Optical path identification device, optical path identification method, and optical path identification program

Abstract

In order to provide an optical path identification device and the like whereby it is possible to identify a switched optical path without incorporating a transceiver mechanism into an optical path switching device, this optical path identification device is provided with: an optical path identification unit that identifies whether a connected optical path connected to a first optical path is any of a plurality of optical paths from return light information regarding inspection light transmitted to the first optical path and representing the change in intensity over time of return light from the connected optical path; and an output unit for outputting the identification result.

Description

[Technical field]

[0001] The present invention relates to an optical path identification device, an optical path identification method, and a storage medium for an optical path identification program for identifying a switched optical path. [Background technology]

[0002] In an optical cable system that uses optical cables to perform optical communication between land stations, an optical path switching device that switches optical paths may be installed in the optical cable. In such a case, it is necessary for the land station to identify the optical path switched by the optical path switching device. The identification of the switched optical path is generally performed by the land station sending a command signal to the optical path switching device and receiving a response signal from the optical path switching device in response to the command signal, the response signal including the optical path switching status.

[0003] Here, Patent Document 1 discloses a method in which an optical time domain reflectometry (OTDR) test signal transmitted on a first optical path is reflected and coupled to a second optical path, and the reflected OTDR test signal is detected to obtain OTDR data.

[0004] Furthermore, Patent Document 2 discloses a network management device that has multiple communication paths connecting multiple devices, has a function for automatically changing the multiple communication paths, and is provided with a processing unit that detects abnormalities in the multiple communication paths. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-060665 A [Patent Document 2] JP 2006-135652 A Summary of the Invention [Problem to be solved by the invention]

[0006] In particular, in an optical submarine cable system, the optical route switching equipment is installed on the seabed and is not easy to repair or replace, so it is necessary to increase the reliability of the optical route switching equipment. Therefore, it may be difficult to incorporate a configuration that receives a command signal and transmits a response signal, which has a higher probability of failure compared to other mechanisms.

[0007] An object of the present invention is to provide an optical path identification device and the like that can identify a switched optical path without incorporating a transmission / reception mechanism in the optical path switching device. [Means for solving the problem]

[0008] The optical path identification device of the present invention includes an optical path identification unit that identifies which of a plurality of optical paths is a connected optical path from return light information, which is information representing a change over time in intensity of return light from a connected optical path, which is an optical path connected to a first optical path, for test light sent to the first optical path, and an output unit that outputs the identification result. The route identification method of the present invention includes the steps of identifying which of a plurality of optical paths is a connected optical path from return light information, which is information representing the change over time in intensity of return light from a connected optical path, which is an optical path connected to a first optical path, for test light sent to the first optical path, and outputting the identification result. The storage medium for the optical path identification program of the present invention stores an optical path identification program that causes a computer to execute a process of identifying which of a plurality of optical paths is a connected optical path from return light information, which is information representing a change over time in intensity of return light from a connected optical path, which is an optical path connected to a first optical path, for inspection light sent to the first optical path, and a process of outputting the identification result. Effect of the Invention

[0009] The optical path identification device and the like of the present invention can identify a switched optical path without incorporating a transmission / reception mechanism in the optical path switching device. [Brief description of the drawings]

[0010] [Figure 1] 1 is a conceptual diagram illustrating a configuration example of an optical submarine cable system according to an embodiment. [Diagram 2] 2 is a conceptual diagram illustrating an example of the configuration of each relay amplifier according to the first embodiment. FIG. [Diagram 3] 1 is a conceptual diagram illustrating an example of the configuration of an optical path identifying device according to a first embodiment. [Figure 4] 10 is a conceptual diagram illustrating an example of return light information in the first embodiment when a first optical path is connected to a second optical path. FIG. [Diagram 5] 11 is a conceptual diagram illustrating an example of return light information in the first embodiment when the first optical path is connected to the third optical path. FIG. [Figure 6] FIG. 11 is a conceptual diagram illustrating a first configuration example of each relay amplifier according to the second embodiment. [Figure 7] 13 is a conceptual diagram illustrating return light information in the second embodiment when the first optical path is connected to the second optical path. FIG. [Figure 8] 13 is a conceptual diagram illustrating return light information in the second embodiment when the first optical path is connected to the third optical path. FIG. [Figure 9] FIG. 11 is a conceptual diagram illustrating a second configuration example of the relay amplifier of the second embodiment. [Figure 10] FIG. 2 is a conceptual diagram illustrating a minimum configuration of the optical path identification device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First Embodiment This embodiment relates to an optical path identifying device that identifies an optical path switched by an optical path switching device based on a time change in intensity of return light caused by Rayleigh scattering of probe light sent to an optical fiber included in an optical cable. [Configuration and Operation] Fig. 1 is a conceptual diagram showing the configuration of an optical submarine cable system 100, which is an example of the optical submarine cable system of this embodiment. Fig. 2 is a conceptual diagram showing the configuration of a repeater amplifier A, which is an example of each repeater amplifier in Fig. 1. Fig. 3 is a conceptual diagram showing an example of the configuration of the optical path identification device 10 in Fig. 1.

