Optical transmission path monitoring system, optical transmission path monitoring method, and control program

Abstract

This disclosure provides an optical transmission path monitoring system, an optical transmission path monitoring method, and a control program that can efficiently monitor a large number of optical transmission paths. [Solution] The optical transmission path monitoring system 1 according to this disclosure comprises a first optical transmission path L1 and a first delay optical transmission path LC1 for propagating a first monitoring light ML1, a second optical transmission path L2 and a second delay optical transmission path LC2 for propagating a second monitoring light ML2, and a detection unit 12 that identifies the monitoring light propagated by the first monitoring light ML1 through the first optical transmission path L1 and the first delay optical transmission path LC1, and the monitoring light propagated by the second monitoring light ML2 through the second optical transmission path L2 and the second delay optical transmission path LC2, and detects an anomaly, wherein the length of the first delay optical transmission path LC1 is different from the length of the second delay optical transmission path LC2.

Description

Technical Field

[0001] The present disclosure relates to an optical transmission line monitoring system, an optical transmission line monitoring method, and a control program.

Background Art

[0002] In a long-distance optical transmission system such as a submarine optical transmission system, a monitoring device for monitoring the state of an optical transmission line composed of optical repeaters, optical fibers, etc. is known. First, the monitoring device outputs monitoring light to the upstream optical transmission line. The output monitoring light is reflected by an optical repeater and input to the monitoring device through the downstream optical transmission line as return light. Then, the monitoring device detects an abnormality in the optical transmission line based on the acquired return light. When considering the upstream and downstream optical transmission lines as one optical transmission line (or one optical transmission line system), the monitoring device monitors the state of the optical transmission line by sequentially performing these operations for each optical transmission line.

[0003] With the increasing demand for high-capacity communication, the number of installed optical transmission lines is increasing. Therefore, if the monitoring device monitors each optical transmission line, the required time for monitoring increases, and the immediacy of warning when an abnormality is detected is impaired. Thus, an optical transmission line monitoring system that can efficiently monitor many optical transmission lines has been proposed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] There is a need for an optical transmission line monitoring system that can efficiently monitor many optical transmission lines, not limited to the system disclosed in Patent Document 1.

[0006] The purpose of this disclosure is to provide an optical transmission path monitoring system, an optical transmission path monitoring method, and a control program that solve the problems described above. [Means for solving the problem]

[0007] The optical transmission path monitoring system according to this disclosure comprises: a first optical transmission path and a first delay optical transmission path for propagating a first monitoring light; a second optical transmission path and a second delay optical transmission path for propagating a second monitoring light; and a detection unit that identifies the first monitoring light as monitoring light propagated through the first optical transmission path and the second monitoring light as monitoring light propagated through the second optical transmission path, based on the time it took to acquire the first monitoring light via the first optical transmission path and the first delay optical transmission path and the time it took to acquire the second monitoring light via the second optical transmission path and the second delay optical transmission path, wherein the length of the first delay optical transmission path is different from the length of the second delay optical transmission path.

[0008] The optical transmission path monitoring method according to this disclosure comprises the steps of: acquiring a first monitoring light via a first optical transmission path and a first delay optical transmission path, and a second monitoring light via a second optical transmission path and a second delay optical transmission path having a different length from the first delay optical transmission path; and identifying, based on the time at which the first monitoring light was acquired and the time at which the second monitoring light was acquired, that the first monitoring light is monitoring light propagated through the first optical transmission path and that the second monitoring light is monitoring light propagated through the second optical transmission path.

[0009] The control program according to this disclosure causes a computer to perform the following processes: acquiring a first monitoring light via a first optical transmission path and a first delay optical transmission path, and acquiring a second monitoring light via a second optical transmission path and a second delay optical transmission path having a different length from the first delay optical transmission path; and identifying the first monitoring light as monitoring light propagated through the first optical transmission path and the second monitoring light as monitoring light propagated through the second optical transmission path, based on the time at which the first monitoring light was acquired and the time at which the second monitoring light was acquired. [Effects of the Invention]

[0010] This disclosure provides an optical transmission path monitoring system, an optical transmission path monitoring method, and a control program that can efficiently monitor a large number of optical transmission paths. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows an example of the configuration of the optical transmission path monitoring system according to this disclosure. [Figure 2] Figure 2 shows an example of another configuration of the optical transmission path monitoring system according to this disclosure. [Figure 3] Figure 3 shows an example of the configuration of an optical repeater according to this disclosure. [Figure 4] Figure 4 is a flowchart showing an example of an optical transmission path monitoring method according to this disclosure. [Figure 5] Figure 5 shows an example of another configuration of the optical transmission path monitoring system according to this disclosure. [Figure 6] Figure 6 is a block diagram showing an example of a hardware configuration that realizes the monitoring function of the optical transmission path monitoring device according to this disclosure. [Modes for carrying out the invention]

