Connection status identifying system and connection status identifying method

Abstract

In order to provide a connection state identification system that makes it possible to confirm the connection state of an optical path by using a branching device during inspection of the operation of an undersea optical cable system, this connection state identification system comprises an identification information addition means and an identification information acquisition means. The undersea optical cable system is provided with undersea optical cables that comprise optical paths provided with optical fibers, and a branching device that switches the connection of the optical paths. When an inspection optical signal, which is an optical signal for inspection transmitted by a first optical communication device to a second optical communication device, is received by the second optical communication device over inter-optical communication device optical paths, which are the optical paths included in the undersea optical cable system between the optical communication devices, the identification information addition means adds, to an unassigned frequency band of the inspection optical signal, the unassigned frequency band being a frequency band other than a frequency band assigned to optical communication, identification information differing for each inter-optical communication device optical path through which the inspection optical signal passes. The identification information acquisition means outputs the identification information in the inspection optical signal received by the second optical communication device.

Description

[Technical field]

[0001] The present invention relates to a connection status specifying system and a connection status specifying method that enable specifying the connection status of an optical path by a branching device. [Background technology]

[0002] In a submarine optical cable system that uses a submarine optical cable to perform optical communication between land terminal stations, a branching unit for switching optical paths may be installed. In such a case, it is necessary for the land terminal station to check the switching operation of the optical switch equipped in the branching unit. For this purpose, it is essential for the land station to grasp the connection status of the optical path in the branching unit.

[0003] When checking the connection status, generally, the optical communication device installed in the land terminal first sends a command signal to the branching device to switch the optical switch, and then checks whether the communication optical signal, which is the optical signal actually used for optical communication, is correctly sent to the optical device of the other land terminal, thereby checking the connection status.

[0004] In recent years, open cable systems, in which an optical submarine cable system consisting of an optical submarine cable and an optical submarine device including a branching device, and optical communication devices installed at land terminal stations are individually introduced from different manufacturers, are becoming mainstream. In an open cable system, optical communication devices for actual communication between land terminal stations are generally not introduced at the time the optical submarine cable system is introduced. In such cases, the transmission characteristics of the optical submarine cable system are inspected by transmitting and receiving optical signals for inspection by the optical communication devices installed at each land terminal station.

[0005] Fig. 1 is a conceptual diagram showing the configuration of an optical communication system 100, which is an example of a general optical communication system that combines an optical submarine cable system with optical communication devices that transmit and receive optical signals for testing. The optical communication system 100 is in a state before optical communication devices for performing actual optical communication are installed in each land terminal station. The optical communication devices K1 to K4 shown in Fig. 1 only have the function of transmitting and receiving optical signals for testing, and do not transmit and receive communication optical signals for performing actual optical communication.

[0006] Fig. 2 is a conceptual diagram showing the configuration of an optical communication device K, which is an example of each of the optical communication devices K1 to K4 shown in Fig. 1. Fig. 3 is an image diagram showing the frequency characteristics (hereinafter, sometimes simply referred to as "frequency characteristics") of the intensity of an inspection optical signal i k, which is an example of an inspection optical signal transmitted by the optical signal transmitting unit 10. Fig. 4 is a conceptual diagram showing an example of the configuration of the optical signal transmitting unit 10 shown in Fig. 2. Fig. 5 is a conceptual diagram showing an example of the configuration of the optical signal receiving unit 20 shown in Fig. 2.

[0007] 1, the optical communication system 100 includes land terminal stations T1 to T4 and an optical submarine cable system CS. The optical communication system 100 transmits and receives test optical signals (test optical signals) between the land terminal stations, and tests the normal operation of the optical submarine cable system CS based on changes in the frequency characteristics of the test optical signals received by the land terminal stations from the time of transmission.

[0008] The optical submarine cable system CS includes branching devices B1 and B2 and optical fibers F11, F12, F21, F22, F31, F32, F41, F42, F51, and F52. Here, each arrow shown in Fig. 1 indicates the traveling direction of an optical signal in each optical fiber. The land terminal stations T1 to T4 include optical communication devices K1 to K4. Each of the optical fibers F11, F12, F21, F22, F31, F32, F41, F42, F51, and F52 is an optical fiber including one or more optical fiber cores, or a group of multiple such optical fibers.

[0009] The branching device B1 switches the connection destination of the first optical path to either the third optical path or the fifth optical path. Here, the first optical path is an optical path including optical fibers F11 and F12. The third optical path is an optical path including optical fibers F31 and F32. The fifth optical path is an optical path including optical fibers F51 and F52.

[0010] The branching device B2 switches the connection destination of the second optical path to either the fourth optical path or the fifth optical path. Here, the second optical path is an optical path including optical fibers F21 and F22. Also, the fourth optical path is an optical path including optical fibers F41 and F42.

[0011] Each of the optical communication devices K1 to K4 in FIG. 1 includes an optical signal transmitting unit 10 and an optical signal receiving unit 20, like the optical communication device K shown in FIG.

[0012] The test optical signal (test optical signal) transmitted by the optical signal transmitter 10 includes a transmission optical signal and a supervisory optical signal in different frequency bands, like the test optical signal ik in FIG.

[0013] The transmitted optical signal is an optical signal having the same or similar frequency characteristics as the transmitted optical signal used for transmission by optical communication equipment (actual optical communication equipment) used for actual communication, not for testing. The actual optical communication equipment is planned to be installed in each land terminal station in the future and connected to the optical submarine cable system CS. Note that the information carried by the transmitted optical signal does not need to have any particular meaning.

[0014] The optical supervisory signal is an optical signal having the same frequency characteristics as the optical supervisory signal used for transmission by the actual optical communication device. Here, the optical supervisory signal is, for example, an SV (supervisory) signal. The information carried by the optical supervisory signal does not need to have any particular meaning.

[0015] The inspection optical signal i k has an unallocated frequency band, which is a frequency band not used for either the transmitted optical signal or the optical supervisory signal. The unallocated frequency band is made up of a low unallocated frequency band and a high unallocated frequency band. The low unallocated frequency band is an unallocated frequency band that is lower than the frequency bands used for the transmitted optical signal and the optical supervisory signal. The high unallocated frequency band is an unallocated frequency band that is higher than the frequency bands used for the transmitted optical signal and the optical supervisory signal.

[0016] Note that the test optical signal ik contains noise, for example, ASE noise, where ASE is an abbreviation for amplified spontaneous emission.

[0017] As shown in Fig. 4, the optical signal transmitting unit 10 in Fig. 2 includes a transmission signal generating unit 11, a supervisory signal generating unit 12, and a multiplexing unit 13. The transmission signal generating unit 11 generates transmission signals, which are optical signals of each frequency constituting the transmission optical signal in Fig. 3, and inputs them to the multiplexing unit 13. The supervisory signal generating unit 12 generates supervisory signals, which are optical signals of each frequency constituting the supervisory optical signal in Fig. 3, and inputs them to the multiplexing unit 13.

[0018] The multiplexer 13 multiplexes the signals of each frequency of the transmission signal input from the transmission signal generator 11 and the signals of each frequency of the supervisory signal input from the supervisory signal generator 12 to generate the inspection optical signal i k in Fig. 3. The multiplexer 13 inputs the generated inspection optical signal i k into the optical fiber FK1. When the optical communication device K in Fig. 2 is the optical communication devices K1, K2, K3, and K4 in Fig. 1, the optical fiber FK1 is the optical fibers F11, F22, F32, and F42 in this order.

[0019] 5, the optical signal receiving unit 20 in Fig. 2 includes an optical receiving unit 21, an analyzing unit 22, a storage unit 26, and an output unit 27. The optical receiving unit 21 wavelength-separates the inspection optical signal i k (received inspection optical signal) in Fig. 3 incident from the optical fiber FK2, and inputs the separated signal to the analyzing unit 22. When the optical communication device K in Fig. 2 is the optical communication devices K1, K2, K3, and K4 in Fig. 1, the optical fiber FK2 is the optical fibers F12, F21, F31, and F41, in this order.

[0020] The analysis unit 22 measures the intensity of each of the wavelength-separated optical signals to obtain the frequency characteristics of the received test optical signal (received test optical signal), and stores the frequency characteristics in the storage unit .

[0021] The optical signal receiving unit 20 performs the above operations using a configuration similar to that of a commercially available optical spectrum analyzer.

[0022] The analysis unit 22 also causes the output unit 27 to output the frequency characteristics of the acquired received inspection optical signal, for example, in response to an external instruction.

[0023] The storage unit 26 holds programs and information for the optical signal receiving unit 20 to perform the above operations. The storage unit 26 sends information instructed by each component of the optical signal receiving unit 20 to the instructed component. The storage unit 26 stores information instructed by each component of the optical signal receiving unit 20.

[0024] The output unit 27 is, for example, a display device or a transmission device. The output unit 27 outputs information instructed by each component of the optical signal receiving unit 20.

