Optical fiber monitor system, remote monitor, and method for monitoring optical fiber

Abstract

To reduce time required to monitor core pairs in an optical cable.SOLUTION: An optical fiber monitor system includes: an optical fiber with a plurality of cores including pair cores (each being a pair of cores), the optical fiber being provided with more than one core pair; and a remote monitor for acquiring a monitor result showing the state of the optical fiber for each core pair by using the monitor light. The remote monitor acquires a second monitor result showing the state of a second core pair according to a first monitor result, which is the monitor result of a first core pair in the core pairs.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an optical fiber monitoring system and the like.

Background Art

[0002] In a transmission system using optical fibers (hereinafter referred to as an "optical transmission system"), for the purpose of efficiently accommodating rapidly increasing traffic demands, a plurality of optical fibers are accommodated in one optical cable, and a pair of corresponding optical fibers may be assigned as a fiber pair (FP). In recent years, an optical transmission system that employs a multi-core fiber (MCF) having a plurality of cores in one optical fiber has also emerged. In such an optical transmission system, a pair of corresponding cores may be assigned as a core pair (CP). Further, in an optical transmission system, an optical repeater including an optical fiber amplifier is often disposed in the middle of an optical cable. A remote monitoring device for monitoring the state of such an FP or CP is known. The remote monitoring device is installed at an end station of the optical transmission system and monitors the state of one FP or one CP by one measurement.

[0003] In relation to the present disclosure, Patent Document 1 describes a technique related to an optical switching device used in an optical transmission system using an MCF.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a remote monitoring device for an optical fiber transmission line, an OTDR (optical time domain reflectometer) is known. In order to miniaturize the remote monitoring device, there are some remote monitoring devices that have a function of switching the connected FPs and CPs and monitoring the FPs and CPs one by one in order. On the other hand, with the increase in the traffic capacity accommodated in the optical transmission system, dozens of FPs and CPs may be accommodated in a single optical cable. In such an optical transmission system, in the method of monitoring FPs and CPs using a single remote monitoring device, it may take a very long time to monitor the states of all FPs and CPs.

[0006] An object of the present disclosure is to provide a technique for shortening the time required for monitoring core pairs in an optical cable.

Means for Solving the Problems

[0007] The optical fiber monitoring system according to the present disclosure includes an optical fiber including a plurality of cores, a pair of cores selected from the plurality of cores as a core pair, and a plurality of the core pairs are assigned, and a remote monitoring device that acquires a monitoring result indicating the state of the optical fiber for each core pair using monitoring light. The remote monitoring device acquires a second monitoring result indicating the state of a second core pair, which is another core pair, according to the first monitoring result, which is the monitoring result of the first core pair included in the plurality of core pairs.

[0008] The remote monitoring device according to the present disclosure includes a first acquisition means for acquiring a monitoring result indicating the state of an optical fiber including a plurality of cores, a pair of cores selected from the plurality of cores as a core pair, and a plurality of the core pairs are assigned, for each core pair using monitoring light, and a second acquisition means for acquiring a second monitoring result indicating the state of a second core pair, which is another core pair, according to the first monitoring result, which is the monitoring result of the first core pair included in the plurality of core pairs.

[0009] The optical fiber monitoring method according to the present disclosure includes a plurality of cores, and a pair of cores is used as a core pair among the plurality of cores. A monitoring result indicating the state of an optical fiber to which a plurality of the core pairs are assigned is obtained for each core pair using monitoring light, and a second monitoring result indicating the state of a second core pair, which is another core pair, is obtained according to the first monitoring result, which is the monitoring result of the first core pair included in the plurality of core pairs.

Advantages of the Invention

[0010] The present disclosure provides a technique for shortening the time required to monitor core pairs in an optical cable.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Embodiments of the present disclosure will be described below with reference to the drawings. In the embodiments and the drawings, the same reference numerals are given to the elements that have already appeared, and redundant descriptions may be omitted.

[0013] (First Embodiment) FIG. 1 is a diagram showing a configuration example of the optical fiber monitoring system 1000 of the present disclosure. The optical fiber monitoring system 1000 includes a terminal station 100, an optical repeater 200, a remote monitoring device 300, a network monitoring device 400, and an optical submarine cable 500.

[0014] The terminal station 100 is an onshore station installed on land and is responsible for the interface function between the optical submarine cable 500 and the onshore communication network 700. The terminal station 100 includes an optical interface 101 and an optical multiplexer / demultiplexer (optical MUX / DEMUX) 102. The optical interface 101 transmits and receives signal light to and from the optical submarine cable 500. The optical multiplexer / demultiplexer 102 is disposed between the optical interface 101 and the optical submarine cable 500 and multiplexes and demultiplexes the monitoring light and the signal light. The optical multiplexer / demultiplexer 102 combines the signal light between the optical submarine cable 500 and the optical interface 101, and combines the monitoring light and the reflected light between the optical submarine cable 500 and the remote monitoring device 300.