[0012] (Embodiment 1) <Configuration of the Optical Transmission Path Monitoring System> The configuration example of the optical transmission path monitoring system 1 will be described below with reference to Figure 1. Figure 1 is a diagram showing an example of the configuration of the optical transmission path monitoring system according to this disclosure. The optical transmission path monitoring system 1 is a system that detects faults in optical transmission paths L1 to Ln (where n is an integer of 2 or more) that constitute various optical networks, such as submarine optical networks. The optical transmission path monitoring system 1 comprises a detection unit 12, optical transmission paths L1 to Ln, and delay optical transmission paths LC1 to LCn (where n is an integer of 2 or more).

[0013] The detection unit 12 detects abnormalities in the optical transmission paths L1 to Ln based on monitoring light ML1 to MLn (where n is an integer of 2 or more) propagating through the optical transmission paths L1 to Ln. More specifically, the detection unit 12 determines the type and degree of abnormality in the optical transmission paths L1 to Ln based, for example, on the amount of fluctuation and fluctuation pattern of the acquired monitoring light ML1 to MLn.

[0014] The delay optical transmission paths LC1 to LCn delay the time it takes for the detection unit 12 to acquire the monitoring light ML1 to MLn. Each of the delay optical transmission paths LC1 to LCn is connected to each of the optical transmission paths L1 to Ln. The lengths of each of the delay optical transmission paths LC1 to LCn are different. As a result, the amount of delay of the monitoring light ML1 to MLn differs for each optical transmission path L1 to Ln. Therefore, the time it takes for the detection unit 12 to acquire the monitoring light ML1 to MLn differs for each optical transmission path L1 to Ln. Consequently, it is possible to suppress the overlapping of the waveforms of the monitoring light ML1 to MLn acquired by the detection unit 12. Furthermore, based on the time it took to acquire the monitoring light ML1 to MLn, the detection unit 12 can identify which optical transmission path L1 to Ln the acquired monitoring light ML1 to MLn propagated.

[0015] The identification method by the detection unit 12 will now be explained in detail. The detection unit 12 acquires the first monitoring light ML1 via the first optical transmission path L1 and the first delay optical transmission path LC1. The detection unit 12 also acquires the second monitoring light ML2 via the second optical transmission path L2 and the second delay optical transmission path LC2. Here, the length of the first delay optical transmission path LC1 is different from the length of the second delay optical transmission path LC2. Therefore, the time it takes for the detection unit 12 to acquire the first monitoring light ML1 is different from the time it takes for the detection unit 12 to acquire the second monitoring light ML2. For example, if the first delay optical transmission path LC1 is longer than the second delay optical transmission path LC2, the time it takes for the detection unit 12 to acquire the first monitoring light ML1 will be later than the time it takes for the detection unit 12 to acquire the second monitoring light ML2.

[0016] The detection unit 12 identifies that the first monitoring light ML1 is the monitoring light that has propagated through the first optical transmission path L1 and the second monitoring light ML2 is the monitoring light that has propagated through the second optical transmission path L2 based on the time when the first monitoring light ML1 was acquired and the time when the second monitoring light ML2 was acquired. More specifically, the detection unit 12 identifies which optical transmission path the acquired first monitoring light ML1 and second monitoring light ML2 have propagated through based on the difference between the time when the first monitoring light ML1 was acquired and the time when the second monitoring light ML2 was acquired.

[0017] As described above, in the optical transmission path monitoring system 1, due to the delay optical transmission paths LC1 to LCn having different lengths, the times at which the detection unit 12 acquires the monitoring lights ML1 to MLn are different for each of the optical transmission paths L1 to Ln. Therefore, the detection unit 12 can identify which optical transmission paths L1 to Ln the acquired monitoring lights ML1 to MLn have propagated through based on the times when the monitoring lights ML1 to MLn were acquired. Thus, the optical transmission path monitoring system 1 can efficiently monitor many optical transmission paths L1 to Ln.

[0018] (Embodiment 2) Hereinafter, another example of the optical transmission path monitoring system will be described with reference to FIG. 2. FIG. 2 is a diagram showing an example of another configuration of the optical transmission path monitoring system according to the present disclosure.