[0025] Here, Patent Document 1 discloses a probe generator that separates optical signals by polarization, adjusts them to have a single polarization direction, combines and splits them, intensity-modulates them with a pilot signal, and combines each optical signal adjusted to have a different polarization direction to generate and output an optical signal for a probe.

[0026] Furthermore, Patent Document 2 discloses a line monitoring device for a wavelength multiplexing optical submarine cable network, which causes a transmitter installed in a transmission terminal device to output a line monitoring signal, extracts the line monitoring signal from a signal returned via an optical loopback circuit in an optical submarine repeater, and detects line faults. [Prior art documents] [Patent documents]

[0027] [Patent Document 1] JP 2016-208276 A [Patent Document 2] Japanese Patent Application Publication No. 09-289494 Summary of the Invention [Problem to be solved by the invention]

[0028] As explained in the Background Art section, the connection status of the optical path in the branching device is generally confirmed by checking whether the communication optical signal, which is the optical signal actually used in the optical communication, is correctly sent to the optical device of the other land terminal station. In order to transmit and receive the communication optical signal, it is necessary to install an optical communication device for actually performing the optical communication in the optical submarine cable system.

[0029] This causes a problem in that the supplier of the optical submarine cable cannot check the connection status of the optical path in the branching device until the optical communication device for actually performing the optical communication is delivered and installed.

[0030] Here, Patent Document 1 discloses a configuration for identifying paths by superimposing a path identifier (ID) onto an optical signal of an unused wavelength. However, Patent Document 1 relates to a configuration for measuring "waveform degradation due to polarization dependence" and makes no mention of grasping the path state (branching state of a branching device). In addition, the path ID is converted into data within the optical signal, and the configuration of Patent Document 1 makes it impossible to know the path ID from the spectrum of the optical signal.

[0031] Moreover, Patent Document 2 relates to a line monitoring system in an optical submarine cable network. In Patent Document 2, a line monitoring signal is electrically superimposed on a main signal, and Patent Document 2 does not disclose route monitoring based on the spectrum of an out-of-band signal.

[0032] Therefore, even if the inventions of Patent Documents 1 and 2 are combined, it is considered that the connection state of the optical path in the branching device cannot be determined in the land terminal station that receives the test optical signal.

[0033] An object of the present invention is to provide a connection status specifying system and the like that enables confirmation of the connection status of an optical path by a branching device during an operational inspection of an optical submarine cable system. [Means for solving the problem]

[0034] The connection status determining system of the present invention is included in an optical submarine cable system having a submarine optical cable with an optical path including optical optical fibers, and a branching device for switching the connection of the optical path, and comprises: an identification information adding means for adding different identification information for each optical path between optical communication devices through which an inspection optical signal passes, to an unallocated frequency band, which is a frequency band other than the frequency bands allocated to optical communications, when the inspection optical signal is received by the second optical communication device via an optical path between optical communication devices, which is the optical path between optical communication devices; and an identification information acquiring means for outputting the identification information of the inspection optical signal received by the second optical communication device. Effect of the Invention

[0035] The connection status specifying system and the like of the present invention make it possible to check the connection status of an optical path by a branching device during an operational inspection of an optical submarine cable system. [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 is a conceptual diagram illustrating an example of the configuration of a typical optical communication system. [Diagram 2] FIG. 1 is a conceptual diagram illustrating an example of the configuration of an optical communication device. [Diagram 3] 1 is an image diagram showing an example of a frequency distribution of the intensity of an inspection optical signal. [Figure 4] 2 is a conceptual diagram illustrating a configuration example of an optical signal transmitting unit. FIG. [Diagram 5] 2 is a conceptual diagram illustrating a configuration example of an optical signal receiving unit. FIG. [Figure 6] FIG. 1 is an image diagram illustrating an example of an inspection light signal according to a first embodiment; [Figure 7] 2 is a conceptual diagram illustrating a configuration example of an optical signal transmitting unit in the first embodiment. FIG. [Figure 8] 11 is a conceptual diagram illustrating a configuration example of an optical signal receiving unit according to a second embodiment. FIG. [Figure 9] FIG. 13 is an image diagram illustrating an example of an inspection optical signal according to the third embodiment. [Figure 10] FIG. 13 is a conceptual diagram illustrating a configuration example of an optical signal transmission unit according to a third embodiment. [Figure 11] FIG. 13 is a conceptual diagram illustrating a configuration example of a branching device according to a fourth embodiment. [Figure 12] FIG. 11 is a conceptual diagram illustrating an example of connected optical fiber pair information. [Figure 13] 10 is a conceptual diagram showing an example of how to assign optical fibers to each pair of connected optical fibers in a branching device. [Figure 14] 1 is a diagram showing an example of a correspondence between a combination of a transmitting optical communication device and a receiving optical communication device and a high unallocated frequency band of a test optical signal received by the receiving optical communication device. [Figure 15] FIG. 1 is an image diagram (part 1) showing the frequency characteristics of the received test optical signal in the high-frequency unallocated frequency band. [Figure 16] FIG. 2 is an image diagram (part 2) showing the frequency characteristics of the received test optical signal in the high unallocated frequency band. [Figure 17] FIG. 3 is an image (part 3) showing the frequency characteristics of the received test optical signal in the high-frequency unallocated frequency band. [Figure 18] FIG. 13 is a conceptual diagram illustrating a configuration example of an optical communication system according to a fifth embodiment. [Figure 19] FIG. 2 is a conceptual diagram illustrating an example of the configuration of a management device. [Figure 20] 1 is a conceptual diagram showing a minimum configuration of a connection status specifying system according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] First Embodiment In the optical communication system of this embodiment, transmitting optical communication device identification information, which is information for identifying the optical communication device (transmitting optical communication device) that is the source of the inspection optical signal, is added to the unallocated frequency band of the inspection optical signal transmitted by the optical communication device. In the optical communication system of this embodiment, this transmitting optical communication device identification information is added by the transmitting optical communication device attenuating noise in the unallocated frequency band. As a result, in the optical communication system of this embodiment, it is possible for the optical communication device that receives the inspection optical signal to identify the optical communication device that transmitted the inspection optical signal using the transmitting optical communication device identification information. As a result, the optical communication system of this embodiment allows the optical communication device that receives the inspection optical signal to grasp the switching status of the optical path in the branching device through which the inspection optical signal has passed. [Configuration and Operation] An example of the configuration of the optical communication system of this embodiment is the optical communication system 100 shown in Fig. 1. An example of the configuration of each of the optical communication devices K1 to K4 of this embodiment in Fig. 1 is the optical communication device K in Fig. 2. The optical communication device K of this embodiment differs from the device described in the Background Art section in the following respects. Below, the differences between the optical communication device K of this embodiment and the device described in the Background Art section will be mainly described.

[0038] First, the test optical signal transmitted by the optical communication device K of this embodiment will be described. Fig. 6 is an image diagram showing test optical signals ik1, ik2, ik3, and ik4, which are examples of the test optical signal of this embodiment. The test optical signals ik1, ik2, ik3, and ik4 are the test optical signals transmitted by the optical communication devices K1, K2, K3, and K4 of Fig. 1 in this order.

[0039] The inspection optical signals ik2, ik3, and ik4 have noise-reduced portions in the frequency bands f1, f1 and f2, and f1, f2, and f3, in that order. Here, the frequency bands f1, f2, and f3 are non-overlapping frequency bands in the high unallocated frequency band. The inspection optical signal ik1 does not have a noise-reduced frequency band in the high unallocated frequency band.

[0040] When the inspection optical signals ik1 to ik4 in Fig. 6 are used, the inspection optical signal received by the optical signal receiving unit 20 in Fig. 2 has a high unallocated frequency band corresponding to the inspection optical signals ik1 to ik4. As described in the Background Art section, the optical signal receiving unit 20 in Fig. 2 can acquire the frequency characteristics of the inspection optical signal. Therefore, the optical signal receiving unit 20 can detect the difference in the above-mentioned transmitting optical communication device identification information, which is represented by the presence or absence of a noise-reduced portion in the frequency bands f1, f1 and f2, f1, f2 and f3. In this case, it becomes possible to determine which of the optical communication devices K1, K2, K3, and K4 has transmitted the inspection optical signal based on the detection result.

[0041] The optical signal receiving section 20 of this embodiment may not be the one described in the Background section, but may be a dedicated one for measuring the frequency characteristics of the high unallocated frequency band.

[0042] The inspection optical signals ik2 to ik4 in Fig. 6 can be generated by attenuating noise in a predetermined frequency band using an optical filter. Fig. 7 is a conceptual diagram showing the configuration of an optical signal transmission unit 10, which is an example of an optical signal transmission unit equipped with an optical filter.

[0043] The optical signal transmission unit 10 in Fig. 7 includes an optical filter FIL1 in addition to the components included in the optical signal transmission unit 10 in Fig. 4. FIL1 reduces noise in at least one of the frequency bands f1, f2, and f3 of the high unallocated frequency band of the inspection optical signal ik in Fig. 3, which is input from the multiplexer 13 through the optical fiber FK1', and generates the inspection optical signals ik2 to ik4 in Fig. 6.

