Fusion splicing method and fusion splicer

Abstract

A fusion splicing method according to one embodiment comprises: a step for aligning a first multicore fiber (F1) and a second multicore fiber (F2); a step for calculating an axial deviation amount (d) from information obtained by observing respective end surfaces (E) of the first multicore fiber (F1) and the second multicore fiber (F2); a step for calculating an angular deviation amount (θ) from information obtained by observing the first multicore fiber (F1) and the second multicore fiber (F2) from the sides of the first multicore fiber (F1) and the second multicore fiber (F2); and a step for calculating an estimated loss in fusion splicing of the first multicore fiber (F1) and the second multicore fiber (F2) from the axial deviation amount (d) and the angular deviation amount (θ).

Description

Fusion connection method and fusion connection machine

[0001] The present disclosure relates to a fusion connection method and a fusion connection machine. This application claims priority based on Japanese Application No. 2024-230772 filed on December 26, 2024, and incorporates all the descriptions described in the above Japanese application.

[0002] Patent Document 1 discloses a method for estimating connection loss of an optical fiber. The connection loss estimation method estimates the connection loss due to reverse-phase core strain from the difference between the amount of axial deviation before immediately after heating the optical fiber and the amount of axial deviation after the end of heating in the fusion connection part of the optical fiber. By observing the outer shape of the optical fiber, the amount of axial deviation or the amount of angular deviation of the optical fiber is measured.

[0003] Patent Document 2 discloses a fusion connection machine. The fusion connection machine includes an optical fiber holder, a rotation mechanism, a bending part, a light source, and a power supply part. The optical fiber holder holds the optical fiber. The rotation mechanism rotates the optical fiber holder around an axis extending along the optical fiber. The bending part bends the optical fiber. The light source emits light from the side of the optical fiber to the optical fiber bent by the bending part. The power supply part supplies power to the light source.

[0004] Patent Document 3 discloses a method and apparatus for fusion connection of an optical fiber. This fusion connection method is a connection method in which an optical fiber is arranged with a predetermined gap, preheated by air discharge, then moved so that the end faces of the optical fibers contact each other, and finally heated to perform fusion connection. The fusion connection method includes a step of photographing the shape of the fused core, performing image processing, and estimating the connection loss by FD-BPM (finite difference beam propagation method). The photographed shape of the core is compared with a database obtained in advance by FD-BPM.

[0005] Patent Document 4 discloses an optical fiber alignment device, a connection device, an alignment method, and a connection method. In this alignment method, the end faces of two optical fibers are photographed. The position coordinates of two or more cores on each end face of the two optical fibers are measured. The position coordinates of the two or more cores are substituted into a theoretical formula that represents the sum of the misalignment losses when the two or more cores are connected. From the theoretical formula, the positional relationship of the end faces of the two optical fibers that minimizes the sum of the misalignment losses is determined.

[0006] Japanese Patent Publication No. 01-196531, International Publication No. 2022 / 244843, Japanese Patent Publication No. 09-138318, Japanese Patent Publication No. 2015-041078

[0007] The fusion splicing method according to this disclosure is a fusion splicing method for fusion splicing together a first multicore fiber having a plurality of first cores exposed on a first end face and a second multicore fiber having a plurality of second cores exposed on a second end face. The fusion splicing method comprises the steps of: aligning the first multicore fiber and the second multicore fiber by rotating at least one of the first multicore fiber and the second multicore fiber; calculating an axial misalignment, which is the amount of misalignment of the axis of the second core with respect to the axis of the first core, from information obtained by observing the first end face and the second end face; calculating an angular misalignment, which is the amount of misalignment of the second core at the second end face with respect to the extending direction of the first core at the first end face, from information obtained by observing the first multicore fiber and the second multicore fiber from the side; and calculating an estimated loss in the fusion splicing of the first multicore fiber and the second multicore fiber from the axial misalignment and the angular misalignment.

[0008] Figure 1 is a perspective view showing a fusion splicer according to an embodiment. Figure 2 is a perspective view showing an example of the internal structure of the fusion splicer of Figure 1. Figure 3 is a perspective view showing a schematic of the rotation mechanism of the fusion splicer. Figure 4 is a diagram showing an example of the end face of an optical fiber. Figure 5 is a diagram schematically showing the optical fiber end face observation section in the fusion splicer. Figure 6 is a diagram for explaining the amount of axial misalignment. Figure 7 is a front view showing an example of the first core at the first end face and the second core at the second end face. Figure 8 is a perspective view showing an example of the first core at the first end face and the second core at the second end face. Figure 9 is a diagram showing the positions of the first and second cores in a coordinate system with the rotation center as the origin. Figure 10 is a diagram showing the positions of the first and second cores in a coordinate system with the centroid of a figure whose vertices are the centers of each core as the origin. Figure 11 is a diagram showing the positions of the first and second cores in a coordinate system with the fixed points of the first and second end faces as the origin. Figure 12 is a schematic diagram showing the lateral observation section of the optical fiber in a fusion splicer. Figure 13 is a diagram illustrating the amount of angular displacement. Figure 14 is a diagram illustrating the outer and inner edges of the optical fiber. Figure 15 is a schematic configuration diagram of the control unit. Figure 16 is a flowchart showing an example of the process of the fusion splicing method according to the embodiment.

[0009] Methods are known for identifying the core position of an optical fiber and calculating the estimated loss in optical fiber fusion splicing. In multicore fibers, the cores may appear to overlap when observing the multicore fiber from the side. The multicore fiber is sometimes rotated to allow observation of each core. Calculating the estimated loss in multicore fiber fusion splicing for each core can be difficult, and there is room for improvement in terms of the accuracy of the estimated loss calculation.

[0010] The purpose of this disclosure is to provide a fusion splicing method and a fusion splicer that can easily and accurately calculate estimated losses in fusion splicing of multicore fibers.

[0011] According to this disclosure, the estimated loss in fusion splicing of multicore fibers can be easily and accurately calculated.

[0012] First, embodiments of the fusion splicing method and fusion splicing machine according to this disclosure will be listed and described. (1) The fusion splicing method according to this embodiment is a fusion splicing method that fusion splices together a first multicore fiber having a plurality of first cores exposed on a first end face and a second multicore fiber having a plurality of second cores exposed on a second end face. The fusion splicing method comprises the steps of: aligning the first multicore fiber and the second multicore fiber by rotating at least one of the first multicore fiber and the second multicore fiber; calculating an axial misalignment, which is the amount of misalignment of the axis of the second core with respect to the axis of the first core, from information obtained by observing the first end face and the second end face; calculating an angular misalignment, which is the amount of misalignment of the second core at the second end face with respect to the extending direction of the first core at the first end face, from information obtained by observing the first multicore fiber and the second multicore fiber from the side; and calculating an estimated loss in the fusion splicing of the first multicore fiber and the second multicore fiber from the axial misalignment and the angular misalignment.

