Method for measuring multicore fiber and device for measuring multicore fiber

Abstract

This method for measuring a multicore fiber (10) comprises: a preparation step (SP11) for preparing a multicore fiber (10) in which the position of a core can be specified by imaging, and a fan-in device (20) in which the position of an optical waveguide can be specified by imaging; an imaging step (SP12) for imaging the multicore fiber (10) and the fan-in device (20); a determination step (SP13) for determining a combination of two or more cores and two or more optical waveguides on the basis of imaging results; an association step (SP14) for associating two or more cores with respective ports optically connected to optical waveguides respectively combined with the two or more cores; a connection step (SP15) for optically connecting the combined two or more cores and two or more optical waveguides individually; and a measurement step (SP16) for measuring the optical characteristics of the cores by causing light to enter the cores from the ports.

Description

Multi-core fiber measurement method and multi-core fiber measurement device

[0001] The present invention relates to a method for measuring a multicore fiber and a device for measuring a multicore fiber.

[0002] In response to the recent increase in the amount of information communication, there is a demand for an increase in the transmission capacity of optical fibers. Multicore fibers have attracted attention because they can improve space utilization efficiency and enable large-volume information transmission in a limited space. Multicore fibers are prone to crosstalk because multiple cores are arranged in one cladding. Therefore, measuring crosstalk is an important measurement item for multicore fibers. Patent Document 1 listed below discloses a method for measuring crosstalk in multicore fibers.

[0003] In this crosstalk measurement method, first, the output end of a light-transmitting optical fiber connected to a light source is optically connected to a specific core at the input end of a measurement multi-core fiber, and the input end of a light-receiving optical fiber connected to a light-receiving unit is optically connected to another core different from the specific core at the output end of the measurement multi-core fiber. Then, light from the light source is incident on the specific core via the light-transmitting optical fiber, causing crosstalk from the specific core to the other cores, and the light emitted from the other cores is received by the light-receiving unit via the light-receiving optical fiber. The power of this received light is measured to measure the crosstalk between the specific core and the other cores.

[0004] JP 2013-130558 A

[0005] In the crosstalk measurement method of Patent Document 1, it is necessary to optically reconnect the light-transmitting optical fiber and the light-receiving optical fiber to the multicore fiber every time a specific core is changed. In multicore fibers, the number of cores arranged in one cladding tends to increase in order to further improve space utilization efficiency, and a technology for efficiently evaluating crosstalk is required. In addition, a technology for efficiently measuring the optical properties of the cores of a multicore fiber, not limited to crosstalk, is required.

[0006] Therefore, an object of the present invention is to provide a multi-core fiber measurement method and a multi-core fiber measurement device that can improve the efficiency of measuring the optical properties of two or more cores.

[0007] A first aspect of the present invention is a method for measuring a multi-core fiber, comprising: a preparation step of preparing a multi-core fiber having a plurality of cores and capable of identifying positions of the cores by photography; and a fan-in device having a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, capable of identifying positions of the optical waveguides by photography; an imaging step of imaging one end of the multi-core fiber and the fan-in device; a determination step of determining, based on the imaging results, combinations of two or more of the cores of the plurality of cores at the one end of the multi-core fiber and two or more of the optical waveguides,

[0008] In this multi-core fiber measurement method, the port into which light is incident is associated with the core optically connected to that port, making it possible to identify which core's optical characteristics are being measured. Therefore, a configuration for associating the core with the measurement results after measurement may be unnecessary. Furthermore, when measuring the optical characteristics of a specific core among two or more cores and when measuring the optical characteristics of other cores, it is sufficient to switch the port into which light is incident, and there is no need to optically reconnect the multi-core fiber and the fan-in device. Therefore, according to this aspect, it is possible to improve the efficiency of measuring the optical characteristics of two or more cores in a multi-core fiber.

[0009] A second aspect of the present invention is the measurement method for a multi-core fiber according to the first aspect, wherein the multi-core fiber further has a marker, the fan-in device has a multi-core fiber including a plurality of cores and a marker as the plurality of optical waveguides, the photographing step photographs the plurality of cores and the marker of the multi-core fiber of the fan-in device, and the plurality of cores and the marker of the multi-core fiber optically connected to the fan-in device, and the determination step determines a combination of the two or more cores and the two or more optical waveguides based on positions of the plurality of cores and the marker in the multi-core fiber of the fan-in device and positions of the plurality of cores and the marker of the multi-core fiber optically connected to the fan-in device.

[0010] In this case, the combination of the cores of the multicore fiber and the optical waveguide of the fan-in device is determined using the cores and markers as landmarks, so that even if the cores are arranged in a rotationally symmetrical manner, it is easy to identify the positions of the cores and the combination can be easily determined. Furthermore, if the layout of the multiple cores and markers is non-linearly symmetrical, it is easy to distinguish between one end of the multicore fiber and the other end, and the combination can be more easily determined.

[0011] In a third aspect of the present invention, in the preparing step, a fan-out device is further prepared, which has a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, and in which positions of the optical waveguides can be identified by photography; in the photographing step, the other end of the multicore fiber and the fan-out device are further photographed; in the determining step, a combination of the two or more cores at the other end of the multicore fiber and two or more of the optical waveguides in the fan-out device is further determined based on the photographing results; and in the associating step, a combination of the two or more cores of the multicore fiber and the optical waveguides of the two or more cores is further determined based on the photographing results. the connecting step further individually optically connects the two or more cores at the other end of the combined multi-core fiber to the two or more optical waveguides of the fan-out device; and the measuring step measures optical properties of the cores of the multi-core fiber into which light is incident from the ports of the fan-in device by measuring light exiting from the ports of the fan-out device.

[0012] Such a measurement method for a multi-core fiber is suitable for measuring the optical characteristics of a core by inputting light into a core from one end of the multi-core fiber and receiving the light output from the other end of the multi-core fiber. In this embodiment, even if the core from which the light is input changes by changing the core from which the light is output, it is sufficient to switch the port from which the light is output and receive the light, and the efficiency of measuring the optical characteristics of two or more cores in a multi-core fiber can be improved.

[0013] A fourth aspect of the present invention is a method for measuring a multi-core fiber, comprising: a preparation step of preparing a multi-core fiber having a plurality of cores and capable of identifying positions of the cores by photography; and a fan-in device having a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, capable of identifying positions of the optical waveguides by photography; a connection step of individually optically connecting two or more of the plurality of cores at one end of the multi-core fiber to two or more of the plurality of optical waveguides; a photography step of photographing the one end of the multi-core fiber and the fan-in device; an associating step of associating each of the cores optically connected to the two or more optical waveguides with each of the ports optically connected to the cores via the optical waveguides based on the photography results; and a measurement step of introducing light into the cores from the ports optically connected to the cores via the optical waveguides, and measuring optical characteristics of the cores through which the light propagates from the ports.

[0014] In this way, the port into which light is incident after the splicing step may be associated with the core optically connected to the port. Even in this case, the efficiency of measuring the optical properties of two or more cores in a multicore fiber can be improved, similar to aspect 1.

[0015] A fifth aspect of the present invention is the measurement method for a multi-core fiber according to Aspect 4, characterized in that in the preparing step, a fan-out device is further prepared which has a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, and wherein positions of the optical waveguides can be identified by photography; in the connecting step, the two or more cores at the other end of the multi-core fiber are further individually optically connected to two or more of the optical waveguides in the fan-out device; in the photographing step, the other end of the multi-core fiber and the fan-out device are further photographed; in the associating step, combinations of the two or more cores of the multi-core fiber and the respective ports optically connected to the two or more cores via the optical waveguides of the fan-out device are further associated based on the photographing results; and in the measuring step, light exiting from the port of the fan-out device is measured, thereby measuring optical properties of the core of the multi-core fiber into which light is incident from the port of the fan-in device.

[0016] In this case, too, similarly to aspect 3, the efficiency of measuring the optical properties of two or more cores in a multicore fiber can be improved.

[0017] A sixth aspect of the present invention is a measurement device for a multi-core fiber having a plurality of cores and capable of identifying positions of the cores by photographing, the measurement device comprising: a fan-in device having a plurality of ports and a plurality of optical waveguides optically connected to the ports individually, and capable of identifying positions of the optical waveguides by photographing; an imaging unit capable of photographing one end of the multi-core fiber and the fan-in device; a determination unit that determines, based on a result of photographing, a combination of two or more of the cores of the plurality of cores at the one end of the multi-core fiber and two or more of the optical waveguides; an associating unit that associates the two or more cores with each of the ports optically connected to the optical waveguides combined with the two or more cores, respectively; a connection unit that optically connects the two or more cores at the one end of the combined multi-core fiber individually to the two or more optical waveguides; and a measurement unit that inputs light from the port optically connected to the core via the optical waveguide, and measures optical characteristics of the core through which the light propagates from the port.

[0018] According to such a multi-core fiber measurement device, similarly to aspect 1, it is possible to improve the efficiency of measuring the optical properties of two or more cores in a multi-core fiber.

[0019] A seventh aspect of the present invention is a measurement device for a multi-core fiber having a plurality of cores and capable of identifying positions of the cores by photography, comprising: a fan-in device having a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, and capable of identifying positions of the optical waveguides by photography; a connection unit that individually optically connects two or more of the plurality of cores at one end of the multi-core fiber to two or more of the optical waveguides; a photography unit that photographs the one end of the multi-core fiber and the fan-in device; an associating unit that associates each of the cores optically connected to the two or more optical waveguides with each of the ports optically connected to the cores via the optical waveguides based on a result of photography; and a measurement unit that inputs light from the port optically connected to the core via the optical waveguide and measures optical characteristics of the core through which the light propagates from the port.