[0019] <Configuration of optical transmission path> First, the optical transmission paths L1 to Ln will be described. The optical transmission paths L1 to Ln include an upstream transmission path LA1 to LAn and a downstream transmission path LB1 to LBn. One end of the optical transmission paths L1 to Ln is connected to the terminal station TS0, and the other end is connected to any one of the terminal stations TS1 to TSn (n is an integer of 2 or more). Also, one or more optical repeaters RP are inserted on the optical transmission paths L1 to Ln.

[0020] Terminal station TS0 is connected to each of the multiple terminal stations TS1 to TSn via optical transmission lines L1 to Ln. Note that terminal stations TS1 to TSn are not necessarily separate terminal stations. For example, some or all of terminal stations TS1 to TSn may be located within a single terminal station. Terminal station TS0 has multiple optical transmission devices TR1 to TRn. Each optical transmission device TR1 to TRn includes a transmitter and a receiver (not shown). Similarly, each terminal station TS1 to TSn also includes a transmitter and a receiver (not shown).

[0021] The optical signals output from each of the optical transmission devices TR1 to TRn are transmitted to each of the terminal stations TS1 to TSn via the uplink transmission lines LA1 to LAn. The optical signals output from each of the terminal stations TS1 to TSn are transmitted to each of the optical transmission devices TR1 to TRn at terminal station TS0 via the downlink transmission lines LB1 to LBn. In other words, the uplink transmission line LAk (where k is an integer between 1 and n) and the downlink transmission line LBk constitute the optical transmission line Lk that connects the optical transmission device TRk at terminal station TS0 to terminal station TSk.

[0022] The optical repeater RP is inserted on the optical transmission path L1 to Ln. Figure 3 shows an example of the configuration of the optical repeater according to this disclosure. As shown in Figure 3, the optical repeater RP comprises optical amplifiers A1 and A2 and couplers CP1 and CP2.

[0023] Optical amplifier A1 is inserted into the uplink transmission path LAk. Optical amplifier A1 amplifies the optical signal transmitted through the uplink transmission path LAk toward the terminal TSk. Coupler CP1 is configured, for example, as a directional coupler or an optical circulator. Coupler CP1 is inserted after optical amplifier A1 in the uplink optical transmission path LAk. Coupler CP1 selectively splits the optical signal propagating in the opposite direction to the optical signal transmitted through the uplink optical transmission path LAk toward the terminal TSk (i.e., the return light BLk described later), and outputs the split optical signal to coupler CP2.

[0024] Optical amplifier A2 is inserted into the downlink transmission line LBk. Optical amplifier A2 amplifies the optical signal transmitted through the downlink transmission line LBk. Coupler CP2, like coupler CP1, is configured, for example, as a directional coupler or an optical circulator. Coupler CP2 is inserted after optical amplifier A2. Coupler CP2 couples the optical signal (return light BLk) output from coupler CP1 to the downstream transmission line LBk. As a result, the coupled optical signal (return light BLk) is transmitted to terminal station TS0 through the downstream transmission line LBk. Alternatively, coupler CP2 may be inserted before optical amplifier A2, and coupler CP2 may couple the optical signal (return light BLk) output from coupler CP1 to the downstream transmission line LBk, and the coupled light (return light BLk) may be input to optical amplifier A2. In this case, optical amplifier A2 may amplify the input light (return light BLk) and output it.

[0025] <Configuration of the Optical Transmission Path Monitoring System> Let's return to the explanation of Figure 2. Next, we will describe the configuration of the optical transmission path monitoring system 1. The optical transmission path monitoring system 1 is a system that detects faults in optical transmission paths L1 to Ln. The optical transmission path monitoring system 1 comprises a monitoring device 10, a connection unit 20, couplers 30a and 30b, a variable optical attenuator 40, delay optical transmission paths LC1 to LCn (where n is an integer of 2 or more), and the optical transmission paths L1 to Ln described above.

[0026] The monitoring device 10 is a device for detecting abnormalities in the optical transmission paths L1 to Ln. The monitoring device 10 comprises an output unit 11 and a detection unit 12. Note that the output unit 11 and the detection unit 12 may be provided in separate monitoring devices 10, respectively.

[0027] The output unit 11 outputs monitoring light ML towards the upstream transmission lines LA1 to LAn. Before the monitoring light ML output by the output unit 11 is input to the upstream transmission lines LA1 to LA, it is branched into multiple monitoring light ML1 to MLn by the coupler 30a. Each of the monitoring light ML1 to MLn is then input to the upstream transmission lines LA1 to LA.

