Control device, fusion connection device, connector connection device, and control program

Abstract

The purpose of the present invention is to appropriately center a multi-core optical fiber. The control device (10) is provided with a processor (10a). A processor (10a) executes: a determination process for determining a core position and a mark position of a multi-core optical fiber; and aligning processing: aligning the multi-core optical fiber by controlling an aligning mechanism, so that the fiber core position and the mark position on the end surface of the multi-core optical fiber meet preset conditions.

Description

Technical Field

[0001] The present invention relates to a control device and a control program for controlling a centering mechanism for centering a multi-core optical fiber, and also to a fusion splicing device and a connector connecting device having such a control device. Background Art

[0002] In the field of optical communication, multi-core optical fibers having a plurality of cores are widely used. As a document disclosing a multi-core optical fiber, for example, Patent Document 1 can be cited. A multi-core optical fiber connector that connects a plurality of multi-core optical fibers is also widely used.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-152866 Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In a multi-core optical fiber, there is a type of multi-core optical fiber that has multiple cores arranged linearly symmetrically with respect to an axis and a marker arranged so that the center does not coincide with the axis. If there is such a marker, the multiple cores can be uniquely identified based on the distance from the marker, etc.

[0008] When aligning a multi-core optical fiber, it is necessary to consider new situations that were not considered in the past when aligning a single-core optical fiber. For example, when connecting two multi-core optical fibers with the same core configuration, it is necessary to perform alignment so that the mark of one multi-core optical fiber is configured at an appropriate position relative to the mark of the other multi-core optical fiber. Here, the consistent core configuration of two multi-core optical fibers means that when the end face of one multi-core optical fiber is overlapped with the end face of another multi-core optical fiber, each core of one multi-core optical fiber can be overlapped with any core of the other multi-core optical fiber. Alternatively, it is necessary to perform alignment so that the position of the mark of the multi-core optical fiber is configured at an appropriate position relative to the key of the connector component. However, in view of such problems, the technology for properly aligning multi-core optical fibers has not been realized.

[0009] The present invention is made in view of the above-mentioned problems, and its purpose is to realize a technology for properly aligning a multi-core optical fiber. For example, the technology for aligning a multi-core optical fiber in the following manner is realized, that is, the mark of the multi-core optical fiber is arranged at an appropriate position relative to the mark of another multi-core optical fiber, or the mark of the multi-core optical fiber is arranged at an appropriate position relative to the key of a connector component, etc.

[0010] (II) Technical solution

[0011] A control device according to one embodiment of the present invention comprises: a measurement control unit that determines a mark position of a multi-core optical fiber; and an alignment control unit that aligns the multi-core optical fiber by controlling an alignment mechanism so that the mark position on the end face of the multi-core optical fiber satisfies a preset condition.

[0012] (III) Beneficial effects

[0013] According to one embodiment of the present invention, a technique for properly aligning a multi-core optical fiber can be realized. For example, the technique for aligning a multi-core optical fiber can be realized in such a manner that a mark of the multi-core optical fiber is arranged at an appropriate position relative to a mark of another multi-core optical fiber, or a mark of the multi-core optical fiber is arranged at an appropriate position relative to a key of a connector component, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a block diagram showing the configuration of a control device according to the first embodiment and the second embodiment of the present invention.

[0015] Figure 2 This is a flowchart showing the flow of the fusion splicing method according to the first embodiment.

[0016] Figure 3 Yes means Figure 2 A perspective view showing the state of a multi-core optical fiber in each step of the fusion splicing method shown.

[0017] Figure 4 As Figure 1 The figures show a multi-core optical fiber as an example of an optical fiber which is an application object of the fusion connection method shown, wherein (a) is a side view of the multi-core optical fiber, (b) is a front view of one end face of the multi-core optical fiber as viewed from the direction of line of sight E1, and (c) is a front view of the other end face of the multi-core optical fiber as viewed from the direction of line of sight E2.

[0018] Figure 5 The figures show the connection parts of two optical fibers that are normally connected, (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0019] Figure 6 The figures show the fusion connection portion of two optical fibers that are not normally connected, (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0020] Figure 7The figures show the fusion connection portion of two optical fibers that are not normally connected, (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0021] Figure 8 The figures show the fusion connection portion of two optical fibers that are not normally connected, (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0022] Fig. 9 The figures show the fusion connection parts of two optical fibers that are flipped connected (flipped connection relative to axis L1), (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0023] Fig.10 The figures show the fusion connection parts of two optical fibers that are flipped connected (flipped connection relative to axis L3), (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0024] Fig.11 The figures show the fusion connection parts of two optical fibers that are flipped connected (flipped connection relative to axis L2), (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0025] Fig.12 The figures show the fusion connection parts of two optical fibers that are flipped connected (flipped connection relative to axis L4), (a) is a side view of the two optical fibers, (b) is a front view of the end face of one of the two optical fibers as viewed from the direction of line of sight E2, and (c) is a front view of the end face of the other of the two optical fibers as viewed from the direction of line of sight E1.

[0026] Fig.13 This is a flowchart showing the flow of the connector connection method according to the second embodiment of the present invention.

[0027] Fig.14 (a) is a side view of a multi-core optical fiber mounted with a connector housing via a ferrule, and (b) and (c) are cross-sectional views of the multi-core optical fiber. DETAILED DESCRIPTION

[0028] (First embodiment)

[0029] (Structure of control device)

[0030] Reference Figure 1 A control device 10 according to a first embodiment of the present invention will be described. Figure 1 It is a block diagram showing the structure of the control device 10.

[0031] like Figure 1 As shown, the control device 10 includes a processor 10a, a primary memory 10b, a secondary memory 10c, a communication interface 10d, and a bus 10e. The processor 10a, the primary memory 10b, the secondary memory 10c, and the communication interface 10d are connected to each other via the bus 10e.

[0032] The secondary memory 10c stores a control program P for controlling a centering mechanism for centering a multi-core optical fiber. The processor 10a expands the control program P stored in the secondary memory 10c on the primary memory 10b. The processor 10a controls the centering mechanism according to the commands included in the control program P expanded on the primary memory 10b.

[0033] As a device that can be used as the processor 10a, for example, a CPU (Central Processing Unit) can be cited. In addition, as a device that can be used as the primary memory 10b, for example, a semiconductor RAM (Random Access Memory) can be cited. In addition, as a device that can be used as the secondary memory 10c, for example, an HDD (Hard Disk Drive) can be cited.

[0034] The communication interface 10d is an interface for communicating with other devices via a network. The processor 10a receives a detection result from a photodetector 12 described later using the communication interface 10d, and sends a control signal to the aforementioned alignment mechanism.

[0035] (Flow of the fusion connection method)

[0036] Reference Figure 2 and Figure 3 The flow of the fusion splicing method S1 of the present embodiment will be described. The fusion splicing method S1 is a method of fusion splicing the multi-core optical fiber MF2 to the multi-core optical fiber MF1 using the fusion splicing device 1. The multi-core optical fibers MF1 and MF2 are multi-core optical fibers with the same core arrangement. Figure 2 is a flow chart showing the process of the fusion connection method S1, Figure 3The 3D diagram is a perspective view showing the state of the multi-core optical fibers MF1 and MF2 in each process included in the fusion splicing method S1. In addition, in the present embodiment, the multi-core optical fibers MF1 and MF2 are set as the following multi-core optical fibers, which have: a cladding, a plurality of cores formed inside the cladding, and a single marker formed inside the cladding. The specific examples of the multi-core optical fibers MF1 and MF2 will be described later with reference to the accompanying drawings.

[0037] like Figure 2 As shown, the welding connection method S1 includes: a preparation step S11, a measurement step S12, an alignment step S13, a butt joint step S14, and a welding step S15. Figure 3 As shown, the fusion splicing device 1 includes: a light source 11, a light detector 12, a heating source 13, a centering mechanism (not shown), and a control device 10. The centering mechanism can perform translational movement of the multi-core optical fibers MF1 and MF2 in the x-axis direction and the y-axis direction, and rotational movement with the z-axis as the rotation axis. The control device 10 functions as the following parts, namely: a measurement control unit for implementing the measurement process S12, a centering control unit for implementing the centering process S13, a docking control unit for implementing the docking process S14, and a fusion control unit for implementing the fusion process S15. Here, the heating source 13 is not particularly limited as long as it is a mechanism for heating the end of the multi-core optical fiber, and examples thereof include lasers, electrodes, etc.

[0038] The preparation step S11 is a step in which the user sets the multi-core optical fibers MF1 and MF2 in the fusion splicing device 1. The multi-core optical fibers MF1 and MF2 are respectively held by the centering mechanism of the fusion splicing device 1 so that their central axes are parallel to the z-axis. Figure 3 (a) shows the state of the multi-core optical fibers MF1 and MF2 after the preparation step S11 is performed.