[0012] The optical submarine cable system 100 is a system for performing optical communications between a land station C1 and a land station C2 or C3. The optical submarine cable system 100 includes land stations C1 to C3, optical fibers D1 to D3 and U1 to U3, and an optical path switching device B1. The optical submarine cable system 100 further includes repeater amplifiers A11 to 1n (n repeater amplifiers), A21 to A2m (m repeater amplifiers), and A31 to A3p (p repeater amplifiers).

[0013] The optical fibers D1 and U1 are optical fibers provided in an optical submarine cable installed between the land station C1 and the optical path switching device B1. The optical fiber D1 transmits an optical communication signal from the land station C1 to the optical path switching device B1. The optical fiber U1 transmits an optical communication signal from the optical path switching device B1 to the land station C1.

[0014] The optical fibers D2 and U2 are optical fibers provided in an optical submarine cable installed between the land station C2 and the optical path switching device B1. The optical fiber D2 transmits an optical communication signal from the optical path switching device B1 to the land station C1. The optical fiber U2 transmits an optical communication signal from the land station C2 to the optical path switching device B1.

[0015] The optical fibers D3 and U3 are optical fibers provided in an optical submarine cable installed between the land station C3 and the optical path switching device B1. The optical fiber D3 transmits an optical communication signal from the optical path switching device B1 to the land station C3. The optical fiber U3 transmits an optical communication signal from the land station C3 to the optical path switching device B1.

[0016] The destination with which the land station C1 performs optical communications is switched between the land station C2 and the land station C3 by the optical path switching device B1. The optical path switching device B1 performs the switching by using, for example, an optical switch.

[0017] The repeater amplifier A in Fig. 2 is each of the repeater amplifiers A11 to 1n, A21 to A2m, and A31 to A3p. The repeater amplifier A includes optical amplifiers OAD and OAU, optical couplers CD and CU, and an optical fiber R. The optical fibers D and U in Fig. 2 are either of the optical fibers D1 and U1, D2 and U2, or D3 and U3 in Fig. 1, depending on whether the repeater amplifier A is the repeater amplifier A11 to 1n, A21 to A2m, or A31 to A3p.

[0018] In relay amplifier A, the light traveling to the right through optical fiber D is amplified by optical amplifier OAD and travels further to the right. The light is Rayleigh scattered in the part of optical fiber D to the right of optical amplifier OAD. The Rayleigh scattered light travels to the left from each scattering point as returned light. The time at which the returned light traveling left through optical fiber D enters relay amplifier A becomes later the longer the optical fiber distance from optical fiber D where the returned light is scattered to relay amplifier A. Here, the optical fiber distance is the length traveled through the optical fiber.

[0019] A portion of the return light that enters repeater amplifier A from the right is separated by optical coupler CD, travels through optical fiber R, and is made incident on optical fiber U by optical coupler CU, traveling to the left. The remaining return light that was not separated by optical coupler CD enters optical amplifier OAD. The incident direction of the remaining return light is opposite to the direction of the light amplified by optical amplifier OAD. Therefore, the remaining return light is extinguished by optical amplifier OAD.

[0020] The return light entering repeater amplifier A from the right through optical fiber D is due to Rayleigh scattering in optical fiber D between repeater amplifier A and the next repeater amplifier A to the right. This is because the return light from optical fiber D further to the right of repeater amplifier A is blocked by the optical amplifier OAD of that repeater amplifier A.

[0021] On the other hand, the light that enters the repeater amplifier A from the right through the optical fiber U is amplified by the optical amplifier OAU and travels further to the left through the optical fiber U. The light that enters the repeater amplifier A from the right through the optical fiber U includes return light from the optical fiber D that has been entered by the optical coupler CU of the repeater amplifier A one level to the right.

[0022] 3 includes a return light information acquisition unit 11 and an optical path identification unit 16. The return light information acquisition unit 11 includes a transmission unit 12, a reception unit 13, an acquisition processing unit 14, and a storage unit 15.

[0023] The return light information acquisition unit 11 has a general configuration for performing, for example, optical time domain reflectometry (OTDR). The return light information acquisition unit 11 includes a transmitter 12, a receiver 13, an acquisition processing unit 14, and a storage unit 15. The transmitter 12 sends out a probe light for OTDR to the optical fiber D1. The receiver 13 converts the return light corresponding to the probe light, which is incident through the optical fiber U1, into an electrical signal and inputs it to the acquisition processing unit 14.

[0024] The probe light transmitted from the transmitter 12 to the optical fiber D1 travels to the right in the optical fiber D1 in Fig. 1. The probe light attenuates as the distance it travels through the optical fiber D1 becomes longer, but each time it passes through each of the relay amplifiers A11 to A1n (relay amplifier A in Fig. 3), it is amplified by the optical amplifier OAD of the relay amplifier A. Therefore, the probe light travels to the right while repeating amplification by the relay amplifier A and attenuation while traveling to the relay amplifier A further to the right.