[0044] The test optical signal ik1 in FIG. 6 is generated by the optical signal transmitting unit 10 shown in FIG. 4 that does not include the FIL1.

[0045] The inspection optical signals ik1 to ik4 generated by the optical signal transmitting unit 10 are input to the optical fiber FK1. When the optical communication device K in FIG. 2 is the optical communication devices K1, K2, K3, and K4 in FIG. 1, the optical fiber FK1 corresponds to the optical fibers F11, F22, F32, and F42 in this order.

[0046] It is optional whether or not the FIL 1 in FIG. 7 is installed in a housing including the transmission signal generating unit 11, the monitor signal generating unit 12, and the multiplexing unit 13.

[0047] An example of the configuration of the optical signal receiving unit 20 included in the optical communication device K of the present embodiment shown in Fig. 2 is the same as that shown in Fig. 5. An operator or the like identifies the optical communication device that is the transmission source of the inspection optical signal from the transmitting optical communication device identification information (see Fig. 6) of the high unallocated frequency band of the received inspection optical signal output from the output unit 27.

[0048] There is a one-to-one relationship between the combination of the optical communication device that receives the inspection optical signal and the optical communication device that transmits the inspection optical signal, and the optical path through which the inspection optical signal has passed. For example, an operator or the like holds correspondence data between the combination and the optical path through which the inspection optical signal has passed. In this case, the operator or the like can use the data to identify the optical path through which the inspection optical signal has passed.

[0049] Furthermore, there is a one-to-one relationship between the optical path through which the inspection optical signal has passed and the optical fiber pairs connected to each optical switch of the branching device belonging to that optical path. For example, the worker or the like holds correspondence data between the optical path and the connection status of each optical switch of the branching device belonging to that optical path. In that case, the worker or the like can use this to identify the optical fiber pairs connected to each optical switch of the branching device belonging to that optical path. The optical fiber pairs represent the connection status of each optical switch.

[0050] The number of branching devices and the number of optical communication devices included in the optical communication system of this embodiment are not limited to those shown in FIG.

[0051] In the above description, an example has been described in which the above-mentioned transmitting optical communication device identification information is provided in a high unallocated frequency band among unallocated frequency bands. However, the frequency band in which the transmitting optical communication device identification information is provided may be any unallocated frequency band. The transmitting optical communication device identification information may be provided in a low unallocated frequency band. Alternatively, the transmitting optical communication device identification information may be provided in both the low unallocated frequency band and the high unallocated frequency band. When the transmitting optical communication device identification information is provided in both the low unallocated frequency band and the high unallocated frequency band, it is possible to set more types of transmitting optical communication device identification information. This is advantageous when the optical communication system of this embodiment has a larger number of optical communication devices.

[0052] The assignment of the transmitting optical communication device identification information to the lower unallocated frequency band can be achieved by the optical filter FIL1 in FIG. 7, in the same way as the assignment of the transmitting optical communication device identification information to the higher unallocated frequency band.

[0053] Furthermore, the transmission optical communication device identification information may be assigned to non-overlapping frequency bands in each transmission optical communication device.

[0054] In addition, the optical communication device identification information may represent multiple optical communication devices having the same frequency band depending on the degree of noise reduction. In this case, it is possible to set more types of optical communication device identification information. This is advantageous when the optical communication system of this embodiment has a larger number of optical communication devices. [effect] The optical communication system of this embodiment assigns transmitting optical communication device identification information, which is information for distinguishing the optical communication device that is the source of the inspection optical signal, to the unallocated frequency band of the inspection optical signal transmitted by the optical communication device. In the optical communication system of this embodiment, the optical communication device that is the source of the inspection optical signal assigns this transmitting optical communication device identification information by reducing noise in a specific frequency band of the unallocated frequency band. This makes it possible for the optical communication system of this embodiment to identify the optical communication device that transmitted the inspection optical signal by the transmitting optical communication device identification information included in the output information of the optical communication device that received the inspection optical signal. Once the optical communication device that is the source of the inspection optical signal and the optical communication device that is the destination of the inspection optical signal are determined, the switching status of the branching device present in the optical path between the two optical communication devices is determined.

[0055] Therefore, the optical communication system of this embodiment makes it possible to grasp the switching status of the optical path in the branching device through which the inspection optical signal has passed, by using the transmitting optical communication device identification information contained in the output information of the optical communication device that received the inspection optical signal.

[0056] In addition, when the configuration of an optical submarine cable system becomes complicated, even if the transmitting optical communication device is identified in the receiving optical communication device of the inspection optical signal, the connection status of the optical fiber of the optical switch in each branching device may not be identified. For example, when the inspection optical signal reaches the receiving optical communication device via a branching device, there may be different routes that pass through the same branching device in the same connection status. In that case, even if the optical route through which the inspection optical signal passed can be identified, the connection status of each branching device cannot be identified. In that case, the connection status of each branching device can be identified by collecting information on the transmitting optical communication device in each receiving optical communication device and making an integrated judgment. For example, artificial intelligence can be used for such an integrated judgment. <Second embodiment> In the optical communication system of the first embodiment, it is possible for an operator or the like to identify an optical communication device that is a source of an inspection optical signal from the transmitting optical communication device identification information of an unallocated frequency band output by an optical communication device that has received the inspection optical signal. In this case, from the pair of the optical communication device that has received the inspection optical signal and the optical communication device that is the source of the inspection optical signal, the operator or the like can identify an optical path through which the inspection optical signal has passed and an optical fiber pair to which an optical switch of a branching device included in the optical path is connected.

[0057] This embodiment relates to an optical communication system that automatically identifies an optical path through which an inspection optical signal has passed and an optical fiber pair connected by an optical switch of a branching device included in the optical path. [Configuration and Operation] The optical communication system of this embodiment differs from that of the first embodiment in the following respects: Hereinafter, the differences between the optical communication system of this embodiment and that of the first embodiment will be mainly described.

[0058] Fig. 8 is a conceptual diagram showing a configuration example of the optical signal receiving unit 20 of this embodiment shown in Fig. 2. The optical signal receiving unit 20 of this embodiment includes a transmitting optical communication device identifying unit 23, a route identifying unit 24, and a connected optical fiber pair identifying unit 25 in addition to the components included in the optical signal receiving unit 20 of Fig. 5.

[0059] The transmitting optical communication device identifying unit 23 identifies the optical communication device (transmitting optical communication device) that is the source of the received inspection optical signal from the transmitting optical communication device identification information (see FIG. 6) of the high unallocated frequency band of the frequency characteristics of the received inspection optical signal stored in the memory unit 26. The memory unit 26 holds in advance correspondence data (first correspondence data) between each transmitting optical communication device identification information and each optical communication device. In this case, the transmitting optical communication device identifying unit 23 identifies the transmitting optical communication device from the transmitting optical communication device identification information of the received inspection optical signal and the first correspondence data. The transmitting optical communication device identifying unit 23 stores the identification result of the transmitting optical communication device in the memory unit 26. The transmitting optical communication device identifying unit 23 also causes the output unit 27 to output the identification result of the transmitting optical communication device, for example, in response to an instruction from outside.

[0060] The path specifying unit 24 specifies an optical path between the optical communication device (receiving optical communication device) equipped with the optical signal receiving unit 20 and the transmitting optical communication device from the specifying result of the transmitting optical communication device stored in the storage unit 26. Here, it is assumed that the optical path (optical path between optical communication devices) between the receiving optical communication device and the source optical communication device in the optical submarine cable system is determined as one when the source and destination optical communication devices of the inspection optical signal are determined. The above holds true in an optical submarine cable system that does not have a redundant configuration in the optical path between the source optical communication device and the destination optical communication device of the inspection optical signal, such as the optical submarine cable system CS shown in FIG. 1. The storage unit 26 is assumed to hold in advance correspondence data (second correspondence data) between the optical path between the optical communication devices and the source optical communication device. In this case, the path specifying unit 24 specifies the optical path between the optical communication devices from the source optical communication device (transmitting optical communication device) and the second correspondence data. The route specifying unit 24 stores information indicating the specified optical route between the optical communication devices in the storage unit 26. The route specifying unit 24 also causes the output unit 27 to output the specified result of the optical route between the optical communication devices, for example, in response to an instruction from outside.