[0039] When the preparation process S11 is completed, the measurement process S12 is implemented. The measurement process S12 is a process in which the fusion splicing device 1 measures the core position and mark position of the multi-core optical fibers MF1 and MF2 before fusion. In the measurement process S12, the processor 10a of the control device 10 controls the centering mechanism of the fusion splicing device 1 to move the multi-core optical fiber MF1 in the negative direction of the z-axis. As a result, the end of the multi-core optical fiber MF1 is located between the light source 11 and the photodetector 12. In addition, the processor 10a of the control device 10 controls the centering mechanism of the fusion splicing device 1 to move the multi-core optical fiber MF2 in the positive direction of the z-axis. As a result, the end of the multi-core optical fiber MF2 is located between the light source 11 and the photodetector 12. As a result, the interval d between the end face of the multi-core optical fiber MF1 and the end face of the multi-core optical fiber MF2 is, for example, about 20μm. In addition, the interval d is arbitrary within the range in which the following detection processing or shooting processing can be implemented, and is not limited to 20μm.

[0040] Furthermore, the processor 10a of the control device 10 uses the photodetector 12 to detect: (1) the intensity I1 of light emitted from the light source 11 and transmitted through the end of the multi-core optical fiber MF1 (hereinafter referred to as the transmitted light intensity I1); and (2) the intensity I2 of light emitted from the light source 11 and transmitted through the end of the multi-core optical fiber MF2 (hereinafter referred to as the transmitted light intensity I2). The processor 10a of the control device 10 controls the centering mechanism of the fusion splicing device 1 to rotate the multi-core optical fibers MF1 and MF2 about the z-axis as the rotation axis, or to rotate the light source 11 and the photodetector 12 about the z-axis as the rotation axis, and repeats the detection process. As a result, the processor 10a of the control device 10 obtains: the directional dependence of the transmitted light intensity I1 of the multi-core optical fiber MF1, and the directional dependence of the transmitted light intensity I2 of the multi-core optical fiber MF2. Furthermore, the processor 10a of the control device 10 performs the following determination processing, namely, determining the core position and the mark position of the multi-core optical fiber MF1 based on the directional dependence of the transmitted light intensity I1 of the multi-core optical fiber MF1, and determining the core position and the mark position of the multi-core optical fiber MF2 based on the directional dependence of the transmitted light intensity I2 of the multi-core optical fiber MF2. Figure 3 (b) shows the state of the multi-core optical fibers MF1 and MF2 during the measurement step S12 .

[0041] In addition, in the above-mentioned detection process, the light detector 12 is set to a photodiode. In this case, the data representing the transmitted light intensities I1 and I2 obtained by each detection process are brightness values ​​representing the light intensities detected by the photodiode. In addition, the data representing the directional dependence of the transmitted light intensities I1 and I2 obtained by repeating the detection process are one-dimensional arrays representing the brightness values ​​of the light intensities detected by the photodiode. On the other hand, when a camera is used as the light detector 12, the above-mentioned detection process is composed of the following processes, namely: a photographing process of photographing the ends of the multi-core optical fibers MF1 and MF2; and a calculation process (for example, a cumulative process, an average process, or a weighted average process) of deriving the transmitted light intensities I1 and I2 from the image obtained by the photographing process. In this case, the data obtained by each photographing process is a two-dimensional array (that is, an image) representing the brightness values ​​of the light intensities detected by each unit of the image sensor constituting the camera, and the data representing the transmitted light intensities I1 and I2 of the multi-core optical fibers MF1 and MF2 obtained by each calculation process are, for example, the cumulative value, average value, or weighted average value of the light intensities detected by each unit of the image sensor constituting the camera. In addition, data representing the directional dependence of the transmitted light intensities I1 and I2 obtained by repeating the detection process (shooting process and calculation process) is, for example, a one-dimensional arrangement of the cumulative value, average value, weighted average value, etc. of the light intensity detected by each unit of the image sensor constituting the camera.

[0042] When the measurement process S12 is completed, the centering process S13 is implemented. The centering process S13 is a process in which the fusion connection device 1 performs centering on the multi-core optical fiber MF2 relative to the multi-core optical fiber MF1. In the present embodiment, the reference for determining the core position and the mark position of the multi-core optical fiber MF2 is the core position and the mark position of the multi-core optical fiber MF1. In the centering process S13, the processor 10a of the control device 10 performs centering processing for centering the multi-core optical fiber MF2 relative to the multi-core optical fiber MF1 by controlling the centering mechanism of the fusion connection device 1, so that the core position on the end face of the multi-core optical fiber MF2 relative to the core position on the end face of the multi-core optical fiber MF1 and the mark position on the end face of the multi-core optical fiber MF2 relative to the mark position on the end face of the multi-core optical fiber MF1 meet the pre-set conditions. Here, the conditions that the core position and the mark position on the end face of the multi-core optical fiber MF2 should meet will be described later with reference to the accompanying drawings. Figure 3 (c) shows the state of the multi-core optical fibers MF1 and MF2 during the centering step S13 .

[0043] In addition, in the present embodiment, the centering step S13 is performed once after the measurement step S12 is performed once, but the present invention is not limited thereto. For example, the following structure may be adopted, that is, the centering operation is performed in stages by alternately repeating the measurement step S12 and the centering step S13.

[0044] When the centering process S13 is completed, the docking process S14 is implemented. The docking process S14 is a process in which the fusion splicing device 1 docks the end face of the multi-core optical fiber MF1 with the end face of the multi-core optical fiber MF2. In the docking process S14, the processor 10a of the control device 10 controls the centering mechanism of the fusion splicing device 1 to move the multi-core optical fiber MF1 in the negative direction of the z-axis by d / 2 (about 10μm in this embodiment). In addition, the processor 10a of the control device 10 controls the centering mechanism of the fusion splicing device 1 to move the multi-core optical fiber MF2 in the positive direction of the z-axis by d / 2 (about 10μm in this embodiment). Figure 3 (d) shows the state of the multi-core optical fibers MF1 and MF2 after the butting step S14 has been performed.

[0045] In addition, in the docking process S14, a pre-discharge can be implemented. Pre-discharge is a process for softening the front ends of the multi-core optical fibers MF1 and MF2. On the basis of implementing the pre-discharge, the front ends of the multi-core optical fibers MF1 and MF2 are docked, so that the front ends of the multi-core optical fibers MF1 and MF2 can be more reliably and tightly joined. In this case, it is preferred to set the movement amount of the multi-core optical fibers MF1 and MF2 to d / 2+ε. ε is an additional movement amount for overlapping the front ends of the optical fibers OF1 and OF2, for example, 10μm.

[0046] When the docking process S14 is completed, the fusion splicing process S15 is implemented. The fusion splicing process S15 is a process in which the fusion splicing device 1 performs fusion splicing on the multi-core optical fiber MF1 and the multi-core optical fiber MF2. In the fusion splicing process S15, the processor 10a of the control device 10 generates arc discharge by controlling the heating source 13 (here, the electrode) to heat and melt the ends of the multi-core optical fiber MF1 and the multi-core optical fiber MF2. When the heated and fused ends of the multi-core optical fiber MF1 and the ends of the multi-core optical fiber MF2 are solidified by natural cooling, the multi-core optical fiber MF1 and the multi-core optical fiber MF2 are fused. Figure 3 (e) shows the state of the multi-core optical fibers MF1 and MF2 after the fusion-splicing step S15 is performed.

[0047] Furthermore, in the above-mentioned centering step S13, the centering may be performed in a manner that improves the following correlation coefficient (overlap integral), which indicates the degree of correlation between the waveform of the brightness distribution of the multi-core optical fiber that has been measured (reference waveform) and the waveform of the brightness distribution of the multi-core optical fiber that is actually measured. In this case, the type of the end face of the multi-core optical fiber may be determined based on whether the position of the peak corresponding to the mark is on the left or right, with the middle of the positions of the peaks corresponding to the two adjacent cores as a reference. In addition, in the case where the above-mentioned centering step S13 is implemented in an end view manner, the centering may be performed in a manner that improves the following correlation coefficient, which indicates the degree of correlation between the image of the end face of the multi-core optical fiber that has been photographed (reference image) and the image of the end face of the multi-core optical fiber that is actually photographed. Here, the above-mentioned waveform and correlation coefficient can be defined as feature quantities. That is to say, the control device can adopt the following structure, namely: the measurement control unit further determines the mark position on the end face of another multi-core optical fiber, and the centering control unit aligns the multi-core optical fiber relative to the other multi-core optical fiber based on a characteristic value that is pre-set or determined before centering, so that the mark position on the end face of the multi-core optical fiber relative to the mark position on the end face of the other multi-core optical fiber meets a pre-set condition.

[0048] (Specific example of multi-core optical fiber)

[0049] Reference Figure 4 A specific example of two multi-core optical fibers MF1 and MF2 will be described. Here, two multi-core optical fibers MF1 and M2 having the same core configuration and label configuration are considered, and these two multi-core optical fibers MF1 and MF2 are referred to as multi-core optical fibers MF. Figure 4In the figure, (a) is a side view of the multi-core optical fiber MF, (b) is a front view of one end face σ1 of the multi-core optical fiber MF observed from the line of sight E1, and (c) is a front view of the other end face σ2 of the multi-core optical fiber MF observed from the line of sight E2. In addition, the two multi-core optical fibers MF1 and MF2 with the same core configuration and marking configuration are only an example of the application object of the present invention. In the two multi-core optical fibers MF1 and MF2, the position, shape, and size of each mark are arbitrary, and the two multi-core optical fibers MF1 and MF2 are not required to have the same marking configuration.