[0020] In this way, the measurement device may be configured to associate a port into which light is incident after the multicore fiber and the fan-in device are optically connected with a core optically connected to the port. Even in this case, the efficiency of measuring the optical properties of two or more cores in a multicore fiber can be improved in the same way as in aspect 6.

[0021] As described above, according to the present invention, it is possible to provide a multi-core fiber measurement method and a multi-core fiber measurement device that can increase the efficiency of measuring the optical properties of two or more cores.

[0022] Fig. 1 is a cross-sectional view showing a multi-core fiber according to an embodiment of the present invention. Fig. 2 is a diagram showing a measurement device according to a first embodiment. Fig. 3 is a cross-sectional view showing a multi-core fiber of a fan-in device. Fig. 4 is a flowchart showing a method for measuring optical characteristics of a multi-core fiber of the first embodiment. Fig. 5 is a flowchart showing a method for measuring optical characteristics of a multi-core fiber in a modified example of the first embodiment. Fig. 6 is a diagram showing a measurement device according to a second embodiment. Fig. 7 is a cross-sectional view showing a multi-core fiber of a fan-out device.

[0023] Hereinafter, embodiments for carrying out a multicore fiber measurement method and a multicore fiber measurement device according to the present invention will be illustrated with reference to the accompanying drawings. The embodiments illustrated below are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified and improved from the following embodiments within the scope of the claims. Furthermore, in this specification, the dimensions of each component may be exaggerated to facilitate understanding.

[0024] (First embodiment) Fig. 1 is a diagram showing a cross section perpendicular to the longitudinal direction of a multicore fiber according to this embodiment. A multicore fiber 10 of this embodiment includes a plurality of cores 11a to 11d, a cladding 12 that tightly surrounds the outer circumferential surfaces of each of the cores 11a to 11d, and a marker 13 that is disposed within the cladding 12. The cores 11a to 11d are waveguides that can propagate light. Note that the cladding 12 is also called a common cladding, as it is a single cladding that commonly surrounds the outer circumferential surfaces of each of the cores 11a to 11d.

[0025] In the multicore fiber 10 of this embodiment, the cores 11a to 11d are arranged at approximately equal intervals on a circle centered on the central axis C of the cladding 12. In this embodiment, the four cores 11a to 11d are arranged at positions rotationally symmetrical about the central axis C. The refractive index of each of the cores 11a to 11d is higher than the refractive index of the cladding 12. The cores 11a to 11d are formed to have approximately the same diameter and approximately the same refractive index, and may propagate only light in the fundamental mode, or may propagate light in several higher-order modes in addition to light in the fundamental mode.

[0026] The markers 13 are provided so that the layout including the markers 13 and the cores 11a to 11d is asymmetric with respect to a line passing through the central axis C of the cladding 12. Therefore, the layout including the markers 13 and the cores 11a to 11d is different between the end face on one side and the end face on the other side of the multicore fiber 10. Therefore, by visually checking the end face on one side and the end face on the other side of the marker 13 by photographing or the like, it is possible to identify each end face. The marker 13 has a refractive index different from that of the cladding 12. The refractive index of the marker 13 is preferably higher than that of the cladding 12 from the viewpoint of easily making the marker 13 illuminate when light is incident and making it easy to visually check by photographing with a camera or the like, and is preferably lower than the refractive index of the cladding 12 from the viewpoint of suppressing crosstalk of light propagating through the cores 11a to 11d.

[0027] 1 shows the cross-sectional view when viewed from one side to the other side in the longitudinal direction of the multi-core fiber 10. Therefore, the appearance of the end face at the end on one side of the multi-core fiber 10 is the same as that in Fig. 1, and the appearance of the end face at the end on the other side of the multi-core fiber 10 is a layout obtained by inverting Fig. 1 in line symmetry.

[0028] The positions of the cores 11a to 11d can be identified by photographing the multicore fiber 10. For example, by photographing the end face on one side or the other side of the multicore fiber 10 with a camera, the positions of the cores 11a to 11d can be identified based on the position of the marker 13. Alternatively, by photographing the multicore fiber 10 from the side with a camera and rotating the multicore fiber 10 around the central axis C, the cores 11a to 11d and the marker 13 can be photographed, and the positions of the cores 11a to 11d can be identified from the positional relationship between the cores 11a to 11d and the marker 13.

[0029] Next, a measurement device capable of measuring the optical characteristics of the cores 11a to 11d of the multi-core fiber 10 will be described.

[0030] 2 is a diagram showing a measurement device for measuring the multicore fiber 10 according to this embodiment. As shown in Fig. 2, the measurement device 1 mainly includes a fan-in device 20, a connection unit 30, an imaging unit 40, a measurement unit 50, a processor 60, a memory 69, and a monitor 100.

[0031] <Fan-in Device 20> The fan-in device 20 includes a multi-core fiber 21, a plurality of optical fibers 22a to 22d, and a bridge section 23, and the multi-core fiber 21 and each of the optical fibers 22a to 22d are optically connected to each other at the bridge section 23.

[0032] As shown in Fig. 2, the side of the multicore fiber 21 opposite to the bridge portion 23 side is an open end. Fig. 3 is a diagram showing a cross section perpendicular to the longitudinal direction of the multicore fiber 21 of the fan-in device 20. The multicore fiber 21 of this embodiment has the same configuration as the multicore fiber 10, and includes cores 211a to 211d having the same configuration as the cores 11a to 11d, clads 212 having the same configuration as the clad 12 and surrounding the outer circumferential surfaces of each of the cores 211a to 211d without any gaps, and markers 213 having the same configuration as the marker 13 and arranged within the clad 12. The cores 211a to 211d and the marker 213 are arranged at the same positions as the cores 11a to 11d and the marker 13. The cores 211a to 211d are waveguides capable of propagating light, similar to the cores 11a to 11d.

[0033] As with the multi-core fiber 10, the positions of the cores 211a to 211d of the multi-core fiber 21 can be identified by photographing. Note that Fig. 3 shows the cross-sectional view when viewing the open end side of the multi-core fiber from the bridge portion 23 side of the multi-core fiber 21. Therefore, the appearance of the end face at the open end of the multi-core fiber 21 has a layout obtained by inverting Fig. 3 in line symmetry.

[0034] Each of the optical fibers 22a to 22d is a single-core fiber and has optical characteristics generally similar to those of the cores 211a to 211d. Therefore, the optical fibers 22a to 22d propagate light in a mode similar to that of the light propagated through the cores 211a to 211d. In this embodiment, the optical fibers 22a to 22d are ports into which light is incident from the measurement unit 50, as described below.

[0035] The bridge portion 23 optically connects the cores of the cores 211a to 211d to the cores 11a to 11d. The bridge portion 23 is, for example, a bridge fiber whose cross-sectional structure is similar to that of the multicore fiber 21 and whose diameter decreases from the optical fibers 22a to 22d side toward the multicore fiber 21 side. When the bridge portion 23 is a bridge fiber, the cores of the optical fibers 22a to 22d are individually connected to the cores on the end face of the bridge fiber on the single-core fiber side, and the cores 211a to 211d of the multicore fiber 21 are individually connected to the cores on the multicore fiber 21 side of the bridge fiber. Note that the bridge portion 23 may have a configuration different from that described above, as long as the cores of the optical fibers 22a to 22d are individually optically connected to the cores 211a to 211d of the multicore fiber 21 in the bridge portion 23. For example, in the bridge section 23, each core of the optical fibers 22a to 22d may be directly connected to the cores 211a to 211d of the multicore fiber 21 individually. Alternatively, in the bridge section 23, each core of the optical fibers 22a to 22d may be optically connected to the cores 211a to 211d of the multicore fiber 21 via a space. Therefore, the fan-in device 20 has a plurality of ports and a plurality of optical waveguides individually optically connected to the ports.

[0036] <Connection part 30> The connection part 30 is a part that individually optically connects each of the cores 11a to 11d of the multicore fiber 10 to each of the cores 211a to 211d of the multicore fiber 21 of the fan-in device 20. The connection part 30 of this example makes the end face at the open end of the multicore fiber 21 and the end face at one end of the multicore fiber 10 face each other. Note that in this specification, one end of the multicore fiber 10 means the end facing the fan-in device 20 side, and the other end of the multicore fiber 10 means the end facing optically opposite to the fan-in device 20 side. The connection part 30 of this embodiment has a fixing part 31 that can fix the multicore fiber 10, and a fixing part 32 that can fix the multicore fiber 21. The fixing unit 31 is configured to be able to move the multi-core fiber 10 along the longitudinal direction and to rotate the multi-core fiber 10 in a rotational direction, and the fixing unit 32 is configured to be able to move the multi-core fiber 21 along the longitudinal direction and to rotate the multi-core fiber 21 in the rotational direction. The connection unit 30 can fix the multi-core fiber 10 and the multi-core fiber 21 in a state where the end face of the multi-core fiber 10 and the end face of the multi-core fiber 21 are in contact with each other or in a state where the end face of the multi-core fiber 10 and the end face of the multi-core fiber 21 are close to each other. Furthermore, in the connection unit 30, optically transparent matching oil may be filled between the end face of the multi-core fiber 10 and the end face of the multi-core fiber 21. It is preferable that the refractive index of the matching oil is approximately the same as that of the cores 11a to 11d, 211a to 211d.