[0028] The detection unit 12 detects abnormalities in the optical transmission paths L1 to Ln based on monitoring light propagating through the optical transmission paths L1 to Ln. The monitoring light acquired by the detection unit 12 is the monitoring light (hereinafter referred to as return light BL1 to BLn) that has been reflected by the optical repeater RP from the monitoring light ML1 to MLn output by the output unit 11. The detection unit 12 determines the type and degree of abnormality in the optical transmission paths L1 to Ln based, for example, on the amount of fluctuation in the intensity and the fluctuation pattern of the return light BL1 to BLn. The return light BL1 to BLn is coupled to the return light BL by the coupler 30b and input to the detection unit 12. Note that coupling of the return light by the coupler 30b is not mandatory. Therefore, the optical transmission path monitoring system 1 does not need to be provided with the coupler 30b.

[0029] The connection section 20 is provided to connect the monitoring device 10 and the optical transmission lines L1 to Ln. The connection point connecting the output unit 11 and the uplink transmission lines LA1 to Lan, and the connection point connecting the detection unit 12 and the downlink transmission lines LB1 to LBn are located within the connection section 20. The connection section 20 is provided, for example, in terminal station TS0, but is not limited thereto. The connection section 20 may also be provided, for example, in the optical repeater RP or in terminal stations TS1 to TSn. Furthermore, the optical transmission line monitoring system 1 may use OCI (open cable interface) as the connection section 20.

[0030] The variable optical attenuator 40 is installed downstream of the coupler 30a and upstream of the uplink transmission lines LA1 to Ln. The variable optical attenuator 40 operates when it is desired to detect an abnormality in a specific optical transmission line L1 to Ln. However, the variable optical attenuator 40 is not an essential element. Therefore, the optical transmission line monitoring system 1 does not need to include the variable optical attenuator 40.

[0031] Each of the delay optical transmission lines LC1 to LCn is connected to each of the optical transmission lines L1 to Ln. More specifically, the delay optical transmission lines LC1 to LCn are installed, for example, on the side of the connection point between the output unit 11 and the uplink transmission lines LA1 to Lan, on the side of the detection unit 12 from the connection point between the detection unit 12 and the downlink transmission lines LB1 to LBn, or in at least one of these locations within the optical repeater RP.

[0032] The delay optical transmission lines LC1 to LCn delay the time it takes for the detection unit 12 to acquire the return light BL1 to BLn. The lengths of each of the delay optical transmission lines LC1 to LCn are different. As a result, the amount of delay of the monitoring light ML1 to MLn differs for each optical transmission line L1 to Ln. Therefore, the time it takes for the detection unit 12 to acquire the return light BL1 to BLn differs for each optical transmission line L1 to Ln, depending on the delay optical transmission lines LC1 to LCn. Consequently, the overlapping of the waveforms of the return light BL1 to BLn acquired by the detection unit 12 can be suppressed. Furthermore, based on the time it takes to acquire the return light BL1 to BLn, the detection unit 12 can identify which optical transmission line L1 to Ln the acquired return light BL1 to BLn is the monitoring light that propagated.

[0033] Here, it is preferable that the length of the delay optical transmission lines LC1 to LCn is longer than the value obtained by converting the pulse width of the monitoring light ML into distance. This allows the optical transmission line monitoring system 1 to suppress the overlapping of the waveforms of the return light BL1 to BLn input to the detection unit 12. Therefore, the optical transmission line monitoring system 1 can identify which optical transmission line L1 to Ln each return light BL1 to BLn propagated as monitoring light. The value obtained by converting the pulse width of the monitoring light ML1 to MLn into distance is, for example, the value obtained by multiplying the pulse width of the monitoring light ML by the speed of light.

[0034] Furthermore, it is preferable that the length of the delay optical transmission lines LC1 to LCn is shorter than the minimum span length of the optical transmission lines L1 to Ln divided by the number of optical transmission lines L1 to Ln. This allows the optical transmission line monitoring system 1 to suppress the overlap between the waveform of the return light BL1 to BLn reflected by the first optical repeater RP and the waveform of the return light BL1 to BLn reflected by the second optical repeater RP in the return light BL1 to BLn input to the detection unit 12. Thus, the optical transmission line monitoring system 1 can identify which optical transmission line L1 to Ln each return light BL1 to BLn propagated as monitoring light. The span length is the length of the optical transmission line between adjacent optical repeaters RP on the optical transmission line L1 to Ln.

[0035] <Optical transmission path monitoring method> Next, the processes performed by the optical transmission path monitoring system 1 will be described with reference to Figure 4. Figure 4 is a flowchart of an example of an optical transmission path monitoring method according to this disclosure. The flowchart shown in Figure 4 is started, for example, when the monitoring device 10 receives some command signal. Alternatively, the flowchart shown in Figure 4 may be started at predetermined time intervals.

