. It becomes a thing. Specifically, one single mode fiber is arranged in the center, and six single mode fibers are arranged around it at equal intervals and bundled. By doing so, the seven second cores 30 of the seven single-mode fibers correspond one-to-one to the seven first cores 20, respectively.

By optically coupling the first optical fiber unit 2 and the second optical fiber unit 3 configured as described above, the optical fiber connection structure 1 is formed.

[Action/effect]
Characteristic configurations of the optical fiber splicing structure and the method of manufacturing the optical fiber splicing structure shown in the above embodiments and modifications thereof, and effects obtained thereby will be described below.

The optical fiber splicing structure 1 shown in the above embodiment and its modification includes a first optical fiber unit 2 in which a plurality of first cores 20 are arranged, and a plurality of second cores 30 in which the plurality of first cores 20 are arranged. and second optical fiber units 3 arranged to correspond to each other.

Further, the end surface 2a of the first optical fiber unit 2 is inclined with respect to a plane perpendicular to the central axis C1 of the first optical fiber unit 2, and the end surface 3a of the second optical fiber unit 3 2 is inclined with respect to a plane perpendicular to the central axis C2 of the optical fiber unit 3. As shown in FIG.

The first optical fiber unit 2 and the second optical fiber unit 3 are arranged such that the inclination direction of the end face 2a of the first optical fiber unit 2 and the inclination direction of the end face 3a of the second optical fiber unit 3 are They are arranged in opposite directions.

Here, the state in which the first optical fiber unit 2 is arranged such that the central axis C1 is horizontal and the most protruding point of the inclined end surface 2a is the upper end 2aa is the first optical fiber unit 2. It is defined as the reference state of The second optical fiber unit 3 is placed such that the center axis C2 is horizontal and the most protruding point of the inclined end surface 3a is the upper end 3aa of the second optical fiber unit 3. Defined as the reference state.

In the reference state of the first optical fiber unit 2, the uppermost core 20a and the lowermost core 20c among the plurality of first cores 20 are located on the end face 2a of the first optical fiber unit 2. He is trying to arrange|position on the line segment L1 which connects upper end 2aa and lower end 2ab.

Furthermore, in the reference state of the second optical fiber unit 3, the uppermost core 30a and the lowermost core 30c among the plurality of second cores 30 are located on the end face 3a of the second optical fiber unit 3. He is trying to arrange|position on the line segment L2 which connects upper end 3aa and lower end 3ab.

Further, the manufacturing method of the optical fiber connection structure 1 shown in the above embodiment and its modification includes a polishing step of polishing the end faces 2a, 3a of the first and second optical fiber units 2, 3. FIG. This polishing step is performed so that the end surfaces 2a and 3a of the first and second optical fiber units 2 and 3 are inclined with respect to planes orthogonal to the central axes C1 and C2 of the respective optical fiber units 2 and 3. The end surfaces 2a and 3a of the respective optical fiber units 2 and 3 are polished.

Further, the method for manufacturing the optical fiber splicing structure 1 includes an alignment step of optically aligning the end surface 2a of the first optical fiber unit 2 and the end surface 3a of the second optical fiber unit 3 so as to face each other. .

Here, in the polishing step, the arrangement of the plurality of first cores 20 is adjusted so that the relationship between the inclination direction of the end surface 2a of the first optical fiber unit 2 and the arrangement direction of the plurality of first cores 20 is the same. It has a first core orientation adjustment step. Second core orientation adjustment for adjusting the arrangement of the plurality of second cores 30 so that the relationship between the inclination direction of the end surface 3a of the second optical fiber unit 3 and the arrangement direction of the plurality of second cores 30 is the same. have a process.

Furthermore, it has a first polishing step of polishing the end face 2a of the first optical fiber unit 2 after performing the first core orientation adjusting step. In this first polishing step, in the reference state, the uppermost core 20a and the lowermost core 20c among the plurality of first cores 20 are aligned with the upper end 2aa of the end face 2a of the first optical fiber unit 2. and the lower end 2ab.