[0037] The connection unit 30 is electrically connected to a processor 60, and determines the positions of the end faces of the multicore fibers 21 and 10 and the positions of the multicore fibers 21 and 10 in the rotational direction based on control signals from the processor 60, which will be described later.

[0038] <Photographing Unit 40> The photographing unit 40 is capable of photographing at least one of the end face at one end of the multicore fiber 10, the end face at the open end of the multicore fiber 21, and the side faces of the multicore fibers 21, 10. The photographing unit 40 of this embodiment has a camera 41 and a mirror 42. The photographing unit 40 is electrically connected to the processor 60, and is controlled by control signals from the processor 60 to start and stop photographing, focus, and the like, and can output data including images photographed by the camera 41 to the processor 60. The mirror 42 includes a driving unit (not shown), and is driven by control signals from the processor 60 to move the mirror 42 in a direction perpendicular to the longitudinal direction of the multicore fibers 10, 21. FIG. 2 shows the mirror 42 positioned between the end faces of the multicore fibers 10, 21. In this state, the end faces of the multicore fibers 10, 21 are reflected on the mirror 42. Therefore, the camera 41 can photograph the cores 11a to 11d, 211a to 211d and the markers 13, 213 at the end faces via the mirror 42. When the end faces of the multicore fibers 10, 21 are brought closer to each other, the mirror 42 moves so as to move away from between the end faces of the multicore fibers 10, 21 in response to a control signal from the processor 60.

[0039] The photographing unit 40 may be configured to photograph only images of the side surfaces of the multicore fibers 10, 21. In this case, the mirror 42 may not be provided. In this case, the photographing unit 40 may include a light source that irradiates light from the side of the multicore fibers 10, 21 toward the camera 41, and the camera 41 may photograph the light from the light source that has passed through the multicore fibers 10, 21, thereby photographing the cores 11a to 11d, 211a to 211d and the markers 13, 213. The photographing unit 40 may also photograph at least one of the end faces and side surfaces of the multicore fibers 10, 21 by another method.

[0040] <Measurement unit 50> The measurement unit 50 inputs light from optical fibers 22a to 22d optically connected to the cores 11a to 11d of the multicore fiber 10 via the cores 211a to 211d of the fan-in device 20, and measures the optical characteristics of the cores 11a to 11d through which the light propagates from the optical fibers 22a to 22d. The measurement unit 50 is electrically connected to the processor 60, and the start and end of measurement are controlled by the processor 60, and the measurement unit 50 can output measured data to the processor 60.

[0041] The measurement unit 50 of this embodiment is configured, for example, by an OTDR (Optical Time Domain Reflectometer). The optical fibers 22a to 22d of the fan-in device 20 are optically connected to the measurement unit 50. The OTDR of this embodiment is a multi-channel type. When the measurement unit 50 is an OTDR, the measurement unit 50 selects one of the optical fibers 22a to 22d under the control of the processor 60, emits measurement light to the selected optical fiber, and measures the light returning from the selected optical fiber. Therefore, the OTDR can measure the optical characteristics of the cores 11a to 11d of the multi-core fiber 10 optically connected to the selected optical fiber 22a to 22d via one of the cores 211a to 211d by receiving light from the cores 11a to 11d of the multi-core fiber 10 optically connected to the optical fiber 22a to 22d into which the measurement light has been incident.

[0042] The measuring unit 50 is not limited to an OTDR as long as it receives light from the optical fibers 22a to 22d and measures the optical characteristics of the cores 11a to 11d of the multicore fiber 10. Even when an OTDR is used as the measuring unit 50, a plurality of single-channel OTDRs connected to the optical fibers 22a to 22d may be used, or one single-channel OTDR may be used and an optical switch may be provided between the OTDR and the optical fibers 22a to 22d so that the optical fiber connected to the OTDR can be switched.

[0043] <Processor 60, etc.> The processor 60 is formed, for example, by an integrated circuit such as a microcontroller, an integrated circuit (IC), a large-scale integrated circuit (LSI), or an application-specific integrated circuit (ASIC), or a numerical control (NC) device. The processor 60 may or may not use a machine learning device. The processor 60 is electrically connected to a memory 69.

[0044] The memory 69 is, for example, a non-transitory recording medium, and is preferably a semiconductor recording medium such as a random access memory (RAM) or a read only memory (ROM), but may include any type of recording medium such as an optical recording medium or a magnetic recording medium. Note that the term "non-transitory" recording medium includes all computer-readable recording media except for transient, propagating signals, and does not exclude volatile recording media.

[0045] The processor 60 of this embodiment mainly comprises a control unit 61, a determination unit 62, an association unit 63, and a data processing unit 64, and is electrically connected to the connection unit 30, the imaging unit 40, and the measurement unit 50 as described above, and controls these units using programs and data stored in the memory 69. Note that Fig. 2 shows an example in which the units within the processor 60 are connected by a bus line.

[0046] The control unit 61 is a part that outputs control signals to the splicing unit 30, the photographing unit 40, and the measuring unit 50. The control unit 61 outputs control signals that control, for example, the positions of the fixing units 31, 32 of the splicing unit 30 in the direction along the longitudinal direction of the multicore fibers 10, 21 and the rotational positions of the fixing units 31, 32 in the rotational direction of the multicore fibers 10, 21. The control unit 61 also outputs control signals that control, for example, the start of photographing, the end of photographing, focus, etc. of the camera 41 of the photographing unit 40. The control unit 61 also outputs control signals that control the measurement unit 50 to select the optical fibers 22a to 22d into which light is incident, the emission of light to the selected optical fibers 22a to 22d, the measurement of light incident from the selected optical fibers 22a to 22d, etc.

[0047] The determination unit 62 determines a combination of two or more cores of the plurality of cores 11a to 11d at one end of the multicore fiber 10 and two or more cores of the plurality of cores 211a to 211d of the multicore fiber 21. The combination of two or more cores of the cores 11a to 11d and two or more cores of the cores 211a to 211d is a combination of cores that face each other and are optically connected. The determination unit 62 determines this combination based on the imaging results of the multicore fibers 10, 21 that are captured by the imaging unit 40 and input to the processor 60.

[0048] In this embodiment, in the multicore fibers 10 and 21, the arrangement of the cores 11a to 11d is similar to the arrangement of the cores 211a to 211d, so when determining a combination of two or more cores, all combinations of the cores 11a to 11d and 211a to 211d are determined.

[0049] The determiner 62 may determine a combination of the multiple cores 11a to 11d and the multiple cores 211a to 211d based on the positions of the cores 11a to 11d, 211a to 211d of the multicore fibers 10, 21 and the positions of the markers 13, 213. For example, the determiner 62 determines a combination of the cores 11a to 11d and the cores 211a to 211d in a case where the markers 13, 213 are located above the cores 11a to 11d, 211a to 211d and the uppermost cores are aligned horizontally. There is a case where the multicore fiber 10 is set in the fixing unit 31 so that the arrangement of the cores 211a to 211d and the markers 213 on the end face of the multicore fiber 21 photographed by the camera 41 and the arrangement of the cores 11a to 11d and the markers 13 on the end face of one end of the multicore fiber 10 facing the multicore fiber 21 are line-symmetrical. In this case, when the combinations are determined as described above, the cores 11a to 11d are combined in order with the cores 211a to 211d. This means that the core 11a is combined with the core 211a, the core 11b is combined with the core 211b, the core 11c is combined with the core 211c, and the core 11d is combined with the core 211d. Conversely, when the end of the multicore fiber 10 is set in the fixing part 31 in the opposite direction and the other end of the multicore fiber 10 is made to be one end facing the multicore fiber 21, the arrangement of the cores 211a to 211d and the markers 213 on the end face of the multicore fiber 21 photographed by the camera 41 may be similar to the arrangement of the cores 11a to 11d and the markers 13 on the end face of the one end of the multicore fiber 10 facing the multicore fiber 21. In this case, once the combinations are determined as described above, core 11a and core 211b are combined, core 11b and core 211a are combined, core 11c and core 211d are combined, and core 11d and core 211c are combined.

[0050] However, the determination unit 62 may determine the combination using a method different from the above, as long as it determines a combination of two or more of the multiple cores 11a to 11d that face each other and two or more of the multiple cores 211a to 211d.

[0051] The associating unit 63 associates the cores 11a to 11d of the multicore fiber 10 with the optical fibers 22a to 22d that are optically connected to the cores 211a to 211d of the multicore fiber 21 that are combined with the cores 11a to 11d, respectively. The memory 69 stores the pairs of the cores 11a to 11d and the optical fibers 22a to 22d that are associated by the associating unit 63. In this example, the cores 211a to 211d and the optical fibers 22a to 22d are optically connected in order, and this information is stored in the memory 69. Therefore, as described in relation to the determining unit 62, for example, when the cores 11a to 11d and the cores 211a to 211d are combined in order, the associating unit 63 associates the cores 11a to 11d with the optical fibers 22a to 22d as if they were combined in order. That is, the core 11a and the optical fiber 22a, the core 11b and the optical fiber 22b, the core 11c and the optical fiber 22c, and the core 11d and the optical fiber 22d are associated with each other.