[0015] The optical repeater 200 is arranged in the middle of the optical submarine cable 500. The optical repeater 200 amplifies the input bidirectional optical signals respectively, and multiplexes the reflected optical signal with the optical signal in the opposite direction. The reflected optical signal is the optical signal that folds back a part of the monitoring optical signal. The reflected optical signal propagates in the direction opposite to the direction (downlink direction) of the monitoring optical signal sent from the terminal station 100 to the optical repeater 200 (uplink direction). For example, the reflectors 201 provided in each of the optical repeaters 200 are used for folding back the monitoring optical signal. Since a general configuration for folding back the monitoring optical signal in the optical repeater 200 is known, detailed description is omitted. The terminal station 100 receives the uplink signal optical signal and the reflected optical signal multiplexed with the signal optical signal.

[0016] The remote monitoring device 300 includes an optical transceiver 310. The optical transceiver 310 transmits the monitoring optical signal to the terminal station 100 under the control from the network monitoring device 400, and receives the reflected optical signal (return optical signal) of the monitoring optical signal from the terminal station 100. The optical transceiver 310 transmits the monitoring optical signal to one core of the selected core pair, and receives the return optical signal of the monitoring optical signal from the other core of the selected core pair. The network monitoring device 400 selects the core of the optical submarine cable 500 to be monitored, and instructs the remote monitoring device 300 to send the monitoring optical signal to the selected core. The wavelength of the monitoring optical signal may be a specific wavelength different from the signal optical signal. The remote monitoring device 300 monitors the reflected optical signal folded back in each of the optical repeaters 200, and obtains the state of the optical submarine cable 500 using the monitoring result. When the acquisition of the monitoring result is completed, the remote monitoring device 300 transmits the monitoring result including the information of the fault point of the optical submarine cable 500 and the monitoring completion notification to the network monitoring device 400. The monitoring result is, for example, information of at least one of the presence or absence of abnormalities such as disconnection of the path through which the monitoring optical signal and the return optical signal propagate and loss, but is not limited thereto.

[0017] FIG. 2 is a diagram for explaining the monitoring of two 2-core MCFs in the optical fiber monitoring system 1000. The optical submarine cable 500 includes optical fibers 510 and 520. Each of the optical fibers 510 and 520 includes one CP. The core 511 of the optical fiber 510 transmits downstream light, and the core 512 transmits upstream light. The same applies to the optical fiber 520. The optical repeater 210 includes four optical amplifiers 211-214 and amplifies the light propagating through each core of the optical fibers 510 and 520. The optical fibers 510 and 520 and the optical repeater 210 may be connected by FIFO (fan-in / fan-out). The optical repeater 210 also includes reflectors 215 and 225. The monitoring light propagating through the core 511 in the downstream direction is reflected by the reflector 215 and propagates through the core 512 as reflected light in the upstream direction. Similarly, the monitoring light propagating through the core 521 in the downstream direction is reflected by the reflector 225 and propagates through the core 522 as reflected light in the upstream direction.

[0018] The network monitoring device 400 first selects the optical fiber 510 as the monitoring target. The remote monitoring device 300 first sends monitoring light to the core 511 of the optical fiber 510. The monitoring light is sent to the core 511 via the terminal station 100. The monitoring light propagating through the core 511 is reflected by the reflector 215 and received by the remote monitoring device 300 via the core 512 and the terminal station 100. When the process regarding the state of the optical fiber 510 is completed and the measurement result of the optical fiber 510 is normal, the remote monitoring device 300 sends monitoring light to the core 521 of the optical fiber 520 and monitors the state of the optical fiber 520 in the same procedure as that of the optical fiber 510.

[0019] In the above procedure, monitoring light is sent to one CP included in one optical fiber 510, and after the monitoring of the one CP is completed, the measurement shifts to another optical fiber 520.

[0020] (Modification of the First Embodiment) FIG. 3 is a diagram for explaining an example of monitoring a 4-core MCF in the optical fiber monitoring system 1000. The optical submarine cable 500 includes an optical fiber 530. The optical fiber 530 is a 4-core MCF including four cores 531-534. Cores 531 and 533 constitute a CP (core pair) 535, and cores 532 and 534 constitute a CP 536. Cores 531 and 532 transmit downstream light, and cores 533 and 534 transmit upstream light.

[0021] FIG. 4 is a diagram showing an example of a cross section of the optical fiber 530. The cores 531-534 are arranged such that their respective positions are the four vertices of a single square. In FIG. 4, the cores 531-534 are arranged in this order at positions that go around the vertices of the square indicated by the dashed line in a clockwise direction.