[0061] The connected optical fiber pair specifying unit 25 specifies connected optical fiber pair information, which is information representing two optical fibers (connected optical fiber pairs) connected to each optical switch of each branching device of the optical path between the optical communication devices, from the optical path between the optical communication devices stored in the storage unit 26. Here, it is assumed that when the optical path between the optical communication devices is determined, the connected optical fiber pairs of each branching device included in the optical path between the optical communication devices are determined. The above holds true in an optical submarine cable system such as the optical submarine cable system CS shown in FIG. 1 in which each branching device does not have a redundant configuration in the optical path with the optical communication device or another branching device. The storage unit 26 is assumed to hold in advance correspondence data (third correspondence data) between the optical path between the optical communication devices and the connected optical fiber pairs of each branching device included in the optical path between the optical communication devices. In this case, the connected optical fiber pair specifying unit 25 specifies the connected optical fiber pairs of each branching device included in the optical path between the optical communication devices from the optical path between the optical communication devices and the third correspondence data. The connected optical fiber pair specifying unit 25 stores connected optical fiber pair information indicating the connected optical fiber pairs of each branching device included in the specified optical path between the optical communication devices in the storage unit 26. The connected optical fiber pair specifying unit 25 also causes the output unit 27 to output the specified result of the optical path between the optical communication devices, for example, in response to an instruction from outside.

[0062] The optical signal receiving unit 20 includes, for example, a computer.

[0063] In addition, when the optical submarine system does not have a redundant optical path configuration as described above, the transmitting optical communication device information, the optical path information between optical communication devices, and the connected optical fiber pair information are in a relationship where one of them is determined and the other is determined. Here, the transmitting optical communication device information is information that represents the transmitting optical communication device. Also, the optical path information between optical communication devices is information that represents the optical path between the optical communication devices. In that case, the transmitting optical communication device information, the optical path information between optical communication devices, and the connected optical fiber pair information are all connection status information that represents the connection status of the optical path by each branching device. The combination of the transmitting optical communication device specifying unit 23, the path specifying unit 24, and the connected optical fiber pair specifying unit 25, which specify this connection status information, will be referred to as the connection status specifying unit 28. [effect] The optical communication system of this embodiment has the same configuration as the optical communication system of the first embodiment and has the same effects. In addition, in the optical communication system of this embodiment, an optical communication device that receives an inspection optical signal automatically identifies the optical communication device that is the source of the inspection optical signal, the optical path through which the inspection optical signal has passed, and the optical fiber pairs connected by each switch of the branching device included in the optical path. Therefore, the optical communication system of this embodiment can save an operator or the like the trouble of identifying the optical communication device that is the source of the inspection optical signal, the optical path through which the inspection optical signal has passed, and the optical fiber pairs connected by each switch of the branching device included in the optical path. <Third embodiment> In the optical communication systems of the first and second embodiments, the optical communication device that transmits the inspection optical signal assigns the transmitting optical communication device identification information by reducing or not reducing noise in a predetermined frequency band of the unallocated frequency band. This embodiment relates to an optical communication system that sets the transmitting optical communication device identification information in the inspection optical signal by a signal of a predetermined frequency set in the unallocated frequency band. [Configuration and Operation] An example of the configuration of the optical communication system of this embodiment is the optical communication system 100 shown in Fig. 1. An example of the configuration of each of the optical communication devices K1 to K4 of this embodiment is the optical communication device K in Fig. 2. The optical communication device K of this embodiment differs from the device described in the Background Art section in the following respects. Below, the differences between the optical communication device K of this embodiment and the device described in the Background Art section will be mainly described.

[0064] First, the test optical signal transmitted by the optical communication device K of this embodiment will be described. Fig. 9 is an image diagram showing test optical signals ik1, ik2, ik3, and ik4, which are examples of the test optical signal of this embodiment. The test optical signals ik1, ik2, ik3, and ik4 are the test optical signals transmitted by the optical communication devices K1, K2, K3, and K4 of Fig. 1 in this order.

[0065] The inspection optical signal ik1 has transmitting optical communication device identification information consisting of a combination of a relatively strong signal near frequency f5 in the high unallocated frequency band and a relatively strong signal near frequency f6. The inspection optical signal ik2 has transmitting optical communication device identification information consisting of a relatively strong signal near frequency f5 in the high unallocated frequency band. The inspection optical signal ik2 does not have a signal near frequency f6.

[0066] The inspection optical signal ik3 has transmitting optical communication device identification information consisting of a combination of a relatively low intensity signal near frequency f5 in the high unallocated frequency band and a relatively low intensity signal near frequency f6. The inspection optical signal ik4 has transmitting optical communication device identification information consisting of a relatively low intensity signal near frequency f5 in the high unallocated frequency band and a relatively high intensity signal near frequency f6.

[0067] The transmitting optical communication device identification information indicates the optical communication device that is the source of the test optical signal by a combination of the frequency and the strength or presence of the optical signal.

[0068] Therefore, the optical signal receiving unit 20 in Figure 2 can determine whether the inspection optical signal was transmitted by optical communication device K1, K2, K3, or K4 by analyzing the frequency, strength, and presence or absence of the optical signal contained in the transmitting optical communication device identification information.

[0069] The transmitting optical communication device identification information may represent the source optical communication device only by a combination of the frequency of the optical signal and the presence or absence of the signal. The transmitting optical communication device identification information may represent the source optical communication device only by a combination of the strength and presence or absence of the optical signal. In contrast, the transmitting optical communication device identification information in Fig. 9 represents the source optical communication device of the inspection optical signal by a combination of the frequency and strength or presence or absence of the optical signal. This makes it possible to set more types of identification optical signals in the unallocated frequency band, making it possible to identify more source optical communication devices.

[0070] Fig. 10 is a conceptual diagram showing an example of the configuration of the optical signal transmission unit 10 in Fig. 2 that generates and transmits the inspection optical signals ik1 to ik4 in Fig. 9. The optical signal transmission unit 10 in Fig. 10 includes an identification signal generation unit 14 in addition to the configuration of the optical signal transmission unit 10 in Fig. 4. The identification signal generation unit 14 generates the identification optical signal in Fig. 9 and inputs it to the multiplexing unit 13. The multiplexing unit 13 converts signals of each frequency of the transmission signal, the supervisory signal, and the identification signal into optical signals, multiplexes these optical signals, thereby generating an inspection optical signal, and inputs it into the optical fiber FK1. The description of the optical fiber FK1 is the same as that of the optical fiber FK1 in Fig. 4.

[0071] The optical signal included in the transmitting optical communication device identification information in Fig. 9 may be one that does not have any meaning in the information it carries. Therefore, as described in the Background Art section, the identification optical signal can be provided in an unallocated frequency band where it is difficult to provide a signal that has meaning in the information it carries.

[0072] Furthermore, the identification optical signal is intended only to enable the optical signal receiving unit 20 to identify the optical communication device that is the sender. Therefore, the identification optical signal does not need to have a frequency band as shown in Fig. 9. The identification optical signal may be a signal with a wider frequency band, for example, a noise-like signal that is added to noise.

[0073] The number of branching devices and the number of optical communication devices included in the optical communication system of this embodiment are not limited to those shown in FIG.

[0074] In the above description of this embodiment, an example has been described in which the above-mentioned transmitting optical communication device identification information is provided in a high unallocated frequency band among unallocated frequency bands. However, the frequency band in which the transmitting optical communication device identification information is provided may be any frequency band as long as it is an unallocated frequency band. The transmitting optical communication device identification information may be provided in a low unallocated frequency band. Alternatively, the transmitting optical communication device identification information may be provided in both the low unallocated frequency band and the high unallocated frequency band. When the transmitting optical communication device identification information is provided in both the low unallocated frequency band and the high unallocated frequency band, it is possible to set more types of transmitting optical communication device identification information. This is advantageous when the optical communication system of this embodiment has a larger number of optical communication devices. [effect] In the optical communication system of this embodiment, the optical communication device that is the source of the inspection optical signal assigns transmitting optical communication device identification information to the unallocated frequency band of the inspection optical signal as an optical signal. This makes it possible to identify the source optical communication device (transmitting optical communication device) by the output of the frequency characteristics of the unallocated frequency band from the optical communication device that receives the inspection optical signal. This allows the optical communication system of this embodiment to achieve the same effects as the optical communication system of the first embodiment. <Fourth embodiment> In the optical communication system of this embodiment, a branching device included in a submarine optical cable system provides connected optical fiber pair information, which is information representing the switching status of an optical path, to an unallocated frequency band of a passing test optical signal. This makes it possible to grasp the switching status of an optical path by a branching device by outputting the frequency characteristics of the unallocated frequency band from an optical communication device that receives the test optical signal. [Configuration and Operation] A configuration example of the optical communication system of this embodiment is the optical communication system 100 shown in Fig. 1. A configuration example of each of the optical communication devices K1 to K4 of this embodiment is the configuration of the optical communication device K in Fig. 2. Moreover, a configuration example of the optical signal transmitting unit 10 of this embodiment is shown in Fig. 4. Moreover, a configuration example of the optical signal receiving unit 20 of this embodiment is shown in Fig. 5 or Fig. 8.

[0075] The branching devices B1 and B2 of this embodiment differ from those described in the Background Art section in the following respects. Below, the branching devices B1 and B2 of this embodiment that differ from those described in the Background Art section will be mainly described.