[0052] The data processing unit 64 processes data relating to the image captured by the imaging unit 40 and data relating to the measurement results of the cores 11a to 11d of the multi-core fiber 10 measured by the measuring unit 50. The processor 60 outputs the processed data.

[0053] The monitor 100 is electrically connected to the processor 60 and displays the data processed by the data processing unit 64 in accordance with the format instructed by the processor 60 .

[0054] Next, a method for measuring the optical characteristics of two or more cores 11a to 11d of the multi-core fiber 10 in this embodiment will be described.

[0055] Fig. 4 is a flowchart showing a method for measuring optical characteristics of the multi-core fiber 10 according to this embodiment. As shown in Fig. 4, the measurement method according to this embodiment includes a preparation step SP11, a photographing step SP12, a determination step SP13, an association step SP14, a connection step SP15, and a measurement step SP16.

[0056] <Preparation Step SP11> This step is a step of preparing the multicore fiber 10 to be measured and the fan-in device 20 optically connected to the multicore fiber 10. As described above, the multicore fiber has a plurality of cores 11a to 11d, and the positions of the cores 11a to 11d can be identified by photography, while the fan-in device 20 has a plurality of optical fibers 22a to 22d and a plurality of cores 211a to 211d individually optically connected to the optical fibers 22a to 22d, and the positions of the cores 211a to 211d can be identified by photography. In this embodiment, the multicore fiber 10 shown in FIG. 1 and a measurement apparatus 1 are prepared. The measurement apparatus 1 includes the fan-in device 20, and therefore the fan-in device 20 is prepared by preparing the measurement apparatus 1.

[0057] One end of the prepared multi-core fiber 10 is set in the fixing portion 31 of the measurement device 1 .

[0058] <Photographing step SP12> This step is a step of photographing one end of the prepared multi-core fiber 10 and the fan-in device 20. First, the control unit 61 of the processor 60 controls the connection unit 30 to move the fixing units 31, 32 so that the end face of one end of the multi-core fiber 10 and the end face of the open end of the multi-core fiber 21 of the fan-in device 20 are separated by a predetermined distance. Furthermore, the control unit 61 controls the photographing unit 40 to move the mirror 42 so that the mirror 42 is positioned between the end faces of the multi-core fibers 10, 21. Then, under the control of the control unit 61, the camera 41 photographs each of the end faces of the multi-core fibers 10, 21 reflected on the mirror 42. In this way, the cores 11a to 11d and the marker 13 at the end face of the multi-core fiber 10, and the cores 211a to 211d and the marker 213 at the end face of the fan-in device 20 are photographed. Thereafter, the control unit 61 controls the mirror 42 to retract the mirror 42 from between the end faces of the multi-core fibers 10 and 21 .

[0059] Note that in this step, the multicore fibers 10, 21 may be photographed from the side. In this case, the control unit 61 controls the splicing unit 30 to move the fixing units 31, 32 so that the end face of one end of the multicore fiber 10 and the end face of the open end of the multicore fiber 21 of the fan-in device 20 are closer than described above. Then, the camera 41 photographs the multicore fibers 10, 21 from the side under the control of the control unit 61. At this time, the photographing unit 40 irradiates light from a light source (not shown) that irradiates light from the side of the multicore fibers 10, 21 toward the camera 41, and the camera 41 photographs the light from the light source that has transmitted through the multicore fibers 10, 21. Furthermore, the control unit 61 controls the fixing units 31, 32 during photographing to rotate the multicore fibers 10, 21 around their axes. In this way, the camera 41 photographs one revolution of the multicore fibers 10, 21.

[0060] The camera 41 outputs captured image data, which is input to a data processing unit 64 of the processor 60. The data processing unit 64 analyzes the input image data and maps the positions of the cores 11a to 11d, 211a to 211d, and the markers 13, 213. In this step, the data processing unit 64 may calculate the relationship between the positions of the cores 11a to 11d, 211a to 211d, and the markers 13, 213 and the positions of the fixed parts 31, 32 in the rotational direction, and store the calculation results in the memory 69.

[0061] <Determining step SP13> This step is a step of determining, based on the imaging results, combinations of two or more cores out of the plurality of cores 11a to 11d at one end of the multicore fiber 10 and two or more cores out of the plurality of cores 211a to 211d that are the plurality of optical waveguides. As described above, in the present embodiment, the arrangement of the cores 11a to 11d and the arrangement of the cores 211a to 211d are similar in the multicore fibers 10 and 21, and therefore, when determining combinations of two or more cores, combinations of all of the cores 11a to 11d and the cores 211a to 211d are determined.

[0062] Prior to this step, based on the data mapped by the data processing unit 64, the determination unit 62 may determine whether the arrangement of the cores 211a to 211d and the markers 213 at the end face of the multicore fiber 21 photographed by the camera 41 and the arrangement of the cores 11a to 11d and the markers 13 at the end face of one end of the multicore fiber 10 facing the multicore fiber 21 are arranged symmetrically with respect to an axis or are the same arrangement.

[0063] In this step, the determiner 62 determines the combinations of the cores 11a to 11d and the cores 211a to 211d based on, for example, the positions of the cores 11a to 11d, 211a to 211d and the markers 13, 213 in the multicore fibers 10, 21. In this case, the determiner 62 determines the combinations of the cores 11a to 11d and the cores 211a to 211d, for example, as in the example described in the description of the determiner 62.

[0064] This step is not limited to the above, and the cores 11a to 11d and 211a to 211d may be combined in other combinations as long as the cores 11a to 11d and 211a to 211d can face each other.

[0065] <Association step SP14> This step is a step of associating the multiple cores 11a to 11d at one end of the multicore fiber 10 with the respective optical fibers 22a to 22d optically connected to the cores 211a to 211d of the multicore fiber 21 combined with the cores 11a to 11d, respectively.

[0066] In this step, the associating unit 63 reads out information about the multicore fiber 21 stored in the memory 69. As described above, in this embodiment, the memory 69 stores the pairs of optical fibers 22a to 22d optically connected to the cores 211a to 211d. The associating unit 63 associates the cores 11a to 11d with the optical fibers 22a to 22d connected to the cores 211a to 211d combined with the cores 11a to 11d. For example, as described above, if the cores 211a to 211d and the optical fibers 22a to 22d are optically connected in order, and the determining unit 62 has combined the cores 11a to 11d with the cores 211a to 211d in order, the associating unit 63 associates the cores 11a to 11d with the optical fibers 22a to 22d as being combined in order. The associating unit 63 stores the associated data in the memory 69.

[0067] <Connection step SP15> This step is a step of individually optically connecting two or more cores at one end of the combined multi-core fiber 10 to two or more cores of the multi-core fiber 21. As described above, in this embodiment, when determining a combination of two or more cores, the combinations of all of the cores 11a to 11d and the cores 211a to 211d are determined. Therefore, in this step of the embodiment, the cores 11a to 11d of the multi-core fiber 10 and the cores 211a to 211d of the multi-core fiber 21 are individually optically connected in the determined combination.

[0068] In this step, the control unit 61 controls the fixing units 31, 32 of the connection unit 30 to align the rotational positions of the multicore fibers 10, 21 so that the cores 11 to 11d and the cores 211a to 211d face each other in the combination determined in the determination step SP13. For example, the markers 13, 213 of the multicore fibers 10, 21 are aligned so that they are positioned above the cores, respectively, and the uppermost cores are aligned horizontally.

[0069] In addition, in the photographing step SP12, when the relationship between the positions of the cores 11a to 11d, 211a to 211d and the markers 13, 213 and the positions of the fixing parts 31, 32 in the rotational direction is stored in the memory 69, the control part 61 may use the relationship to control the fixing parts 31, 32 and align the rotational positions of the multicore fibers 10, 21 so that the cores 11 to 11d and the cores 211a to 211d face each other. Alternatively, in this step, similar to the photographing step SP12, while photographing the multicore fibers 10, 21 with the photographing part 40, the rotational positions of the multicore fibers 10, 21 may be aligned using image data of the photographed image so that the cores 11 to 11d and the cores 211a to 211d face each other.

[0070] <Measurement step SP16> This step is a step of incidenting light from optical fibers 22a to 22d optically connected to the cores 11a to 11d of the multicore fiber 10 via the cores 211a to 211d of the multicore fiber 21, and measuring the optical characteristics of the cores of the multicore fiber 10 through which the light propagates from the optical fibers 22a to 22d.

[0071] In this embodiment, the measurement unit 50 selects a predetermined optical fiber from the optical fibers 22a to 22d under the control of the control unit 61 of the processor 60, and emits measurement light to the selected optical fiber. In this embodiment, for example, the optical fibers 22a to 22d are selected in order. When the measurement unit 50 is an OTDR, the measurement unit 50 measures the timing of emitting the measurement light, the timing until the measurement unit 50 receives the light emitted from the optical fibers 22a to 22d due to Rayleigh scattering or the like in the cores 11a to 11d of the multicore fiber 10, the power of the received light, and the like. The measurement unit 50 outputs data related to the measurement results, and the data is input to the processor 60. Therefore, the fan-in device 20 also functions as a fan-out device that emits light from the cores 11a to 11d of the multicore fiber 10 from the optical fibers 22a to 22d.

[0072] It should be noted that the measurement unit 50 is not limited to an OTDR. For example, the measurement unit 50 may include a light incident unit that incidents measurement light into the optical fibers 22 a to 22 d and a camera that photographs the multicore fiber 10 from the side, and may measure the optical characteristics of the cores 11 a to 11 d optically connected to the optical fiber into which the measurement light is incident, based on the image photographed by the camera.