[0013] In the fusion splicing method described above, the axial misalignment between the first and second multicore fibers is calculated by observing the first and second end faces. The angular misalignment between the first and second multicore fibers is calculated by observing them from the side. The estimated loss in the fusion splicing of the first and second multicore fibers is calculated from the axial misalignment and angular misalignment. By performing both lateral and end face observations of the multicore fibers, the three-dimensional positions of the first and second cores can be easily determined. The estimated loss in the fusion splicing of multicore fibers can be easily calculated. The estimated loss can be calculated for all first cores and all second cores, allowing for highly accurate calculation of the estimated loss in the fusion splicing of multicore fibers.

[0014] (2) In the rotation step in (1) above, the rotation center, which is the center of rotation, may be obtained at the first end face and the second end face. In the step of calculating the amount of axial misalignment, the position of the first core and the position of the second core in a coordinate system with the rotation center as the origin may be calculated. The rotation center obtained when the rotation of the first multicore fiber and the second multicore fiber is centered can be reused as the origin of the coordinate system at the first end face and the second end face. The position of the first core at the first end face and the position of the second core at the second end face can be used as coordinates in a coordinate system with the rotation center as the origin, and the amount of axial misalignment can be easily calculated.

[0015] (3) In the step of calculating the amount of axial misalignment in (1) or (2) above, the positions of the first core and the second core may be calculated in a coordinate system with fixed points on the first and second end faces as the origin. The coordinate system with fixed points on the first and second end faces as the origin can be used as the reference coordinate system. By using this coordinate system, the positions of the first core and the second core can be set as coordinates in a coordinate system with the fixed points as the origin, and the amount of axial misalignment can be easily calculated.

[0016] (4) In any of (1) to (3) above, the fusion splicing method may further include a step of calculating an anomaly degree indicating the degree of anomaly in the fusion splicing of the first multicore fiber and the second multicore fiber. In the step of calculating the estimated loss, the estimated loss may be calculated from the amount of axial misalignment, the amount of angular misalignment, and the anomaly degree. By calculating the estimated loss from the amount of axial misalignment, the amount of angular misalignment, and the anomaly degree, the accuracy of the estimated loss value can be improved. The estimated loss in the fusion splicing of multicore fibers can be calculated with higher accuracy.

[0017] (5) In any of (1) to (4) above, the estimated loss calculated in the step of calculating the estimated loss may be stored in a viewable format. The stored estimated loss can be viewed.

[0018] (6) In (4) above, the fusion splicing method may include a step for correcting the amount of axial misalignment, the amount of angular misalignment, and the degree of abnormality. In the step for calculating the estimated loss, the estimated loss may be calculated from the corrected amount of axial misalignment, the corrected amount of angular misalignment, and the corrected degree of abnormality. The amount of axial misalignment, the amount of angular misalignment, and the degree of abnormality can be corrected using correction values ​​that match the conditions of the fusion splicing. The estimated loss can be calculated using the corrected values ​​of the amount of axial misalignment, the amount of angular misalignment, and the degree of abnormality, and the accuracy of the estimated loss value can be further improved. The estimated loss in the fusion splicing of multicore fibers can be calculated with even higher accuracy.

[0019] (7) The fusion splicer according to this embodiment is a fusion splicer that fusion splices together a first multicore fiber having a plurality of first cores exposed on a first end face and a second multicore fiber having a plurality of second cores exposed on a second end face. The fusion splicer includes a rotation mechanism that rotates at least one of the first multicore fiber and the second multicore fiber to align the first multicore fiber and the second multicore fiber; an end face observation unit that observes the first end face and the second end face; a first calculation unit that calculates an axial misalignment, which is the amount of misalignment of the axis of the second core with respect to the axis of the first core, from the observation results of the end face observation unit; a side observation unit that observes the first multicore fiber and the second multicore fiber from the side of the first multicore fiber and the second multicore fiber; a second calculation unit that calculates an angular misalignment, which is the amount of misalignment of the second core at the second end face with respect to the extending direction of the first core at the first end face, from the observation results of the side observation unit; and an estimated loss calculation unit that calculates an estimated loss in the fusion splicing of the first multicore fiber and the second multicore fiber from the axial misalignment and the angular misalignment.

[0020] The fusion splicer described above comprises a rotating mechanism, an end face observation unit, a first calculation unit, a lateral observation unit, a second calculation unit, and an estimated loss calculation unit. The end face observation unit observes the first and second end faces. The first calculation unit calculates the amount of axial misalignment. The lateral observation unit observes the first and second multicore fibers from the side. The second calculation unit calculates the amount of angular misalignment. The estimated loss calculation unit calculates the estimated loss. By performing both lateral and end face observation of the multicore fibers, the three-dimensional positions of the first and second cores can be easily determined, and the estimated loss can be easily calculated, similar to the fusion splicing method described above. The estimated loss can be calculated for all first cores and all second cores, and the estimated loss in the fusion splicing of multicore fibers can be calculated with high accuracy.

[0021] Specific examples of fusion splicing methods and fusion splicers according to the embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the following examples, but is as defined by the claims and is intended to include all modifications within the scope equivalent to the claims. In the description of the drawings, identical or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The drawings may be simplified or exaggerated in part for ease of understanding, and dimensional ratios, etc., are not limited to those shown in the drawings. The XYZ Cartesian coordinate system shown in the drawings may be referred to below.

[0022] The configuration of the fusion splicer 1 according to this embodiment will be described with reference to Figures 1, 2, and 3. Figure 1 is a perspective view showing the fusion splicer 1 according to this embodiment. Figure 2 is a perspective view showing an example of the internal structure of the fusion splicer 1 of Figure 1. Figure 2 shows the fusion splicer 1 with the windbreak cover 2 open. Figure 3 is a perspective view showing a schematic of the rotation mechanism 20 of the fusion splicer 1.

[0023] The fusion splicer 1 comprises a box-shaped housing 3. The fusion splicer 1 has a fusion splicing section 4 and a heater 5. The fusion splicing section 4 is located at the top of the housing 3 and fuses optical fibers F together. The heater 5 heats and shrinks the fiber reinforcing sleeve that is placed over the connection of the optical fibers F fused in the fusion splicing section 4. The windbreak cover 2 is provided to prevent wind from entering the fusion splicing section 4.

[0024] The fusion splicer 1 includes a monitor 7. The monitor 7 displays the fusion splice status of the optical fiber F, captured by, for example, a camera 32 (see Figure 5) located inside the housing 3. The fusion splicer 1 includes a power switch 8 and a connection start switch 9. The power switch 8 switches the power of the fusion splicer 1 on and off. The connection start switch 9 initiates the fusion splice of the optical fiber F.

[0025] The fusion splicer 1 fuses a pair of optical fibers F together. The fusion splicer 1 includes an optical fiber holder 10 having a V-groove 11 and a rotating mechanism 20 for rotating the optical fiber holder 10. The axes of the pair of optical fibers F coincide with each other. The "axis" refers to the centerline of the optical fiber that passes through the center of the optical fiber and is aligned with the direction of extension of the optical fiber.

