Optical branching and coupling device, method for monitoring optical signals, and program

Abstract

This invention provides an optical branching and coupling device, an optical signal monitoring method, and a program that can monitor separated and multiplexed optical signals on a wavelength-by-wavelength basis without requiring the addition of a dedicated configuration. [Solution] The first and second wavelength separation means separate optical signals of specific wavelengths from the input optical signal. The first and second branching means branch the first and second wavelength-division multiplexed optical signals to the first and second wavelength separation means, respectively. The first and second photodetection means detect the optical signals separated by the first and second wavelength separation means, respectively. The control means monitors the intensity of optical signals of each wavelength within a predetermined wavelength range, based on one or both of the results of the first photodetection means detecting the optical signals separated by the first wavelength separation means and the second photodetection means detecting the optical signals separated by the second wavelength separation means, while changing the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range.

Description

[Technical Field]

[0001] This disclosure relates to an optical branching and coupling device, a method for monitoring optical signals, and a program. [Background technology]

[0002] For example, in optical communication networks such as submarine cable systems, multiplexing technologies such as WDM (Wavelength Division Multiplexing) are used to ensure transmission capacity. In WDM optical communication, an optical branching and coupling device with ROADM (Reconfigurable Optical Add and Drop Multiplexing) functionality is inserted into the submarine cable to flexibly switch the transmission path of optical signals. The ROADM is inserted into the trunk path connecting opposing optical termination devices, and branches (drops) the optical signal transmitted by the trunk path to the branch path, and couples (adds) the optical signal transmitted by the branch path to the trunk path. By controlling the branching and coupling of optical signals by the ROADM, the transmission path of optical signals can be controlled on a wavelength basis.

[0003] Patent Document 1 describes a redundant configuration in which the optical signal add-drop section is provided with two wavelength separation function sections, each having a wavelength selection switch. This allows the transmission of the optical signal to be maintained even if one of the wavelength separation function sections in the add-drop section fails, by using the other wavelength separation function section that is not malfunctioning. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2020 / 175020 [Overview of the project] [Problems that the invention aims to solve]

[0005] In general, optical components mounted in an optical branching and coupling device have wavelength dependence. Therefore, even for the same component, the attenuation amount of an optical signal varies depending on the wavelength (that is, the wavelength band). In particular, an optical branching and coupling device is provided with a wavelength selective switch (WSS) to select optical signals to be branched or coupled for each wavelength. A WSS separates and multiplexes input optical signals for each wavelength, and is known to have wavelength dependence. In an optical communication system such as a submarine cable system, a wavelength is assigned to each customer, so it is required to monitor the intensity of optical signals separated and multiplexed by the WSS of the optical branching and coupling device for each wavelength.

[0006] To monitor the intensity of optical signals separated and multiplexed by a WSS, it is conceivable to provide an Optical Channel Monitor (OCM) at a position before coupling an optical signal to an optical transmission line for transmission to a destination. This allows the OCM to monitor the intensity of the optical signals separated and multiplexed by the WSS. However, this necessitates adding an OCM to the optical branching and coupling device. As a result, this causes problems of increased size and increased cost of the optical branching and coupling device. [Means for Solving the Problem]

[0007] An optical branching and coupling device according to one aspect of the present disclosure includes: first and second wavelength separation means for separating an optical signal of a specific wavelength from an input optical signal; first branching means for branching a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength separation means; second branching means for branching a second wavelength-division multiplexed optical signal input from a second node to the first and second wavelength separation means; first photodetection means for detecting the optical signal separated by the first wavelength separation means; second photodetection means for detecting the optical signal separated by the second wavelength separation means; and control means for monitoring the intensity of an optical signal of each wavelength within a predetermined wavelength range, based on one or both of the results of detecting the optical signal separated by the first wavelength separation means by the first photodetection means and the results of detecting the optical signal separated by the second wavelength separation means by the second photodetection means, while changing the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range.

[0008] An optical signal monitoring method according to one aspect of the present disclosure is an optical branching and coupling device comprising: first and second wavelength separation means for separating optical signals of specific wavelengths from an input optical signal; first branching means for branching a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength separation means; second branching means for branching a second wavelength-division multiplexed optical signal input from a second node to the first and second wavelength separation means; first photodetection means for detecting the optical signals separated by the first wavelength separation means; and second photodetection means for detecting the optical signals separated by the second wavelength separation means. The optical signal monitoring method comprises: first and second wavelength separation means for changing the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range; and monitoring the intensity of optical signals of each wavelength within the predetermined wavelength range based on either or both of the results of detecting the optical signals separated by the first wavelength separation means by the first photodetection means and the results of detecting the optical signals separated by the second wavelength separation means by the second photodetection means.