[0073] The data processing unit 64 of the processor 60 analyzes the input data and outputs data relating to the analysis results to the monitor 100. The monitor 100 displays an image based on the received data.

[0074] In this way, the optical characteristics of the cores 11a to 11d of the multi-core fiber 10 are measured.

[0075] As described above, the measurement method for the multi-core fiber 10 of the present embodiment includes a preparation step SP11 of preparing the multi-core fiber 10 having a plurality of cores 11a to 11d and allowing the positions of the cores 11a to 11d to be identified by photography, and the fan-in device 20 having a plurality of optical fibers 22a to 22d and a plurality of cores 211a to 211d individually optically connected to the optical fibers 22a to 22d and allowing the position of the optical waveguide to be identified by photography; an imaging step SP12 of imaging one end of the multi-core fiber 10 and the fan-in device 20; and an imaging step SP13 of imaging a combination of the plurality of cores 11a to 11d at one end of the multi-core fiber 10 and the plurality of cores 211a to 211d of the fan-in device 20. based on the photographing results; an associating step SP14 of associating the cores 11a to 11d with the optical fibers 22a to 22d optically connected to the cores 211a to 211d combined with the cores 11a to 11d, respectively; a connecting step SP15 of optically connecting the cores 11a to 11d and the cores 211a to 211d individually at one end of the combined multicore fiber 10; and a measuring step SP16 of incident light from the optical fibers 22a to 22d optically connected to the cores 11a to 11d via the cores 211a to 211d to measure the optical characteristics of the cores of the multicore fiber 10 through which the light propagates from the optical fibers 22a to 22d.

[0076] According to this measurement method for the multi-core fiber 10, the optical fibers 22a to 22d into which measurement light is incident are associated with the cores 11a to 11d of the multi-core fiber 10 optically connected to the optical fibers 22a to 22d, so it is possible to identify which core's optical characteristics are being measured. Therefore, a process of associating the cores 11a to 11d with the measurement results after measurement can be eliminated. Furthermore, when measuring the optical characteristics of one of the cores 11a to 11d and when measuring the optical characteristics of another core, it is sufficient to switch the optical fiber into which light is incident, and there is no need to optically reconnect the multi-core fiber 10 and the fan-in device 20. Therefore, according to the measurement method for the multi-core fiber of this embodiment, it is possible to improve the efficiency of measuring the optical characteristics of two or more cores in the multi-core fiber 10.

[0077] Furthermore, the multicore fiber 10 of this embodiment has a plurality of cores 11a to 11d and a marker 13, and the fan-in device 20 has a multicore fiber 21 including a plurality of cores 211a to 211d and a marker 213. In an imaging step SP12, the plurality of cores 211a to 211d and the marker 213 of the multicore fiber 21 of the fan-in device 20, and the plurality of cores 11a to 11d and the marker 13 of the multicore fiber 10 optically connected to the fan-in device 20 are imaged. In a determination step SP13, a combination of the cores 11a to 11d of the multicore fiber 10 and the cores 211a to 211d of the multicore fiber 21 is determined based on the positions of the plurality of cores 211a to 211d and the marker 213 in the multicore fiber 21 of the fan-in device 20 and the positions of the plurality of cores 11a to 11d and the marker 13 of the multicore fiber 10 optically connected to the fan-in device 20.

[0078] The cores 11a to 11d, 211a to 211d and the markers 13, 213 are used as marks to determine the combination of the cores 11a to 11d of the multicore fiber 10 and the cores 211a to 211d of the fan-in device 20, and therefore even when the multiple cores 11a to 11d, 211a to 211d are arranged rotationally symmetrically as in this embodiment, it is easy to identify the positions of the cores 11a to 11d, 211a to 211d, and the combination of cores can be easily determined. Furthermore, when the layout of the multiple cores 11a to 11d, 211a to 211d and the markers 13, 213 is arranged non-linearly symmetrically as in this embodiment, it is easy to distinguish between the ends on one side and the ends on the other side of the multicore fibers 10, 21, and the combination can be more easily determined.

[0079] (Modification) Next, a modification of this embodiment will be described.

[0080] In this modification, the optical characteristics of the cores 11a to 11d of the multicore fiber 10 are measured in the same manner as in the above embodiment, and a measuring device similar to the measuring device 1 in the above embodiment is used. Therefore, the description of the same configuration as in the above description will be omitted unless otherwise specified.

[0081] Fig. 5 is a flowchart showing a method for measuring the optical characteristics of the multi-core fiber 10 in this modified example. As shown in Fig. 5, the measurement method of this embodiment includes a preparation step SP21, a connection step SP22, a photographing step SP23, an association step SP24, and a measurement step SP25. That is, in this modified example, the procedure of the measurement method differs from that of the above embodiment.

[0082] (Preparation Step SP21) This step is the same as the preparation step SP11 in the above embodiment. The prepared multi-core fiber 10 is set in the measurement device 1 in the same manner as in the first embodiment.

[0083] (Connection step SP22) Unlike the above embodiment, this modification does not include the determination step SP13. Therefore, the combination of the cores 211a to 211d of the multicore fiber 21 and the cores 11a to 11d of the multicore fiber 10 has not been determined. For this reason, the control unit 61 controls the fixing units 31, 32 of the connection unit 30 so that the cores 11a to 11d of the multicore fiber 10 and the cores 211a to 211d of the multicore fiber 21 face each other. At this time, in this modification, for example, the imaging unit 40 images the cores 11a to 11d, 211a to 211d and the markers 13, 213, and the multicore fibers 10, 21 are rotationally aligned so that the cores 11a to 11d of the multicore fiber 10 and the cores 211a to 211d of the multicore fiber 21 face each other individually. For example, by photographing as described above, the markers 13, 213 are positioned above the cores 11a to 11d, 211a to 211d, and the cores 11a to 11d and 211a to 211d are individually made to face each other so that the markers 13, 213 are positioned above the cores 11a to 11d, 211a to 211d, and the uppermost cores are aligned horizontally. Alternatively, the multicore fibers 10, 21 may be rotated so that the rotation angle during rotational alignment is minimized, and the cores 11a to 11d and 211a to 211d may be individually made to face each other. Note that when performing rotational alignment by photographing with the photographing unit 40, the end faces or side faces of the multicore fibers 10, 21 may be photographed. Alternatively, without taking an image using the imaging unit 40, rotational alignment may be performed while light is being incident on at least one of the optical fibers 22a to 22d of the fan-in device 20, and the cores 11a to 11d may be individually opposed to the cores 211a to 211d in a state in which the light is most efficiently propagated to the cores 11a to 11d of the multicore fiber 10.

[0084] (Photographing step SP23) This step is a photographing step of photographing one end of the multi-core fiber 10 and the fan-in device 20. In the connection step SP22, the cores 11a to 11d and the cores 211a to 211d are optically connected. Therefore, in this step, the end face of the multi-core fiber 10 and the end face of the multi-core fiber 21 are generally close to or in contact with each other. Therefore, in this step, it is preferable that the photographing unit 40 photographs the multi-core fibers 10, 21 from the side. At this time, the control unit 61 controls the connection unit 30 to rotate the multi-core fibers 10, 21 about their axes, and causes the photographing unit 40 to photograph the multi-core fibers 10, 21, in the same way as the photographing unit 40 photographs the multi-core fibers 10, 21 from the side in the photographing step SP12 of the above embodiment. The camera 41 outputs the photographed image data, and the image data is input to the data processing unit 64 of the processor 60. The data processing unit 64 analyzes the input image data and maps the positions of the cores 11a to 11d, 211a to 211d, and the markers 13, 213. The mapped data is stored in the memory 69.

[0085] (Association process SP24) This process is a process of associating each of the cores 11a to 11d optically connected to the cores 211a to 211d of the multicore fiber 21 with each of the optical fibers 22a to 22d optically connected to the cores 11a to 11d via the cores 211a to 211d based on the imaging results.

[0086] The associating unit 63 reads information about the cores 11a to 11d and the cores 211a to 211d that are optically connected to each other, which information is stored in the memory 69. At this time, for example, pairs of the optically connected cores 11a to 11d and the cores 211a to 211d may be determined based on the mapped positions of the cores 11a to 11d and 211a to 211d. As described above, the memory 69 stores pairs of the cores 211a to 211d and the optical fibers 22a to 22d that are optically connected to the cores 211a to 211d. Therefore, the associating unit 63 associates the cores 11a to 11d with the optical fibers 22a to 22d that are connected to the cores 211a to 211d that are optically connected to the cores 11a to 11d. For example, when the cores 211a to 211d are optically connected in order to the optical fibers 22a to 22d, and the cores 11a to 11d are optically connected in order to the cores 211a to 211d, the associating unit 63 associates the cores 11a to 11d with the optical fibers 22a to 22d as being optically coupled in order. The associating unit 63 stores the associated data in the memory 69.

[0087] (Measuring Step SP25) The measuring step of this modified example is the same as the measuring step SP16 of the above embodiment.