[0022] In the configuration of FIG. 3, the optical repeater 210 includes four optical amplifiers 211-214. The optical amplifiers 211-214 amplify the light propagating through their respective cores of the cores 531-534. The monitoring light propagating through the core 531 in the downstream direction is reflected by the reflector 215 and propagates through the core 533 in the upstream direction as reflected light. Similarly, the monitoring light propagating through the core 532 in the downstream direction is reflected by the reflector 225 and propagates through the core 534 in the upstream direction as reflected light.

[0023] When the configuration of FIG. 3 is applied to the optical fiber monitoring system 1000, the network monitoring device 400 first selects the CP 535 as the monitoring target. Then, the remote monitoring device 300 sends monitoring light to the core 531 of the CP 535. The monitoring light is sent to the core 531 via the terminal station 100. The monitoring light propagating through the core 531 is reflected by the reflector 215 and received by the remote monitoring device 300 via the core 533 and the terminal station 100. When the monitoring of the CP 535 is completed and the monitoring result of the CP 535 is normal, the remote monitoring device 300 ends the monitoring of the optical fiber 530, and if there is another optical fiber, starts the monitoring of that optical fiber. That is, in the procedure of this modification example, first, monitoring light is sent only to one CP (CP 535) included in one optical fiber 530.

[0024] The above-described optical fiber monitoring procedure using the remote monitoring device 300 can also be described as shown in FIG. 17. FIG. 17 is a flowchart showing an example of an optical fiber monitoring method. The optical fiber includes a plurality of cores, and a pair of cores is set as a core pair from among the plurality of cores, and a plurality of core pairs are assigned to the optical fiber. A first monitoring result indicating the state of a first core pair (CP535 in FIG. 3) included in such an optical fiber is acquired using monitoring light (step S01). Then, according to the first monitoring result, a second monitoring result indicating the state of a second core pair (a core pair of another optical fiber), which is another core pair, is acquired (step S02).

[0025] In the first embodiment and its modification, when the monitoring of one core pair in one optical fiber is completed, the monitoring of another optical fiber is performed. Therefore, the time required for monitoring the core pairs in the optical cable can be shortened.

[0026] In the modification of the first embodiment, core 531 and core 533 are set as CP535, and core 532 and core 534 are set as CP536. When the distance between the cores constituting one CP is small, due to crosstalk between the cores, the reflected light leaks as crosstalk light to the upstream core also in portions other than the reflector 215. Such crosstalk light becomes noise with respect to the reflected light that is originally monitored in the remote monitoring device 300. In this modification, among cores 531 - 534, in optical fiber 530, core 531 and core 533 with a large distance between the cores are set as CP535, and core 532 and core 534 are set as CP536. By selecting the cores constituting CP535 and 536 in this way, the influence of crosstalk light on the reflected light can be reduced as compared with the case where a CP is constituted by a combination of other cores.

[0027] (Second Embodiment) FIG. 5 is a diagram showing a configuration example of the optical fiber monitoring system 2000 according to the second embodiment. The optical fiber monitoring system 2000 includes an end station 100, an optical repeater 200, a remote monitoring device 300, a network monitoring device 400, and an optical submarine cable 600.

[0028] The terminal station 100 is a land station installed on land and undertakes the interface function between the optical submarine cable 600 and the land communication network 700. The optical interface 101 transmits and receives signal light to and from the optical submarine cable 600. The optical multiplexer / demultiplexer 102 is arranged between the optical interface 101 and the optical submarine cable 600, and multiplexes and demultiplexes the monitoring light and the signal light. The optical multiplexer / demultiplexer 102 propagates the signal light between the optical submarine cable 600 and the optical interface 101, and propagates the monitoring light and the reflected light between the optical submarine cable 600 and the remote monitoring device 300.

[0029] The optical transceiver 310 included in the remote monitoring device 300 may include a first acquisition circuit 301 and a second acquisition circuit 302. The first acquisition circuit 301 serves as a first acquisition means for acquiring, for each core pair, a first monitoring result that is a monitoring result indicating the state of a first core pair included in a plurality of core pairs assigned to the optical fiber 610, using monitoring light. The second acquisition circuit 302 serves as a second acquisition means for acquiring a second monitoring result that is a monitoring result indicating the state of a second core pair that is another core pair according to the first monitoring result.

[0030] The optical submarine cable 600 of the present embodiment includes three optical fibers 610, 620, and 630. The optical fibers 610, 620, and 630 are all 8-core MCFs. The optical fiber 610 includes cores 611-618, and the optical fiber 620 includes cores 621-628. The optical fiber 630 includes cores 631-638. The optical fibers 610, 620, and 630 each include one or more optical repeaters 660. In the present embodiment, it is assumed that the configurations of the optical repeaters 660 are all the same.