Then, after performing the second core orientation adjustment process, there is a second polishing process of polishing the end face 3a of the second optical fiber unit 3. FIG. In this second polishing step, the uppermost core 30a and the lowermost core 30c of the plurality of second cores 30 are aligned with the upper end 3aa of the end surface 3a of the second optical fiber unit 3 in the reference state. and the lower end 3ab.

Furthermore, in the alignment process, the inclination direction of the end face 2a of the first optical fiber unit 2 and the inclination direction of the end face 3a of the second optical fiber unit 3 are opposite to each other. It has a core orientation alignment process for aligning the orientations of the first core 20 and the second core 30 .

The alignment process includes an optical axis alignment process of aligning the optical axis after performing the core orientation alignment process.

With such an optical fiber splicing structure 1 and a method of manufacturing the optical fiber splicing structure, the end faces 2a of the first optical fiber units 2 and the second cores 20 and 30 are arranged in a state in which the arrangement directions of the first cores 20 and the second cores 30 are defined. The end surface 3a of the two optical fiber units 3 can be inclined. Therefore, it is possible to make the relationship between the inclination direction of the end faces 2a and 3a and the arrangement direction of the first core 20 and the second core 30 the same.

As a result, the manufacturing process can be simplified when optically coupling the first optical fiber unit 2 and the second optical fiber unit 3 (when manufacturing and assembling the optical fiber connection structure 1). , it becomes possible to shorten the manufacturing time. Furthermore, when connecting the first optical fiber unit 2 and the second optical fiber unit 3 (performing alignment work), errors and variations in the insertion loss of the first core 20 and the second core 30 are reduced. It becomes possible to reduce the time required for the alignment work.

By making the relationship between the inclination direction of the end faces 2a and 3a and the arrangement direction of the first core 20 and the second core 30 the same, the variation in the coupling loss in the first core 20 and the second core 30 can be reduced. be able to suppress it.

Thus, with the configuration shown in the above embodiment and its modification, the optical fiber splicing structure 1 and the method for manufacturing the optical fiber splicing structure are capable of performing optical connection with high precision (low loss) and in a short time. can be obtained.

Also, the first optical fiber unit 2 and the second optical fiber unit 3 are arranged in a state in which the central axis C1 of the first optical fiber unit 2 and the central axis C2 of the second optical fiber unit 3 are aligned. may be placed.

Also, the plurality of first cores 20 may be arranged at equal intervals on a circumference around the central axis C1 of the first optical fiber unit 2 . A plurality of second cores 30 may be arranged at regular intervals in a circle around the central axis C2 of the second optical fiber unit 3 .

In this way, even if the two first cores 20 and second cores 30 facing each other across the central axes C1 and C2 are arbitrarily selected, the arrangement of the first cores 20 and the second cores 30 on the end surfaces 2a and 3a can be minimized. The states can be almost the same. Therefore, when the first optical fiber unit 2 and the second optical fiber unit 3 are optically coupled, the positional variations in the end surfaces 2a and 3a of the first core 20 and the second core 30 corresponding to each other can be further reduced. can be suppressed with certainty. As a result, the coupling loss in the first core 20 and the second core 30 can be further reduced.

Moreover, the first ferrule 22 that suppresses the bending of the first optical fiber unit 2 may be fixed to the side where the end surface 2a of the first optical fiber unit 2 is formed. Furthermore, a second ferrule 32 that suppresses bending of the second optical fiber unit 3 may be fixed to the side where the end surface 3a of the second optical fiber unit 3 is formed. Markings M1 may be formed on the first ferrule 22 and the second ferrule 32 so that the inclination directions of the respective end surfaces 2a and 3a can be aligned with the core arrangement.