[0088] As described above, the measurement method for the multi-core fiber 10 of this modified example includes a preparation step SP21 similar to the preparation step SP11 of the first embodiment, a connection step SP22 of individually optically connecting the multiple cores 11a to 11d at one end of the multi-core fiber 10 to the multiple cores 211a to 211d, an imaging step SP23 of imaging the one end of the multi-core fiber 10 and the fan-in device 20, and an imaging step SP24 of imaging the multiple cores 211a to 211d optically connected to the cores 211a to 211d of the multi-core fiber 21. The method includes an associating step SP24 of associating, based on the photographing results, each of the cores 11a to 11d of the multicore fiber 10 with each of the optical fibers 22a to 22d optically connected to the cores 11a to 11d of the multicore fiber 10 via the cores 211a to 211d, and a measuring step SP25 of measuring the optical characteristics of the cores 11a to 11d through which the light propagates from the optical fibers 22a to 22d.

[0089] As in this modification, the optical fibers 22 a to 22 d, which are ports into which light is incident after the connection step SP22, may be associated with the cores 11 a to 11 d optically connected to the optical fibers 22 a to 22 d. Even in this case, the efficiency of measuring the optical properties of two or more cores in the multicore fiber 10 can be improved, similar to the above embodiment.

[0090] Second Embodiment Next, a second embodiment of the present invention will be described. Note that the same components as those described above are denoted by the same reference numerals, and descriptions thereof will be omitted unless otherwise specified.

[0091] This embodiment is similar to the first embodiment in that it measures the optical characteristics of the cores 11a to 11d of the multicore fiber 10. Fig. 6 is a diagram showing the measurement device 1 of this embodiment. As shown in Fig. 6, the measurement device 1 of this embodiment differs from the measurement device 1 of the first embodiment mainly in that it includes a fan-out device 70, a connection unit 80, and an imaging unit 90, and the configuration of the measurement unit 50 differs from the configuration of the measurement unit 50 of the first embodiment.

[0092] <Fan-out device 70> The fan-out device 70 includes a multi-core fiber 71, a plurality of optical fibers 72a to 72d, and a bridge unit 73. In this embodiment, the configuration of the fan-out device 70 is the same as that of the fan-in device 20. The description of the fan-out device 70 is the same as that of the fan-in device 20, except that the multi-core fiber 21 is replaced with the multi-core fiber 71, the optical fibers 22a to 22d are replaced with the optical fibers 72a to 72d, and the bridge unit 23 is replaced with the bridge unit 73. FIG. 7 is a cross-sectional view showing the multi-core fiber 71 of the fan-out device 70. As shown in FIG. 7, the multi-core fiber 71 of this embodiment has the same configuration as the multi-core fiber 21. Therefore, in the description of the multi-core fiber 71, the cores 211a to 211d are replaced with the cores 711a to 711d, the cladding 212 is replaced with the cladding 712, and the marker 213 is replaced with the marker 713 in the description of the multi-core fiber 21. Therefore, the fan-out device 70 has a plurality of ports and a plurality of optical waveguides that are individually optically connected to the ports.

[0093] <Connection portion 80> The connection portion 80 is a portion that individually optically connects each of the cores 11a to 11d of the multicore fiber 10 to each of the cores 711a to 711d of the multicore fiber 71 of the fan-out device 70. If the connection portion 30 is an incident-side connection portion, the connection portion 80 is an output-side connection portion. In this embodiment, the configuration of the connection portion 80 is the same as the configuration of the connection portion 30. Therefore, the description of the connection portion 80 is the same as the description of the connection portion 30, and in the description of the connection portion 30, the fixed portion 31 is replaced with the fixed portion 81, the fixed portion 32 is replaced with the fixed portion 82, and the multicore fiber 21 is replaced with the multicore fiber 71.

[0094] <Photographing unit 90> The photographing unit 90 is capable of photographing at least one of the end face at the other end of the multicore fiber 10 and the end face at the open end of the multicore fiber 71, and the side faces of the multicore fibers 71, 10. If the photographing unit 40 is an incident-side photographing unit, the photographing unit 90 is an output-side photographing unit. In this embodiment, the configuration of the photographing unit 90 is the same as the configuration of the photographing unit 40. Therefore, the description of the photographing unit 90 is the same as the description of the photographing unit 40, and in the description of the photographing unit 40, the camera 41 is replaced with the camera 91, the mirror 42 is replaced with the mirror 92, and the multicore fiber 21 is replaced with the multicore fiber 71.

[0095] <Measurement Unit 50> The measurement unit 50 inputs light from the optical fibers 22a to 22d optically connected to the cores 11a to 11d of the multicore fiber 10 via the cores 211a to 211d of the fan-in device 20, and measures the light output from the optical fibers 72a to 72d of the fan-out device 70, thereby measuring the optical characteristics of the cores 11a to 11d through which light propagates from the optical fibers 22a to 22d of the fan-in device 20. In this embodiment, the measurement unit 50 has a light source unit 51 and a light receiving unit 52.

[0096] The light source unit 51 is optically connected to the optical fibers 22a to 22d of the fan-in device 20. The light source unit 51 is electrically connected to the processor 60, and selects one of the optical fibers 22a to 22d in response to a control signal from the control unit 61, and emits measurement light to the selected optical fiber 22a to 22d.

[0097] The light receiving unit 52 is optically connected to the optical fibers 72a to 72d of the fan-out device 70. When the light receiving unit 52 receives light from one of the optical fibers 72a to 72d, it outputs data related to the optical fiber that emitted the light and the power of the received light. The light receiving unit 52 is electrically connected to the processor 60, and the output data is input to the processor 60.

[0098] In this way, the measuring unit 50 measures the optical characteristics of the cores 11a to 11d of the multicore fiber 10 by irradiating light from the light source unit 51 into the optical fibers 22a to 22d, propagating the light through the cores 11a to 11d of the multicore fiber, and receiving the light emitted from the optical fibers 72a to 72d with the light receiving unit 52.

[0099] Note that there are cases where the optical fibers 22a to 22d into which the light source unit 51 inputs light are not optically coupled to the optical fibers 72a to 72d that output light to the light-receiving unit 52. For example, when measuring crosstalk in the multi-core fiber 10, the light source unit 51 inputs light into a specific optical fiber among the optical fibers 22a to 22d, and in the light-receiving unit 52, light crosstalks from a specific core of the multi-core fiber 10 into which light from the specific optical fiber is input to another core. Therefore, the optical fiber of the fan-out device 70 that outputs light to the light-receiving unit 52 is not optically coupled to the specific optical fiber of the fan-in device 20.

[0100] Next, a method for measuring the optical characteristics of two or more cores 11a to 11d of the multi-core fiber 10 in this embodiment will be described.

[0101] The flowchart of the method for measuring the optical characteristics of the multi-core fiber 10 according to this embodiment is similar to the flowchart of the first embodiment shown in FIG.

[0102] <Preparation step SP11> This step of the present embodiment differs from the preparation step SP11 of the first embodiment in that, in addition to the preparation step SP11 of the first embodiment, a fan-out device 70 is further prepared, which has a plurality of optical fibers 72 a to 72 d and a plurality of cores 711 a to 711 d individually optically connected to the optical fibers 72 a to 72 d, and which can identify the positions of the cores 711 a to 711 d by photography.

[0103] As described above, the fan-out device 70 of this embodiment has the same configuration as the fan-in device 20. Therefore, it is sufficient to prepare the multi-core fiber 10 and two fan-in fan-out devices having the same configuration as the fan-in device 20. As described above, the measurement apparatus 1 of this embodiment includes the fan-in device 20 and the fan-out device 70. Therefore, in this step of this embodiment, the multi-core fiber 10 and the measurement apparatus 1 shown in FIG. 6 are prepared.

[0104] One end of the prepared multi-core fiber 10 is set to the fixing part 31 of the measurement device 1 , and the other end is set to the fixing part 81 .

[0105] <Photographing step SP12> This step of the present embodiment differs from the photographing step SP12 of the first embodiment in that, in addition to the photographing step SP12 of the first embodiment, the other end of the multicore fiber 10 and the fan-out device are further photographed. Furthermore, in the present embodiment, when photographing the multicore fiber 10, if the end face of the multicore fiber 10 is to be photographed, the end faces of one end and the other end of the multicore fiber 10 are photographed. Furthermore, if the multicore fiber 10 is photographed from the side, the one end and the other end of the multicore fiber 10 are photographed from the side. Therefore, in this step, the step of photographing the multicore fiber 10 and the fan-in device 20 at one end side of the multicore fiber 10 is the same as the photographing step SP12 in the first embodiment. Furthermore, for the description of the step of photographing the multicore fiber 10 and the fan-out device 70 at the other end side of the multicore fiber 10, the description of the photographing step SP12 in the first embodiment is rephrased as follows. That is, the fan-in device 20 and each configuration of the fan-in device 20 are read as the fan-out device 70 and each configuration of the fan-out device 70, one end of the multi-core fiber 10 is read as the other end, the connection unit 30 and each configuration of the connection unit 30 are read as the connection unit 80 and each configuration of the connection unit 80, and the photographing unit 40 and each configuration of the photographing unit 40 are read as the photographing unit 90 and each configuration of the photographing unit 90.