[0050] The multi-core optical fiber MF has n (n is a natural number greater than 2) cores a1 to an and a cladding b. The cladding b is a cylindrical component. The cladding b is composed of, for example, quartz glass. Each core ai (i is a natural number greater than 1 and less than n) is a cylindrical region arranged inside the cladding b and having a higher refractive index than the cladding b and extending in the same direction as the cladding b. Each core ai is composed of, for example, quartz glass to which a rising dopant such as germanium is added. In addition, the cladding b can be columnar, and its cross-sectional shape is arbitrary. The cross-sectional shape of the cladding b can be, for example, a polygonal shape such as a quadrilateral or hexagon, or a cylindrical shape.

[0051] In the end faces σ1 and σ2, the cores a1 to an are arranged line-symmetrically with respect to the axis L1 orthogonal to the central axis L0 of the multi-core optical fiber MF. In addition, in the end faces σ1 and σ2, the cores a1 to an are arranged in a manner avoiding the axis L1. In other words, in the end faces σ1 and σ2, the cores a1 to an are arranged at positions other than the axis L1.

[0052] The multi-core optical fiber MF also has a marker c. The marker c is a columnar region that is arranged inside the cladding b and has a refractive index different from that of the cladding b and extends in the same direction as the cladding b. The cross-sectional shape of the marker c is arbitrary, for example, a circle, a triangle, a quadrilateral, etc. The marker c is composed of, for example, quartz glass to which a down-doping agent such as fluorine or boron is added. In this case, the refractive index of the marker c is lower than the refractive index of the cladding b. Alternatively, the marker c is composed of quartz glass to which a rising doping agent such as germanium, aluminum, phosphorus, or chlorine is added. In this case, the refractive index of the marker c is higher than the refractive index of the cladding b. When forming the marker c, for example, a hole opening method, a stacking method, a drawing method, etc. can be used. Usually, the outer diameter of the marker c is smaller than the outer diameter of the core ai.

[0053] In the end faces σ1 and σ2, the center of the mark c is arranged so as to avoid the axis L1. In other words, in the end faces σ1 and σ2, the center (geometric center) of the mark c is arranged at a position other than the axis L1. In addition, the mark c only needs to be arranged so that its center avoids the axis L1, and a part of the mark c may overlap with the axis L1.

[0054] also, Figure 4The cores a1 to a4 of the illustrated multi-core optical fiber MF can also be considered to be arranged in line symmetry with respect to the axis L2, can also be considered to be arranged in line symmetry with respect to the axis L3, and can also be considered to be arranged in line symmetry with respect to the axis L4. Here, the axis L2 is an axis orthogonal to both the central axis L0 and the axis L1. In addition, the axes L3 and L4 are axes orthogonal to the central axis L0 and form an angle of 45 degrees with the axis L1.

[0055] Here, as the cores a1 to an, four cores a1 to a4 arranged at the vertices of a square are considered, and as the axis of linear symmetry, axes L1 to L4 that do not pass through the four cores a1 to a4 are considered, but the present invention is not limited to this. The number n of the cores a1 to an is arbitrary, and the axis of linear symmetry may pass through the cores a1 to an or may not pass through the cores a1 to an. For example, when n is an even number, the following may be considered: n cores a1 to an arranged at the vertices of a regular n-gon, n / 2 axes of linear symmetry passing through the vertices of the regular n-gon opposite to each other, and n / 2 axes of linear symmetry passing through the midpoints of the sides of the regular n-gon opposite to each other. In addition, when n is an odd number, the following may be considered: n cores a1 to an arranged at the vertices of a regular n-gon, and n axes of linear symmetry passing through the vertices of the regular n-gon and the midpoints of the sides opposite to the vertices. In addition to the cores a1 to an, another core may be present at the center of the multi-core optical fiber MF (the center of the regular n-gon at the vertices of which the cores a1 to an are arranged).

[0056] In addition, the cores a1 to an may not be arranged at the vertices of the regular n-gon. Figure 4 In the multi-core optical fiber MF shown, the core a1 and the core a4 are moved in the direction close to the axis L1, and the core a2 and the core a3 are moved in the direction away from the axis L1, thereby obtaining a multi-core optical fiber MF, that is, a multi-core optical fiber MF in which the cores a1 to a4 are arranged at the vertices of an isosceles trapezoid. In this case, the axis L1 is an axis of linear symmetry. In addition, consider: two line segments parallel to each other in the cross section of the multi-core optical fiber MF, that is, two line segments equidistant from the cross-sectional center of the multi-core optical fiber MF. It is also possible to consider: a multi-core optical fiber MF in which four cores a1 to a4 of the eight cores a1 to a8 are arranged at equal intervals on one line segment, and the remaining four cores a5 to a8 are arranged at equal intervals on another line segment. Here, it is set that the interval between the cores adjacent to each other in the cores a1 to a4 is consistent with the interval between the cores adjacent to each other in the cores a5 to a8. In addition, the two cores a1 and a5, the two cores a2 and a6, the two cores a3 and a7, and the two cores a4 and a8 are respectively located on a straight line orthogonal to the above two straight lines. In this case, the axis L1 parallel to the above two straight lines and the axis L2 perpendicular to the above two straight lines are axes of linear symmetry.

[0057] (Specific example of the connection point of multi-core optical fiber)

[0058] Reference Figure 5 to Figure 12 A specific example of the connection point between the multi-core optical fibers MF1 and MF2 will be described.

[0059] The connection methods of multi-core optical fibers MF1 and MF2 include: heterogeneous end face connection in which the end face σ1 of one side is connected to the end face σ2 of the other side; homogeneous end face connection in which the end faces σ1 of both sides are connected or the end faces σ2 of both sides are connected. In heterogeneous end face connection, there are: normal connection and non-normal connection. In homogeneous end face connection, there is: flip connection of the cores a1 to a4 relative to the axes L1 to L4 of symmetry of each line. These connection methods are explained below.

[0060] Figure 5 The figures show the connection parts that are usually connected, (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of the line of sight E2, and (c) is a front view of the end face σ1 of the multi-core optical fiber MF2 as viewed from the direction of the line of sight E1. The connection parts that are usually connected are the connection parts where the end face σ2 of the multi-core optical fiber MF1 as heterogeneous end faces and the end face σ1 of the multi-core optical fiber MF2 are connected, or the connection parts where the end face σ1 of the multi-core optical fiber MF1 as heterogeneous end faces and the end face σ2 of the multi-core optical fiber MF2 are connected ( Figure 5 The former). The connection parts usually meet the following conditions.

[0061] Condition 1: The cores a1 to an of the end face σ1 of the multi-core optical fiber MF2 overlap with any of the cores a1 to an of the end face σ2 of the multi-core optical fiber MF1. Specifically, (1) the core a1 of the end face σ1 of the multi-core optical fiber MF2 overlaps with the core a1 of the end face σ2 of the multi-core optical fiber MF1, (2) the core a2 of the end face σ1 of the multi-core optical fiber MF2 overlaps with the core a2 of the end face σ2 of the multi-core optical fiber MF1, (3) the core a3 of the end face σ1 of the multi-core optical fiber MF2 overlaps with the core a3 of the end face σ2 of the multi-core optical fiber MF1, and (4) the core a4 of the end face σ1 of the multi-core optical fiber MF2 overlaps with the core a4 of the end face σ2 of the multi-core optical fiber MF1.

[0062] Condition 2a: The mark c on the end face σ1 of the multi-core optical fiber MF2 overlaps with the mark c on the end face σ2 of the multi-core optical fiber MF1.

[0063] In short, the usual connection is a heterogeneous end-face connection, in which the fiber cores a1 to an are optically coupled and the marker c is connected.

[0064] In addition, only a part of the mark c of the multi-core optical fiber MF2 may be connected to a part other than the mark c of the multi-core optical fiber MF1, or only a part of the mark c of the multi-core optical fiber MF1 may be connected to a part other than the mark c of the multi-core optical fiber MF2. For example, when this structure is realized by moving the mark c in the multi-core optical fibers MF1 and MF2 in a direction away from the core a1, it is possible to suppress: deformation of the core a1 that may occur when manufacturing the multi-core optical fiber MF1 due to the proximity of the mark c; and characteristic degradation that occurs when using the multi-core optical fiber MF due to the proximity of the mark c.

[0065] Furthermore, the position of the mark c in the multi-core optical fibers MF1 and MF2 can be determined as follows.

[0066] Condition β1: On the end face of the first multi-core optical fiber MF1, the mark c coincides with a virtual perpendicular bisector of a virtual line segment connecting the center of the core a1 closest to the mark c and the center of the second closest core a4 among the cores a1 to a4 of the first multi-core optical fiber MF1.

[0067] Condition β2: On the end face of the second multi-core optical fiber MF2, the mark c coincides with a virtual perpendicular bisector of a virtual line segment connecting the center of the core a1 closest to the mark c and the center of the second closest core a4 among the cores a1 to a4 of the second multi-core optical fiber MF2.