[0076] Fig. 11 is a conceptual diagram showing the configuration of branching device B, which is an example of branching devices B1 and B2 of the present embodiment shown in Fig. 1. Branching device B includes optical switches S2 and S3, and optical filters FIL21, FIL22, FIL31, and FIL32. Branching device B assigns connected optical fiber pair information, which is information showing the switching status of the optical paths of each of the optical switches S2 and S3, to the inspection optical signal passing through. Branching device B assigns the connected optical fiber pair information by reducing noise in the unallocated frequency band of the inspection optical signal using each optical filter.

[0077] When the branching device B is the branching device B1 in Fig. 1, the optical fibers FB11, FB12, FB21, FB22, FB31, and FB32 are F11, F12, F31, F51, F32, and F52 in this order in Fig. 1. When the branching device B is the branching device B2 in Fig. 1, the optical fibers FB11, FB12, FB21, FB22, FB31, and FB32 are F22, F21, F41, F52, F42, and F51 in this order in Fig. 1. The arrows attached to each optical fiber indicate the traveling direction of the inspection optical signal.

[0078] Here, it is assumed that the optical switch S2 connects the optical fiber FB11 to the optical fiber FB21. In this case, the optical fiber FB11 is disconnected from the optical fiber FB22. In this case, the inspection optical signal traveling to the right through the optical fiber FB11 passes through the optical filter FIL21 and travels to the right through the optical fiber FB21. At that time, the optical filter FIL21 reduces noise in a first frequency band included in the unallocated frequency band of the passing inspection optical signal, thereby providing the inspection optical signal with connected optical fiber pair information.

[0079] Also, assume that the optical switch S2 connects the optical fiber FB11 to the optical fiber FB22. In this case, the optical fiber FB11 is disconnected from the optical fiber FB21. In this case, the inspection optical signal traveling to the right through the optical fiber FB11 passes through the optical filter FIL22 and travels to the right through the optical fiber FB22. At that time, the optical filter FIL22 adds connected optical fiber pair information to the inspection optical signal by reducing noise in a second frequency band included in the unallocated frequency band of the passing inspection optical signal.

[0080] Also, assume that the optical switch S3 connects the optical fiber FB12 to the optical fiber FB31. In this case, the optical fiber FB12 is disconnected from the optical fiber FB32. In this case, the inspection optical signal traveling leftward through the optical fiber FB31 passes through the optical filter FIL31 and travels leftward through the optical fiber FB12. At that time, the optical filter FIL31 reduces noise in a third frequency band included in the unallocated frequency band of the passing inspection optical signal, thereby providing the inspection optical signal with connected optical fiber pair information.

[0081] Also, assume that the optical switch S3 connects the optical fiber FB12 to the optical fiber FB32. In this case, the optical fiber FB12 is disconnected from the optical fiber FB31. In this case, the inspection optical signal traveling leftward through the optical fiber FB32 passes through the optical filter FIL32 and travels leftward through the optical fiber FB12. At that time, the optical filter FIL32 reduces noise in a fourth frequency band included in the unallocated frequency band of the passing inspection optical signal, thereby providing the inspection optical signal with connected optical fiber pair information.

[0082] It is assumed that the optical filters FIL21, FIL22, FIL31, and FIL32 do not at all reduce the intensity of the unallocated frequency band of the inspection optical signal. In that case, the information represented by not at all reducing the intensity of the unallocated frequency band of the inspection optical signal is the connection optical fiber pair information attached to the inspection optical signal. In that case, it means that there is no optical filter in reality, but instead there is an optical fiber that does not reduce the intensity of the optical signal in the unallocated frequency band. In the embodiment, such an optical fiber is considered to be an optical filter that does not at all reduce the intensity of the optical signal in the unallocated frequency band of the inspection optical signal.

[0083] In the optical communication system of the present embodiment, the frequency bands for reducing noise are different between the optical filters FIL21 and FIL22, and the frequency bands for reducing noise are different between the optical filters FIL31 and FIL32. In addition, in the optical submarine cable system CS of FIG. 1, it is assumed that both branching devices B1 and B2 are included in the signal path through which the inspection optical signal passes. In this case, the frequency bands attenuated by the optical filters of the branching devices B1 and B2 in the signal path are different. In the optical communication system of the present embodiment, when the inspection optical signal received by the optical communication device passes through different optical paths, the noise of the different frequency bands of the unallocated frequency band is always reduced, thereby providing the inspection optical signal with connection optical fiber pair information. As a result, in the optical communication system of the present embodiment, it is possible to specify the switching status of the optical path in the branching device through which the received inspection optical signal passes, by outputting the frequency characteristic of the unallocated frequency band from the optical communication device that receives the inspection signal.

[0084] Next, a specific example of how to assign, to each optical filter, connected optical fiber pair information, which is expressed by a noise reduction in a predetermined frequency band, that enables the above will be described.

[0085] Fig. 12 is a conceptual diagram showing an example of candidates for connected optical fiber pair information to be assigned to each optical filter. Note that Fig. 12 shows only the part of the test optical signal in the high unallocated frequency band.

[0086] In the high unallocated frequency band in Fig. 12(a), the noise in any of the frequency bands f21, f22, and f23 is not reduced. The information represented by the fact that the noise in any of the frequency bands f21, f22, and f23 is not reduced is the connected optical fiber pair information attached to the test optical signal having this high unallocated frequency band. This connected optical fiber pair information will be referred to as the first connected optical fiber pair information.

[0087] In the high unallocated frequency band in Fig. 12(b), the noise is reduced only in the frequency band f21 among the frequency bands f21, f22, and f23. The information represented by the reduction in noise only in the frequency band f21 is the connected optical fiber pair information added to the test optical signal having this high unallocated frequency band. This connected optical fiber pair information will be referred to as the second connected optical fiber pair information.

[0088] In the high unallocated frequency band in Fig. 12(c), the noise is reduced only in the frequency band f22 among the frequency bands f21, f22, and f23. The information represented by the noise reduction only in the frequency band f22 is the connected optical fiber pair information added to the test optical signal having this high unallocated frequency band. This connected optical fiber pair information will be referred to as third connected optical fiber pair information.

[0089] In the high unallocated frequency band in Fig. 12(d), the noise is reduced only in the frequency band f23 among the frequency bands f21, f22, and f23. The information represented by the reduction in noise only in the frequency band f23 is the connected optical fiber pair information added to the test optical signal having this high unallocated frequency band. This connected optical fiber pair information will be referred to as the fourth connected optical fiber pair information.

[0090] In the high unallocated frequency band in Fig. 12(e), the noise is reduced in the frequency bands f21 and f23 among the frequency bands f21, f22, and f23. The information represented by the reduction in noise only in the frequency bands f1 and f23 is the connected optical fiber pair information added to the test optical signal having this high unallocated frequency band. This connected optical fiber pair information will be referred to as the fifth connected optical fiber pair information.

[0091] Fig. 13 is a conceptual diagram showing how the first to fifth connected optical fiber pair information in Fig. 12 is assigned to each connected optical fiber pair in each branching device. Here, each connected optical fiber pair is an optical path connected by the optical switches S2 and S3 in Fig. 11 provided in each of the branching devices B1 and B2 in Fig. 1. In Fig. 13, the connected optical fiber pair is represented by a pair of a first optical fiber and a second optical fiber, which are two optical fibers connected by the optical switch S2 or S3. Any of the optical filters FIL21, FIL22, FIL31, and FIL32 in Fig. 11 exists between these two connected optical fibers. The optical filter existing between these two optical fibers provides the type of connected optical fiber pair information shown in Fig. 13 to the passing inspection optical information.

[0092] In the allocation of Fig. 13, when the optical paths to be connected are different, different connected optical fiber pair information among the first to fifth connected optical fiber pair information is assigned. When the inspection optical signal passes through multiple branching devices, different connected optical fiber pair information among the first to fifth connected optical fiber pair information is assigned for each branching device. The frequency bands f21 to f23 of the assigned first to fifth connected optical fiber pair information are common to branching device B1 and branching device B2.

[0093] As a result, in each receiving optical communication device, the identification information (see Figs. 14 to 17) is different for each optical path through which the test optical signal has passed. Therefore, in each receiving optical communication device, it becomes possible to identify the optical path through which the test optical signal has passed from the identification information of the test optical signal that has arrived.

[0094] In the allocation of FIG. 13, furthermore, when the two optical paths to be connected are the same, the same connected optical fiber pair information is given regardless of the traveling direction of the optical signal.

[0095] This point is not essential for identifying the optical path through which the inspection optical signal has passed, but it is a preferable point. The reason is that the number of types of connected optical fiber pair information required can be reduced by providing the same connected optical fiber pair information regardless of the traveling direction of the optical signal. Therefore, in the allocation of Fig. 13, five types of connected optical fiber pair information, the first to fifth connected optical fiber pair information, are sufficient as the number of types of connected optical fiber pair information required.

[0096] Specifically, the first to fifth connected optical fiber pair information in FIG. 13 can be assigned to the connected optical fiber pairs by, for example, causing a computer or the like to execute the following process.