[0026] The optical fiber holder 10 and the rotation mechanism 20 are aligned along the axial direction, which is the direction in which the axis of the optical fiber F extends. If an XYZ three-dimensional Cartesian coordinate system is set up and the axis of the optical fiber F is the Z-axis, then the axial direction of the optical fiber F is the Z-axis direction.

[0027] The fusion splicer 1 comprises a pair of optical fiber holders 10 and a pair of rotating mechanisms 20. The pair of optical fiber holders 10 are aligned along the Z-axis direction, which is the respective extending direction of the pair of optical fibers F. The pair of rotating mechanisms 20 are aligned along the Z-axis direction. The rotating mechanism 20 includes a first rotating mechanism 20A and a second rotating mechanism 20B. The first rotating mechanism 20A and the second rotating mechanism 20B are aligned along the Z-axis direction.

[0028] The optical fiber holder 10 is, for example, made of metal. The optical fiber holder 10 holds, for example, the portion of the optical fiber F that has its coating. The optical fiber holder 10 holds the optical fiber F with its end face E protruding in the Z-axis direction. The rotation mechanism 20 is positioned opposite the end face E of the optical fiber F as viewed from the optical fiber holder 10.

[0029] The optical fiber holder 10 has, for example, a V-groove 11 extending along the Z-axis direction. The optical fiber F to be fusion spliced ​​is positioned in the V-groove 11 of each optical fiber holder 10. The optical fiber holder 10 has a base 12 on which the optical fiber F is placed and a cover 13 that is placed on the base 12. The base 12 and the cover 13 are arranged, for example, along the Y-axis direction which intersects both the X-axis direction and the Z-axis direction.

[0030] A pair of discharge electrodes 15 are positioned where the end faces E of a pair of optical fibers F face each other. The pair of discharge electrodes 15 fuse the end faces E of the pair of optical fibers F together by electrical discharge. The pair of discharge electrodes 15 are positioned facing each other along a direction intersecting the optical fibers F (for example, the X-axis direction).

[0031] The fusion splicer 1 has a control unit 6 that controls each part of the fusion splicer 1. The control unit 6 controls the discharge current and discharge time of the discharge electrode 15 so that fusion splicing is performed under fusion splicing conditions appropriate to the type of optical fiber F. In the fusion splicer 1, the control unit 6 performs alignment of the pair of optical fibers F.

[0032] The control unit 6 adjusts the position of each optical fiber F in the X-axis and Y-axis directions, and aligns the pair of optical fibers F so that they are aligned in a straight line along the Z-axis direction. The control unit 6 aligns the pair of optical fibers F in the X-axis, Y-axis, and Z-axis directions.

[0033] The control unit 6 controls the rotation mechanism 20 and rotates the optical fiber F around its axis (a line along the Z-axis in the figure), thereby aligning the optical fiber F in the ω direction along a ring centered on its axis. For example, in aligning the optical fiber F, the control unit 6 determines the rotation center of the optical fiber F.

[0034] Optical fiber F is a multicore fiber. A multicore fiber is an example of an optical fiber in which the positions of the core, cladding, and markers in the ω direction must be matched with those of the multicore fiber to be connected. Optical fiber F includes a first multicore fiber F1 and a second multicore fiber F2.

[0035] The fusion splicer 1 fusion splices the first multicore fiber F1 and the second multicore fiber F2 together. The rotating mechanism 20 rotates at least one of the first multicore fiber F1 and the second multicore fiber F2 to align the first multicore fiber F1 and the second multicore fiber F2.

[0036] Figure 4 shows an example of the end face E of an optical fiber F to be fusion spliced ​​in a fusion splicer 1. As shown in Figure 4, the first multicore fiber F1 has a plurality of first cores C1 exposed on the first end face E1. The second multicore fiber F2 has a plurality of second cores C2 exposed on the second end face E2. In this embodiment, when it is not necessary to distinguish between the first multicore fiber F1 and the second multicore fiber F2, they may be described together as an optical fiber F.

[0037] Figure 5 shows the end face observation section 30 of the optical fiber F in the fusion splicer 1. The fusion splicer 1 includes the end face observation section 30. The end face observation section 30 receives light L1 irradiated onto the first multicore fiber F1 and the second multicore fiber F2 along the axial direction of the first multicore fiber F1 and the second multicore fiber F2, and observes the first end face E1 and the second end face E2. The end face observation section 30 observes the first end face E1 and the second end face E2 before fusion splicing.

[0038] The end face observation unit 30 includes, for example, a mirror 31, a camera 32, and a light source 33. The mirror 31 is positioned between the first multicore fiber F1 and the second multicore fiber F2. The mirror 31 is positioned at an intermediate position in the Z-axis direction such that the axes of the first multicore fiber F1 and the second multicore fiber F2 are substantially aligned. The mirror 31 is installed to be movable in the Y-axis direction, for example.

[0039] The mirror 31 extends, for example, in the X-axis direction. The mirror 31 is, for example, triangular prism-shaped. The cross-sectional shape of the mirror 31 in the YZ plane is, for example, an isosceles triangle. The mirror 31 has two faces inclined, for example, at 45 degrees with respect to both the Y-axis and Z-axis directions. Each of these two faces is a reflective surface 31a.

[0040] The light source 33 irradiates the first multicore fiber F1 with light L1 along its axial direction, and also irradiates the second multicore fiber F2 with light L1 along its axial direction. The light source 33 causes light L1 to enter from the end face of the optical fiber F opposite to the opposing end faces E.

[0041] Light L1 incident from each light source 33 onto the first multicore fiber F1 and the second multicore fiber F2 respectively is emitted from the first end face E1 and the second end face E2, which are opposite each other. The light L1 emitted from the first end face E1 and the second end face E2 is reflected toward the camera 32 by the reflective surface 31a of the mirror 31.

[0042] The camera 32 observes the end faces E of the first multicore fiber F1 and the second multicore fiber F2 by receiving light L1 that has been reflected by the reflective surface 31a of the mirror 31 and has traveled along the Y-axis. The camera 32 may include a first camera 32b for observing the end face of the first multicore fiber F1 and a second camera 32c for observing the end face of the second multicore fiber F2.

[0043] In the above description, an example in which light L1 is incident from the end face of the optical fiber F opposite to the end faces E facing each other has been described. Instead of the light source 33, a light source that makes light incident from the side on the first multi-core fiber F1 and the second multi-core fiber F2 may be used, or a light source that directly irradiates light on the first end face E1 and the second end face E2 may be used. The method of making light incident on the optical fiber F is not particularly limited.