[0068] When the condition β1 or the condition β2 is satisfied, in the first multi-core optical fiber MF1, the marker c can be at least further away from the core a1 closest to the marker c, and in the second multi-core optical fiber MF2, the marker c can be at least further away from the core a1 closest to the marker c. Therefore, it is possible to suppress the characteristic degradation problem that occurs in the following cases: in the first multi-core optical fiber MF1, the marker c is at least close to the core a1; in the second multi-core optical fiber MF2, the marker c is at least close to the core a1.

[0069] In addition, the above-mentioned condition β1 may be the following condition β1', and the condition β2 may be the following condition β2'. In this case, in the first multi-core optical fiber MF1, the marker c can be further away from the cores a1 to a4, and in the second multi-core optical fiber MF2, the marker c can be further away from the cores a1 to a4. Therefore, the characteristic degradation problem that occurs in the following situations can be further suppressed, namely: in the first multi-core optical fiber MF1, the marker c is close to the cores a1 to a4; in the second multi-core optical fiber MF2, the marker c is close to the cores a1 to a4.

[0070] Condition β1': In the end face of the first multi-core optical fiber MF1, the center of the mark c coincides with the virtual perpendicular bisector of the virtual line segment connecting the center of the core a1 closest to the mark c and the center of the second closest core a4 among the cores a1 to a4 of the first multi-core optical fiber MF1. In addition, in this case, the distance from the mark c to the core a1 is equal to the distance from the mark c to the core a2. Therefore, the "center of the core a1 closest to the mark c and the second closest core a4" mentioned here are the two cores a1 and a4 closest to the mark c. In addition, even if the distance from the mark c to the core a1 is equal to the distance from the mark c to the core a2, as long as the cross-sectional structure of the first multi-core optical fiber MF1 is asymmetric with respect to the axis L1, the core a1 and the core a2 can be identified.

[0071] Condition β2': In addition, in the end face of the second multi-core optical fiber MF2, the center of the mark c coincides with the virtual perpendicular bisector of the virtual line segment connecting the center of the core a1 closest to the mark c and the center of the second closest core a4 among the cores a1 to a4 of the second multi-core optical fiber MF2. In addition, in this case, the distance from the mark c to the core a1 is equal to the distance from the mark c to the core a2. Therefore, the "center of the core a1 closest to the mark c and the second closest core a4" mentioned here are the two cores a1 and a4 closest to the mark c. In addition, even if the distance from the mark c to the core a1 is equal to the distance from the mark c to the core a2, as long as the cross-sectional structure of the second multi-core optical fiber MF2 is asymmetric with respect to the axis L1, the core a1 and the core a2 can be identified.

[0072] Alternatively, the position of the mark c in the multi-core optical fibers MF1 and MF2 may be determined so as to satisfy the following condition γ1 or γ2.

[0073] Condition γ1: On the end face of the first multi-core optical fiber MF1, the center of the mark c does not overlap with the virtual perpendicular bisector of the virtual line segment connecting the center of the core a1 closest to the mark c and the center of the second closest core a4 among the cores a1 to a4 of the first multi-core optical fiber MF1.

[0074] Condition γ2: On the end face of the second multi-core optical fiber MF2, the center of the mark c does not overlap with the virtual perpendicular bisector of the virtual line segment connecting the center of the core a1 closest to the mark c and the center of the second closest core a4 among the cores a1 to a4 of the second multi-core optical fiber MF2.

[0075] In this case, the center of the mark c of the first multi-core optical fiber MF1 or the center of the mark c of the second multi-core optical fiber MF2 will be offset from the above-mentioned virtual perpendicular bisector. Therefore, compared with the case where the mark c of the first multi-core optical fiber MF1 and the mark c of the second multi-core optical fiber MF2 completely overlap, or the center of the mark c of the first multi-core optical fiber MF1 and the center of the mark c of the second multi-core optical fiber MF2 overlap with the above-mentioned virtual perpendicular bisector, it is easy to: identify the end face of the first multi-core optical fiber MF1 and the end face of the second multi-core optical fiber MF2, or identify the core number of the first multi-core optical fiber MF1, or identify the core number of the second multi-core optical fiber MF2. As a result, it is easy to connect the first multi-core optical fiber MF1 or the second multi-core optical fiber MF2 to an external transceiver or an external fan-in / fan-out device.

[0076] In addition, the multi-core optical fibers MF1 and MF2 are Figure 4 In the case of the multi-core optical fiber MF shown as an example, as a connection method for connecting the end face σ2 of the multi-core optical fiber MF1 and the end face σ1 of the multi-core optical fiber MF2, in addition to the normal connection, it is considered Figure 6 The connection method shown, Figure 7 The connection method shown, Figure 8 Connection method shown.

[0077] Figure 6 FIG. 2 shows a connection method in which the core a1 of the multi-core optical fiber MF1 is connected to the core a2 of the multi-core optical fiber MF2. Figure 6 , (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of line of sight E2, and (c) is a front view of the end face σ1 of the multi-core optical fiber MF2 as viewed from the direction of line of sight E1.

[0078] Figure 7 FIG. 2 shows a connection method in which the core a1 of the multi-core optical fiber MF1 is connected to the core a3 of the multi-core optical fiber MF2. Figure 7 , (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of line of sight E2, and (c) is a front view of the end face σ1 of the multi-core optical fiber MF2 as viewed from the direction of line of sight E1.

[0079] Figure 8 FIG. 2 shows a connection method in which the core a1 of the multi-core optical fiber MF1 is connected to the core a4 of the multi-core optical fiber MF2. Figure 8 , (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of line of sight E2, and (c) is a front view of the end face σ1 of the multi-core optical fiber MF2 as viewed from the direction of line of sight E1.

[0080] Figure 6 to Figure 8 The connection shown satisfies condition 1 but not condition 2a. Therefore, Figure 6 to Figure 8 The connection method shown is not called a normal connection but a non-normal connection.

[0081] Fig. 9 The figures show the connection parts of the flip connection, (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of the line of sight E2, and (c) is a front view of the end face σ2 of the multi-core optical fiber MF2 as viewed from the direction of the line of sight E1. The connection part of the flip connection is a connection part where the end face σ2 of the multi-core optical fiber MF1, which is the same end face, is connected to the end face σ2 of the multi-core optical fiber MF2, or a connection part where the end face σ1 of the multi-core optical fiber MF1, which is the same end face, is connected to the end face σ1 of the multi-core optical fiber MF2 ( Fig. 9 The connection part of the flip connection meets the following conditions.

[0082] Condition 1: The cores a1 to an of the end face σ2 of the multi-core optical fiber MF2 overlap with any of the cores a1 to an of the end face σ2 of the multi-core optical fiber MF1. Specifically, (1) the core a1 of the end face σ2 of the multi-core optical fiber MF2 overlaps with the core a4 of the end face σ2 of the multi-core optical fiber MF1, (2) the core a2 of the end face σ2 of the multi-core optical fiber MF2 overlaps with the core a3 of the end face σ2 of the multi-core optical fiber MF1, (3) the core a3 of the end face σ2 of the multi-core optical fiber MF2 overlaps with the core a2 of the end face σ2 of the multi-core optical fiber MF1, and (4) the core a4 of the end face σ2 of the multi-core optical fiber MF2 overlaps with the core a1 of the end face σ2 of the multi-core optical fiber MF1.

[0083] Condition 2b: The mark c on the end face σ2 of the multi-core optical fiber MF2 overlaps with a region x on the end face σ2 of the multi-core optical fiber MF1 that is line-symmetric to the mark c on the multi-core optical fiber MF1 with respect to the axis L1.

[0084] In short, the flip connection is a connection of the same end face, in which the fiber cores a1 to an are optically coupled and the marker c is not connected.

[0085] In addition, the multi-core optical fibers MF1 and MF2 are Figure 4 In the case of the multi-core optical fiber MF shown as an example, as a connection method for connecting the end face σ2 of the multi-core optical fiber MF1 and the end face σ2 of the multi-core optical fiber MF2, Fig. 9 In addition to the flip connection shown, consider Fig.10 The connection method shown, Fig.11 The connection method shown, Fig.12 Connection method shown.

[0086] Fig.10FIG. 2 shows a connection method in which the core a1 of the multi-core optical fiber MF1 is connected to the core a3 of the multi-core optical fiber MF2. Fig.10 , (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of line of sight E2, and (c) is a front view of the end face σ1 of the multi-core optical fiber MF2 as viewed from the direction of line of sight E1. Fig.10 The connection shown satisfies condition 1 and condition 2b by changing the axis L1 to axis L3. Fig. 9 The connection shown is called an inverted connection relative to the axis L3.

[0087] Fig.11 FIG. 2 shows a connection method in which the core a1 of the multi-core optical fiber MF1 is connected to the core a2 of the multi-core optical fiber MF2. Fig.11 , (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of line of sight E2, and (c) is a front view of the end face σ1 of the multi-core optical fiber MF2 as viewed from the direction of line of sight E1. Fig.11 The connection shown satisfies condition 1 and condition 2b by changing the axis L1 to axis L2. Fig.11 The connection shown is called an inverted connection relative to the axis L2.