[0009] A program according to one aspect of the present disclosure, for a computer that controls the operation of an optical branching and coupling device comprising: first and second wavelength separation means that separate an optical signal of a specific wavelength from an input optical signal; first branching means that branches a first wavelength-multiplexed optical signal input from a first node to the first and second wavelength separation means; second branching means that branches a second wavelength-multiplexed optical signal input from a second node to the first and second wavelength separation means; first light detection means that detects the optical signal separated by the first wavelength separation means; and second light detection means that detects the optical signal separated by the second wavelength separation means, causes the computer to execute: a process of changing the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range; and a process of monitoring the intensity of the optical signal at each wavelength within the predetermined wavelength range based on one or both of a detection result of the optical signal separated by the first wavelength separation means obtained by the first light detection means and a detection result of the optical signal separated by the second wavelength separation means obtained by the second light detection means. Effects of the Invention

[0010] According to the present disclosure, there can be provided an optical branching and coupling device, an optical signal monitoring method, and a program capable of monitoring separated and multiplexed optical signals for each wavelength without adding a dedicated configuration. Brief Description of the Drawings

[0011] [Figure 1] It is a diagram schematically illustrating a configuration example of an optical communication network including an optical branching and coupling device according to an embodiment. [Figure 2] It is a diagram schematically illustrating the configuration of an optical branching and coupling device according to an embodiment. [Figure 3] It is a diagram illustrating transmission paths of optical signals when monitoring optical signals in the optical branching and coupling device according to an embodiment. [Figure 4] It is a diagram illustrating a configuration of main parts when monitoring optical signals in the optical branching and coupling device according to an embodiment. [Figure 5]This is a flowchart of the optical signal monitoring operation in an optical branching and coupling device according to one embodiment. [Figure 6] This diagram shows the transmission path of an optical signal when monitoring an optical signal in an optical branching and coupling device according to one embodiment. [Figure 7] This is a flowchart of the optical signal monitoring operation in an optical branching and coupling device according to one embodiment. [Figure 8] This diagram shows the transmission path of an optical signal when monitoring an optical signal in an optical branching and coupling device according to one embodiment. [Figure 9] This is a flowchart of the optical signal monitoring operation in an optical branching and coupling device according to one embodiment. [Figure 10] This diagram shows the transmission path of an optical signal when monitoring an optical signal in an optical branching and coupling device according to one embodiment. [Figure 11] This is a flowchart of the optical signal monitoring operation in an optical branching and coupling device according to one embodiment. [Figure 12] This diagram shows the transmission path of an optical signal when monitoring an optical signal in an optical branching and coupling device according to one embodiment. [Figure 13] This is a flowchart of the optical signal monitoring operation in an optical branching and coupling device according to one embodiment. [Figure 14] This figure shows an example of a computer configuration for realizing the control unit of an optical branching and coupling device. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will now be described with reference to the drawings. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary.

[0013] When we refer to one embodiment below, it means that it is applicable to any of the embodiments described below, or to a combination of two or more embodiments, and that its application is not limited to a specific embodiment.

[0014] Embodiment 1 As a prerequisite for understanding the optical branching and coupling device according to the following embodiment, an optical branching and coupling device in an optical communication network will be described. Figure 1 is a schematic diagram showing an example of the configuration of an optical communication network including an optical branching and coupling device according to one embodiment. The optical branching and coupling device 100 is a node device having ROADM functionality. The optical branching and coupling device 100 is inserted into the optical signal transmission path in an optical communication network 1000 consisting of terminal stations A 1, B 2, and C 3 installed on land. Terminal stations A 1 to C 3 are node devices that include a communication interface capable of transmitting and receiving WDM (Wavelength Division Multiplexing) optical signals, for example, equipped with optical communication devices that perform bidirectional communication.

[0015] Terminal A 1 and Terminal B 2 are connected by a trunk optical transmission path 1010. The optical branching and coupling device 100 is inserted into the optical transmission path 1010. Terminal C 3 is connected to the optical branching and coupling device 100 by a branch optical transmission path 1020. Optical transmission paths 1010 and 1020 are, for example, optical fiber cables housing multi-core optical fibers. Optical transmission paths 1010 and 1020 may be laid on land, or partly or entirely laid underwater. The optical branching and coupling device 100 may be installed on land or underwater.