[0044] The mirror 31 and the end face E of the optical fiber F are arranged to face each other. The mirror 31 and the camera 32 are arranged to face each other. In the above description, an example of the mirror 31 having a reflecting surface 31a on two surfaces has been described. The shape of the mirror is not limited to the above example. For example, instead of the mirror 31, a mirror having a reflecting surface on only one surface may be provided.

[0045] The camera 32 is, for example, a CCD camera (Charge-Coupled Device Camera) or a CMOS camera (Complementary Metal Oxide Semiconductor Camera). The camera 32 photographs the optical fiber F. The image of the optical fiber F photographed by the camera 32 is transmitted to the control unit 6 of the fusion splicer 1 as, for example, image data.

[0046] As the control unit 6, for example, a CPU (Central Processing Unit) composed of one or more integrated circuits (ICs) is used. The functional elements of the control unit 6 are executed by the CPU. The fusion splicer 1 has a memory. The control unit 6 acquires the photographing result of the optical fiber F from the camera 32. The photographing result of the optical fiber F is stored in the memory by the control unit 6.

[0047] The control unit 6 has a first calculation unit 35. The first calculation unit 35 calculates the axial deviation amount d from the observation result of the end face E of the end face observation unit 30. FIG. 6 is a diagram for explaining the axial deviation amount d. The axial deviation amount d is the deviation amount of the axis C2a of the second core C2 with respect to the axis C1a of the first core C1. The "axis of the core" indicates the central axis of the core that passes through the center of the core and extends along the extending direction of the core.

[0048] FIG. 7 is a front view of an optical fiber F showing an example of a first core C1 on a first end face E1 and a second core C2 on a second end face E2. FIG. 8 is a perspective view of the optical fiber F showing an example of the first core C1 on the first end face E1 and the second core C2 on the second end face E2. On the first end face E1 of the first multi-core fiber F1, for example, four first cores C1 are exposed. The first core C1 includes a core C11, a core C12, a core C13, and a core C14. On the second end face E2 of the second multi-core fiber F2, for example, four second cores C2 are exposed. The second core C2 includes a core C21, a core C22, a core C23, and a core C24.

[0049] The camera 32 acquires an image of the end face E. When the optical fiber F is fusion-connected, the core C11 on the first end face E1 is connected to the core C21 on the second end face E2. The core C12 is connected to the core C22. The core C13 is connected to the core C23. The core C14 is connected to the core C24. By acquiring images of the two end faces E, it is possible to grasp which core of the second core C2 on the second end face E2 each core of the first core C1 on the first end face E1 is connected to.

[0050] On the first end face E1, the centroid of the figure formed by connecting the centers of each core of the first core C1 may not coincide with the outer diameter center P1 of the first multi-core fiber F1. On the second end face E2, the centroid of the figure formed by connecting the centers of each core of the second core C2 may not coincide with the outer diameter center P2 of the second multi-core fiber F2.

[0051] In this embodiment, when it is not necessary to distinguish between the outer diameter center P1 of the first multicore fiber F1 and the outer diameter center P2 of the second multicore fiber F2, they may be collectively described as the outer diameter center P of the optical fiber F. As mentioned above, the centroid of the figure formed by connecting the centers of each core may be offset from the outer diameter center P of the optical fiber F. When fusion splicing optical fibers F, if one simply attempts to connect them by aligning the outer diameter centers of the optical fibers F, the centroid of the figure formed by connecting the centers of each core of the first core C1 may not coincide with the centroid of the figure formed by connecting the centers of each core of the second core C2. The axis C1a of the first core C1 and the axis C2a of the second core C2 may be offset from each other.

[0052] To address the above case, the amount of axial misalignment d in the fusion splice is calculated based on points determined, for example, on the first end face E1 and the second end face E2, according to common conditions or rules. Figure 9 shows an example of the positions of the first core C1 and the second core C2 in a coordinate system with the rotation center of the optical fiber F as the origin O.

[0053] For example, the first calculation unit 35 calculates the amount of axial misalignment d by calculating the position of the first core C1 and the position of the second core C2 in a coordinate system where the rotation center of the optical fiber F during rotational alignment of the optical fiber F is the origin O, at the first end face E1 and the second end face E2. By forming a coordinate system common to the first end face E1 and the second end face E2 and converting the positions of the first core C1 and the second core C2 into points on that coordinate system, the amount of axial misalignment d can be easily calculated.

[0054] An xy coordinate system is formed on the first end face E1 of the first multicore fiber F1, with the rotation center of the first multicore fiber F1 as the origin O. The position of the first core C1 is transformed into a point on this xy coordinate system. An xy coordinate system is formed on the second end face E2 of the second multicore fiber F2, with the rotation center of the second multicore fiber F2 as the origin O. The position of the second core C2 is transformed into a point on this xy coordinate system.

[0055] The xy coordinate systems formed on the first end face E1 and the second end face E2 share the common point that the rotation center of the optical fiber F is the origin O. The x-axis direction of the coordinate system of the second end face E2 is reversed with respect to the x-axis direction of the coordinate system of the first end face E1, and the reversed coordinate system of the second end face E2 is superimposed on the coordinate system of the first end face E1. This makes it easier to calculate the amount of axial misalignment d.

[0056] By using a coordinate system with the rotation center as the origin O, the process of creating a new coordinate system for calculating the axial misalignment amount d can be omitted. By reusing the rotation center of the optical fiber F, which was determined during rotational alignment of the optical fiber F, as the origin O of the coordinate system for calculating the axial misalignment amount d, the process of transforming the positions of the first core C1 and the second core C2 multiple times can be omitted.

[0057] The method for calculating the axial misalignment amount d is not limited to the method described above. For example, the first calculation unit 35 may calculate the axial misalignment amount d by calculating the position of the first core C1 and the position of the second core C2 in a coordinate system with the origin O being fixed points on the first end face E1 and the second end face E2. A "fixed point" refers to a point defined on the end face. The fixed point may be a point defined on both end faces based on common conditions or rules, or it may be a point defined on each end face based on different conditions or rules. Figure 10 shows an example of the positions of the first core C1 and the second core C2 in a coordinate system with the origin O being the centroid of a figure whose vertices are the centers of each core.

[0058] An xy coordinate system is formed on the first end face E1 of the first multicore fiber F1, with the centroid M1 of a figure whose vertices are the centers C11c, C12c, C13c, and C14c of the first core C1 as the origin. The position of the first core C1 is transformed into a point on this xy coordinate system.

[0059] An xy coordinate system is formed on the second end face E2 of the second multicore fiber F2, with the centroid M2 of a figure whose vertices are the centers C21c, C22c, C23c, and C24c of the second core C2 as the origin. The position of the second core C2 is transformed into a point on this xy coordinate system.

[0060] The xy coordinate systems formed on the first end face E1 and the second end face E2 share the commonality that the centroid of the figure with the centers of each core as vertices is the origin O. The x-axis direction of the coordinate system of the second end face E2 is reversed with respect to the x-axis direction of the coordinate system of the first end face E1, and the reversed coordinate system of the second end face E2 is superimposed on the coordinate system of the first end face E1.