[0106] <Determining step SP13> This step of the present embodiment differs from the determining step SP13 of the first embodiment in that, in addition to the determining step SP13 of the first embodiment, the determining unit 62 further determines, based on the imaging results, combinations of two or more cores at the other end of the multicore fiber 10 with two or more cores among the multiple cores 711a to 711d that constitute the multiple optical waveguides in the fan-out device 70. These two or more cores at the other end are the two or more cores combined with cores of the multicore fiber 21 in the first embodiment. However, as described above, the multicore fiber 10 and the multicore fiber 21 have the same configuration, and all of the cores 11a to 11d are individually combined with all of the cores 211a to 211d. Therefore, in the present embodiment, the determining unit 62 further individually combines all of the cores 11a to 11d with all of the cores 711a to 711d. The explanation of the determination unit 62 individually combining the cores 11a to 11d with the cores 711a to 711d is given by replacing one end of the multicore fiber 10 with the other end, each of the cores 211a to 211d of the multicore fiber 21 with each of the cores 711a to 711d of the multicore fiber 71, and replacing the marker 213 with the marker 713 in the explanation of the determination step SP13 of the first embodiment.

[0107] <Associating Step SP14> This step of the present embodiment differs from the associating step SP14 of the first embodiment in that, in addition to the associating step SP14 of the first embodiment, the present embodiment further associates combinations of two or more of the cores 11a to 11d with the respective optical fibers optically connected to the cores in the fan-out device 70 combined with the two or more cores. As described above, in the present embodiment, all of the cores 11a to 11d are individually combined with all of the cores 711a to 711d. Therefore, in this step of the present embodiment, the associating unit 63 further associates combinations of the cores 11a to 11d with the respective optical fibers 72a to 72d optically connected to the cores 711a to 711d of the multi-core fiber 71 in the fan-out device 70 combined with the respective cores 11a to 11d. The explanation of the associating unit 63 associating the cores 11a to 11d with the optical fibers 72a to 72d is given by replacing one end of the multicore fiber 10 with the other end in the explanation of the associating step SP14 of the first embodiment, replacing the cores 211a to 211d of the multicore fiber 21 with the cores 711a to 711d of the multicore fiber 71, and replacing the optical fibers 22a to 22d with the optical fibers 72a to 72d.

[0108] <Connection step SP15> This step of the present embodiment differs from the connection step SP15 of the first embodiment in that, in addition to the connection step SP15 of the first embodiment, two or more cores at the other end of the combined multi-core fiber 10 are individually optically connected to two or more optical waveguides of the fan-out device 70. As described above, in the present embodiment, all of the cores 11a to 11d and all of the cores 711a to 711d are individually combined. Therefore, in this step of the present embodiment, the connection unit 80 individually optically connects the cores 11a to 11d at the other end of the combined multi-core fiber 10 to the cores 711a to 711d of the multi-core fiber 71 of the fan-out device 70. The explanation of how the connection portion 80 optically connects the cores 11a to 11d and the cores 711a to 711d is given by replacing the multicore fiber 21 with the multicore fiber 71, the cores 211a to 211d with the cores 711a to 711d in the explanation of the connection step SP15 of the first embodiment, and replacing the connection portion 30 and each component of the connection portion 30 with the connection portion 80 and each component of the connection portion 80.

[0109] <Measurement step SP16> This step in the present embodiment is a step of measuring the optical characteristics of the cores of the multi-core fiber 10 into which light has been incident from the optical fibers 22a to 22d optically connected to the cores 11a to 11d of the multi-core fiber 10 via the cores 211a to 211d of the fan-in device 20, by incidenting light from the optical fibers 22a to 22d optically connected to the cores 11a to 11d of the multi-core fiber 10 via the cores 211a to 211d of the fan-in device 20 and measuring the light exiting from the optical fibers 72a to 72d of the fan-out device 70.

[0110] In this step, the control unit 61 controls the light source unit 51 to select one of the optical fibers 22a to 22d and emit measurement light into the selected optical fiber. The measurement light passes through one of the cores 211a to 211d that is optically connected to the selected optical fiber, enters one of the cores 11a to 11d that is optically connected to the selected optical fiber, and propagates through the core. The light is then emitted from a predetermined core of the multicore fiber 10 to one of the cores 711a to 711d of the fan-out device 70. The light emitted to one of the cores 711a to 711d propagates to one of the optical fibers 72a to 72d that is optically connected to the core, and emits from the optical fiber. The light emitted from the optical fiber is received by the light receiving unit 52. When the light receiving unit 52 receives light from one of the optical fibers 72a to 72d, it outputs data related to the optical fiber that emitted the light and the power of the received light. The output data is input to the processor 60 .

[0111] The data processing unit 64 of the processor 60 analyzes the input data in the same manner as in the first embodiment, and outputs data relating to the analysis results to the monitor 100. The monitor 100 displays an image based on the received data.

[0112] In this way, the optical characteristics of the cores 11 to 11d of the multi-core fiber 10 are measured.

[0113] As described above, in addition to the measurement method for the multi-core fiber 10 of the first embodiment, the measurement method for the multi-core fiber 10 of the present embodiment further includes the steps of: in a preparation step SP11, further preparing a fan-out device 70 having a plurality of optical fibers 72a to 72d and a plurality of cores 711a to 711d optically connected individually to the optical fibers 72a to 72d, and capable of identifying the positions of the cores 711a to 711d by photographing; in a photographing step SP12, further photographing the fan-out device 70; in a determination step SP13, further determining combinations of the cores 11a to 11d at the other end of the multi-core fiber 10 and the cores 711a to 711d in the fan-out device 70 based on the photographing results; The combinations of the cores 11a to 11d of the multi-core fiber 10 and the optical fibers 72a to 72d optically connected to the cores 711a to 711d in the fan-out device 70 combined with the cores 11a to 11d are further associated, and in a connection step SP15, the cores 11a to 11d at the other end of the combined multi-core fiber 10 are further optically connected individually to the cores 711a to 711d of the fan-out device 70, and in a measurement step SP16, the light emitted from the optical fibers 72a to 72d of the fan-out device 70 is measured, thereby measuring the optical characteristics of the cores of the multi-core fiber 10 into which light is incident from the optical fibers 22a to 22d of the fan-in device 20.

[0114] Such a measurement method for the multi-core fiber 10 is suitable for measuring the optical characteristics of a core by inputting light into a core from one end of the multi-core fiber 10 and receiving the light output from the other end of the multi-core fiber 10. In this embodiment, even if the core from which the light exits changes by changing the core into which the light enters, it is only necessary to switch the optical fiber from which the light exits and receive the light, and the efficiency of measuring the optical characteristics of two or more cores in the multi-core fiber 10 can be improved.

[0115] (Modification) Next, a modification of this embodiment will be described.

[0116] This modification measures the optical characteristics of the cores 11a to 11d of the multicore fiber 10 similar to that of the present embodiment, and uses a measuring device similar to the measuring device 1 of the present embodiment. Therefore, the description of the same configuration as that described above will be omitted unless otherwise specified.

[0117] The flowchart showing the method for measuring the optical characteristics of the multicore fiber 10 in this modified example is similar to the flowchart of the modified example of the first embodiment shown in Fig. 4. Therefore, the same explanation as that of the modified example of the first embodiment will be omitted unless otherwise specified.

[0118] (Preparation Step SP21) This step in this modified example is the same as the preparation step SP11 in the second embodiment. The prepared multi-core fiber 10 is set in the measurement device 1 in the same manner as in the second embodiment.

[0119] (Connection step SP22) This step of the present modification differs from the modification of the first embodiment in that, in addition to the connection step of the modification of the first embodiment described above, two or more cores at the other end of the multicore fiber 10 are further individually optically connected to two or more cores of the plurality of cores 711 a to 711 d in the fan-out device 70. In this modification, similar to the second embodiment, all of the cores 11 a to 11 d at the other end of the multicore fiber 10 are individually optically connected to all of the cores 711 a to 711 d of the multicore fiber 71 of the fan-out device 70. The description of the connection unit 80 optically connecting the cores 11 a to 11 d and the cores 711 a to 711 d can be made by replacing the multicore fiber 21 and each configuration of the multicore fiber 21 with the multicore fiber 71 and each configuration of the multicore fiber 71, and the connection unit 30 and each configuration of the connection unit 30 with the connection unit 80 and each configuration of the connection unit 80.

[0120] (Photographing step SP23) This step in this modified example differs from the photographing step SP23 in the modified example of the first embodiment in that, in addition to the photographing step SP23 in the modified example of the first embodiment, the other end of the multicore fiber 10 and the fan-out device are further photographed. In this modified example, when photographing the multicore fiber 10, one end and the other end of the multicore fiber 10 are photographed. The description of the step of photographing the multicore fiber 10 and the fan-out device 70 on the other end side of the multicore fiber 10 is the same as the description of the photographing step SP23 in the modified example of the first embodiment, except that the fan-in device 20 and the respective components of the fan-in device 20 are replaced with the fan-out device 70 and the respective components of the fan-out device 70, one end of the multicore fiber 10 is replaced with the other end, the connection unit 30 and the respective components of the connection unit 30 are replaced with the connection unit 80 and the respective components of the connection unit 80, and the photographing unit 40 and the respective components of the photographing unit 40 are replaced with the photographing unit 90 and the respective components of the photographing unit 90.