[0031] FIG. 6 is a diagram showing an example of a cross-section of an optical fiber 610. Cores 611-618 are arranged such that their respective positions are the eight vertices of a regular octagon. The center of the regular octagon shown by the dashed line in FIG. 6 is at the center of the cross-section of the optical fiber 610. In other words, cores 611-618 are arranged at equal intervals on a circumference centered on the center of the cross-section of the optical fiber 610. In FIG. 6, cores 611-618 are arranged in this order at positions that go around the vertices of the regular octagon in a clockwise direction. The core arrangement and core numbers in optical fibers 620 and 630 are also defined according to the optical fiber 610.

[0032] FIG. 7 is a diagram showing a configuration example of an optical repeater 660. In FIG. 7, the optical repeater 660 provided in the middle of the optical fiber 610 will be described. The configuration of the optical repeater 660 provided in the optical fibers 620 and 630 is the same. The optical repeater 660 includes eight optical amplifiers 661-668. The optical amplifiers 661-668 amplify the light propagating through the cores 611-618, respectively. FIFOs 671 and 672 are arranged between the two ends of the optical fiber 610 connected to the optical repeater 660 and the optical amplifiers 661-668. Both FIFOs 671 and 672 connect the cores 611-618 of the optical fiber 610 and the optical amplifiers 661-668. The optical fiber 610 and one end of the FIFO 671, and the optical fiber 610 and one end of the FIFO 672 are connected by MCFs. The one end of the optical amplifiers 661-668 and the other end of the FIFO 671, and the other end of the optical amplifiers 661-668 and the other end of the FIFO 672 are connected by SCFs. The numbers 611-618 between the FIFO 671 and the FIFO 672 indicate the numbers of the cores of the optical fiber 610 to which the SCF is connected. In FIG. 7, cores 611 and 615 are assigned as CP11, and cores 612 and 616 are assigned as CP12. Also, cores 613 and 617 are assigned as CP13, and cores 614 and 618 are assigned as CP14. The correspondence between the core pairs and the cores constituting them is the same as that of CP11-14 in CP21-24 of the optical fiber 620 and CP31-34 of the optical fiber 630.

[0033] FIG. 8 and FIG. 9 are diagrams for explaining an example of the order of monitoring optical fibers 610, 620, and 630 with time on the horizontal axis. FIG. 8 shows a general monitoring procedure, and FIG. 9 shows the monitoring procedure in the present embodiment. In the general monitoring procedure shown in FIG. 8, two adjacent cores are monitored as one core pair. For example, first, the core pair CP191 of the optical fiber 610 is monitored. CP191 is a core pair composed of cores 611 and 612. Then, the remaining core pairs CP192, CP193, and CP194 of the optical fiber 610 are monitored. CP192 is composed of cores 613 and 614, CP193 is composed of cores 615 and 616, and CP194 is composed of cores 617 and 618. When the monitoring of CP191-194 is completed, for each core pair CP291-294 and CP391-394 of the optical fibers 620 and 630, monitoring is performed in the same procedure as that of the optical fiber 610. In the description of the general procedure such as FIG. 8, it is assumed that the optical amplifiers in the optical repeater 660 are arranged in a direction that enables monitoring by the core pairs used in each procedure.

[0034] In the procedure of FIG. 8, even when the optical submarine cable 600 includes four or more optical fibers, similarly, after the monitoring of all the core pairs of one optical fiber is completed, the monitoring of the core pairs of other optical fibers is started.

[0035] Assuming that the time T required to monitor one core pair is the same for each core pair, in FIG. 8, the time required to monitor one optical fiber is 4T. And the time required to monitor the three optical fibers 610, 620, and 630 included in the optical submarine cable 600 is 4×3T = 12T. Hereinafter, in the optical fibers 610, 620, and 630 included in the optical submarine cable 600, the period in which the monitoring of the monitored optical fiber makes one round may be described as the "monitoring period". In FIG. 8, the monitoring period is 12T.

[0036] FIG. 9 is an example of the monitoring procedure for core pairs in this embodiment. In the procedure of FIG. 9, first, CP11 of the optical fiber 610 is monitored, and then CP13 is monitored. When the monitoring of CP13 is completed, the monitoring of the optical fiber 620 is executed without monitoring CP12 and CP14. By shifting to the monitoring of the optical fiber 620 after monitoring CP13 following the monitoring of CP11, the states of the optical amplifiers used in each core of the optical fiber 610 can be comprehensively obtained to a certain extent.

[0037] Also, in the optical fiber 620, only the core pairs CP21 and CP23 of the optical fiber 620 are monitored. And for the optical fiber 630, only CP31 and CP33 are monitored. Thus, in the procedure of FIG. 9, when the monitoring of two core pairs per optical fiber is completed, the monitoring of the core pairs of other optical fibers is executed. Therefore, in FIG. 9, the monitoring period of the optical submarine cable 600 is 6T. In this way, the procedure of FIG. 9 can monitor all the optical fibers in half the time compared with the procedure of FIG. 8. The reason is that when monitoring an optical fiber including a plurality of core pairs, instead of monitoring all the core pairs of the optical fiber and then monitoring other optical fibers, only a part of the core pairs (for example, CP11, 13, 21, 23, 31, and 33) are monitored in one monitoring period. Such a procedure can shorten the time until shifting to the monitoring of other optical fibers, so the time required for monitoring the core pairs in the optical cable can be shortened.