Moreover, the polishing process may have a marking forming process. In this marking forming step, the marking M1 that can match the inclination direction of the end face 2a of the first optical fiber unit 2 with the core arrangement of the first core 20 is formed on the second optical fiber unit 2 to which the first optical fiber unit 2 is fixed. It is formed in one ferrule 22 . Furthermore, the second ferrule 32 to which the second optical fiber unit 3 is fixed is provided with a marking M1 capable of matching the inclination direction of the end surface 3a of the second optical fiber unit 3 with the core arrangement of the second core 30. forming.

In this way, even if the direction of polishing of the end surfaces 2a and 3a cannot be visually observed from the outside, the markings M1 can be used as a reference in subsequent steps. That is, the core arrangement can be roughly aligned with the marking M1 as a reference. By doing this, it becomes possible to perform the alignment work of the core orientation without taking much time at the time of subsequent adjustment.

Further, in the core orientation alignment step, the orientations of the first core 20 and the second core 30 may be aligned based on the relationship between the amount of angular deviation θz about the central axis C1 calculated in advance and the amount of loss. .

By doing this, it becomes possible to define the allowable range of angular deviation based on the results calculated in advance, and according to the required amount of loss (specification), the optical fiber connection structure 1 can be constructed more simply and in a short time. can be manufactured.

[others]
Although the present embodiment has been described above, the present embodiment is not limited to these, and various modifications are possible within the scope of the gist of the present embodiment.

For example, it is possible to appropriately combine the configurations and methods shown in the above embodiments and their modifications.

In addition, in the above embodiment and its modification example, the numbers of the first cores 20 and the number of the second cores 30 are 4 and 7, but the number of the first cores 20 and the number of the second cores 30 is two. The number is not limited to four or seven. In this case, it is preferable to arrange at least two cores on a line segment passing through the central axis of the optical fiber unit.

Further, in the above-described embodiment and its modified example, the optical fiber connection structure 1 is exemplified as a spatial coupling type connection system using a lens, but it is not limited to this.

In addition, in the above-described embodiment and its modification, the multi-core fiber was exemplified as the first optical fiber unit 2, and the bundled single-mode fiber was exemplified as the second optical fiber unit 3, but the present invention is limited to this. is not. For example, it is possible to apply the present invention to optical coupling between multi-core fibers, and it is also possible to apply the present invention to optical coupling between bundles of single mode fibers. Alternatively, one of the first optical fiber unit 2 and the second optical fiber unit 3 may be a fu-mode fiber, and the other may be a bundle of multi-core fibers or single-mode fibers. It is also possible that both the first optical fiber unit 2 and the second optical fiber unit 3 are fumode fibers.

In addition, collimator pipes, adapters, and other detailed specifications (shape, size, layout, etc.) can be changed as appropriate.

REFERENCE SIGNS LIST 1 optical fiber connection structure 2 first optical fiber unit 20 first core 2a end surface 2aa upper end 2ab lower end 22 first ferrule L1 line segment C1 central axis M1 marking 3 second optical fiber unit 30 second core 3a end surface 3aa upper end 3ab Lower end 32 Second ferrule L2 Line segment C2 Central axis

Claims (7)