[0025] As the probe light is repeatedly amplified and attenuated as it travels to the right in the optical fiber D1, the intensity of the probe light returning due to Rayleigh scattering at each position in the optical fiber D1 also repeatedly increases and attenuates. Furthermore, the arrival time of the returned light at the land station C1 increases the longer the position in the optical fiber D1 that is farther away from the land station C1 due to Rayleigh scattering. Therefore, the intensity of the returned light represented by the electrical signal input to the acquisition processing unit 14 reflects the repetition over time of the attenuation of the probe light as it travels through the optical fiber D1 and the amplification by the repeater amplifier A.

[0026] Hereinafter, the change in the intensity of the return light over time represented by the electrical signal input to the acquisition processing unit 14 will be referred to as "return light information." The return light information of the optical path in the section between the land station C1 and the optical path switching device B1 (hereinafter referred to as the "first optical path") is specific to the configuration of the first optical path. The configuration includes, for example, the optical amplification factor of each repeater amplifier A, and the length of the optical submarine cable between two adjacent repeater amplifiers A. Alternatively, if another configuration (another optical submarine device) not shown in the figure that attenuates the intensity of the probe light is installed in the first optical path, the presence of that configuration also becomes a factor that makes the return light information specific to the first optical path.

[0027] Here, it is assumed that the optical route switching device B1 connects the first optical path to the second optical path (the optical path in the section between the optical route switching device B1 and the land station C2). In this case, the first optical path and the third optical path (the optical path in the section between the optical route switching device B1 and the land station C3) are not connected.

[0028] In this case, the return light information of the second optical path is acquired by the acquisition processing unit 14 after the return light information of the first optical path. The return light information of the second optical path is specific to the configuration of the second optical path for the same reason as the return light information of the first path.

[0029] Also, assume that the optical path switching device B1 connects the first optical path to the third optical path, in which case the first optical path and the second optical path are not connected.

[0030] In this case, the return light information of the third optical path is acquired by the acquisition processing unit 14 following the return light information of the first optical path. The return light information of the third optical path is specific to the configuration of the third optical path for the same reason as the return light information of the first optical path.

[0031] Here, the explanation of Fig. 3 will be interrupted to explain an example of the return light information. Fig. 4 is an image diagram showing an example of the return light information when the optical path switching device B1 connects the first optical path to the second optical path. Time 0 in Fig. 4 is the time when the transmitter 12 in Fig. 3 transmits the probe light to the optical fiber D1. The return light information between time 0 and time Ti is the return light information of the first optical path. The return light information between time Ti and time Tm2 is the return light information of the second optical path.

[0032] The return light information of the first optical path reflects the configuration of the first optical path, such as the number n of repeater amplifiers A in this section, the optical cable distance of the optical submarine cable between two adjacent repeater amplifiers A, and the amplification factor of each repeater amplifier A. Therefore, the return light information of this section is unique to the first optical path.

[0033] The return light information of the second optical path reflects the configuration of the second optical path, such as m, which is the number of repeater amplifiers A in this section, the optical cable distance of the optical submarine cable between two adjacent repeater amplifiers A, and the amplification factor of each repeater amplifier A. Therefore, the return light information of this section is unique to the second optical path.

[0034] Fig. 5 is an image diagram showing an example of return light information when the optical path switching device B1 connects the first optical path to the third optical path. Time 0 in Fig. 5 is the time when the transmitter 12 in Fig. 3 transmits the probe light to the optical fiber D1. The return light information between time 0 and time Ti is the return light information of the first optical path. The return light information between time Ti and time Tm3 is the return light information of the third optical path.

[0035] The return light information of the first optical path is the same as that shown in Fig. 4. The return light information of the third optical path reflects the configuration unique to the third optical path, such as the number p of relay amplifiers A of the third optical path, the optical cable distance of the optical submarine cable between two adjacent relay amplifiers A, and the amplification factor of each relay amplifier A. Therefore, the return light information of the third optical path is unique to the third optical path.

[0036] 4 and 5, it is assumed that each relay amplifier A amplifies the return light having different intensities attenuated by traveling through the optical fiber to an equal level. However, each relay amplifier A does not necessarily have to amplify in this way. The pattern of the return light information has a shape according to the amplification factor of each relay amplifier.

[0037] Here, the return light information in Fig. 4 is compared with the return light information in Fig. 5. In this case, the pattern shape of the return light information between time 0 and Ti is the same in Fig. 4 and Fig. 5. However, the pattern shape of the return light information after time Ti is different in Fig. 4 and Fig. 5. Therefore, by utilizing this difference in the pattern shape of the return light information, it is possible to identify whether the connection destination of the optical fibers D1 and U1 in the optical path switching device B1 is the optical fibers D2 and U2, or the optical fibers D3 and U3.

[0038] The optical path identification unit 16 in FIG. 3 performs this identification using the most recent return light information acquired by the acquisition processing unit 14 and stored in the storage unit 15.