[0097] First, it is assumed that when two optical paths to be connected are the same, the same connection optical fiber pair information is assigned regardless of the direction of optical signal travel. For example, the same optical fiber pair information is assigned to the optical fiber pair of optical fibers F11 and F51 and the optical fiber pair of optical fibers F52 and F12. The same applies to other optical fiber pairs.

[0098] Then, the computer etc. identifies all combinations in which each optical fiber pair is combined with the first through fifth connected optical fiber pair information. Then, for each identified combination, the computer determines whether the identification information of the received inspection optical signal differs depending on the optical path at each receiving optical communication device. Then, the computer selects a combination in which the identification information of the received inspection optical signal differs depending on the optical path at each receiving optical communication device. In this way, the first through fifth connected optical fiber pair information are assigned to the connected optical fiber pairs.

[0099] 13, the above allocation is possible using five pieces of connected optical fiber pair information, namely, the first to fifth connected optical fiber pair information. However, if the above allocation cannot be performed using five pieces of connected optical fiber pair information, the computer or the like increases the types of connected optical fiber pair information to six or more, and then executes the same process as above.

[0100] 14 is a diagram showing an example of a combination of an optical communication device for transmitting and an optical communication device for receiving, and a correspondence example of the high unallocated frequency band of the test optical signal received by the optical communication device for receiving. Here, the optical communication device for transmitting is the optical communication device that transmitted the test optical signal, and the optical communication device for receiving is the optical communication device that received the test optical signal.

[0101] The frequency characteristics of the high unallocated frequency bands corresponding to the symbols formed by adding two digits after the alphabet p, which are shown for the combination of the transmitting optical communication device and the receiving optical communication device in Fig. 14, are shown in Fig. 15 to Fig. 17. The combination of high and low noise in the frequency bands f21, f22, and f23 of each high unallocated frequency band in Fig. 15 to Fig. 17 is identification information that indicates the optical path between the optical communication devices through which the test optical signal has passed.

[0102] When the connection optical fiber pair information is assigned to each connection optical fiber pair in the manner shown in Fig. 13, the inspection optical signal that arrives at an optical communication device is assigned all of the connection optical fiber pair information assigned by each branching device through which the inspection optical signal has passed, and these pieces of information form identification information. In each optical communication device that receives the inspection optical signal, if the optical path through which the inspection optical signal has passed is different, the identification information is different. As described above, the assignment in Fig. 13 is set so that when the inspection optical signal passes through multiple branching devices, the frequency bands of the connection optical fiber pair information assigned by each branching device do not overlap with each other. Below, it will be specifically explained that the identification information is different when the optical path through which the inspection optical signal has passed is different.

[0103] The optical paths through which the inspection optical signal received by the optical communication device K1 in FIG. 1 passes are three types: an optical path from the optical communication device K2 through the branching devices B2 and B1, an optical path from the optical communication device K3 through the branching device B1, and an optical path from the optical communication device K4 through the branching devices B2 and B1. The identification information of the inspection optical signal that has passed through these optical paths is included in p21 of FIG. 15, p31 of FIG. 16, and p41 of FIG. 17, in this order, and they are different from each other. Therefore, the optical communication device K1 can specify the optical path between the optical communication devices through which the received inspection optical signal has passed. In addition, if the optical path between the optical communication devices through which the inspection optical signal has passed is determined, the switching status of the optical path in the branching device included in the optical path between the optical communication devices is determined. Therefore, the optical communication device K1 can specify the switching status of the optical path in the branching device through which the received inspection optical signal has passed.

[0104] In addition, the optical paths through which the inspection optical signal received by the optical communication device K2 in FIG. 1 passes are three types: an optical path from the optical communication device K1 through the branching devices B1 and B2, an optical path from the optical communication device K3 through the branching devices B1 and B2, and an optical path from the optical communication device K4 through the branching device B2. The identification information of the inspection optical signal that has passed through these optical paths is included in the high unallocated frequency bands on p12 of FIG. 15, p32 of FIG. 16, and p42 of FIG. 17, in this order, and they are different from each other. Therefore, the optical communication device K2 can specify the optical path between the optical communication devices through which the received inspection optical signal has passed. Furthermore, if the optical path between the optical communication devices through which the inspection optical signal has passed is determined, the optical path switching status of the branching devices included in the optical path between the optical communication devices is determined. Therefore, the optical communication device K2 can specify the switching status of the optical path in the branching device through which the received inspection optical signal has passed.

[0105] In addition, the optical paths through which the inspection optical signal received by the optical communication device K3 in FIG. 1 passes are three types: an optical path from the optical communication device K1 through the branching device B1, an optical path from the optical communication device K2 through the branching devices B1 and B2, and an optical path from the optical communication device K4 through the branching devices B2 and B1. The identification information of the inspection optical signal that has passed through these optical paths is included in the high unallocated frequency bands on p13 of FIG. 15, p23 of FIG. 16, and p43 of FIG. 17, in this order, and these are different from each other. Therefore, the optical communication device K3 can specify the optical path between the optical communication devices through which the received inspection optical signal has passed. Furthermore, if the optical path through which the inspection optical signal has passed is determined, the optical path switching status of the branching devices included in that optical path is determined. Therefore, the optical communication device K3 can specify the switching status of the optical path in the branching device through which the received inspection optical signal has passed.

[0106] In addition, the optical paths through which the inspection optical signal received by the optical communication device K4 in FIG. 1 passes are three types: an optical path from the optical communication device K1 through the branching devices B1 and B2, an optical path from the optical communication device K2 through the branching device B2, and an optical path from the optical communication device K3 through the branching devices B1 and B2. The frequency characteristics of the high unallocated frequency band of the inspection optical signal that has passed through these optical paths are, in this order, p14 in FIG. 15, p24 in FIG. 16, and p34 in FIG. 17, which are different from each other. Therefore, the optical communication device K4 can identify the optical path through which the received inspection optical signal has passed. Furthermore, if the optical path through which the inspection optical signal has passed is determined, the optical path switching status of the branching devices included in that optical path is determined. Therefore, the optical communication device K4 can identify the connected optical fiber pair that represents the switching status of the optical path in the branching device through which the received inspection optical signal has passed.

[0107] The number of branching devices and the number of optical communication devices included in the optical communication system of this embodiment are not limited to those shown in FIG.

[0108] In the above description of this embodiment, an example has been described in which the above-mentioned connected optical fiber pair information is provided in a high unallocated frequency band among unallocated frequency bands. However, the frequency band in which the connected optical fiber pair information is provided may be any frequency band as long as it is an unallocated frequency band. The connected optical fiber pair information may be provided in a low unallocated frequency band. Alternatively, the connected optical fiber pair information may be provided in both the low unallocated frequency band and the high unallocated frequency band. When the connected optical fiber pair information is provided in both the low unallocated frequency band and the high unallocated frequency band, more types of connected optical fiber pair information can be set. This is advantageous when the optical communication system of this embodiment includes a larger number of branching devices and therefore the number of optical communication devices is also increased. [effect] In the optical communication system of the present embodiment, an optical filter is provided in the optical path (connected optical fiber pair) to which the branching device is connected, and the optical filter reduces noise in a predetermined frequency band of the unallocated frequency band of the inspection optical signal, thereby adding optical path connection information to the inspection optical signal. In the optical communication system of the present embodiment, the optical path connection information is added to each connected optical fiber pair in such a way that, when the optical paths through which the received inspection optical signal has passed are different, the frequency characteristics of the unallocated frequency band of the inspection optical signal are different. In this case, when the optical paths through which the received inspection optical signal has passed are different, the frequency characteristics of the unallocated frequency band are different, so that it is possible to identify the optical path through which the inspection optical signal has passed. In addition, when the optical path through which the inspection optical signal has passed is determined, the optical path switching status of the branching device included in the optical path is determined. Therefore, it is possible to identify the connected optical fiber pair that represents the switching status of the optical path in the branching device through which the received inspection optical signal has passed. <Fifth embodiment> In the optical communication systems according to the first to fourth embodiments, it is possible to identify the connected optical fiber pairs connected by the optical switches provided in the optical paths through which the received inspection optical signal has passed. However, it is not possible to identify the connected optical fiber pairs connected by the optical switches of the optical paths through which the received inspection optical signal has not passed. Therefore, it is not possible to grasp the connected optical fiber pairs connected by all the optical switches of the branching device.

[0109] In the optical communication system of this embodiment, each optical communication device transmits information on connected optical fiber pairs connected to each optical switch within the range known to that optical communication device via communication, which enables the management device to obtain information on connected optical fiber pairs connected to all optical switches included in the optical submarine cable system. [Configuration and Operation] 18 is a conceptual diagram showing a configuration of an optical communication system 100, which is an example of the optical communication system of this embodiment. The optical communication system 100 of FIG. 18 includes a management device CT in addition to the components included in the optical communication system 100 of FIG.