[0038] Also, in the procedure of FIG. 9, the cores 611, 613, 615, and 617 of the optical fiber 610 are used for monitoring. These cores are not adjacent to each other in the optical fiber 610. In this way, by increasing the distance between each core included in a plurality of core pairs used for monitoring, the state of a wider area within the cross-section of the optical fiber 610 can be monitored. Furthermore, by increasing the distance between the two cores constituting one core pair, the influence on the reflected light caused by the crosstalk light generated between the cores constituting the core pair can be reduced. For example, in the optical fiber 610, by constituting CP11 with the core 611 and the core 615, the influence caused by the crosstalk light generated between the core 611 and the core 615 can be reduced.

[0039] Specifically, in the procedure of FIG. 9, in the first monitoring cycle of the optical fiber 610, monitoring is performed using CP1 constituted by the cores 611 and 615 and CP3 constituted by the cores 613 and 617. In this case, none of the cores 611, 615 of CP1 and the cores 613, 617 of CP3 are adjacent to each other in the optical fiber 610. Therefore, by using CP1 and CP3, the state of a wider area within the cross-section of the optical fiber 610 can be monitored.

[0040] Also, the distance between the core 611 and the core 615 and the distance between the core 613 and the core 617 are both the maximum distance between the cores within the cross-section of the optical fiber 610. Therefore, compared with the case where core pairs with a smaller distance between cores are used, neither CP1 nor CP3 is easily affected by crosstalk in the monitoring results. The same applies to the core pairs of the other optical fibers 620 and 630.

[0041] In the procedure of FIG. 9, when the first monitoring period P1 with a length of 6T ends, the second monitoring period starts. In the second monitoring period P2, the optical fibers 610, 620, and 630 may be monitored using the core pairs that were not monitored in the monitoring period P1. FIG. 9 shows that in the monitoring period P2, the optical fibers 610, 620, and 630 are monitored using CP1214, 22, 24, 32, and 34. In this case, by monitoring in the periods P1 and P2, all core pairs are monitored once. And even when CP12 and CP14 are used in the period P2, the same effect as the monitoring using CP11 and CP13 can be obtained. And after the period P3, the monitoring using the same core pairs as in the periods P1 and P2 may be repeated.

[0042] (Modification of the Second Embodiment) FIG. 10 is a diagram showing an example of the occurrence of a failure (breakage failure) in which an optical fiber breaks in the optical fiber monitoring system 2000. FIG. 10 shows that a breakage failure has occurred at a point D between two optical repeaters 660a and 660b on the optical fiber 610. The optical repeaters 660a and 660b are both examples of the optical repeater 660 described above. Until the occurrence of the breakage failure is detected, the optical fiber monitoring system 2000 monitors the optical fibers 610 - 630 according to the procedure described in FIG. 9.

[0043] The breakage failure of the optical fiber is detected at the terminal station 100 by detecting the interruption of the signal light or the monitoring light, etc. The terminal station 100 that has detected the breakage failure notifies the network monitoring device 400 of the occurrence of the breakage failure. When the network monitoring device 400 receives a notification that a breakage failure has occurred, it starts monitoring the optical submarine cable 600 according to the corresponding procedure.

[0044] FIG. 11 is a diagram showing an example of a monitoring procedure after the occurrence of a breakage failure at location D. In FIG. 11, an example is shown in which the monitoring of the core pair of the optical fiber 610 is prioritized over the monitoring of the other optical fibers 620 and 630. The procedure of FIG. 9 is shown at the upper part of FIG. 11 for reference. The lower part of FIG. 11 shows that when a breakage failure occurs in the optical fiber 610, after the monitoring of CP11 and CP13, the CP12 and CP14 of the optical fiber 610 are monitored. In the procedure at the upper part of FIG. 11, the monitoring of CP12 and CP14 was carried out after the monitoring of the optical fibers 620 and 630. However, in the procedure at the lower part of FIG. 11, when a breakage failure occurs in the optical fiber 610, the monitoring of CP12 and 14 is executed prior to the monitoring of the core pairs of the other optical fibers 620 and 630. By such a change in the procedure, the status of the other cores in the optical fiber 610 where the failure was detected can be obtained earlier.