[0039] In the return light information in Fig. 4 and Fig. 5, all the maxima (peaks) of the return light caused by the amplification by the relay amplifier A appear. In general, the number m, which is the number of relay amplifiers A in the second optical path, is different from the number p, which is the number of relay amplifiers A in the third optical path. In such a case, the optical path identifying unit 16 can identify whether the connection destination of the first optical path in the optical path switching device B1 is the second optical path or the third optical path, based on the number of maxima (peaks) of the return light. In this case, the optical path identifying unit 16 performs this identification by, for example, comparing the number of maxima (peaks) of the return light with reference information of m and p previously stored in the storage unit 15.

[0040] However, for example, when the land station C2 is located very far from the optical path switching device B1, the maximum (peak) of the return light for the relay amplifier A far from the optical path switching device B1 may be buried in noise and not appear in the return light information. In that case, the optical path identification unit 16 may identify the connection destination of the optical fibers D1 and U1 in the optical path switching device B1 based on the return light intensity at each time and the interval between the maximum (peak) of the return light in the return light information that has been acquired. In that case, the optical path identification unit 16 performs the identification by comparing the reference information of the return light intensity of each optical path and the interval between the maximum (peak) of the return light with these data in the acquired return light information, which are stored in advance in the storage unit 15.

[0041] Alternatively, the optical path specifying unit 16 may specify the connection destination by judging whether the return light information itself is similar to the reference information when the connection destination of the first optical path is the second optical path or the third optical path, which is stored in the storage unit 15. In this case, a general method for judging whether data is similar to each other can be applied as a method for judging whether data is similar to each other.

[0042] As the reference information, for example, data of return light information obtained by actually switching the connection destination of the first optical path to the optical path switching device B1 and having a computer learn by machine learning may be used. The method of determining whether the return light information itself is similar to the reference information can also be applied to cases where the optical path does not include a repeater amplifier.

[0043] Alternatively, the optical path identifying unit 16 may identify the destination of the first optical path based on the intensity of the return light in the return light information. In this case, the intensity of the return light is, for example, an average value or a maximum value of the intensity of the return light. In this case, the optical path identifying unit 16 performs the identification by comparing the intensity of the return light previously stored in the storage unit 15 with the intensity of the return light in the acquired return light information.

[0044] The method using the degree of intensity of the return light can also be applied to a case where the optical path does not include a repeater amplifier.

[0045] Alternatively, the optical path identifying unit 16 may identify the connection destination of the first optical path based on the time (time from the probe light is sent out) at which the return light from the maximum (peak) of intensity at the position with the longest optical cable distance in the return light information arrives. In this case, the optical path identifying unit 16 performs the identification by comparing the time (time from the probe light is sent out) at which the return light from the position with the longest optical cable distance, which is stored in advance in the storage unit 15, with the data in the acquired return light information.

[0046] Alternatively, the optical path identifying unit 16 may identify the connection destination of the first optical path by combining the methods described above.

[0047] An optical path identified by the optical path identification device of this embodiment may include two or more optical path switching devices as long as return light information can be obtained. Here, the reason why "as long as return light information can be obtained" is that for an optical path in which the optical cable distance from the optical path identification device is too long, return light information may not be obtained due to the influence of noise or the like. In that case, the optical path identification device identifies an optical path that is included in an optical path in a range in which return light information can be obtained and that has been switched by an optical path switching device. For an optical path of each optical path switching device included in an optical path in a range in which return light information can be obtained, the return light information corresponds to the optical path switched by each optical path switching device. Therefore, an optical path can be identified by the return light information.

[0048] 3 outputs and stores the result of identifying the destination optical path to the storage unit 15. The optical path identifying unit 16 also outputs the identification result to the outside by the output unit 17. The outside is, for example, a display device, an audio output device, a printing device, a transmitting device, or the like.

[0049] 3, the combination of the acquisition processing unit 14, the storage unit 15, the optical path identification unit 16, and the output unit 17 may be provided in a computer or may be provided in a computer. In this case, the computer performs processing related to the operations described in the embodiments by a program stored in advance in the storage unit 15.

[0050] [effect] The optical path identification device of this embodiment acquires return light information, which is information representing a time change in intensity of return light due to Rayleigh scattering from each position of the optical fiber with respect to the probe light sent to the optical fiber included in the optical submarine cable. The return light information includes return light information from the optical path beyond the optical path switching device. In this case, the return light information from the optical path beyond the optical path switching device is specific to the configuration of the optical path of the switching destination, which reflects the configuration of the optical path switching device. The optical path identification device of this embodiment identifies the switching destination based on the return light information specific to the configuration of the optical path of the switching destination. Therefore, the optical path identification device of this embodiment does not need to acquire information on the optical path of the switching destination by communicating with the optical path switching device. Therefore, the optical path identification device of this embodiment makes it possible to identify the switched optical path without incorporating a transmission / reception mechanism in the optical path switching device.