[0036] First, the output unit 11 outputs monitoring light ML toward the optical transmission paths L1 to Ln (step S101). More specifically, the output unit 11 outputs monitoring light ML toward the uplink transmission paths LA1 to LAn.

[0037] Next, coupler 30a splits the output monitoring light ML into multiple monitoring lights ML1 to MLn (step S102). Here, coupler 30a splits the monitoring light ML before it is input to the uplink transmission lines LA1 to LA. Then, each of the monitoring lights ML1 to MLn is input to the uplink transmission lines LA1 to LA.

[0038] Next, the detection unit 12 acquires monitoring light via the optical transmission paths L1 to Ln and the delay optical transmission paths LC1 to LCn (step S103). The monitoring light acquired by the detection unit 12 is the return light BL1 to BLn that has been reflected by the optical repeater RP from each of the monitoring lights ML1 to MLn that were branched in step 102. The detection unit 12 acquires the first monitoring light (return light BL1) via the first optical transmission path L1 and the first delay optical transmission path LC1. The detection unit 12 also acquires the second monitoring light (return light BL2) via the second optical transmission path L2 and the second delay optical transmission path LC2. The length of the first delay optical transmission path LC1 is different from the length of the second delay optical transmission path LC2.

[0039] Next, the detection unit 12 identifies which optical transmission path the monitoring light (return light BL1~BLn) propagated through, based on the time at which the monitoring light (return light BL1~BLn) was acquired (step S104). More specifically, the detection unit 12 identifies, based on the time at which the first monitoring light ML1 was acquired and the time at which the second monitoring light ML2 was acquired, that the first monitoring light ML1 propagated through the first optical transmission path L1 and that the second monitoring light ML2 propagated through the second optical transmission path L2.

[0040] Finally, the detection unit 12 detects an abnormality in the optical transmission path L1 to Ln based on the monitoring light (return light BL1 to BLn) (step S105). The detection unit 12 determines the type and degree of the abnormality in the optical transmission path L1 to Ln based, for example, on the amount of fluctuation and fluctuation pattern of the acquired monitoring light (return light BL1 to BLn).

[0041] In the optical transmission path monitoring system 1, the time it takes for the detection unit 12 to acquire monitoring light (return light BL1 to BLn) differs for each optical transmission path L1 to Ln due to the delay optical transmission paths LC1 to LCn, which have different lengths. Therefore, the detection unit 12 can identify which optical transmission path L1 to Ln the acquired monitoring light (return light BL1 to BLn) propagated based on the time it took to acquire the monitoring light (return light BL1 to BLn). As a result, the optical transmission path monitoring system 1 can monitor optical transmission paths L1 to Ln almost simultaneously by simply outputting one monitoring light ML. Therefore, the optical transmission path monitoring system 1 can efficiently monitor many optical transmission paths L1 to Ln.

[0042] (Embodiment 3) The following describes Embodiment 3, focusing on the differences from Embodiment 2. The optical transmission path monitoring system 1 according to Embodiment 2 includes delay optical transmission paths LC1 to LCn of different lengths in order to identify which optical transmission path L1 to Ln each monitoring light (return light BL1 to BLn) acquired by the detection unit 12 propagated through.

[0043] However, for example, if optical transmission paths L1 to Lk are trunk paths and optical transmission paths Lk to Ln are branch paths, there is a risk that the waveform of any of the return light BL1 to BLk that propagated through optical transmission paths L1 to Lk may overlap with the waveform of any of the return light BLk to BLn that propagated through optical transmission paths Lk to Ln.

[0044] Therefore, the optical transmission path monitoring system 1 according to this third embodiment also identifies whether the acquired monitoring light (return light BL1~BLn) propagated along the trunk path or the branch path.

[0045] <Configuration of the Optical Transmission Path Monitoring System> Another example of an optical transmission path monitoring system will be described with reference to Figure 5. Figure 5 is a diagram showing another example of the configuration of the optical transmission path monitoring system according to the present disclosure. As shown in Figure 5, the optical transmission path monitoring system 1 according to Embodiment 3 further comprises a bandpass filter 50 and a control unit 51 compared to the optical transmission path monitoring system 1 shown in Figure 2. Each of the optical transmission paths L1 to Ln is either a trunk path or a branch path, with at least one of the optical transmission paths L1 to Ln being a trunk path and at least one of the optical transmission paths L1 to Ln being a branch path. Here, the optical transmission paths L1 to Lk are considered trunk paths, and the optical transmission paths Lk to Ln are considered branch paths.