[0110] The control device CT communicates with the optical communication devices K1 to K4. The communication is, for example, via the Internet. The control device CT causes each optical communication device to send connected optical fiber pair information connected to each optical switch of each branching device that the optical communication device recognizes. Here, the connected optical fiber pair information is information that indicates two optical fibers connected to each other by each optical switch.

[0111] The control device CT integrates the connected optical fiber pair information received from each optical communication device, generates a list of connected optical fiber pair information of each optical switch of each branching device (each of branching devices B1 and B2) included in the optical submarine cable system CS, and outputs the list. The output is, for example, displayed on a display unit, output as audio, or transmitted to another device.

[0112] The management device CT may transmit the list of connected optical fiber pair information to all or some of the optical communication devices K1 to K4.

[0113] The control device CT may be provided in any one of the land terminal stations T1 to T4. The number of branching devices and the number of optical communication devices provided in the optical communication system of this embodiment are not limited to those shown in FIG. 18 and may be arbitrary.

[0114] Fig. 19 is a conceptual diagram showing an example of the configuration of the management device CT in Fig. 18. The management device CT in Fig. 19 includes a receiving unit 31, an integrating unit 32, a storage unit 33, and an output unit 34. The receiving unit 31 stores information received from the optical communication devices K1 to K4 in Fig. 18 in the storage unit 33. When the information received by the receiving unit 31 from the optical communication devices K1 to K4 in Fig. 18 is the above-mentioned connection status information, the integrating unit 32 integrates the connection status information.

[0115] Here, it is assumed that the connection status information sent to the receiving unit 31 from each optical communication device is connected optical fiber pair information. In this case, the integrating unit 32 integrates the connected optical fiber pair information sent to the receiving unit 31 from each optical communication device to generate a list of connected optical fiber pair information of each optical switch of each branching device (each of branching devices B1 and B2) included in the optical submarine cable system CS. The integrating unit 32 may perform the integration by using artificial intelligence, for example. The integrating unit 32 stores the created list of connected optical fiber pair information in the storage unit 33. The integrating unit 32 causes the output unit 34 to output the list of connected optical fiber pair information in accordance with, for example, an instruction from outside. The integrating unit 32 may cause the output unit 34, which is a transmitting device, to transmit the list of connected optical fiber pair information to each optical communication device in FIG. 18.

[0116] Alternatively, it is assumed that the connection status information sent to the receiving unit 31 from each optical communication device is optical path information between optical communication devices. In this case, the integrating unit 32 integrates the optical path information between optical communication devices sent to the receiving unit 31 from each optical communication device to generate a list of optical path information between optical communication devices formed in the optical submarine cable system CS. Then, the integrating unit 32 creates a list of connected optical fiber pair information from the generated list of optical path information between optical communication devices.

[0117] Alternatively, it is assumed that the connection status information sent to the receiving unit 31 from each optical communication device is the optical communication device that is the source of the inspection optical signal as viewed from the optical communication device that sent the information. In this case, the integrating unit 32 integrates the combination (transmitting / receiving optical communication device pair) of the receiving optical communication device sent to the receiving unit 31 from each optical communication device and the optical communication device that is the source as viewed from the optical communication device to generate a list of transmitting / receiving optical communication device pairs. Then, the integrating unit 32 creates a list of optical path information between the optical communication devices from the created list of transmitting / receiving optical communication device pairs, for example, by the correspondence information between the transmitting / receiving optical communication device pair and the optical path information between the optical communication devices held in the storage unit 33. Then, the integrating unit 32 creates a list of connected optical fiber pair information from the created list of optical path information between the optical communication devices, for example, by the correspondence information between the optical path information between the optical communication devices and the connected optical fiber pair information held in the storage unit 33. Then, the integrating unit 32 stores the created list of connected optical fiber pair information in the storage unit 33.

[0118] Alternatively, it is assumed that the connection status information sent to the receiving unit 31 from each optical communication device is optical path information between optical communication devices. In this case, the integrating unit 32 integrates the optical path information between optical communication devices sent to the receiving unit 31 from each optical communication device to generate a list of optical path information between optical communication devices formed in the optical submarine cable system CS. Then, the integrating unit 32 creates a list of connected optical fiber pair information from the created list of optical path information between optical communication devices, for example, by correspondence information between the optical path information between optical communication devices and connected optical fiber pair information held in the storage unit 33. Then, the integrating unit 32 stores the created list of connected optical fiber pair information in the storage unit 33.

[0119] In addition, when the configuration of the optical submarine cable system becomes complicated, even if the transmitting optical communication device and the optical path are identified in the receiving optical communication device of the inspection optical signal, the connection status of the optical fiber of the optical switch in each branching device may not be identified. For example, when the inspection optical signal reaches the receiving optical communication device via a branching device, there may be different paths that pass through the same branching device in the same connection state. In that case, even if the optical path through which the inspection optical signal passed can be identified, the connection status of each branching device cannot be identified. In that case, the integration unit 32 identifies the connection status of each branching device by integrating and judging the list of transmitting / receiving optical communication device pairs and the list of optical path information between the optical communication devices. For example, artificial intelligence may be used for the comprehensive judgment.

[0120] The integrating unit 32 outputs a list of connected optical fiber pair information created in accordance with, for example, an external instruction to the output unit 34. The integrating unit 32 may also output a list of transmitting / receiving optical communication device pairs or a list of optical path information between optical communication devices to the output unit 34.

[0121] The management device CT is, for example, a computer. The storage unit 33 holds in advance programs and information for the management device CT to perform the above operations. The storage unit 33 sends information designated by each component of the management device CT to the designated component of the management device CT. The storage unit 33 stores information designated by each component of the management device CT.

[0122] The output unit 34 is, for example, a display device, an audio output device, or a transmission device. The output unit 34 outputs instructed information to an instructed output destination in accordance with instructions from each component of the management device CT.

[0123] 18 includes, for example, the optical signal receiving unit 20 shown in Fig. 8. In this case, the output unit 27, which is a transmitting device, transmits the above information to the receiving unit 31 in Fig. 19. [effect] In the optical communication system of this embodiment, each optical communication device transmits information about connected optical fiber pairs connected by each optical switch within the range recognized by the optical communication device to the management device via communication. In this way, the management device is able to recognize information about connected optical fiber pairs connected by each optical switch of each branching device included in the optical submarine cable system. This enables the management device to recognize the connection status of each optical switch. 20 is a conceptual diagram showing the configuration of a connection status specifying system 100x, which is a minimum configuration of the connection status specifying system according to the embodiment. The connection status specifying system 100x includes an identification information adding unit 19x and an identification information acquiring unit 22x.

[0124] The identification information adding unit 19x adds different identification information for each inter-optical communication device optical path through which the inspection optical signal passes to an unallocated frequency band when the inspection optical signal is received by the second optical communication device through the inter-optical communication device optical path. Here, the inter-optical communication device optical path is the optical path between optical communication devices included in an optical submarine cable system including an optical path including an optical fiber, and a branching device that switches the connection of the optical path. The inspection optical signal is an inspection optical signal transmitted from the first optical communication device to the second optical communication device. The unallocated frequency band is a frequency band other than the frequency bands allocated to optical communication.

[0125] The identification information acquisition unit 22x outputs the identification information of the test optical signal received by the second optical communication device.

[0126] The connection status specifying system 100x, with the above configuration, enables the specification of information representing the connection status of the optical path in the branching device by the identification information of the outputted inspection optical signal received by the second optical communication device. Therefore, the connection status specifying system 100x enables the confirmation of the connection status of the optical path by the branching device during the operation inspection of the optical submarine cable system.

[0127] Therefore, the connection status identifying system 100x, with the above-described configuration, exhibits the effects described in the section "Effects of the Invention."

[0128] 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.