[0051] <Second embodiment> The optical path identification device of the first embodiment identifies an optical path switched by an optical path switching device by return light information of return light by Rayleigh scattering. However, return light by Rayleigh scattering is relatively weak. Therefore, when return light by Rayleigh scattering is used, it may be difficult to obtain return light information for an optical path with a long optical cable distance from the optical path identification device due to the influence of noise, etc. Therefore, in the optical submarine cable system of this embodiment, a return light path different from the return light path of the first embodiment is provided in the repeater amplifier. This return light path is of a type in which a part of the probe light is extracted by the transmitting optical fiber and inputted to the receiving optical fiber. By this return light path, the amount of return light returning from each repeater amplifier is significantly larger than the return light by Rayleigh scattering. Therefore, the optical path identification device in the optical submarine cable system of this embodiment can use return light information for an optical path with a longer optical cable distance than the optical path identification device in the optical submarine cable system of the first embodiment. Therefore, the optical route identifying device in the optical submarine cable system of this embodiment can identify an optical route switched by an optical route switching device for an optical route with a longer optical cable distance than the optical route identifying device in the optical submarine cable system of the first embodiment.

[0052] [Configuration and Operation] A configuration example of the optical submarine cable system of this embodiment is the configuration of the optical submarine cable system 100 shown in Fig. 1, but the configuration of each relay amplifier is different from that of the relay amplifier of the first embodiment. Here, each relay amplifier is each of the relay amplifiers A11 to A1n, A21 to A1m, and A31 to A3p in Fig. 1. A configuration example of the optical path identification device 10 in Fig. 1 is the same as that shown in Fig. 3.

[0053] 6 is a conceptual diagram showing the configuration of a relay amplifier A, which is a first example of each relay amplifier of this embodiment. The relay amplifier A includes optical amplifiers OAD and OAU, optical couplers CD and CU, and an optical fiber R. The optical fibers D and U are the same as those in FIG.

[0054] The pulsed probe light traveling to the right through the optical fiber D is amplified by the optical amplifier OAD. A part of the amplified probe light is separated by the optical coupler CD and input to the optical fiber R. The separated probe light is input to the optical fiber U by the optical coupler CU and travels through the optical fiber U as return light toward the optical path identification device 10. Thereafter, the return light from the repeater amplifier A on the right passes through the optical fiber U at the position of this repeater amplifier A. The difference between the time when this repeater amplifier A inputs the return light into the optical fiber U and the time when the return light input to the optical fiber U by the repeater amplifier A on the right passes through the optical fiber U at the position of this repeater amplifier A is a value proportional to the optical cable distance. The optical cable distance is the optical cable distance between this repeater amplifier A and the repeater amplifier A on the right.

[0055] Each relay amplifier in Fig. 1 performs the operation of the relay amplifier A. Therefore, the return light from each relay amplifier A enters the receiving unit 13 in Fig. 3 with a time difference according to the optical cable distance between two adjacent relay amplifiers A. The combination of the distance between two adjacent relay amplifiers A is specific to the second optical path and the third optical path. Therefore, the return light information of the second optical path is different from the return light information of the third optical path.

[0056] Fig. 7 is an image diagram showing return light information when the optical path switching device B1 in Fig. 1 connects the first optical path to the second optical path. The return light information is acquired by the acquisition processing unit 14 in Fig. 3. The acquisition processing unit 14 acquires the return light information of the second path following the return light information of the first optical path.

[0057] Fig. 8 is an image diagram showing return light information when the optical path switching device B1 in Fig. 1 connects the first optical path to the third optical path. The return light information is acquired by the acquisition processing unit 14 in Fig. 3. The acquisition processing unit 14 acquires the return light information of the third optical path following the return light information of the first optical path.

[0058] 7 and 8 show examples of return light information when each relay amplifier A performs optical amplification so that the intensity of the return light pulse is equal. However, each relay amplifier A does not necessarily have to perform such optical amplification. The intensity of each return light pulse becomes a value that depends on the amplification factor of the optical amplification performed by each relay amplifier A.

[0059] Here, the return light information in Fig. 7 and Fig. 8 will be compared. The return light information of the first optical path is the same in Fig. 7 and Fig. 8. In contrast, the return light information of the second optical path in Fig. 7 is different from the return light information of the third optical path in Fig. 8.

[0060] First, the number of pulses of the return light in the return light information of the second optical path is m, whereas the number of pulses of the return light in the return light information of the third optical path is p. When the configuration of each relay amplifier A is as shown in FIG. 6, one pulse of the return light is generated in each relay amplifier A. Therefore, the number of pulses of the return light is the number of relay amplifiers A included in each optical path. The number of relay amplifiers A included in each optical path is generally different. In that case, the optical path identification unit 16 in FIG. 3 identifies whether the connection destination of the first optical path is the second optical path or the third optical path from the number of peaks of the return light.

[0061] Furthermore, the combination of optical cable distances between two adjacent relay amplifiers A generally differs between the second optical path and the third optical path. In this case, the optical path identifying unit 16 identifies whether the connection destination of the first optical path is the second optical path or the third optical path based on the difference in the combination of optical cable distances between two adjacent relay amplifiers A in the second optical path and the third optical path. This method is effective when part of the return light information cannot be acquired for a distant portion of the optical path due to the influence of noise or the like.