[0046] The bandpass filter 50 is provided in the optical transmission path monitoring system 1 for each optical transmission path L1 to Ln that is to be monitored. In this embodiment 3, the bandpass filter 50 is provided on the side of the connection point connecting the output unit 11 and the uplink transmission paths LA1 to Lan, but is not particularly limited. The bandpass filter 50 may be provided, for example, on the side of the connection point connecting the detection unit 12 and the downlink transmission paths LB1 to LBn.

[0047] The bandpass filter 50 transmits light of a predetermined wavelength. The transmission wavelength of the bandpass filter 50 corresponding to the trunk paths L1 to Lk is different from the transmission wavelength of the bandpass filter 50 corresponding to the branch paths Lk to Ln. As a result, the detection unit 12 acquires monitoring light (return light BLk to BLn) with a different wavelength from the monitoring light (return light BL1 to BLk) acquired from the trunk paths L1 to Lk, from the branch paths Lk to Ln. The detection unit 12 can then identify which optical transmission path L1 to Ln the acquired monitoring light (return light BL1 to BLn) propagated based on the time the monitoring light (return light BL1 to BLn) was acquired and the wavelength of the monitoring light (return light BL1 to BLn).

[0048] The control unit 51 is connected to the bandpass filter 50 and controls the transmission wavelength of the bandpass filter 50. The control unit 51 may, for example, receive an identification signal indicating whether each of the multiple optical transmission paths L1 to Ln is a trunk path or a branch path, and control the transmission wavelength of the bandpass filter 50 based on the identification signal.

[0049] As described above, in the optical transmission path monitoring system 1, by providing a bandpass filter 50, the detection unit 12 can identify whether the acquired monitoring light (return light BL1~BLn) propagated along the trunk path or the branch path based on the wavelength of the monitoring light (return light BL1~BLn). As a result, even if the waveforms of the return light BL1~BLn overlap, the detection unit 12 can identify which optical transmission path L1~Ln the acquired monitoring light (return light BL1~BLn) propagated.

[0050] Furthermore, the method for identifying whether the acquired monitoring light (return light) propagated through the trunk path or the branch path is not limited to using the bandpass filter 50. For example, the output unit 11 may output monitoring light of a different wavelength to the branch path than the monitoring light output to the trunk path, and perform the above identification based on the wavelength of the acquired monitoring light (return light). Alternatively, the length of the delay optical transmission path may be adjusted so that the time at which the monitoring light (return light) propagated through the trunk path was acquired does not match the time at which the monitoring light (return light) propagated through the branch path was acquired, thereby suppressing the overlap of the waveforms of the return light.

[0051] <Hardware configuration for implementing monitoring functions in an optical transmission path monitoring system> The monitoring device 10, the connection part 20, the couplers 30a and 30b, the variable optical attenuator 40, the bandpass filter 50, the control unit 51, and the delay optical transmission lines LC1 to LCn may be configured as an optical transmission line monitoring device. Some or all of the monitoring processing realized by the optical transmission line monitoring device can be realized by a general-purpose computer system. A brief explanation follows with reference to Figure 6.

[0052] Figure 6 is a block diagram showing an example of a hardware configuration for realizing the monitoring function of an optical transmission line monitoring device according to this disclosure. The computer 300 includes, for example, a CPU (Central Processing Unit) 301 which is a control device, RAM (Random Access Memory) 302, and ROM (Read Only Memory) 303. The computer 300 further includes an IF (Interface) 304 which is an interface to the outside world, and an HDD (Hard Disk Drive) 305 which is an example of a non-volatile storage device. Furthermore, the computer 300 may also include other configurations not shown, such as input devices such as a keyboard and mouse, and display devices such as a display.

[0053] HDD305 stores an OS (Operating System) and a control program 306, which are not shown in the diagram. The control program 306 is a computer program (a control program for optical transmission path monitoring) that implements the monitoring functions of the optical transmission path monitoring system.

[0054] The CPU 301 controls various processes in the computer 300, including access to RAM 302, ROM 303, IF 304, and HDD 305. The computer 300 reads and executes the OS and control program 306 stored in HDD 305 by the CPU 301. This enables the computer 300 to perform monitoring functions for the optical transmission line monitoring system.

[0055] The program described above includes a set of instructions (or software code) that, when loaded into a computer, causes the computer to perform one or more of the functions described in this disclosure. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include RAM, ROM, flash memory, SSD (Solid-State Drive), or other memory technologies, CD-ROM, DVD (Digital Versatile Disc), Blu-ray® disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically, or otherwise propagating signals.