[0061] For example, the positions of the first core C1 and the second core C2 coincide, while the outer diameter center P1 of the first multicore fiber F1 and the outer diameter center P2 of the second multicore fiber F2 are offset from each other. The first calculation unit 35 calculates the amount of offset d of the axis passing through the outer diameter center P2 of the second multicore fiber F2 with respect to the axis passing through the outer diameter center P1 of the first multicore fiber F1.

[0062] Figure 11 shows an example of the positions of the first core C1 and the second core C2 in a coordinate system where the origin O is one fixed point on the first end face E1 and the second end face E2, respectively. The fixed points on the first end face E1 and the second end face E2 are, for example, the center points of the markers formed on the first end face E1 and the second end face E2. The point designated as the origin O is not limited to the center points of the markers, but may be determined based on other conditions or rules.

[0063] An xy coordinate system with a fixed point as the origin O is formed on the first end face E1 of the first multicore fiber F1. The position of the first core C1 is transformed into a point on this xy coordinate system. An xy coordinate system with a fixed point as the origin O is formed on the second end face E2 of the second multicore fiber F2. The position of the second core C2 is transformed into a point on this xy coordinate system.

[0064] The xy coordinate system formed on the first end face E1 and the xy coordinate system formed on the second end face E2 share the common point that one fixed point on the end face E is the origin O. Similarly, the coordinate system of the second end face E2 is superimposed on the coordinate system of the first end face E1.

[0065] The first calculation unit 35 calculates the amount of deviation of the axis C2a of the second core C2 with respect to the axis C1a of the first core C1 as the axial deviation d. The first calculation unit 35 may also calculate the amount of deviation of the axis passing through the outer diameter center P2 of the second multicore fiber F2 with respect to the axis passing through the outer diameter center P1 of the first multicore fiber F1 as the axial deviation d.

[0066] Figure 12 shows a lateral observation section 40 of the optical fiber F in the fusion splicer 1. The fusion splicer 1 includes a lateral observation section 40. The lateral observation section 40 receives light L2 irradiated onto the first multicore fiber F1 and the second multicore fiber F2 from the side of the first multicore fiber F1 and the second multicore fiber F2, and observes the first multicore fiber F1 and the second multicore fiber F2.

[0067] The fusion splicer 1 comprises an end-face observation section 30 and a side observation section 40. The end-face observation section 30 observes the end face of the optical fiber F. The side observation section 40 observes the side of the optical fiber F. The fusion splicer 1 enables both end-face and side observation of the optical fiber F. The side observation section 40 comprises a light source 41 and a microscope 42. The light source 41 includes a first light source 41b and a second light source 41c. The microscope 42 includes a first microscope 42b and a second microscope 42c.

[0068] The first light source 41b is, for example, a light-emitting element such as a light-emitting diode. For example, the first light source 41b emits light L2 as red light. The first microscope 42b includes, for example, an observation lens and an image sensor. The first microscope 42b is a CCD camera or a CMOS camera, etc.

[0069] For example, the position of the first microscope 42b is variable. The observation results from the first microscope 42b are acquired, for example, as brightness information of light L2. The brightness information of light L2 acquired by the first microscope 42b is output to the control unit 6. For example, the function and configuration of the second light source 41c are the same as or similar to the function and configuration of the first light source 41b. For example, the function and configuration of the second microscope 42c are the same as or similar to the function and configuration of the first microscope 42b.

[0070] The first light source 41b and the first microscope 42b are arranged along the first direction D1 shown in Figure 12, with the optical fiber F in between. The second light source 41c and the second microscope 42c are arranged along the second direction D2, which intersects the first direction D1, with the optical fiber F in between. The angle between the first direction D1 and the second direction D2 is, for example, greater than 0° and less than 180°, and may be 60° or more and 120° or less (90° as an example).

[0071] The first light source 41b emits light L2 to the first multicore fiber F1 and the second multicore fiber F2 along the first direction D1. The second light source 41c emits light L2 to the first multicore fiber F1 and the second multicore fiber F2 along the second direction D2. The first microscope 42b observes the first multicore fiber F1 and the second multicore fiber F2 by receiving the light L2 emitted from the first light source 41b to the first multicore fiber F1 and the second multicore fiber F2. The second microscope 42c observes the first multicore fiber F1 and the second multicore fiber F2 by receiving the light L2 emitted from the second light source 41c to the first multicore fiber F1 and the second multicore fiber F2.

[0072] The microscope 42 acquires images of the first multicore fiber F1 and the second multicore fiber F2. These images are output to the control unit 6. For example, the microscope 42 receives light L2 that has passed through the first multicore fiber F1 and the second multicore fiber F2 and obtains brightness information of the first multicore fiber F1 and the second multicore fiber F2.

[0073] For example, the microscope 42 acquires images of the first multicore fiber F1 and the second multicore fiber F2 after fusion splicing. By positioning the fusion splice between the first multicore fiber F1 and the second multicore fiber F2 near the center of the acquired image, images of both the first multicore fiber F1 and the second multicore fiber F2 can be acquired simultaneously with a single microscope.

[0074] The control unit 6 has a second calculation unit 45. The second calculation unit 45 calculates the angular displacement amount θ from the observation results of the lateral observation unit 40. Figure 13 is a diagram illustrating the angular displacement amount θ. The angular displacement amount θ is the amount of displacement in the direction of extension of the second core C2 at the second end face E2 with respect to the direction of extension of the first core C1 at the first end face E1.

[0075] The angular displacement θ may be calculated as the angle between the axis C2a of the second core C2 at the second end face E2 and the axis C1a of the first core C1 at the first end face E1. The second calculation unit 45 calculates the angular displacement θ from the images of the first multicore fiber F1 and the second multicore fiber F2 acquired by the first microscope 42b and the images of the first multicore fiber F1 and the second multicore fiber F2 acquired by the second microscope 42c.

[0076] The second calculation unit 45 calculates the angular displacement θ from images of the first multicore fiber F1 and the second multicore fiber F2, which are fusion-spliced ​​together. The angular displacement θ is calculated as the amount of displacement of the second core C2 in the direction of extension relative to the direction of extension of the first core C1. The method for calculating the angular displacement θ is not limited to the method described above. For example, in a lateral image of the optical fiber F, a groove may be visible on the inside of the optical fiber F. The angular displacement θ may be calculated from the inclination of the groove in the second multicore fiber F2 relative to the groove in the first multicore fiber F1.

[0077] Figure 14 is a diagram illustrating the outer edge G and inner edge N in an image of an optical fiber F. Figure 14 is an example of a multicore fiber having two cores. Figure 14 shows the state when light L1 is incident on the optical fiber F from the side. As shown in Figures 13 and 14, the angular displacement θ may be calculated from the outer edge G and inner edge N of the optical fiber F. In Figure 14, the hatched areas indicate parts that are brightened by light L1, and the finely hatched areas indicate parts of light L1 passing through the core of the optical fiber F. The left part of Figure 14 is an image of the optical fiber F and its surroundings observed toward the end face E, and corresponds to a front view of the optical fiber F. The right part of Figure 14 is a part of the image of the observation surface of the left part of Figure 14, and corresponds to a side view of the optical fiber F.