[0062] Alternatively, the optical path identification unit 16 may identify whether the connection destination of the first optical path by the optical path switching device B1 is the second optical path or the third optical path by judging whether the connection destination is the second optical path or the third optical path with reference information of the return light information including the return light information of the second optical path and the third optical path held by the storage unit 15. In this case, a general method for judging whether two pieces of data are similar or not may be used as a method for judging whether the connection destination is the second optical path or the third optical path. As the reference information, for example, data of the return light information obtained by actually switching the connection destination of the first optical path to the optical path switching device B1 and having a computer learn the data by machine learning may be used. The method of using the similarity judgment is also effective when a part of the return light information cannot be obtained for a distant part of the optical path due to the influence of noise or the like.

[0063] Fig. 9 is a conceptual diagram showing the configuration of a repeater amplifier A, which is a second example of the repeater amplifier of this embodiment. The repeater amplifier A in Fig. 9 includes optical amplifiers OAD and OAU, optical couplers CD and CU, optical fibers R and Rm, and a reflector M. The optical fibers D and U are the same as those in Fig. 2.

[0064] The pulsed probe light traveling to the right through the optical fiber D is amplified by the optical amplifier OAD. A part of the amplified probe light is separated by the optical coupler CD and is incident on the reflector M through the optical fiber Rm. The reflected light reflected by the reflector M is incident on the optical fiber R through the optical fiber Rm and the optical coupler CD. The reflected light incident on the optical fiber R is incident on the optical fiber U by the optical coupler CU and travels through the optical fiber U as return light toward the optical path identification device 10. Thereafter, the return light from the relay amplifier A on the right passes through the optical fiber U at the position of this relay amplifier A. The difference between the time when this relay amplifier A incidents the return light into the optical fiber U and the time when the return light incident on the optical fiber U by the relay amplifier A on the right passes through the optical fiber U at the position of this relay amplifier A is a value proportional to the optical cable distance. The optical cable distance is the optical cable distance between this relay amplifier A and the relay amplifier A on the right.

[0065] The acquisition processing unit 14 in FIG. 3 acquires the same return light information when the relay amplifier A in FIG. 9 is used as when the relay amplifier A in FIG. 6 is used.

[0066] The optical path specifying unit 16 performs the above-mentioned specifying operation based on the return light information similar to that in the case where the repeater amplifier A in FIG. 6 is used.

[0067] The optical path identification device of the second embodiment can identify an optical path switched by an optical path switching device even if the optical path is provided with two or more optical path switching devices. This identification is possible as long as return light information of the optical path beyond the optical path switching device can be acquired. To that extent, the optical path switched by each optical path switching device has return light information unique to the configuration of the optical path switched by each optical path switching device. Therefore, the optical path identification device can identify the switched optical path from the unique return light information.

[0068] [effect] The optical path identification device of this embodiment acquires return light information of return light in each repeater amplifier in response to the probe light sent to the optical fiber of the optical submarine cable. The return light information includes return light information from the optical path beyond the optical path switching device. In this case, the return light information from the optical path beyond the optical path switching device is specific to the configuration of the optical path of the switching destination, which reflects the configuration of the optical path switching device. The optical path identification device of this embodiment identifies the switching destination based on the return light information specific to the configuration of the optical path of the switching destination. Therefore, the optical path identification device of this embodiment does not need to acquire information of the optical path of the switching destination by communicating with the optical path switching device. Therefore, the optical path identification device of this embodiment can identify the optical path switched by the optical path without incorporating a transmission / reception mechanism in the optical path switching device.

[0069] Furthermore, in the optical submarine cable system of this embodiment, a return light path is provided in the relay amplifier, in which a part of the probe light traveling through the transmitting optical fiber is extracted and input to the receiving optical fiber. Due to this return light path, the intensity of the return light returning from each relay amplifier is significantly greater than that of the return light due to Rayleigh scattering. Therefore, the optical route identification device of the optical submarine cable system of this embodiment can identify an optical route connected to an optical route switching device for an optical route having a longer optical cable distance than the optical route identification device of the optical submarine cable system of the first embodiment.

[0070] In the above description, an example has been described in which the acquisition processing unit also acquires return light information for the first optical path. However, the acquisition processing unit does not need to acquire return light information for the first optical path. In addition, if the acquisition processing unit does not acquire return light information for the first optical path, the relay amplifier of the first optical path does not need to have a return light path.

[0071] Moreover, the optical cable does not necessarily have to be an optical submarine cable, but may be an optical cable installed on land.

[0072] 10 is a block diagram showing a configuration of an optical path identifying device 10x which is an example of an optical path identifying device according to an embodiment. The optical path identifying device 10x includes an optical path identifying unit 16x and an output unit 17x. The optical path identifying unit 16x identifies which of a plurality of optical paths is the connected optical path from return light information which is information representing a time change in intensity of return light from a connected optical path which is an optical path connected to a first optical path, for test light sent to the first optical path. The output unit 17x outputs the identification result.