a first optical fiber unit in which a plurality of first cores are arranged;
a second optical fiber unit in which a plurality of second cores are arranged so as to correspond to each of the plurality of first cores;
with
an end surface of the first optical fiber unit is inclined with respect to a plane perpendicular to the central axis of the first optical fiber unit,
the end face of the second optical fiber unit is inclined with respect to a plane orthogonal to the central axis of the second optical fiber unit,
In the first optical fiber unit and the second optical fiber unit, the direction of inclination of the end surface of the first optical fiber unit and the direction of inclination of the end surface of the second optical fiber unit are opposite to each other. are arranged so that
The first optical fiber unit is positioned at the top of the plurality of first cores in a state in which the center axis is horizontal and the most protruding point of the inclined end face is the upper end. the core and the lowest core are arranged on a line segment connecting the upper end and the lower end of the end surface of the first optical fiber unit,
The second optical fiber unit is positioned at the top of the plurality of second cores in a state in which the center axis is horizontal and the most protruding point of the inclined end face is the upper end. The core and the lowest core are arranged on a line segment connecting the upper end and the lower end of the end face of the second optical fiber unit,
Optical fiber connection structure. The first optical fiber unit and the second optical fiber unit are arranged with the central axis of the first optical fiber unit and the central axis of the second optical fiber unit aligned. ,
The optical fiber connection structure according to claim 1. The plurality of first cores are arranged at equal intervals on a circumference around the central axis of the first optical fiber unit,
The plurality of second cores are arranged at equal intervals on a circumference centered on the central axis of the second optical fiber unit,
The optical fiber connection structure according to claim 1 or 2. A first ferrule that suppresses bending of the first optical fiber unit is fixed to the side where the end surface of the first optical fiber unit is formed,
A second ferrule that suppresses bending of the second optical fiber unit is fixed to the side on which the end surface of the second optical fiber unit is formed,
Markings are formed on the first ferrule and the second ferrule so that the inclination direction of each end surface and the core arrangement can be aligned.
The optical fiber connection structure according to any one of claims 1 to 3. A first optical fiber unit in which a plurality of first cores are arranged, and a second optical fiber unit in which a plurality of second cores are arranged so as to correspond to each of the plurality of first cores are optically An optical fiber connection structure manufacturing method for manufacturing an optical fiber connection structure connected to
The end face of each optical fiber unit is polished so that the end face of the first optical fiber unit and the end face of the second optical fiber unit are inclined with respect to a plane perpendicular to the central axis of each optical fiber unit. a polishing process to
an alignment step of optically aligning the end face of the first optical fiber unit and the end face of the second optical fiber unit facing each other;
with
The polishing step includes
a first core orientation adjusting step of adjusting the arrangement of the plurality of first cores so that the relationship between the inclination direction of the end surface of the first optical fiber unit and the arrangement direction of the plurality of first cores is the same;
a second core orientation adjusting step of adjusting the arrangement of the plurality of second cores so that the relationship between the inclination direction of the end surface of the second optical fiber unit and the arrangement direction of the plurality of second cores is the same;
After performing the first core orientation adjustment step, while the central axis of the first optical fiber unit is horizontal, the most protruding point of the inclined end face is the upper end, and the The uppermost core and the lowermost core among the plurality of first cores are arranged on a line segment connecting the upper end and the lower end of the end surface of the first optical fiber unit. a first polishing step of polishing the end face of the first optical fiber unit;
After performing the second core orientation adjustment step, while the center axis of the second optical fiber unit is horizontal, the most protruding point of the inclined end face is the upper end, and the The uppermost core and the lowermost core among the plurality of second cores are arranged on a line segment connecting the upper end and the lower end of the end surface of the second optical fiber unit. a second polishing step of polishing the end face of the second optical fiber unit;
has
The alignment step includes:
By arranging such that the inclination direction of the end face of the first optical fiber unit and the inclination direction of the end face of the second optical fiber unit are opposite to each other, a core orientation alignment step for aligning the orientation;
an optical axis alignment step of aligning an optical axis after performing the core orientation alignment step;
having
A method for manufacturing an optical fiber connection structure. In the polishing step, a marking capable of matching the inclination direction of the end surface of the first optical fiber unit and the core arrangement of the first core is applied to the first ferrule to which the first optical fiber unit is fixed. a marking capable of matching the direction of inclination of the end surface of the second optical fiber unit and the core arrangement of the second core is formed on the second ferrule to which the second optical fiber unit is fixed. Having a marking formation process,
In the core orientation alignment step, orientations of the first core and the second core are aligned with reference to markings formed on the first ferrule and the second ferrule.
6. A method for manufacturing an optical fiber connection structure according to claim 5. In the core orientation alignment step, the orientations of the first core and the second core are aligned based on the relationship between the amount of angular deviation about the central axis calculated in advance and the amount of loss.
7. The method for manufacturing an optical fiber splicing structure according to claim 5 or 6.

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