[0045] FIG. 12 is a diagram showing another example of a monitoring procedure after the occurrence of a breakage failure. The procedure of FIG. 9 is shown at the upper part of FIG. 12 for reference. The lower part of FIG. 12 shows that when a breakage failure occurs in the optical fiber 610, the monitoring of one core pair (CP11, CP21, and CP31) of the optical fibers 610, 620, and 630 is prioritized. That is, in the procedure at the lower part of FIG. 12, when the monitoring of CP11 in the optical fiber 610 where the failure occurred is completed, without monitoring the other core pairs of the optical fiber 610, only CP21 of the optical fiber 620 and CP31 of the optical fiber 630 are monitored. After the monitoring of CP11, 21, and 31 is completed, the optical fibers 610, 620, and 630 may be similarly monitored using CP13, 23, and 33. Also, the procedure may be similarly changed for CP12, 22, and 32, and CP14, 24, and 34.

[0046] Thus, the procedure of FIG. 12 prioritizes the monitoring of the core pairs of other optical fibers over the monitoring of the other core pairs within the same optical fiber. According to the procedure of FIG. 12, the presence or absence of failures in other optical fibers such as the optical fibers 620 and 630 in the optical submarine cable 600 including the optical fiber 610 where the failure was detected can be detected earlier.

[0047] (Another modification of the second embodiment) FIG. 13 is a diagram showing the occurrence of a failure (LD failure) in which the excitation LD (laser diode) of the optical repeater 660a fails in the optical fiber monitoring system 2000. The excitation LD is a light-emitting element that outputs excitation light. FIG. 14 is a diagram showing that an LD failure has been detected in the optical amplifier 665 among the eight optical amplifiers 661 - 668 provided in the optical repeater 660b on the optical fiber 610. The optical repeater 660b is an example of the optical repeater 660 described above. Until the occurrence of the LD failure is detected, the optical fiber monitoring system 2000 monitors the optical fibers 610, 630, and 630 according to the procedure described with reference to FIG. 9.

[0048] In an optical repeater used in an optical transmission system using MCF or a core pair, a configuration including an excitation light source that combines and branches excitation light output from a plurality of excitation LDs is known. The excitation light source supplies excitation light to optical fiber amplifiers connected to each of the plurality of core pairs. Such a configuration is sometimes called pump sharing. By means of pump sharing, the excitation LDs can be made redundant and the power efficiency of the optical repeater can be improved.

[0049] Under such circumstances, FIG. 14 shows an example in which the optical repeater 660b is provided with excitation light sources 671 and 672. The excitation light source 671 branches and combines the excitation light output from a plurality of excitation LDs, and supplies the excitation light to the optical amplifiers 661, 665, 662, and 666. The excitation light source 672 branches and combines the excitation light output from a plurality of excitation LDs different from the excitation light source 671, and supplies the excitation light to the optical amplifiers 663, 667, 664, and 668. In this configuration, the optical amplifiers 661 and 665 connected to CP11 and the optical amplifiers 662 and 666 connected to CP12 share the excitation LDs. Therefore, when an LD failure is detected in the optical amplifier 665, it is highly likely that an LD failure has also occurred in the transmission path including the core 611 or CP12 at the same time. Therefore, when an LD failure is detected in the optical amplifier 665, it is not always necessary to increase the priority of monitoring of the other core pair (CP12) that shares the excitation LD.

[0050] FIG. 15 is a diagram showing an example of a monitoring procedure after the occurrence of an LD failure. The procedure shown in FIG. 15 is the same as that in FIG. 9. As described above, when an LD failure is detected in CP11 of the optical fiber 610, after monitoring CP11, instead of monitoring CP12 of the same optical fiber, CP13 of the optical fiber 610 that does not share the excitation LD may be monitored, and then the monitoring may shift to other optical fibers. CP11 and CP12 share the excitation LDs of the excitation light source 671, and CP13 and CP14 share the excitation LDs of the excitation light source 672. Therefore, the states of the optical amplifiers 661-668 may be determined by monitoring only CP11 and CP13. FIG. 15 shows a procedure for monitoring the other core pairs of the optical fiber 610 including CP11 next when the monitoring result of CP11 indicates an abnormality.

[0051] FIG. 16 is a diagram showing another example of the monitoring procedure after the occurrence of an LD failure. The procedure of FIG. 16 is different from that of FIG. 15. After the detection of the LD failure in CP11, the monitoring of CP11, CP12, and CP13 is performed in the optical fiber 610. The procedure of FIG. 16 preferentially monitors other core pairs included in the optical fiber 610 in which the failure has been detected, and the situation of other core pairs or the entire optical fiber 610 can be confirmed at an early stage. In the procedure of FIG. 16, after the LD failure is detected, in the first several monitoring cycles, the core pairs that may be affected by the detected failure are preferentially monitored, and then, for example, the monitoring procedure during normal operation shown in FIG. 9 may be restored. Note that FIGS. 15 and 16 illustrate the configuration in the case where the excitation LD is shared. However, the procedures described in FIGS. 15 and 16 may also be applied to a configuration in which the shared component is other than the excitation LD. Note that the embodiments according to the present disclosure may also be described as follows in the appended claims, but are not limited thereto.