[0073] The optical path identification device 10x identifies which of a plurality of optical paths the connected optical path is from the return light information, and outputs the identified path. Therefore, the optical path identification device 10x can identify the switched optical path without incorporating a transmission / reception mechanism in the optical path switching device. Therefore, the optical path identification device 10x has the effects described in the section [Effects of the Invention] due to the above configuration.

[0074] Although each embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiments, and further modifications, substitutions, and adjustments can be made without departing from the basic technical idea of ​​the present invention. For example, the configurations of elements shown in each drawing are examples to help understand the present invention, and the present invention is not limited to the configurations shown in these drawings.

[0075] Furthermore, some or all of the above-described embodiments may be described as, but are not limited to, the following supplementary notes. (Appendix 1) an optical path identification unit that identifies which of a plurality of optical paths is a connected optical path based on return light information that represents a time change in intensity of return light from a connected optical path, which is an optical path connected to a first optical path, for an inspection light sent to the first optical path; an output unit that outputs the specified result; An optical path determination device comprising: (Appendix 2) 2. The optical path identifying device according to claim 1, wherein the optical path identifying unit performs the identification by determining whether the return light information is similar to reference information about the return light information that has been acquired in advance. (Appendix 3) 3. The optical path identifying device according to claim 1, wherein the optical path identifying unit performs the identification based on acquired information that is information acquired from the return light information. (Appendix 4) 4. The optical path identification device according to claim 3, wherein the optical path identification unit performs the identification by comparing reference information about the acquired information with the acquired information. (Appendix 5) The optical path identification device described in Appendix 4, wherein the acquired information includes at least one of the following information: the number of relay amplifiers included in the connected optical path; the length of an optical path between two adjacent relay amplifiers included in the connected optical path; the intensity of the return light in each of the plurality of optical paths; and the time from when the inspection light is sent to when the return light arrives from a position with the longest optical cable distance in each of the plurality of optical paths. (Appendix 6) 6. The optical path identification device according to claim 1, wherein the return light is return light from a second optical fiber with respect to the inspection light sent to a first optical fiber. (Appendix 7) 7. An optical path identification device as described in claim 6, wherein the return light is caused by Rayleigh scattering at each position of the first optical fiber, traveling in a direction opposite to a direction of travel of the inspection light through the first optical fiber. (Appendix 8) a first return optical path provided in the connected optical path and between the first optical fiber and the second optical fiber; The return light due to Rayleigh scattering is incident on the second optical fiber through the first return light path in a direction opposite to the traveling direction of the inspection light. 8. An optical path determination device as described in appended claim 7. (Appendix 9) The first return optical path is provided in a relay amplifier provided in each of the connected optical paths. 9. An optical path determination device according to claim 8. (Appendix 10) a second return optical path that is provided in the connected optical path, is installed at a predetermined position of the first optical path and the connected optical path, and is an optical path that causes a part of the inspection light traveling through the first optical fiber to enter the second optical fiber in a direction opposite to the traveling direction of the inspection light; The return light is derived from light passing through the second return light path. 7. An optical path determination device as described in appended claim 6. (Appendix 11) The second return optical path is provided in a relay amplifier provided in the connected optical path. 11. An optical path determination device as described in claim 10. (Appendix 12) The optical fiber is provided in a land station connected to the first optical path. 12. An optical path identification device according to any one of claims 1 to 11. (Appendix 13) Further comprising a return light information acquisition unit which acquires the return light information. 13. An optical path identification device according to any one of claims 1 to 12. (Appendix 14) Further comprising the first optical path and the plurality of optical paths. 14. An optical path identification device according to any one of claims 1 to 13. Optical path determination device. (Appendix 15) Identifying which of a plurality of optical paths is the connected optical path from return light information, which is information representing a time change in intensity of return light from a connected optical path, which is an optical path connected to the first optical path, for the inspection light sent to the first optical path; outputting the particular result; Optical routing method. (Appendix 16) A process of identifying which of a plurality of optical paths is a connected optical path from return light information representing a time change in intensity of return light from a connected optical path, which is an optical path connected to a first optical path, with respect to the test light transmitted to the first optical path; outputting the specific result; An optical path determination program that causes a computer to execute the above.

[0076] Here, the "first optical path" in the above supplementary note is, for example, the first optical path in FIG. 1. Also, the "inspection light" is, for example, the probe light described above. Also, the "connected optical path" is, for example, the second optical path or the third optical path in FIG. 1. Also, the "multiple optical paths" are, for example, the second optical path and the third optical path in FIG. 1.

[0077] Moreover, the "optical path determining unit" is, for example, the optical path determining unit 16 in FIG. 3 or the optical path determining unit 16x in FIG. 10. Moreover, the "output unit" is, for example, the output unit 17 in FIG. 3 or the output unit 17x in FIG. 10. Moreover, the "optical path determining device" is, for example, the optical path determining device 10 or the optical path determining unit 16 in FIG. 3 or the optical path determining device 10x in FIG. 10. Moreover, the "return light information" is, for example, the return light information described above.