[0088] Fig.12 FIG. 2 shows a connection method in which the core a1 of the multi-core optical fiber MF1 is connected to the core a1 of the multi-core optical fiber MF2. Fig.12 , (a) is a side view of the multi-core optical fibers MF1 and MF2, (b) is a front view of the end face σ2 of the multi-core optical fiber MF1 as viewed from the direction of line of sight E2, and (c) is a front view of the end face σ1 of the multi-core optical fiber MF2 as viewed from the direction of line of sight E1. Fig.12 The connection shown satisfies condition 1 and condition 2b by changing the axis L1 to axis L4. Fig.12 The connection shown is called an inverted connection relative to the axis L4.

[0089] (Pre-set conditions)

[0090] As described above, in the centering step S13, the processor 10a of the control device 10 aligns the multi-core optical fibers MF1 and MF2 so that the core position and mark position of the multi-core optical fiber MF2 relative to the core position and mark position of the multi-core optical fiber MF1 meet the "pre-set conditions".

[0091] In the present embodiment, the above-mentioned condition 1 is considered as the "predetermined condition" that the core position of the multi-core optical fiber MF2 should satisfy relative to the core position of the multi-core optical fiber MF1. In this case, the following eight positional relationships are considered as the relationship between the mark position of the multi-core optical fiber MF2 and the mark position of the multi-core optical fiber MF1.

[0092] Relation 1: In Figure 5 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection mode (normal connection) shown is a positional relationship in which the center of the mark c of the multi-core optical fiber MF1 and the center of the mark c of the multi-core optical fiber MF2 coincide with each other.

[0093] Relation 2: In Figure 6 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection method (non-normal connection) shown.

[0094] Relation 3: In Figure 7 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection method (non-normal connection) shown.

[0095] Relation 4: In Figure 8 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection method (non-normal connection) shown.

[0096] In addition, relations 2 to 4 can be expressed as positional relations in which one of the normally connected multi-core optical fibers MF1 and MF2 is rotated by i×360° / 4 (i=1, 2, 3). In general, when the cores a1 to an of the multi-core optical fibers MF1 and MF2 have m-fold symmetry, there are m-1 types of connection methods in which one of the normally connected multi-core optical fibers MF1 and MF2 is rotated by i×360° / m (i=1, 2, ..., m-1) as an abnormal connection.

[0097] Relation 5: In Fig. 9 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection mode (inverted connection with respect to the axis L1) shown.

[0098] Relation 6: In Fig.10 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection mode (inverted connection with respect to the axis L3) shown.

[0099] Relation 7: In Fig.11 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection mode (inverted connection with respect to the axis L2) shown.

[0100] Relation 8: In Fig.12 The positional relationship between the mark c of the multi-core optical fiber MF1 and the mark c of the multi-core optical fiber MF2 produced in the connection mode (inverted connection with respect to the axis L4) shown.

[0101] In addition, relations 6 to 8 can be expressed as a positional relationship in which one of the multi-core optical fibers MF1 and MF2 connected by flipping is rotated by i×360° / 4 (i=1, 2, 3) relative to the axis L1. In general, when the cores a1 to an of the multi-core optical fibers MF1 and MF2 have m-fold symmetry, there are m-1 connection methods in which one of the multi-core optical fibers MF1 and MF2 connected by flipping is rotated by i×360° / m (i=1, 2, ..., m-1) as different flip connections.

[0102] In addition, the relationship 1 and the relationship 5 can be said to be a relationship in which the pair of core a1 closest to the mark c and the second closest core a4 among the pair of two cores selected from the cores a1 to a4 of the multi-core optical fiber MF1 are connected to the pair of core a1 closest to the mark c and the second closest core a4 among the pair of two cores selected from the cores a1 to a4 of the multi-core optical fiber MF2. In this case, the effect of reducing the crosstalk between the cores can be concentrated on the pair of core a1 closest to the mark c and the second closest core a4. On the other hand, the relationships 2 to 4 and 6 to 8 can be said to be the relationship in which the pair of core a1 closest to the mark c and the second closest core a4 among the pair of two cores selected from the cores a1 to a4 of the multi-core optical fiber MF1 is connected to the pair other than the pair of core a1 closest to the mark c and the second closest core a4 among the pair of two cores selected from the cores a1 to a4 of the multi-core optical fiber MF2. In this case, the effect of reducing crosstalk between cores can be dispersed.

[0103] In the present embodiment, regarding heterogeneous end face connection, relationship 1 is considered as a "pre-set condition" that the mark position of the multi-core optical fiber MF2 should satisfy relative to the mark position of the multi-core optical fiber MF1. In addition, in the present embodiment, regarding homogeneous end face connection, relationships 5 to 8 are considered as "pre-set conditions" that the mark position of the multi-core optical fiber MF2 should satisfy relative to the mark position of the multi-core optical fiber MF1. Thus, a multi-core optical fiber connector can be obtained, which is connected by normal connection or flip connection.

[0104] Furthermore, the control device 10 may use the relationship specified by the user as the "pre-set condition" that the mark position of the multi-core optical fiber MF2 should satisfy relative to the mark position of the multi-core optical fiber MF1. Alternatively, the control device 10 may use the relationship automatically selected by the control device 10 as the "pre-set condition" that the mark position of the multi-core optical fiber MF2 should satisfy relative to the mark position of the multi-core optical fiber MF1. The method for the control device 10 to automatically select the "pre-set condition" from the relationships 1 to 8 is, for example, as follows.

[0105] That is, the control device 10 (centering control unit) determines whether the connection target end face of the multi-core optical fibers MF1 and MF2 is the end face σ1 or the end face σ2 based on the core positions and mark positions of the multi-core optical fibers MF1 and MF2 measured in the measurement step S12. When the connection target end faces of the multi-core optical fibers MF1 and MF2 are both the end face σ1, or when the connection target end faces of the multi-core optical fibers MF1 and MF2 are both the end face σ2, the control device 10 determines that the connection to be made is a connection with the same type of end faces. On the other hand, when the connection target end face of one of the multi-core optical fibers MF1 and MF2 is the end face σ1, and the connection target end face of the other of the multi-core optical fibers MF1 and MF2 is the end face σ2, the control device 10 determines that the connection to be made is a connection with different types of end faces. When the connection to be made is a connection with the same type of end faces, the control device 10 selects relationship 1 as the "preset condition". On the other hand, when the connection to be made is a connection with different types of end faces, the control device 10 selects any one of relationships 5 to 8 as the pre-set relationship. Furthermore, when the connection to be performed is a heterogeneous end surface connection, which of the relationships 5 to 8 is to be selected may be determined in advance or may be determined based on a user's instruction.

[0106] In addition, the position of the mark c may vary depending on the manufacturing batch or manufacturer. Even in this case, when the cores a1 to a4 identified by the distance from the mark c in the end face σ2 of the first multi-core optical fiber MF1 and the end face σ1 of the second multi-core optical fiber MF2 are as follows: Figure 5 When the connection is performed as shown in FIG. 1 , it is considered as a normal connection. In addition, when the cores a1 to a4 identified by the distance from the mark c in the end face σ2 of the first multi-core optical fiber MF1 and the end face σ1 of the second multi-core optical fiber MF2 are as shown in FIG. Figures 9 to 12 When the connection is made as shown, it is considered a flip connection.

[0107] Furthermore, when one end face of the first multi-core optical fiber MF1 and one end face of the second multi-core optical fiber MF2 are butted against each other, alignment may be performed so as to satisfy the following condition η.

[0108] Condition η: A virtual straight line connecting the center of mark c of the first multi-core optical fiber MF1 and the center of mark c of the second multi-core optical fiber MF2 at one end face of the first multi-core optical fiber MF1 or one end face of the second multi-core optical fiber MF2 is parallel to a virtual straight line connecting the center of core a1 closest to mark c of the first multi-core optical fiber MF1 and the center of the second closest core a4 at the end face of the first multi-core optical fiber MF1, or a virtual straight line connecting the center of core a1 closest to mark c of the second multi-core optical fiber MF2 and the center of the second closest core a4 at the end face of the second multi-core optical fiber MF2.

[0109] In this case, similar to the above-mentioned effects, it is easy to identify the end face of the first multi-core optical fiber MF1 and the end face of the second multi-core optical fiber MF2, or to identify the core number of the first multi-core optical fiber MF1, or to identify the core number of the second multi-core optical fiber MF2. As a result, it is easy to connect the first multi-core optical fiber MF1 or the second multi-core optical fiber MF2 to an external transceiver or an external fan-in / fan-out device. In addition, compared with the case where the virtual straight line connecting the two marks c is arranged non-parallel, there is a case where at least one of the two marks c can be away from the periphery of the cladding b, so that the effect of suppressing the increase in the thickness of the cladding b or the deformation of the cladding b during manufacturing can be obtained.

[0110] Furthermore, when one end face of the first multi-core optical fiber MF1 and one end face of the second multi-core optical fiber MF2 are butted against each other, alignment may be performed so as to satisfy the following condition δ1 or condition δ2.