[0129] 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 submarine cable system including a submarine optical cable having an optical path including an optical fiber, and a branching device for switching a connection of the optical path, the optical submarine cable system including an optical path between optical communication devices, and an identification information adding means for adding different identification information for each optical path between optical communication devices through which an inspection optical signal passes, the inspection optical signal being an optical signal for inspection transmitted from a first optical communication device to a second optical communication device via an optical path between optical communication devices, to an unallocated frequency band that is a frequency band other than the frequency bands allocated for optical communication, when the inspection optical signal is received by the second optical communication device; an identification information acquiring unit that outputs the identification information of the test optical signal received by the second optical communication device; Equipped with Connection status identification system. (Appendix 2) the identification information is represented by a decrease in noise intensity of the test optical signal in a predetermined frequency band included in the unallocated frequency band; 2. A connection status determination system as described in Appendix 1. (Appendix 3) the identification information is added by an optical filter through which the test optical signal generated by the first optical communication device passes; 2. A connection status determination system as described in Appendix 2. (Appendix 4) The optical filter is provided in the first optical communication device. 2. A connection status determination system as described in Appendix 3. (Appendix 5) The optical filter is provided in the branching device. 2. A connection status determination system as described in Appendix 3. (Appendix 6) The identification information is represented by a signal of the test optical signal present in the unallocated frequency band. 2. A connection status determination system as described in Appendix 1. (Appendix 7) The identification information is generated by the first optical communication device. 4. A connection status determination system as described in Appendix 6. (Appendix 8) a connection status specifying unit that specifies connection status information representing a connection status of the optical path in the branching device from the identification information, A connection status determination system according to any one of appendixes 1 to 7. (Appendix 9) the connection status information includes first optical communication device information that is information representing the first optical communication device, the connection status specifying means includes a transmission optical communication device specifying means for specifying the first optical communication device information from the identification information acquired by the identification information acquiring means; 7. A connection status determination system as described in Appendix 8. (Appendix 10) the connection status specifying means specifies optical path information between the optical communication devices, which is information representing the optical path between the optical communication devices, from information representing the first optical communication device specified by the transmission optical communication device specifying means; Further comprising a route specifying means. 10. A connection status determination system according to claim 8 or 9. (Appendix 11) the connection status specifying means further includes a connected optical fiber pair specifying means for specifying, from the optical path information between the optical communication devices, connected optical fiber pair information which is information representing a connected optical fiber pair which is a pair of the optical fibers included in the optical path between the optical communication devices and which is connected by an optical switch provided in the branching device; 10. A connection status determination system as described in Clause 10. (Appendix 12) The communication device further includes an integration unit that integrates the connection status information sent from a plurality of the connection status determination units. 13. A connection status determination system as described in Appendix 11. (Appendix 13) an optical submarine cable system including an optical submarine cable having an optical path including an optical fiber, and a branching device for switching a connection of the optical path, the optical path being between optical communication devices, wherein an inspection optical signal, which is an optical signal for inspection transmitted from a first optical communication device to a second optical communication device via an optical path between optical communication devices, is received by the second optical communication device by adding different identification information to an unallocated frequency band, which is a frequency band other than the frequency bands allocated for optical communication, for each optical path between optical communication devices through which the inspection optical signal passes; acquiring the identification information of the test optical signal received by the second optical communication device; identifying connection status information representing a connection status of the optical path in the branching device from the identification information; How to determine connection status.

[0130] Here, the "optical fiber" refers to, for example, the optical fibers F11, F12, F21, F22, F31, F32, F41, F42, F51, and F52 in Fig. 1 or Fig. 18. Moreover, the "optical path" refers to, for example, the first optical path, the second optical path, the third optical path, the fourth optical path, and the fifth optical path in Fig. 1 or Fig. 18. Moreover, the "submarine optical cable" refers to, for example, a submarine optical cable in which the optical fiber is provided.

[0131] Moreover, the "branching device" is, for example, branching devices B1 and B2 in Fig. 1 or 18. Moreover, the "optical submarine cable system" is, for example, the optical submarine cable system CS in Fig. 1 or 18. Moreover, the "optical communication device" is, for example, the optical communication devices K1, K2, K3, and K4 in Fig. 1 or 18, or the optical communication device K in Fig. 2.

[0132] Moreover, the "optical path between optical communication devices" is, for example, the optical path between the two optical communication devices. Moreover, the "first optical communication device" is, for example, any one of the optical communication devices. Moreover, the "second optical communication device" is, for example, any one of the optical communication devices that has the inter-device optical path formed with the first optical communication device. Moreover, the "inspection optical signal" is, for example, the inspection optical signals ik1, ik2, ik3, ik4 in FIG. 6 or FIG. 9.

[0133] Moreover, the "unallocated frequency band" is, for example, the low-frequency unallocated frequency band or the high-frequency unallocated frequency band in Fig. 3, or the high-frequency unallocated frequency band in Fig. 6, Fig. 9, Fig. 12, or Fig. 15 to Fig. 17. Moreover, the "identification information" is, for example, the low-frequency unallocated frequency band in Fig. 3, or the high-frequency unallocated frequency band in Fig. 3, Fig. 6, Fig. 9, Fig. 12, Fig. 15, Fig. 16, Fig. 17. Moreover, the "identification information adding unit" is, for example, the optical filter FIL1 in Fig. 7, the optical filters FIL21, FIL22, FIL31, FIL32 in Fig. 11, the identification signal generating unit 14 in Fig. 10, or the identification information adding unit 19x in Fig. 20. The "identification information acquisition unit" is, for example, the analysis unit 22 in Fig. 5 or 8, or the identification information acquisition unit 22x in Fig. 20. The "connection status information" is, for example, the above-mentioned information indicating the optical communication device that is the transmission source of the inspection optical signal, the optical path through which the inspection optical signal has passed, or the optical fiber pair connected by the optical switch of the branching device included in the optical path through which the inspection optical signal has passed. The "connection status specification unit" is, for example, the connection status specification unit 28 in Fig. 8.

[0134] Moreover, the "connection status determining system" is, for example, the optical communication system 100 in FIG. 1 or FIG. 18, or the connection status determining system 100x in FIG. 20. Moreover, the "optical filter" is, for example, the optical filter FIL1 in FIG. 7, or the optical filters FIL21, FIL22, FIL31, and FIL32 in FIG. 11. Moreover, the "transmitting optical communication device determining unit" is, for example, the transmitting optical communication device determining unit 23 in FIG. 8. Moreover, the "route determining unit" is, for example, the route determining unit 24 in FIG. 8. Moreover, the "connected optical fiber pair determining unit" is, for example, the connected optical fiber pair determining unit in FIG. 8. Moreover, the "integrating unit" is, for example, the management device CT in FIG. 18 or FIG. 19, or the integrating unit 32 in FIG. 19.

[0135] This application claims priority to Japanese Patent Application No. 2021-016376, filed on February 4, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0136] 10 Optical signal transmitter 11 Transmission signal generator 12 Monitoring signal generation section 13 Multiplexing section 14 Identification signal generator 19x Identification information addition section 20 Optical signal receiving section 21 Optical receiving section 22 Analysis Department 22x Identification information acquisition unit 23 Transmission optical communication device specification section 24 Route Identification Unit 25 Connection optical fiber pair specific part 26 Memory section 27 Output section 28 Connection Status Identification Unit 100 Optical communication system 100x Connection Status Identification System T1, T2, T3, T4 Land Terminal Station K, K1, K2, K3, K4 Optical communication equipment F11, F12, F21, F22, F31, F32, F41, F42, F51, F52, FB11, FB12, FB21, FB22, FB31, FB32, FK1, FK1', FK2 Optical fiber B, B1, B2 branching device CS Optical Submarine Cable System ik, ik1, ik, ik3, ik4 Inspection light signals FIL1, FIL21, FIL22, FIL31, FIL32, Optical filters S2, S3 Optical Switch f1, f2, f3, f21, f22, f23, f24 frequency bands f5, f6 frequency

Claims

1. an optical submarine cable system including a submarine optical cable having an optical path including an optical fiber, and a branching device for switching a connection of the optical path, the optical submarine cable system including an optical path between optical communication devices, and an identification information adding means for adding different identification information for each optical path between optical communication devices through which an inspection optical signal passes, the inspection optical signal being an optical signal for inspection transmitted from a first optical communication device to a second optical communication device via an optical path between optical communication devices, when the inspection optical signal is received by the second optical communication device; an identification information acquiring unit that outputs the identification information of the test optical signal received by the second optical communication device; Equipped with the identification information is represented by a decrease in noise intensity of the test optical signal in a predetermined frequency band included in the unallocated frequency band; Connection status identification system.

2. the identification information is added by an optical filter through which the test optical signal generated by the first optical communication device passes; 2. A connection status determining system according to claim 1.

3. The optical filter is provided in the first optical communication device.

3. A connection status determining system according to claim 2.

4. The optical filter is provided in the branching device.

3. A connection status determining system according to claim 2.

5. a connection status specifying unit that specifies connection status information representing a connection status of the optical path in the branching device from the identification information, A connection status specifying system according to any one of claims 1 to 4.

6. the connection status information includes first optical communication device information that is information representing the first optical communication device, the connection status specifying means includes a transmission optical communication device specifying means for specifying the first optical communication device information from the identification information acquired by the identification information acquiring means, 6. A connection status determining system according to claim 5.

7. an optical submarine cable system including a submarine optical cable having an optical path including an optical fiber, and a branching device for switching a connection of the optical path, the optical path being between optical communication devices, wherein an inspection optical signal, which is an optical signal for inspection transmitted from a first optical communication device to a second optical communication device via an optical path between optical communication devices, is received by the second optical communication device by adding different identification information to an unallocated frequency band, which is a frequency band other than the frequency bands allocated for optical communication, for each optical path between optical communication devices through which the inspection optical signal passes; acquiring the identification information of the test optical signal received by the second optical communication device; Identifying connection status information representing a connection status of the optical path in the branching device from the identification information; the identification information is represented by a decrease in noise intensity of the test optical signal in a predetermined frequency band included in the unallocated frequency band; How to determine connection status.

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