[0078] For example, the angular displacement θ may be calculated from the outer edge G of the optical fiber F. The "outer edge" refers to the portion corresponding to the edge of the optical fiber extending in the direction of extension, in a cross-section passing through the center of the outer diameter of the optical fiber along the direction of extension of the optical fiber. The angular displacement θ is calculated as the amount of displacement in the direction of extension of the outer edge G of the second multicore fiber F2 relative to the direction of extension of the outer edge G of the first multicore fiber F1.

[0079] The angular displacement θ may be calculated from the inner edge N of the optical fiber F. The "inner edge" refers to the edge along the direction of extension of the optical fiber in a cross-section passing through the center of the outer diameter of the optical fiber along the direction of extension of the optical fiber, where light incident on the optical fiber from the side of the optical fiber is refracted and focused. The inner edge N of the optical fiber F is the edge of the bright area where the light L1 that has passed through the optical fiber F has converged. The angular displacement θ is calculated as the displacement in the direction of extension of the inner edge N of the second multicore fiber F2 relative to the direction of extension of the inner edge N of the first multicore fiber F1.

[0080] Figure 15 is a schematic diagram of the control unit 6. The control unit 6 has an estimated loss calculation unit 50. The estimated loss calculation unit 50 calculates the estimated loss in the fusion splicing between the first multicore fiber F1 and the second multicore fiber F2 from the axial misalignment amount d and the angular misalignment amount θ. The estimated loss of the optical fiber F is, for example, an estimated value of the connection loss that occurs between the first multicore fiber F1 and the second multicore fiber F2.

[0081] The estimated loss calculation unit 50 calculates the estimated loss for each core, for example, from the axial misalignment d and angular misalignment θ between the first multicore fiber F1 and the second multicore fiber F2. In addition to the axial misalignment d and angular misalignment θ, the estimated loss calculation unit 50 may also calculate the estimated loss from the mode field diameter (MFD) of the first core C1 and the mode field diameter of the second core C2.

[0082] For example, the estimated loss calculation unit 50 calculates the estimated losses of the first multicore fiber F1 and the second multicore fiber F2 from the axial misalignment d, angular misalignment θ, and MFD mismatch. The estimated loss calculation unit 50 calculates the estimated losses using, for example, Marcuse's formula. MFD mismatch refers to, for example, the difference between the MFD of the first multicore fiber F1 and the MFD of the second multicore fiber F2.

[0083] The estimated loss calculated by the estimated loss calculation unit 50 is stored in a viewable format. For example, the estimated loss is stored in memory as a log. The estimated loss can be viewed, for example, by accessing the memory. The estimated loss in past optical fiber F fusion splicing can be checked.

[0084] The estimated loss may be displayed on the monitor 7 of the fusion splicer 1. The monitor 7 may display the estimated loss for each core of the first core C1 and each core of the second core C2, or it may display the average value of the estimated losses of multiple cores, or it may display the worst-case value of the estimated losses of multiple cores. The "worst-case value of estimated loss" is, for example, the estimated loss value of the core with the highest estimated loss among the cores of the first core C1. The content displayed on the monitor 7 may be changeable by the user.

[0085] The estimated loss may be displayed on a display unit other than the monitor 7 of the fusion splicer 1. For example, the estimated loss may be viewable using a dedicated application and displayed on the screen of an information terminal. An operator located away from the fusion splicer 1 may be able to view the estimated loss information by looking at the estimated loss displayed on the screen of an information terminal.

[0086] The control unit 6 includes, for example, an abnormality calculation unit 60. The abnormality calculation unit 60 calculates the abnormality. "Abnormality" indicates the degree of abnormality in the fusion splicing of the first multicore fiber and the second multicore fiber. "Abnormality" refers to bubbles formed near the fusion point of the first multicore fiber and the second multicore fiber, constriction of the optical fiber near the fusion point, or grooves formed near the fusion point. "Degree of abnormality" indicates the extent of the abnormality. The abnormality may include the degree of mismatch in core diameter between the first core C1 and the second core C2. The abnormality may be calculated numerically, for example, as the amount of misalignment in the connection of the optical fiber F by image matching. The estimated loss calculation unit 50 may calculate the estimated loss from the axial misalignment d, the angular misalignment θ, and the abnormality. The estimated loss calculation unit 50 may calculate a value by adding the abnormality to the estimated loss calculated from the axial misalignment d and the angular misalignment θ.

[0087] The control unit 6 includes, for example, a correction unit 70. The correction unit 70 corrects the axial misalignment d, the angular misalignment θ, and the degree of abnormality. The correction unit 70 multiplies the axial misalignment d, the angular misalignment θ, and the degree of abnormality by coefficients A, B, and C, respectively. Coefficients A, B, and C are determined, for example, by the connection conditions of the optical fiber F. Coefficients A, B, and C may be values ​​obtained experimentally. Coefficients A, B, and C may be calculated by AI (Artificial Intelligence). Coefficients A, B, and C are, for example, fixed values.

[0088] The estimated loss calculation unit 50 may calculate the estimated loss from the corrected axial misalignment dA, the corrected angular misalignment θB, and the corrected anomaly score. In the following, the anomaly score will be denoted as e, and the corrected anomaly score as eC. When the connection loss is S, the estimated loss calculation unit 50 calculates S using, for example, the following equation (1): S = dA + θB + eC ... (1) The estimated loss calculation unit 50 may also add the intercept D as shown in the following equation (2): S = dA + θB + eC + D ... (2)

[0089] An example of a fusion splicing method according to this embodiment will be described with reference to the flowchart in Figure 16. Figure 16 is a flowchart showing an example of the steps of the fusion splicing method according to this embodiment. Below, an example of a method for performing fusion splicing and calculating estimated loss using a fusion splicer 1 will be described. A pair of optical fibers F are set in the fusion splicer 1 so that their end faces E face each other. The first end face E1 of the first multicore fiber F1 is brought into contact with the second end face E2 of the second multicore fiber F2 (step S1).

[0090] The rotating mechanism 20 aligns the first multicore fiber F1 and the second multicore fiber F2 by rotating at least one of the first multicore fiber F1 and the second multicore fiber F2 in the ω direction (alignment process, step S2). For example, rotational alignment is performed by the first rotating mechanism 20A rotating the first multicore fiber F1 and the second rotating mechanism 20B rotating the second multicore fiber F2. In rotational alignment, the positions of the plurality of first cores C1 of the first multicore fiber F1 in the ω direction are aligned with the positions of the plurality of second cores C2 of the second multicore fiber F2 in the ω direction.