[0078] Moreover, the "first optical fiber" is, for example, the optical fiber D in Fig. 2 or 6. Moreover, the "second optical fiber" is, for example, the optical fiber U in Fig. 2 or 6. Moreover, the "first return optical path" is, for example, the combination of the optical coupler CD, the optical fiber R, and the optical coupler CU in Fig. 2. Moreover, the "repeater amplifier" is, for example, the relay amplifier A in Fig. 2 or Fig. 6. Moreover, the "second return optical path" is, for example, the combination of the optical coupler CD, the optical fiber R, and the optical coupler CU in Fig. 6.

[0079] Moreover, the "land station" is, for example, the land station C1 in Fig. 1. Moreover, the "return light information acquisition unit" is, for example, the return light information acquisition unit 11 in Fig. 3. Moreover, the "computer" is, for example, a computer including a combination of the storage unit 15, the optical path identification unit 16, and the output unit 17 in Fig. 3. Moreover, the "optical path identification program" is, for example, a program that causes the computer to execute processing, and is held, for example, in the storage unit 15.

[0080] This application claims priority based on Japanese Patent Application No. 2021-005430, filed on January 18, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0081] 10, 10x Optical Path Identification Device 11. Return light information acquisition section 12 Transmitter 13 Receiving section 14 Acquisition processing section 15 Storage section 16, 16x Optical Path Identification Unit 17, 17x Output Section 100 Optical Submarine Cable System A, A11, A12, A13, A1n, A21, A22, A23, A2m, A31, A32, A33, A3p Relay amplifier B1 Optical Route Switching Equipment C1, C2, C3 land station CD, CU optical coupler D, D1, D2, D3, U, U1, U2, U3, R, Rm Optical fiber M reflector OAD, OAU Optical Amplifier

Claims

1. an optical path identification unit that identifies which of a plurality of optical paths is a connected optical path based on return light information that represents a time change in intensity of return light from a connected optical path that is an optical path connected to a first optical path, for an inspection light sent to the first optical path; an output unit that outputs the specified result; the connected optical path includes a first optical fiber and a second optical fiber, and further includes a first return optical path provided between the first optical fiber and the second optical fiber; the return light is return light from the second optical fiber with respect to the inspection light transmitted to the first optical fiber, the return light travels through the first optical fiber in a direction opposite to a direction in which the inspection light travels, and is caused by Rayleigh scattering at each position of the first optical fiber; The return light caused by Rayleigh scattering is incident on the second optical fiber via the first return light path in a direction opposite to the traveling direction of the inspection light.

2. 2. The optical path identifying device according to claim 1, wherein the optical path identifying unit performs the identification by determining whether or not the return light information is similar to previously acquired reference information for the return light information.

3. 3. The optical path identifying device according to claim 1, wherein the optical path identifying unit performs the identification based on acquired information that is information acquired from the return light information.

4. The optical path identification device according to claim 3 , wherein the optical path identification unit performs the identification by comparing reference information about the acquired information with the acquired information.

5. 5. The optical path identification device of claim 4, wherein the acquired information includes at least one of the following information: the number of relay amplifiers in the connected optical path; the length of the optical path between two adjacent relay amplifiers in the connected optical path; the intensity of the return light in each of the plurality of optical paths; and the time from when the inspection light is sent to when the return light arrives from a position with the longest optical cable distance in each of the plurality of optical paths.

6. Identifying which of a plurality of optical paths is the connected optical path from return light information, which is information representing a time change in intensity of return light from a connected optical path, which is an optical path connected to the first optical path, for the inspection light sent to the first optical path; Outputting the identified results; the return light is return light from a second optical fiber provided in the connected optical path with respect to the inspection light transmitted to a first optical fiber provided in the connected optical path, the return light travels through the first optical fiber in a direction opposite to a direction in which the inspection light travels, and is caused by Rayleigh scattering at each position of the first optical fiber; The optical path identification method, in which the return light due to Rayleigh scattering is incident on the second optical fiber in a direction opposite to the direction of travel of the inspection light through a first return light path provided between the first optical fiber and the second optical fiber.

7. A process of identifying which of a plurality of optical paths is a connected optical path from return light information representing a time change in intensity of return light from a connected optical path, which is an optical path connected to a first optical path, for the inspection light sent to the first optical path; and outputting the specific result. the return light is return light from a second optical fiber provided in the connected optical path with respect to the inspection light transmitted to a first optical fiber provided in the connected optical path, the return light travels through the first optical fiber in a direction opposite to a direction in which the inspection light travels, and is caused by Rayleigh scattering at each position of the first optical fiber; The return light due to Rayleigh scattering is incident on the second optical fiber in a direction opposite to the direction of travel of the inspection light through a first return light path provided between the first optical fiber and the second optical fiber.

Images