[0111] Condition δ1: The entire mark c of the second multi-core optical fiber MF2 is connected to a portion other than the mark c of the first multi-core optical fiber MF1 (such as the cladding b of the first multi-core optical fiber MF1 ).

[0112] Condition δ2: The entire mark c of the first multi-core optical fiber MF1 is connected to a portion other than the mark c of the second multi-core optical fiber MF2 (such as the cladding b of the second multi-core optical fiber MF2 ).

[0113] Compared with connecting the mark c of the first multi-core optical fiber MF1 with a smaller area to the mark c of the second multi-core optical fiber MF2 with a smaller area, or connecting the mark c of the first multi-core optical fiber MF1 across the mark c and cladding b of the second multi-core optical fiber MF2, the mark c of the first multi-core optical fiber MF1 is only connected to the cladding b of the second multi-core optical fiber MF2 with a larger area, which can reduce (relax) the stress on the mark c of the first multi-core optical fiber MF1. As a result, it is possible to suppress the damage to the mark c by the first multi-core optical fiber MF1. The same can be said for the mark c of the second multi-core optical fiber MF2.

[0114] Furthermore, when one end face of the first multi-core optical fiber MF1 and one end face of the second multi-core optical fiber MF2 are butted against each other, alignment may be performed so as to satisfy the following condition ε1 or condition ε2.

[0115] Condition ε1: Alignment is performed in the following manner: in the end face of the first multi-core optical fiber MF1, with respect to the center of the mark c of the second multi-core optical fiber MF2, (1) is located inside a virtual circumscribed circle centered at the center of the cladding b of the first multi-core optical fiber MF1, the virtual circumscribed circle circumscribing the core a1 closest to the mark c and the second closest core a4 among the multiple cores a1 to a4 of the first multi-core optical fiber MF1; and is connected to a region (hereinafter also referred to as region B) sandwiched by (2) a virtual bisector of an angle formed by a virtual straight line passing through the center of the core a1 closest to the mark c and the center of the second closest core a4 and a virtual straight line passing through the center of the core a1 and the center of the cladding b, and (3) a virtual bisector of an angle formed by a virtual straight line passing through the center of the core a1 and the center of the core a4 and a virtual straight line connecting the center of the core a4 and the center of the cladding b and including the core a1 and the core a4.

[0116] Condition ε2: Alignment is performed in the following manner: in the end face of the second multi-core optical fiber MF2, with respect to the center of the mark c of the first multi-core optical fiber MF1, (1) is located inside a virtual circumscribed circle centered at the center of the cladding b of the second multi-core optical fiber MF2, the virtual circumscribed circle circumscribing the core a1 closest to the mark c and the second closest core a4 among the multiple cores a1 to a4 of the second multi-core optical fiber MF2; and is connected to a region (hereinafter also referred to as region C) sandwiched by (2) a virtual bisector of an angle formed by a virtual straight line passing through the center of the core a1 closest to the mark c and the center of the second closest core a4 and a virtual straight line passing through the center of the core a1 and the center of the cladding b, and (3) a virtual bisector of an angle formed by a virtual straight line passing through the center of the core a1 and the center of the core a4 and a virtual straight line connecting the center of the core a4 and the center of the cladding b and including the core a1 and the core a4.

[0117] In this case, in the first multi-core optical fiber MF1, both the above-mentioned former effect and the latter effect can be obtained, but especially compared with the case of condition ζ1 or condition ζ2 described later, since the mark c of the second multi-core optical fiber MF2 is connected to a position away from the outer periphery of the cladding b, it is possible to suppress an increase in the thickness of the cladding b or deformation of the cladding b during manufacturing, etc., so that the latter effect can be further increased. The same can be said for the second multi-core optical fiber MF2.

[0118] Furthermore, when one end face of the first multi-core optical fiber MF1 and one end face of the second multi-core optical fiber MF2 are butted against each other, alignment may be performed so as to satisfy the following condition ζ1 or condition ζ2.

[0119] Condition ζ1: Alignment is performed in the following manner, namely: in the end face of the first multi-core optical fiber MF1, with respect to the center of the mark c of the second multi-core optical fiber MF2, (1) is located outside a virtual circumscribed circle centered at the center of the cladding b of the first multi-core optical fiber MF1, the virtual circumscribed circle circumscribing the core a1 closest to the mark c and the second closest core a4 among the multiple cores a1 to a4 of the first multi-core optical fiber MF1; and is connected to (2) a virtual bisector of an angle formed by a virtual straight line passing through the center of the core a1 closest to the mark c and the center of the second closest core a4 and a virtual straight line passing through the center of the core a1 and the center of the cladding b, (3) a virtual bisector of an angle formed by a virtual straight line passing through the center of the core a1 and the center of the core a4 and a virtual straight line connecting the center of the core a4 and the center of the cladding b, and (4) a region (hereinafter also referred to as region D) sandwiched by the outer periphery of the cladding b and in contact with the core a1 and the core a4.

[0120] Condition ζ2: Alignment is performed in the following manner: in the end face of the second multi-core optical fiber MF2, the center of the mark c of the first multi-core optical fiber MF1 is connected to (1) a virtual circumscribed circle centered on the center of the cladding b of the second multi-core optical fiber MF2 and circumscribed to the core a1 closest to the mark c and the second closest core a4 among the multiple cores a1 to a4 of the second multi-core optical fiber MF2, (2) a virtual bisector of the angle formed by a virtual straight line passing through the center of the core a1 closest to the mark c and the center of the second closest core a4 and a virtual straight line passing through the center of the core a1 and the center of the cladding b, (3) a virtual bisector of the angle formed by a virtual straight line passing through the center of the core a1 and the center of the core a4 and a virtual straight line connecting the center of the core a4 and the center of the cladding b, and (4) a region clamped by the outer periphery of the cladding b and connected to the cores a1 and a4 (hereinafter also referred to as region E).

[0121] In this case, in the first multi-core optical fiber MF1, both the above-mentioned former effect and the latter effect can be obtained, but especially compared with the case of condition ε1 or condition ε2, since the mark c of the second multi-core optical fiber MF2 is connected to a position away from the core a1 or the core a4, the deformation of the core a1 or the core a4 can be suppressed, so that the former effect can be further increased. The same can be said for the second multi-core optical fiber MF2.

[0122] In addition, for the condition ε1, the condition ε2, the condition ζ1 or the condition ζ2, the following structure can also be adopted in the end face of the first multi-core optical fiber MF1, that is, a structure in which at least a part of the mark c of the second multi-core optical fiber MF2 is connected to the region B or the region D (hereinafter also described as structure 1), a structure in which the mark c of the second multi-core optical fiber MF2 is connected as a whole to the region B or the region D (hereinafter also described as structure 2), or a structure in which at least a part of the mark c of the second multi-core optical fiber MF2 is connected across the boundary between the region B and the region D (hereinafter also described as structure 3). Structures 1 to 3 can all obtain the former effect and the latter effect. However, in particular, with respect to the structure in which the mark c of the second multi-core optical fiber MF2 is connected as a whole to the region B in the case of structure 2, compared with the structure in which the mark c is connected as a whole to the region D in the case of structure 2 and structure 3, since the mark c of the second multi-core optical fiber MF2 is connected to a position away from the outer periphery of the cladding b, the latter effect can be particularly further increased. In addition, especially with respect to the structure in which the entire mark c of the second multi-core optical fiber MF2 is connected to the region D in the case of structure 2, the mark c of the second multi-core optical fiber MF2 is connected to a position away from the core a1 or the core a4, as compared with the structure in which the mark c of the second multi-core optical fiber MF2 is connected to the region B in the case of structure 2 and structure 3, so that the effect of the former can be further increased. In addition, especially with respect to structure 3, as compared with structure 2, the mark c of the second multi-core optical fiber MF2 is connected to a position away from the periphery of the cladding b and the core a1 or the core a4, so that the effect of the former and the effect of the latter can be obtained in a balanced manner. Similarly, in the end face of the second multi-core optical fiber MF2, it is also possible to adopt: a structure in which at least a part of the mark c of the first multi-core optical fiber MF1 is connected to the region C or the region E, a structure in which the mark c of the first multi-core optical fiber MF1 is connected to the region C or the region E as a whole, or a structure in which at least a part of the mark c is connected to the boundary between the region C and the region E. The effect obtained in this case is the same as the effect obtained in the above-mentioned first multi-core optical fiber MF1.

[0123] Furthermore, the centering may be performed in the following manner: in both end faces of the multi-core optical fiber connector obtained by connecting the multi-core optical fibers MF1 and MF2, the cores for inputting optical signals are arranged diagonally to each other and the cores for outputting optical signals are arranged diagonally to each other. In this case, the crosstalk between the cores for inputting optical signals and the crosstalk between the cores for outputting optical signals can be reduced.

[0124] In addition, when performing fusion splices more than two times in sequence to manufacture a multi-core optical fiber connector composed of more than three multi-core optical fibers MF, the fusion splice device 1 can store the state of the fusion splice (the conditions of the fusion splice) each time the fusion splice is performed, and determine the pth fusion splice with reference to the state of the fusion splices up to the p-1th time. In addition, when manufacturing a multi-core optical fiber connector composed of more than three multi-core optical fibers MF, the connection conditions can be determined in advance, and each fusion splice set to the connection conditions can be implemented.