[0056] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0057] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments rather than with only one specific embodiment. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps shown in any of the drawings may be changed as appropriate.

[0058] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0059] (Note 1) A first optical transmission path and a first delay optical transmission path for propagating a first monitoring light, A second optical transmission path and a second delay optical transmission path for propagating a second monitoring light, The system includes a detection unit that distinguishes the first monitoring light from the monitoring light propagated through the first optical transmission path and the second monitoring light propagated through the second optical transmission path, based on the time it took to acquire the first monitoring light via the first optical transmission path and the first delay optical transmission path, and the time it took to acquire the second monitoring light via the second optical transmission path and the second delay optical transmission path. The length of the first delay optical transmission path is different from the length of the second delay optical transmission path. Optical transmission path monitoring system.

[0060] (Note 2) The system further includes an output unit that outputs the monitoring light toward the optical transmission path, The monitoring light acquired by the detection unit is the reflected light obtained when the monitoring light output by the output unit is reflected by one or more optical repeaters inserted in the optical transmission path. The optical transmission path monitoring system described in Appendix 1.

[0061] (Note 3) The length of the delay optical transmission path is longer than the value obtained by converting the pulse width of the monitoring light into distance. Optical transmission path monitoring system as described in Appendix 1 to 2.

[0062] (Note 4) The length of the delay optical transmission path is shorter than the minimum length of the optical transmission path between adjacent optical repeaters divided by the number of optical transmission paths. Optical transmission path monitoring system as described in Appendix 1 to 3.

[0063] (Note 5) The first optical transmission path is a trunk path, and the second optical transmission path is a branch path. The wavelength of the first monitoring light acquired by the detection unit is different from the wavelength of the second monitoring light acquired by the detection unit due to the bandpass filter. The detection unit performs the identification based on the time the monitoring light was acquired and the wavelength of the monitoring light. Optical transmission path monitoring system as described in Appendix 1 to 4.

[0064] (Note 6) The first optical transmission path is a trunk path, and the second optical transmission path is a branch path. The output unit outputs a first monitoring light and a second monitoring light with different wavelengths. The detection unit performs the identification based on the time the monitoring light was acquired and the wavelength of the monitoring light. Optical transmission path monitoring system as described in Appendix 1 to 4.

[0065] (Note 7) The first optical transmission path is a trunk path, and the second optical transmission path is a branch path. The length of the first delay optical transmission path and the length of the second delay optical transmission path are such that the time at which the detection unit acquires the first monitoring light does not coincide with the time at which the detection unit acquires the second monitoring light. Optical transmission path monitoring system as described in Appendix 1 to 4.

[0066] (Note 8) The delay optical transmission path is installed on the side of the detection unit from the connection point between the detection unit and the optical transmission path, on the side of the output unit from the connection point between the output unit and the optical transmission path, or in at least one of the optical repeaters. Optical transmission path monitoring system as described in Appendix 1 to 7.

[0067] (Note 9) The steps include obtaining a first monitoring light via a first optical transmission path and a first delay optical transmission path, and a second monitoring light via a second optical transmission path and a second delay optical transmission path having a different length from the first delay optical transmission path, The method includes the step of identifying, based on the time at which the first monitoring light was acquired and the time at which the second monitoring light was acquired, that the first monitoring light is monitoring light propagated through the first optical transmission path and that the second monitoring light is monitoring light propagated through the second optical transmission path. Optical transmission path monitoring method.

[0068] (Note 10) A process of acquiring a first monitoring light via a first optical transmission path and a first delay optical transmission path, and a second monitoring light via a second optical transmission path and a second delay optical transmission path having a different length from the first delay optical transmission path, Based on the time at which the first monitoring light was acquired and the time at which the second monitoring light was acquired, the computer is instructed to perform a process to identify the first monitoring light as monitoring light propagated through the first optical transmission path and the second monitoring light as monitoring light propagated through the second optical transmission path. Control program.

[0069] (Note 11) The bandpass filter further includes a control unit that controls the wavelength transmitted through the bandpass filter. The optical transmission path monitoring system described in Appendix 5.

[0070] (Note 12) The system further includes a control unit that controls the wavelength of the monitoring light output by the output unit. The optical transmission path monitoring system described in Appendix 6.

[0071] (Note 13) The control unit, Each of the multiple optical transmission paths receives an identification signal indicating whether it is a trunk path or a branch path. Based on the identification signal, the wavelength is controlled. The optical transmission path monitoring system described in Appendix 11 or 12.