[0121] (Associating Step SP24) This step of the present modification differs from the associating step SP24 in the modification of the first embodiment in that, in addition to the associating step SP24 in the modification of the first embodiment described above, combinations of two or more cores of the multicore fiber 10 and respective optical fibers optically connected to the two or more cores via cores of the fan-out device 70 are further associated based on the imaging results. In the present modification, as described above, all of the cores 11 a to 11 d at the other end of the multicore fiber 10 are individually optically connected to all of the cores 711 a to 711 d of the multicore fiber 71 of the fan-out device 70. Therefore, in the present modification, the associating unit 63 further associates combinations of the cores 11 a to 11 d of the multicore fiber 10 and respective optical fibers 72 a to 72 d optically connected to the cores 11 a to 11 d via the cores 711 a to 711 d of the fan-out device 70 based on the imaging results. The explanation of the associating unit 63 associating the cores 11a to 11d with the optical fibers 72a to 72d is given by replacing one end of the multicore fiber 10 with the other end, replacing the multicore fiber 21 and each configuration of the multicore fiber 21 with the multicore fiber 71 and each configuration of the multicore fiber 71, and replacing the optical fibers 22a to 22d with the optical fibers 72a to 72d in the explanation of the associating step SP24 in the modified example of the first embodiment.

[0122] (Measuring Step SP25) The measuring step of this modified example is similar to the measuring step SP25 of the second embodiment.

[0123] As described above, in addition to the measurement method for the multi-core fiber 10 in the modification of the first embodiment, the measurement method for the multi-core fiber 10 in this modification further includes the steps of: in the preparation step SP21, preparing a fan-out device 70 having a plurality of optical fibers 72a to 72d and a plurality of cores 711a to 711d optically connected individually to the optical fibers 72a to 72d, and capable of identifying the positions of the cores 711a to 711d by photography; and in the connection step SP22, further individually optically connecting the cores 11a to 11d at the other end of the multi-core fiber 10 to the cores 711a to 711d in the fan-out device 70. and in a photographing step SP23, the fan-out device 70 is further photographed, and in an associating step SP24, the combinations of the cores 11a to 11d of the multicore fiber 10 and the respective optical fibers 72a to 72d optically connected to the cores 11a to 11d via the cores 711a to 711d of the fan-out device 70 are further associated based on the photographing results, and in a measuring step SP25, the light emitted from the optical fibers 72a to 72d of the fan-out device 70 is measured, thereby measuring the optical characteristics of the cores of the multicore fiber 10 into which light is incident from the optical fibers of the fan-in device 20.

[0124] In this modification, as in the modification of the first embodiment, the efficiency of measuring the optical properties of two or more cores in the multicore fiber 10 can be improved.

[0125] Although the present invention has been described above using the above embodiment as an example, the present invention is not limited to the above embodiment.

[0126] For example, in the above-described embodiment and modified example, an example has been described in which the arrangement of the cores 11a to 11d and the markers 13 of the multicore fiber 10 is the same as the arrangement of the cores 211a to 211d, 711a to 711d and the markers 213, 713 of the multicore fibers 21, 71. However, as long as two or more cores of the cores 11a to 11d of the multicore fiber 10 and the cores 211a to 211d, 711a to 711d of the multicore fibers 21, 71 face each other, the number and arrangement of the cores of the multicore fiber 10 and the cores of the multicore fibers 21, 71 may be different from each other. Also, the fan-in device 20 and the fan-out device 70 have been described as examples including the multicore fibers 21, 71, respectively. However, the fan-in device 20 and the fan-out device 70 of the present invention may have, instead of the multi-core fibers 21 and 71, a waveguide substrate having optical waveguides that serve as the cores 211a to 211d and 711a to 711d.

[0127] Moreover, in the above-described embodiments, the multicore fibers 10, 21, and 71 have been described as examples having the markers 13, 213, and 713, respectively. However, if the positions of the cores of the multicore fibers 10, 21, and 71 can be identified by imaging, the multicore fibers 10, 21, and 71 do not need to have the markers 13, 213, and 713. If the outer shape of the clads 12, 212, and 712 of the multicore fibers 10, 21, and 71 is not circular but, for example, D-shaped, the positions of the cores of the multicore fibers 10, 21, and 71 can be identified by imaging the clads 12, 212, and 712. Furthermore, for example, if the cores of the multicore fibers 10, 21, and 71 are arranged non-rotationally symmetrically, the positions of the cores can be identified by imaging the cores.

[0128] According to the present invention, a multi-core fiber measurement method and a multi-core fiber measurement device that can increase the efficiency of measuring the optical properties of two or more cores can be provided, and can be used in fields such as optical communications, for example.

Claims

1. A method for measuring a multi-core fiber, comprising: a preparation step of preparing a multi-core fiber having a plurality of cores, the positions of which can be identified by photography; and a fan-in device having a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, the positions of which can be identified by photography; a photography step of photographing one end of the multi-core fiber and the fan-in device; a determination step of determining, based on the photography results, a combination of two or more of the plurality of cores at the one end of the multi-core fiber and two or more of the optical waveguides; an associating step of associating the two or more cores with each of the ports optically connected to the optical waveguides combined with the two or more cores; a connection step of individually optically connecting the two or more cores at the one end of the combined multi-core fiber to the two or more optical waveguides; and a measurement step of irradiating light from the port optically connected to the core via the optical waveguide, and measuring the optical characteristics of the core through which the light propagates from the port.

2. The method for measuring a multi-core fiber according to claim 1, wherein the multi-core fiber further has a marker; the fan-in device has a multi-core fiber including a plurality of cores and markers as the plurality of optical waveguides; the photographing step photographs the plurality of cores and the markers of the multi-core fiber of the fan-in device, and the plurality of cores and the markers of the multi-core fiber optically connected to the fan-in device; and the determining step determines a combination of the two or more cores and the two or more optical waveguides based on the positions of the plurality of cores and the markers in the multi-core fiber of the fan-in device and the positions of the plurality of cores and the markers of the multi-core fiber optically connected to the fan-in device.

3. In the preparing step, a fan-out device is further prepared, which has a plurality of ports and a plurality of optical waveguides optically connected to the ports individually, and the positions of the optical waveguides can be identified by photography; in the photographing step, the other end of the multi-core fiber and the fan-out device are further photographed; in the determining step, a combination of the two or more cores at the other end of the multi-core fiber and two or more of the optical waveguides in the fan-out device is further determined based on the photographing results; in the associating step, a combination of the two or more cores of the multi-core fiber and each of the ports optically connected to the optical waveguides in the fan-out device combined with the two or more cores respectively is further associated; in the connecting step, the two or more cores at the other end of the combined multi-core fiber are further optically connected individually to the two or more optical waveguides of the fan-out device; 3. The multi-core fiber measurement method according to claim 1, wherein the measurement step measures optical characteristics of the cores of the multi-core fiber into which light is incident from the ports of the fan-in device by measuring light exiting from the ports of the fan-out device.

4. A method for measuring a multi-core fiber, comprising: a preparation step of preparing a multi-core fiber having a plurality of cores, the positions of which can be identified by photography; and a fan-in device having a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, the positions of which can be identified by photography; a connection step of individually optically connecting two or more of the plurality of cores at one end of the multi-core fiber to two or more of the plurality of optical waveguides; a photography step of photographing the one end of the multi-core fiber and the fan-in device; an association step of associating each of the cores optically connected to the two or more optical waveguides with each of the ports optically connected to the core via the optical waveguide based on the photography results; and a measurement step of irradiating light from the port optically connected to the core via the optical waveguide and measuring the optical characteristics of the core through which the light propagates from the port.

5. The method for measuring a multi-core fiber according to claim 4, wherein the preparing step further prepares a fan-out device having a plurality of ports and a plurality of optical waveguides optically connected to the ports individually, and wherein positions of the optical waveguides can be identified by photography; the connecting step further optically connects the two or more cores at the other end of the multi-core fiber to two or more of the plurality of optical waveguides in the fan-out device individually; the photographing step further photographs the other end of the multi-core fiber and the fan-out device; the associating step further associates, based on the photographing results, combinations of the two or more cores of the multi-core fiber and the respective ports optically connected to the two or more cores via the optical waveguides of the fan-out device; and the measuring step measures optical characteristics of the cores of the multi-core fiber into which light is incident from the ports of the fan-in device by measuring light exiting from the ports of the fan-out device.

6. A measuring device for a multi-core fiber having a plurality of cores and capable of identifying the positions of the cores by photographing, comprising: a fan-in device having a plurality of ports and a plurality of optical waveguides optically connected to the ports individually, and capable of identifying the positions of the optical waveguides by photographing; an imaging unit capable of photographing one end of the multi-core fiber and the fan-in device; a determining unit that determines, based on the photographing results, a combination of two or more of the plurality of cores at the one end of the multi-core fiber and two or more of the optical waveguides; an associating unit that associates the two or more cores with each of the ports optically connected to the optical waveguides combined with the two or more cores, respectively; a connecting unit that optically connects the two or more cores at the one end of the combined multi-core fiber individually with the two or more optical waveguides; and a measuring unit that inputs light from the port optically connected to the core via the optical waveguide, and measures optical characteristics of the core through which the light propagates from the port.

7. A measuring device for a multi-core fiber having a plurality of cores and capable of identifying the positions of the cores by photography, comprising: a fan-in device having a plurality of ports and a plurality of optical waveguides individually optically connected to the ports, and capable of identifying the positions of the optical waveguides by photography; a connection section that optically connects two or more of the plurality of cores at one end of the multi-core fiber individually to two or more of the plurality of optical waveguides; a photographing section that photographs the one end of the multi-core fiber and the fan-in device; an associating section that associates each of the cores optically connected to the two or more optical waveguides with each of the ports optically connected to the cores via the optical waveguides based on the photographing results; and a measuring section that inputs light from the ports optically connected to the cores via the optical waveguides and measures the optical characteristics of the cores through which the light propagates from the ports.

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