[0125] The fusion-splicing device 1 can manufacture a multi-core optical fiber connection body in which the multi-core optical fiber MF1, the multi-core optical fiber MF2, and the multi-core optical fiber MF3 are connected in sequence by connecting the multi-core optical fibers MF1 to MF3 that satisfy the conditions A1 and A2 so as to satisfy the condition B.

[0126] Condition A1: The number of cores of the multi-core optical fiber MF1 and the number of cores of the multi-core optical fiber MF3 are each n (n is a natural number equal to or greater than 2).

[0127] Condition A2: (1) The core numbers of the multi-core optical fiber MF1 can be identified according to the arrangement order of the cores in a manner that the core closest to the mark c is the first and the core second closest to the mark c is the second, (2) The core numbers of the multi-core optical fiber MF2 can be identified according to the arrangement order of the plurality of cores in a manner that the core closest to the mark c is the first and the core second closest to the mark c is the second, (3) The core numbers of the multi-core optical fiber MF3 can be identified according to the arrangement order of the plurality of cores in a manner that the core closest to the mark c is the first and the core second closest to the mark c is the second.

[0128] Condition B: The i-th (i is a natural number greater than or equal to 1 and less than or equal to n) core of the multi-core optical fiber MF3 is connected to the core connected to the i-th core of the multi-core optical fiber MF1 among the plurality of cores of the multi-core optical fiber MF2 .

[0129] According to the above-mentioned structure, a multi-core optical fiber connector can be manufactured in which each core on one end face is connected to a core having the same number on the other end face.

[0130] Alternatively, the fusion-splicing device 1 may manufacture a multi-core optical fiber connection product by connecting L multi-core optical fibers so as to satisfy the following condition C1.

[0131] Condition C1: Among the L-1 connection sites, the number of connection sites that are reversed connections is an even number.

[0132] According to the above structure, when the cores are numbered according to the distance from the mark in the two end faces of the multi-core optical fiber connector, if the flip connection that satisfies the same relationship is adopted in the even-numbered connection parts, it is possible to manufacture a multi-core optical fiber connector in which the cores on one end face are connected to the cores with the same number on the other end face. Even when the connection parts of the flip connection that satisfy different relationships are mixed, the same effect can be obtained as long as the number of the connection parts of the flip connection that satisfy each relationship is an even number. For example, if the number of the connection parts of the flip connection that satisfies relationship 5 is 2, the number of the connection parts of the flip connection that satisfies relationship 6 is 0, the number of the connection parts of the flip connection that satisfies relationship 7 is 6, and the number of the connection parts of the flip connection that satisfies relationship 8 is 4, the same effect can be obtained.

[0133] Furthermore, the fusion-splicing device 1 may manufacture a multi-core optical fiber connection product by connecting L multi-core optical fibers so as to satisfy the following condition C2.

[0134] Condition C2: Among the L-1 connection locations, the number of connection locations that are reversed and connected is an odd number.

[0135] According to the above structure, when the cores are numbered according to the distance from the mark on both end faces of the multi-core optical fiber connector, a multi-core optical fiber connector can be manufactured in which each core on one end face is connected to a core with a different number on the other end face. For example, a multi-core optical fiber connector can be manufactured in which a No. 1 core on one end face is connected to a No. 2 core on the other end face, and a No. 2 core on one end face is connected to a No. 1 core on the other end face.

[0136] (Second embodiment)

[0137] The above describes the embodiment of connecting the multi-core optical fiber MF2 to the multi-core optical fiber MF1, but the present invention is not limited to this. For example, regarding the embodiment of connecting the multi-core optical fiber MF to the connector housing CH, this embodiment is also included in the scope of the present invention. The following describes the method of connecting the multi-core optical fiber MF to the connector housing CH. In addition, the control device of this embodiment is also constructed in the same manner as the control device 10 of the first embodiment, so its description is omitted.

[0138] (Connector connection method flow)

[0139] Reference Fig.13 The flow of the connector connection method S2 of the present embodiment will be described. The connector connection method S2 is a method of bonding the multi-core optical fiber MF2 to the connector C using a connector connection device. Fig.13Flow chart showing the process of the connector connection method S2. In addition, in the present embodiment, as the multi-core optical fiber MF, it is set as a multi-core optical fiber as follows, that is, the multi-core optical fiber has: a cladding, a plurality of cores formed inside the cladding, and a single marker formed inside the cladding. The specific example of the multi-core optical fiber MF is the same as that described in the first embodiment.

[0140] like Fig.13 As shown, the connector connection method S2 includes: a preparation process S21, a measurement process S22, a centering process S23, an insertion process S24, and a bonding process S25. The connector connection device is a device for connecting a connector component to a multi-core optical fiber, and comprises: a light source, a light detector, a centering mechanism, a holding mechanism (a mechanism for holding a connector component or a multi-core optical fiber), and a control device 10. The centering mechanism can perform translational movement of the multi-core optical fiber MF in the x-axis and y-axis directions, and rotational movement with the z-axis as the rotation axis. The control device 10 functions as the following parts, namely: a measurement control unit for implementing the measurement process S22, a centering control unit for implementing the centering process S23, an insertion control unit for implementing the insertion process S24, and a bonding control unit for implementing the bonding process S25.

[0141] The preparation step S21 is a step of placing the multi-core optical fiber MF with the coating removed at the end thereof in the centering mechanism. The multi-core optical fiber MF is held by the centering mechanism so that the central axis thereof is parallel to the z-axis.

[0142] When the preparation step S21 is completed, the measurement step S22 is implemented. The measurement step S22 is a step of measuring the core position and the mark position of the multi-core optical fiber MF. In the measurement step S22, the processor 10a of the control device 10 controls the centering mechanism to move the multi-core optical fiber MF in the negative direction of the z-axis. As a result, the end of the multi-core optical fiber MF is located between the light source and the photodetector. In addition, the processor 10a of the control device 10 uses the photodetector to detect: (1) the intensity I of the light emitted from the light source and passing through the end of the multi-core optical fiber MF (hereinafter referred to as the transmitted light intensity I). The processor 10a of the control device 10 controls the centering mechanism to rotate the light source and the photodetector with the z-axis as the rotation axis while repeating the detection process. As a result, the processor 10a of the control device 10 obtains the directional dependence of the transmitted light intensity of the multi-core optical fiber MF. In addition, the processor 10a of the control device 10 performs a determination process based on the directional dependence of the transmitted light intensity I of the multi-core optical fiber MF, that is, determines the core position and the mark position of the multi-core optical fiber MF.

[0143] When the measurement process S22 is completed, the centering process S23 is implemented. The centering process S23 is a process in which the connector connection device performs centering on the multi-core optical fiber relative to the connector housing CH. In the present embodiment, the reference for determining the core position and the mark position of the multi-core optical fiber MF is the key position of the connector housing CH. In the centering process S23, the processor 10a of the control device 10 performs the centering process by controlling the centering mechanism, that is, the multi-core optical fiber MF is centered relative to the connector housing CH in such a way that the core position and the mark position on the end face of the multi-core optical fiber MF meet the pre-set conditions relative to the key position of the connector housing CH. Here, the conditions that the core position and the mark position on the end face of the multi-core optical fiber MF should meet will be described later with reference to the accompanying drawings.

[0144] In addition, in the present embodiment, the centering step S23 is performed once after the measuring step S22 is performed once, but the present invention is not limited thereto. For example, the following structure may be adopted, that is, the centering operation is performed in stages by alternately repeating the measuring step S22 and the centering step S23.

[0145] When the centering process S23 is completed, the insertion process S24 is implemented. The insertion process S24 is a process of installing a ferrule at the end of the multi-core optical fiber MF from which the coating has been removed, and then inserting the end of the multi-core optical fiber MF with the ferrule installed into the connector housing CH. In the insertion process S24, the processor 10a of the control device 10 controls the centering mechanism, for example, to move the multi-core optical fiber MF in the z-axis direction, and inserts the end of the multi-core optical fiber MF into the connector housing CH.

[0146] When the insertion step S24 is completed, the bonding step S25 is performed. The bonding step S25 is a step of bonding the end of the multi-core optical fiber MF to the connector housing. The bonding step S25 can be performed by the user or by the processor 10a of the control device 10 controlling the syringe.

[0147] Furthermore, although the process of installing a ferrule on the multi-core optical fiber MF after centering is described here, the present invention is not limited to this. Alternatively, the ferrule may be installed on the multi-core optical fiber MF before centering. In this case, in order to determine the core position and the mark position, since the above-mentioned side view measurement method cannot be used, the end view measurement method is used to determine the core position and the mark position. In addition, instead of installing the multi-core optical fiber MF with the ferrule installed in the connector housing, a structure in which the multi-core optical fiber MF is inserted into the connector housing with the ferrule installed may be adopted.