[0052] (Appendix 1) An optical fiber including a plurality of cores, a pair of cores selected from the plurality of cores as a core pair, and a plurality of the core pairs are assigned; A remote monitoring device that obtains a monitoring result indicating the state of the optical fiber for each core pair using monitoring light; The remote monitoring device is A second monitoring result indicating the state of a second core pair, which is another core pair, is obtained according to a first monitoring result, which is the monitoring result of a first core pair included in the plurality of core pairs; An optical fiber monitoring system.

[0053] (Appendix 2) The remote monitoring device includes an optical transceiver that transmits the monitoring light to one core of the selected core pair and receives the return light of the monitoring light from the other core of the selected core pair; The optical fiber monitoring system according to Appendix 1, wherein the monitoring result includes information indicating whether the path through which the monitoring light propagates is normal or abnormal.

[0054] (Appendix 3) The optical fiber monitoring system according to Supplementary Note 2, wherein the monitoring result includes information on at least one of the presence or absence of a disconnection and loss in the path through which the monitoring light and the return light propagate.

[0055] (Supplementary Note 4) The optical fiber monitoring system according to Supplementary Note 2 or 3, wherein the remote monitoring device selects the second core pair from another optical fiber that does not include the first core pair when the first monitoring result indicates the normality of the path.

[0056] (Supplementary Note 5) The optical fiber monitoring system according to any one of Supplementary Notes 2 to 4, wherein the remote monitoring device selects the second core pair from a core pair with less crosstalk of the monitoring light between the second core pair and the first core pair when the first monitoring result indicates the normality of the path.

[0057] (Supplementary Note 6) The optical fiber monitoring system according to any one of Supplementary Notes 2 to 5, wherein the remote monitoring device selects the second core pair from another core pair of the optical fiber including the first core pair when the first monitoring result indicates the abnormality of the path.

[0058] (Supplementary Note 7) The optical fiber monitoring system according to any one of Supplementary Notes 2 to 5, wherein the remote monitoring device selects the second core pair from another optical fiber that does not include the second core pair when the first monitoring result indicates the abnormality of the path.

[0059] (Supplementary Note 8) The optical fiber monitoring system according to any one of Supplementary Notes 2 to 5, wherein the remote monitoring device selects the second core pair from another core pair to which a component shared with the first core pair is connected when the first monitoring result indicates the abnormality of the path.

[0060] (Supplementary Note 9) The optical fiber monitoring system according to Appendix 8, wherein the first core pair and the second core pair share the excitation light source of the optical amplifier used in each core pair.

[0061] (Appendix 10) The excitation light source includes a plurality of light emitting elements, branches and combines the excitation light output from the light emitting elements, and supplies the excitation light to the optical amplifier connected to each of the plurality of core pairs. The optical fiber monitoring system according to Appendix 9.

[0062] (Appendix 11) A first acquisition means for acquiring a monitoring result indicating the state of an optical fiber to which a plurality of core pairs are assigned, where a pair of cores is defined as a core pair from among the plurality of cores, and acquiring the monitoring result for each core pair using monitoring light; A second acquisition means for acquiring a second monitoring result indicating the state of a second core pair, which is another core pair, according to the first monitoring result, which is the monitoring result of the first core pair included in the plurality of core pairs; A remote monitoring device comprising the above.

[0063] (Appendix 12) Including a plurality of cores, where a pair of cores is defined as a core pair from among the plurality of cores, and acquiring a monitoring result indicating the state of an optical fiber to which a plurality of core pairs are assigned for each core pair using monitoring light, and acquiring a second monitoring result indicating the state of a second core pair, which is another core pair, according to the first monitoring result, which is the monitoring result of the first core pair included in the plurality of core pairs. An optical fiber monitoring method.

[0064] (Appendix 13) Transmitting the monitoring light to a selected core pair, including the step of receiving the return light of the monitoring light, wherein the monitoring result includes information indicating whether the path through which the monitoring light propagates is normal or abnormal. The optical fiber monitoring method according to Appendix 12.

[0065] (Appendix 14) The optical fiber monitoring method according to Supplementary Note 13, wherein the monitoring result includes information on at least one of the presence or absence of a disconnection and loss in the path through which the monitoring light and the return light propagated.

[0066] (Supplementary Note 15) The optical fiber monitoring method according to Supplementary Note 13 or 14, wherein when the first monitoring result indicates normality of the path, the second core pair is selected from other optical fibers that do not include the first core pair.