[0091] The light source 33 irradiates the first multicore fiber F1 and the second multicore fiber F2 with light L1 along their axial directions. The first calculation unit 35 calculates the amount of axial misalignment d based on the light L1 (step S3, step of calculating the amount of axial misalignment).

[0092] As a method for calculating the axial misalignment amount d, for example, the rotation center, which is the center of rotation of the optical fiber F at the first end face E1 and the second end face E2, is obtained. The position of the first core C1 and the position of the second core C2 are calculated in a coordinate system with the rotation center as the origin O. The first calculation unit 35 calculates the axial misalignment amount d from the coordinates of the second core C2 relative to the coordinates of the first core C1. The method for calculating the axial misalignment amount d is not limited to the above method. For example, the first calculation unit 35 may calculate the axial misalignment amount d by calculating the position of the first core C1 and the position of the second core C2 in a coordinate system with the fixed points at the first end face E1 and the second end face E2 as the origin O. The axial misalignment amount d may be calculated for each core, or it may be calculated as an average value for multiple cores.

[0093] From the calculated axial misalignment amount d, for example, axial alignment is performed by adjusting the positions of the first multicore fiber F1 and the second multicore fiber F2 so that the outer diameter center of one first core C1 and the outer diameter center of one second core C2 to be connected to it coincide (step S4). Axial alignment is performed by observing the optical fiber F from the side and adjusting the position of the optical fiber F in the X-axis direction and the Y-axis direction. Alternatively, the positions of the first multicore fiber F1 and the second multicore fiber F2 are adjusted so that the positions of the outer diameter center of the first core C1 and the outer diameter center of the second core C2 are shifted by a predetermined amount. The positions of the first multicore fiber F1 and the second multicore fiber F2 are adjusted so that the sum of the positional misalignments of the centers of core C11 and core C21, core C12 and core C22, core C13 and core C23, and core C14 and core C24 is minimized. The positions of the first multicore fiber F1 and the second multicore fiber F2 are adjusted so that the rotation centers of the first core C1 and the second core C2 coincide. Alternatively, the positions of the first multicore fiber F1 and the second multicore fiber F2 are adjusted so that the rotation centers of the first core C1 and the second core C2 are offset by a predetermined amount.

[0094] The first end face E1 of the first multicore fiber F1 is fusion-spliced ​​to the second end face E2 of the second multicore fiber F2 (step S5). The first multicore fiber F1 and the second multicore fiber F2 are fusion-spliced ​​to each other by discharge heating using a pair of discharge electrodes 15.

[0095] The light source 41 irradiates the first multicore fiber F1 and the second multicore fiber F2 with light L2 from the side. The second calculation unit 45 calculates the angular displacement amount θ based on the light L2 (step S6, step of calculating the angular displacement amount).

[0096] The first microscope 42b and the second microscope 42c each observe the first multicore fiber F1 and the second multicore fiber F2, and acquire lateral images of the optical fiber F. The images of the first multicore fiber F1 and the second multicore fiber F2 acquired by the first microscope 42b and the images of the first multicore fiber F1 and the second multicore fiber F2 acquired by the second microscope 42c are output to the control unit 6, and the second calculation unit 45 calculates the angular displacement amount θ.

[0097] Step S7 calculates the degree of abnormality in the fusion splicing of the first multicore fiber F1 and the second multicore fiber F2. The degree of abnormality is calculated numerically, for example, from the results of a lateral observation of the optical fiber F. From the axial misalignment d, angular misalignment θ, and degree of abnormality, the estimated loss in the fusion splicing of the first multicore fiber F1 and the second multicore fiber F2 is calculated (step S8, step of calculating the estimated loss). In step S8, the estimated loss calculation unit 50 calculates the estimated loss using, for example, Marcuse's formula. With this, the series of steps of the fusion splicing method according to this embodiment is completed.

[0098] In the fusion splicing method described above, the axial misalignment d, angular misalignment θ, and anomaly degree may be corrected by using coefficients A, B, and C. The estimated loss calculation unit 50 may calculate the estimated loss from the corrected axial misalignment dA, the corrected angular misalignment θB, and the corrected anomaly degree.

[0099] The effects and advantages obtained from the fusion splicing method and fusion splicer 1 according to this embodiment will be explained. In the fusion splicing method and fusion splicer 1 according to this embodiment, the axial misalignment amount d between the first multicore fiber F1 and the second multicore fiber F2 is calculated by observing the first end face E1 and the second end face E2. The angular misalignment amount θ between the first multicore fiber F1 and the second multicore fiber F2 is calculated by observing the first multicore fiber F1 and the second multicore fiber F2 from the side. The estimated loss in the fusion splicing of the first multicore fiber F1 and the second multicore fiber F2 is calculated from the axial misalignment amount d and the angular misalignment amount θ. By performing both lateral observation and end face observation of the optical fiber F, the three-dimensional positions of the first core C1 and the second core C2 can be easily determined.

[0100] For example, if the distance from the side observation camera differs between multiple cores, it may be necessary to adjust the focus for each core being observed. In contrast, in this embodiment, the axial displacement d of the core is calculated by end face observation, and the angular displacement θ is calculated by side observation, thereby eliminating the need to adjust the focus for each core. Since the observation and position identification of the cores can be easily performed, the estimated loss in the fusion splicing of optical fibers F can be easily calculated. The estimated loss can be calculated for all first cores C1 and all second cores C2, enabling highly accurate calculation of the estimated loss in the fusion splicing of optical fibers F.

[0101] As mentioned above, in the rotation process, the rotation center, which is the center of rotation, may be obtained at the first end face E1 and the second end face E2. In the process of calculating the axial misalignment amount d, the positions of the first core C1 and the second core C2 in a coordinate system with the rotation center as the origin O may be calculated. The rotation centers obtained when the first multicore fiber F1 and the second multicore fiber F2 are rotationally aligned can be reused as the origin O of the coordinate system at the first end face E1 and the second end face E2. The position of the first core C1 at the first end face E1 and the position of the second core C2 at the second end face E2 can be used as coordinates in the coordinate system with the rotation center as the origin O, and the axial misalignment amount d can be easily calculated.

[0102] As mentioned above, in the step of calculating the axial displacement d, the positions of the first core C1 and the second core C2 may be calculated in a coordinate system with the fixed points on the first end face E1 and the second end face E2 as the origin O. The coordinate system with the fixed points on the first end face E1 and the second end face E2 as the origin O can be used as the reference coordinate system. By using this coordinate system, the positions of the first core C1 and the second core C2 can be expressed as coordinates in a coordinate system with the fixed points as the origin O, and the axial displacement d can be easily calculated.