[0148] In addition, although it is set here that the reference for the centering of the multi-core optical fiber MF is the key position of the connector housing, the present invention is not limited to this. When a key is formed on the ferrule, the key can be used as a reference to perform the centering of the multi-core optical fiber MF. In addition, when a key is formed on the fixture that fixes the connector and the ferrule, the key can be used as a reference to perform the centering of the multi-core optical fiber MF. In addition, the key position of the optical fiber holder can also be used as a reference to perform the centering of the multi-core optical fiber MF relative to the optical fiber holder. In this case, the user can fix the multi-core optical fiber MF fixed to the optical fiber holder to the connector housing in a manner that aligns the key position of the optical fiber holder with the key position of the connector housing. In addition, in addition to the above-mentioned key, the centering of the multi-core optical fiber MF and the ferrule can also be performed by the following other methods. It can be that when the manufacturing device is placed on a plane in a manner that the holding mechanism holding the ferrule and the holding mechanism holding the MCF are opposite, the centering of the multi-core optical fiber MF is performed in a manner that the relationship between the ferrule reference surface corresponding to the key position when the connector housing is connected to the ferrule and the mark of the multi-core optical fiber MF is in an appropriate position. Based on the above, when the connector shell CH and the ring are collectively referred to and defined as a connector component, the control device can be constructed such that the alignment control unit aligns the multi-core optical fiber relative to the connector component in a manner that makes the mark position of the multi-core optical fiber meet a preset condition relative to the key position of the connector shell and based on a reference that is preset or determined before alignment.

[0149] (Pre-set conditions)

[0150] As described above, the processor 10a of the control device 10 performs centering of the multi-core optical fiber MF in the centering step S23 so that the core position and the mark position of the multi-core optical fiber MF meet the "predetermined conditions" relative to the key position of the connector housing CH. Fig.14 The "pre-set condition" is explained. Fig.14 In the drawings, (a) is a side view of a multi-core optical fiber MF to which a connector housing CH is attached via a ferrule F, and (b) and (c) are cross-sectional views of the multi-core optical fiber MF.

[0151] In the present embodiment, as the "predetermined condition" that the core position of the multi-core optical fiber MF should satisfy with respect to the key position of the connector housing CH, the following condition is considered, namely, the symmetry axis L1 of the core on the end face of the multi-core optical fiber MF coincides with the axis L0 of the connector housing CH determined by the position of the key K of the connector housing CH. Here, the axis L0 determined by the position of the key K of the connector housing CH refers to, for example, the axis of the connector housing CH on the cross section perpendicular to the insertion direction of the multi-core optical fiber MF, which passes through the center of the key K.

[0152] In this case, as the positional relationship between the key K of the connector housing CH and the mark C of the multi-core optical fiber MF, there are the following relationship 1 and relationship 2. Fig.14 As shown in (b), compared with relation 2, the label c is closer to the key K; relation 2 is as follows Fig.14 As shown in (c), compared with relation 1, label c is far away from key K.

[0153] In the present embodiment, as the "pre-set condition" that the mark position of the multi-core optical fiber MF should satisfy with respect to the key position of the connector housing CH, either relationship 1 or relationship 2 is considered. In this way, the relationship between the mark position of the multi-core optical fiber MF and the key position of the connector housing CH is made consistent for all the multi-core optical fibers, so that when two multi-core optical fibers MF are connected, only by matching the key positions of the two multi-core optical fibers MF, it is not necessary to measure the mark position, and either the above-mentioned normal connection or flip connection can be performed.

[0154] (Summarize)

[0155] The control device of method 1 of the present invention comprises: a measurement control unit, which determines the mark position of the multi-core optical fiber; and an alignment control unit, which aligns the multi-core optical fiber by controlling the alignment mechanism so that the mark position on the end face of the multi-core optical fiber meets a preset condition.

[0156] Regarding the control device of method 2 of the present invention, according to the control device of method 1, the measurement control unit further determines the mark position on the end face of another multi-core optical fiber, and the centering control unit aligns the multi-core optical fiber relative to the other multi-core optical fiber so that the mark position on the end face of the multi-core optical fiber relative to the mark position on the end face of the other multi-core optical fiber meets a predetermined condition.

[0157] Regarding the control device of aspect 3 of the present invention, according to the control device of aspect 2, the alignment control unit aligns the multi-core optical fiber with respect to the other multi-core optical fiber so that the connection between the multi-core optical fiber and the other multi-core optical fiber becomes a normal connection.

[0158] Regarding the control device of aspect 4 of the present invention, according to the control device of aspect 2, the alignment control unit aligns the multi-core optical fiber with respect to the other multi-core optical fiber so that the connection between the multi-core optical fiber and the other multi-core optical fiber becomes a reverse connection.

[0159] Regarding the control device of method 5 of the present invention, according to the control device of method 2, the centering control unit determines whether the connection between the multi-core optical fiber and the other multi-core optical fiber is a same-type end face connection or a different-type end face connection. If it is a same-type end face connection, the multi-core optical fiber is centering relative to the other multi-core optical fiber to become a normal connection; if it is a different-type end face connection, the multi-core optical fiber is centering relative to the other multi-core optical fiber to become a flipped connection.

[0160] Regarding the control device of mode 6 of the present invention, according to the control device of mode 2, the alignment control unit aligns the multi-core optical fiber relative to the connector housing so that the mark position of the multi-core optical fiber relative to the key position of the connector housing satisfies a preset condition.

[0161] Regarding the control device of method 7 of the present invention, according to the control device of method 6, the centering control unit aligns the multi-core optical fiber relative to the connector housing so that the symmetry axis of the core on the end face of the multi-core optical fiber coincides with the axis of the connector housing determined according to the position of the key.

[0162] Regarding the control device of mode 8 of the present invention, according to the control device of mode 7, the alignment control unit aligns the multi-core optical fiber relative to the connector housing so that the mark on the end face of the multi-core optical fiber is arranged on a side close to the key.

[0163] A fusion splicing device according to a ninth aspect of the present invention includes the control device according to any one of the second to fourth aspects and the centering mechanism.

[0164] A connector connection device according to a tenth aspect of the present invention includes: the control device according to any one of aspects 6 to 8, and the centering mechanism.

[0165] The control program of aspect 11 of the present invention causes a computer to operate as the control device according to any one of aspects 1 to 8, and causes the computer to function as the measurement control unit and the alignment control unit.

[0166] (Appendix)

[0167] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical solutions disclosed in the above-described embodiments are also included in the technical scope of the present invention.

[0168] In addition, in this embodiment, the configuration in which various controls are implemented by software using the control device 10 is described, but the present invention is not limited thereto. Each component of the control device 10 may be implemented by software as described above, or may be implemented by hardware such as circuits.

[0169] Description of Reference Numerals

[0170] 10-control device; 10a-processor; 10b-primary memory; 10c-secondary memory; 10d-communication interface; 10e-bus; P-control program.

Claims

1. A control device, characterized in that: have: a measurement control unit that determines a marking position of the multi-core optical fiber; and The centering control unit controls the centering mechanism to center the multi-core optical fiber so that the mark position on the end face of the multi-core optical fiber meets a preset condition.

2. The control device according to claim 1, characterized in that: The measurement control unit further determines the mark position on the end face of another multi-core optical fiber, and the centering control unit aligns the multi-core optical fiber relative to the other multi-core optical fiber so that the mark position on the end face of the multi-core optical fiber relative to the mark position on the end face of the other multi-core optical fiber meets a pre-set condition.

3. The control device according to claim 2, characterized in that: The alignment control unit aligns the multi-core optical fiber with respect to the other multi-core optical fiber so that the multi-core optical fiber and the other multi-core optical fiber are normally connected.

4. The control device according to claim 2, characterized in that: The alignment control unit aligns the multi-core optical fiber with respect to the other multi-core optical fiber so that the connection between the multi-core optical fiber and the other multi-core optical fiber becomes a reverse connection.

5. The control device according to claim 2, characterized in that: The centering control unit determines whether the connection between the multi-core optical fiber and the other multi-core optical fiber is a same-type end face connection or a different-type end face connection. If it is a same-type end face connection, the multi-core optical fiber is centered relative to the other multi-core optical fiber to become a normal connection. If it is a different-type end face connection, the multi-core optical fiber is centered relative to the other multi-core optical fiber to become a flipped connection.

6. The control device according to claim 1, characterized in that: The alignment control unit aligns the multi-core optical fiber with respect to the connector housing so that the position of the mark of the multi-core optical fiber relative to the position of the key of the connector housing satisfies a preset condition.

7. The control device according to claim 6, characterized in that: The alignment control unit aligns the multi-core optical fiber with respect to the connector housing so that the symmetric axis of the cores on the end surface of the multi-core optical fiber coincides with the axis of the connector housing determined according to the position of the key.

8. The control device according to claim 7, characterized in that: The alignment control unit aligns the multi-core optical fiber with respect to the connector housing so that the mark on the end surface of the multi-core optical fiber is arranged on a side close to the key.

9. A fusion connection device, characterized in that: The invention comprises: the control device according to any one of claims 2 to 4, and the centering mechanism.

10. A connector connection device, characterized in that: The invention comprises: the control device according to any one of claims 6 to 8, and the centering mechanism.

11. A control program, characterized in that: A computer is made to operate as the control device according to any one of claims 1 to 8, and the computer is made to function as the measurement control unit and the alignment control unit.

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