[0067] (Supplementary Note 16) The optical fiber monitoring method according to any one of Supplementary Notes 13 to 15, wherein when the first monitoring result indicates normality of the path, the second core pair is selected from a core pair having less crosstalk of the monitoring light between the first core pair.

[0068] (Supplementary Note 17) The optical fiber monitoring method according to any one of Supplementary Notes 13 to 16, wherein when the first monitoring result indicates an abnormality of the path, the second core pair is selected from other core pairs of the optical fiber including the first core pair.

[0069] (Supplementary Note 18) The optical fiber monitoring method according to any one of Supplementary Notes 13 to 16, wherein when the first monitoring result indicates an abnormality of the path, the second core pair is selected from other optical fibers that do not include the second core pair.

[0070] (Supplementary Note 19) The optical fiber monitoring method according to any one of Supplementary Notes 13 to 16, wherein when the first monitoring result indicates an abnormality of the path, the second core pair is selected from other core pairs to which components shared with the first core pair are connected.

[0071] The present disclosure has been described with reference to the embodiments above, but the present disclosure is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure. For example, the optical fiber monitoring system described in each embodiment also discloses an optical fiber monitoring method applicable to the system.

[0072] In addition, the configurations described in each embodiment are not necessarily mutually exclusive. The operations and effects of the present disclosure may be realized by a configuration combining all or part of the above-described embodiments.

Description of Reference Numerals

[0073] 100 Terminal station 101 Optical interface 102 Optical multiplexer / demultiplexer (optical MUX / DEMUX) 200, 210 Optical repeaters 201, 215, 225 Reflectors 211 - 214 Optical amplifiers 300 Remote monitoring device 301 First acquisition circuit 302 Second acquisition circuit 400 Network monitoring device 500, 600 Optical submarine cables 510, 520, 530, 610, 620, 630 Optical fibers 511, 512, 521, 522, 531 - 534 Cores 611 - 618, 621 - 628, 631 - 638 Cores 660, 660a, 660b Optical repeaters 661 - 668 Optical amplifiers 671, 672 Excitation light sources 700 Communication network 1000, 2000 Optical fiber monitoring systems

Claims

1. An optical fiber including a plurality of cores, a pair of cores selected from the plurality of cores being defined as a core pair, and a plurality of the core pairs being assigned; and a remote monitoring device configured to obtain a monitoring result indicating a state of the optical fiber for each of the core pairs by using monitoring light. The remote monitoring device obtains a second monitoring result indicating a state of a second core pair, which is another core pair, according to a first monitoring result, which is the monitoring result of a first core pair included in the plurality of core pairs. An optical fiber monitoring system.

2. The remote monitoring device includes an optical transceiver configured to transmit the monitoring light to one core of a selected core pair and receive return light of the monitoring light from another core of the selected core pair. The optical fiber monitoring system according to claim 1, wherein the monitoring result includes information indicating whether a path along which the monitoring light has propagated is normal or abnormal.

3. The optical fiber monitoring system according to claim 2, wherein the monitoring result includes information on at least one of presence or absence of a disconnection and loss of a path along which the monitoring light and the return light have propagated.

4. The remote monitoring device selects the second core pair from other core pairs included in the optical fiber including the first core pair when the first monitoring result indicates an abnormality in the path, according to claim 2 or 3.

5. The remote monitoring device selects the second core pair from other optical fibers not including the second core pair when the first monitoring result indicates an abnormality in the path, according to claim 2 or 3.

6. The remote monitoring device selects the second core pair from other core pairs to which components shared with the first core pair are connected when the first monitoring result indicates an abnormality in the path, according to claim 2 or 3.

7. In the optical fiber monitoring system according to claim 6, the first core pair and the second core pair share an excitation light source of an optical amplifier used in each core pair.

8. The excitation light source includes a plurality of light emitting elements, and branches and combines excitation light output from the light emitting elements to supply the excitation light to the optical amplifiers connected to respective ones of the plurality of core pairs. The optical fiber monitoring system according to claim 7.

9. A first acquisition means that includes a plurality of cores, designates a pair of cores as a core pair from among the plurality of cores, and acquires a monitoring result indicating the state of an optical fiber to which a plurality of the core pairs are assigned, for each core pair, using monitoring light; A second acquisition means that acquires a second monitoring result indicating the state of a second core pair, which is another core pair, according to the first monitoring result, which is the monitoring result of the first core pair included in the plurality of core pairs; A remote monitoring device comprising the above.

10. A method for monitoring an optical fiber, the method including: including a plurality of cores, designating a pair of cores as a core pair from among the plurality of cores, and acquiring a monitoring result indicating the state of an optical fiber to which a plurality of the core pairs are assigned, for each core pair, using monitoring light; acquiring a second monitoring result indicating the state of a second core pair, which is another core pair, according to the first monitoring result, which is the monitoring result of the first core pair included in the plurality of core pairs. The optical fiber monitoring method according to claim 6.

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