[0072] Some or all of the elements (e.g., configuration and function) described in Appendices 2-8 and 11-13, which are dependent on Appendice 1, may also be dependent on Appendices 9 and 10 in the same manner as those described in Appendices 2-8 and 11-13. Some or all of the elements described in any appendice may be applicable to various hardware, software, recording means, systems, and methods for recording software. [Explanation of Symbols]

[0073] 1. Optical transmission path monitoring system 10 Monitoring equipment 11 Output section 12 Detection unit 20 Connection part 30a, 30b Coupler 40 Variable Optical Attenuator 50 Bandpass Filter 51 Control Unit 300 Computers 301 CPU 302 RAM 303 ROM 304 IF 305 HDD 306 Control Program A1, A2 Optical Amplifiers CP1, CP2 coupler L1-Ln Optical Transmission Path LA1-LAn Upstream Transmission Line LB1-LBn Downlink Transmission Line LC1-LCn optical transmission path for delay ML, ML1-MLn monitoring light BL, BL1-BLn reflected light RP Optical Repeater TR1-TRn Optical Transmission Device TS0, TS1-TSn terminal station

Claims

1. A first optical transmission path and a first delay optical transmission path for propagating a first monitoring light, A second optical transmission path and a second delay optical transmission path for propagating a second monitoring light, The system includes a detection unit that distinguishes the first monitoring light from the monitoring light propagated through the first optical transmission path and the second monitoring light propagated through the second optical transmission path, based on the time it took to acquire the first monitoring light via the first optical transmission path and the first delay optical transmission path, and the time it took to acquire the second monitoring light via the second optical transmission path and the second delay optical transmission path. The length of the first delay optical transmission path is different from the length of the second delay optical transmission path. Optical transmission path monitoring system.

2. The system further includes an output unit that outputs the monitoring light toward the optical transmission path, The monitoring light acquired by the detection unit is the reflected light obtained when the monitoring light output by the output unit is reflected by one or more optical repeaters inserted in the optical transmission path. The optical transmission path monitoring system according to claim 1.

3. The length of the delay optical transmission path is longer than the value obtained by converting the pulse width of the monitoring light into distance. The optical transmission path monitoring system according to claim 2.

4. The length of the delay optical transmission path is shorter than the minimum length of the optical transmission path between adjacent optical repeaters divided by the number of optical transmission paths. The optical transmission path monitoring system according to claim 2 or 3.

5. The first optical transmission path is a trunk path, and the second optical transmission path is a branch path. The wavelength of the first monitoring light acquired by the detection unit is different from the wavelength of the second monitoring light acquired by the detection unit due to a bandpass filter. The detection unit performs the identification based on the time the monitoring light was acquired and the wavelength of the monitoring light. The optical transmission path monitoring system according to claim 4.

6. The first optical transmission path is a trunk path, and the second optical transmission path is a branch path. The output unit outputs a first monitoring light and a second monitoring light, each having different wavelengths. The detection unit performs the identification based on the time the monitoring light was acquired and the wavelength of the monitoring light. The optical transmission path monitoring system according to claim 4.

7. The first optical transmission path is a trunk path, and the second optical transmission path is a branch path. The length of the first delay optical transmission path and the length of the second delay optical transmission path are such that the time at which the detection unit acquires the first monitoring light does not coincide with the time at which the detection unit acquires the second monitoring light. The optical transmission path monitoring system according to claim 4.

8. The delay optical transmission path is installed on the side of the detection unit from the connection point between the detection unit and the optical transmission path, on the side of the output unit from the connection point between the output unit and the optical transmission path, or in at least one of these locations within the optical repeater. The optical transmission path monitoring system according to claim 4.

9. The steps include obtaining a first monitoring light via a first optical transmission path and a first delay optical transmission path, and a second monitoring light via a second optical transmission path and a second delay optical transmission path having a different length from the first delay optical transmission path, The method includes the step of identifying, based on the time at which the first monitoring light was acquired and the time at which the second monitoring light was acquired, that the first monitoring light is monitoring light propagated through the first optical transmission path and that the second monitoring light is monitoring light propagated through the second optical transmission path. Optical transmission path monitoring method.

10. A process of acquiring a first monitoring light via a first optical transmission path and a first delay optical transmission path, and a second monitoring light via a second optical transmission path and a second delay optical transmission path having a different length from the first delay optical transmission path, Based on the time at which the first monitoring light was acquired and the time at which the second monitoring light was acquired, the computer is instructed to perform a process to identify the first monitoring light as monitoring light propagated through the first optical transmission path and the second monitoring light as monitoring light propagated through the second optical transmission path. Control program.

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