[0103] As mentioned above, the fusion splicing method may further include a step of calculating an anomaly degree indicating the degree of abnormality in the fusion splicing of the first multicore fiber F1 and the second multicore fiber F2. In the step of calculating the estimated loss, the estimated loss may be calculated from the axial misalignment amount d, the angular misalignment amount θ, and the anomaly degree. By calculating the estimated loss from the axial misalignment amount d, the angular misalignment amount θ, and the anomaly degree, the accuracy of the estimated loss value can be improved. The estimated loss in the fusion splicing of the optical fiber F can be calculated with higher accuracy.

[0104] As mentioned above, the estimated loss calculated in the process of calculating the estimated loss may be stored in a viewable format. The stored estimated loss can be viewed.

[0105] As mentioned above, the fusion splicing method may include a step for correcting the axial misalignment d, the angular misalignment θ, and the degree of anomaly. In the step for calculating the estimated loss, the estimated loss may be calculated from the corrected axial misalignment dA, the corrected angular misalignment θB, and the corrected degree of anomaly. The axial misalignment d, the angular misalignment θ, and the degree of anomaly can be corrected using correction values ​​that match the conditions of the fusion splicing. The estimated loss can be calculated using the corrected values ​​of the axial misalignment d, the angular misalignment θ, and the degree of anomaly, thereby improving the accuracy of the estimated loss value. The estimated loss in the fusion splicing of optical fiber F can be calculated with even higher accuracy.

[0106] Embodiments of fusion splicing methods and fusion splicers relating to this disclosure have been described. However, this disclosure is not limited to the embodiments described above. It will be readily apparent to those skilled in the art that various modifications and changes are possible within the scope of the gist described in the claims. The steps of the fusion splicing method and the configuration of each part of the fusion splicer can be modified as appropriate within the scope of the gist described above. The content and sequence of the steps of the fusion splicing method, as well as the configuration, shape, size, number, material and arrangement of each part of the fusion splicer, are not limited to the embodiments described above and can be modified as appropriate. It should be understood that at least one configuration and feature described in the embodiments and examples can be combined with other embodiments and examples, or modified in various ways.

[0107] For example, in the embodiment described above, an example was described in which the angular misalignment amount θ is calculated (step S6) after fusion splicing (step S5). However, the order of steps S5 and S6 may be reversed. Alternatively, the angular misalignment amount θ may be calculated after axial alignment of the optical fiber F, and then fusion splicing of the optical fiber F may be performed.

[0108] In the embodiment described above, an example was described in which the amount of axial misalignment d is calculated (step S3) after rotational alignment of the optical fiber F (step S2). However, the amount of axial misalignment d may also be calculated based on the results of the second and subsequent end face observations, after the rotational alignment has been performed and the end face E has been observed again.

[0109] 1...Fusion splicer 2...Windshield cover 3...Housing 4...Fusion splicing section 5...Heating unit 6...Control unit 7...Monitor 8...Power switch 9...Connection start switch 10...Optical fiber holder 11...V-groove 12...Base 13...Lid 15...Discharge electrode 20...Rotation mechanism 20A...First rotation mechanism 20B...Second rotation mechanism 30...End face observation section 31...Mirror 31a...Reflective surface 32...Camera 32b...First camera 32c...Second camera 33...Light source 35...First calculation unit 40...Side observation unit 41...Light source 41b...First light source 41c...Second light source 42...Microscope 42b...First microscope 42c...Second microscope 45...Second calculation unit 50...Estimated loss calculation unit 60...Anomaly degree calculation unit 70...Correction unit d...Axis misalignment dA...Corrected axial misalignment θ...Angular misalignment θB...Corrected angular misalignment C1...First core C2...Second core C1a, C2a...Axis C11-C14, C21-C24...Core C11c-C14c, C21c-C24c...Center D1...First direction D2...Second direction E...End face E1...First end face E2...Second end face F...Optical fiber F1...First multicore fiber F2...Second multicore fiber G...Outer edge L1, L2...Optical fiber M1, M2...Centrist N...Inner edge O...Origin P, P1, P2...Center

Claims

1. A fusion splicing method for fusion splicing together a first multicore fiber having a plurality of first cores exposed on a first end face and a second multicore fiber having a plurality of second cores exposed on a second end face, comprising: a step of aligning the first multicore fiber and the second multicore fiber by rotating at least one of the first multicore fiber and the second multicore fiber; a step of calculating an axial misalignment, which is the amount of misalignment of the axis of the second core with respect to the axis of the first core, from information obtained by observing the first end face and the second end face; a step of calculating an angular misalignment, which is the amount of misalignment of the second core at the second end face with respect to the extending direction of the first core at the first end face, from information obtained by observing the first multicore fiber and the second multicore fiber from the side; and a step of calculating an estimated loss in the fusion splicing of the first multicore fiber and the second multicore fiber from the axial misalignment and the angular misalignment.

2. The fusion splicing method according to claim 1, wherein in the centering step, the rotation center which is the center of rotation is obtained at the first end face and the second end face, and in the step of calculating the amount of axial misalignment, the position of the first core and the position of the second core in a coordinate system with the rotation center as the origin are calculated.

3. The fusion splicing method according to claim 1 or claim 2, wherein the step of calculating the amount of axial misalignment is to calculate the position of the first core and the position of the second core in a coordinate system with fixed points on the first end face and the second end face as the origin.

4. A fusion splicing method according to any one of claims 1 to 3, further comprising a step of calculating an abnormality degree indicating the degree of abnormality in the fusion splicing of the first multicore fiber and the second multicore fiber, wherein the step of calculating the estimated loss is to calculate the estimated loss from the axial misalignment amount, the angular misalignment amount and the abnormality degree.

5. The fusion splicing method according to any one of claims 1 to 4, wherein the estimated loss calculated in the step of calculating the estimated loss is stored in a viewable format.

6. A fusion splicing method according to claim 4, comprising a step of correcting the axial misalignment, the angular misalignment, and the degree of abnormality, wherein the step of calculating the estimated loss is to calculate the estimated loss from the corrected axial misalignment, the corrected angular misalignment, and the corrected degree of abnormality.

7. A fusion splicer for fusion splicing together a first multicore fiber having a plurality of first cores exposed on a first end face and a second multicore fiber having a plurality of second cores exposed on a second end face, comprising: a rotation mechanism for rotating at least one of the first multicore fiber and the second multicore fiber to align the first multicore fiber and the second multicore fiber; an end face observation unit for observing the first end face and the second end face; a first calculation unit for calculating an axial misalignment amount, which is the amount of misalignment of the axis of the second core with respect to the axis of the first core, from the observation results of the end face observation unit; a side observation unit for observing the first multicore fiber and the second multicore fiber from the side of the first multicore fiber and the second multicore fiber; and a second calculation unit for calculating an angular misalignment amount, which is the amount of misalignment of the second core at the second end face with respect to the extending direction of the first core at the first end face, from the observation results of the side observation unit. A fusion splicer comprising: an estimated loss calculation unit that calculates an estimated loss in the fusion splicing of a first multicore fiber and a second multicore fiber from the axial misalignment and the angular misalignment.

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