[0016] The optical branching and coupling device 100 branches the optical signal transmitted between terminal station A 1 and terminal station B 2 via the optical transmission path 1010, on a wavelength-by-wavelength basis, toward terminal station C 3 via the optical transmission path 1020. The optical branching and coupling device 100 also couples the optical signal transmitted from terminal station C 3 toward the optical branching and coupling device 100 via the optical transmission path 1020 back into the optical transmission path 1010 on a wavelength-by-wavelength basis.

[0017] Hereafter, the optical signal transmitted from terminal A 1 to terminal B 2 will be referred to as optical signal [AB]. The optical signal transmitted from terminal A 1 to terminal C 3 will be referred to as optical signal [AC]. The optical signal transmitted from terminal B 2 to terminal A 1 will be referred to as optical signal [BA]. The optical signal transmitted from terminal B 2 to terminal C 3 will be referred to as optical signal [BC]. The optical signal transmitted from terminal C 3 to terminal A 1 will be referred to as optical signal [CA]. Let optical signal [CB] be the optical signal transmitted from terminal C 3 to terminal B 2. Let [XX] be the dummy light output by terminal C 3.

[0018] The optical branching and coupling device 100 passes the optical signal [AB] output from terminal station A 1 through to terminal station B 2 and branches the optical signal [AC] toward terminal station C 3. The optical branching and coupling device 100 passes the optical signal [BA] output from terminal station B 2 through to terminal station A 1 and branches the optical signal [BC] toward terminal station C 3. The optical branching and coupling device 100 couples the optical transmission path 1010 so that the optical signal [CA] output from terminal station C 3 is transmitted toward terminal station A 1. The optical branching and coupling device 100 couples the optical transmission path 1010 so that the optical signal [CB] output from terminal station C 3 is transmitted toward terminal station B 2. Note that the dummy light output from terminal station C 3 is blocked by the optical branching and coupling device 100.

[0019] In the following explanation, for the sake of simplicity, we will focus on the path in which optical signals are transmitted from terminal A 1 to terminal B 2 and terminal C 3, and from terminal C 3 to terminal B 2.

[0020] Figure 2 is a schematic diagram showing the configuration of an optical branching and coupling device according to one embodiment. The optical branching and coupling device 100 includes optical switches 11 to 13, couplers 21 to 26, wavelength selective switches 31 and 32, photodetectors 41 and 42, and a control unit 50. Hereinafter, the wavelength selective switch will be denoted as WSS (Wavelength selective switch). Also, in the figure, the coupler will be denoted as CPL and the photodetector as PD.

[0021] Optical switches 11 and 13 are 1x2 optical switches. Optical switch 12 is a 2x2 optical switch. Optical switches 11 to 13 can be various types of optical switches, such as optical waveguide switches, mechanical switches, and MEMS (micro electro mechanical systems) switches. Switching of optical switches 11 to 13 may be controlled externally (for example, by any of terminals A1 to C3) or by the control unit 50.

[0022] Couplers 21-26 are 1x2 optical couplers. Couplers 21-26 split the optical signal input to the input port into two and output it from two output ports. Couplers 22 and 23 are also referred to as the first and second branching sections or branching means, respectively.

[0023] WSS31 and 32 are wavelength-selective switches having two input ports and one output port. However, the number of input ports for WSS31 and 32 is illustrative, and three or more input ports may be provided as needed. Each of WSS31 and 32 separates and multiplexes wavelength-division multiplexed optical signals input from multiple input ports on a wavelength basis and outputs an optical signal of the wavelength designated as the transmission wavelength from its output port. Wavelength selection by WSS31 and 32 may be controlled externally (for example, by any of terminals A1 to C3) or by the control unit 50. In this embodiment, the control unit 50 specifies the transmission wavelength of WSS31 and 32 by control signals C1 and C2. WSS31 and 32 are also referred to as the first and second wavelength separation units or wavelength separation means, respectively.

[0024] Coupler 21 splits the optical signals [AB] and [AC] input from terminal A 1 into two: one to optical switch 11 and the other to coupler 22. Coupler 22 splits the optical signals [AB] and [AC] input from coupler 21 into two: one to WSS 31 and the other to WSS 32. Coupler 24 splits the optical signal [CB] and dummy light [XX] input from terminal C 3 into two: one to optical switch 13 and the other to coupler 23. Coupler 23 splits the optical signal [CB] and dummy light [XX] input from coupler 24 into two: one to WSS 31 and the other to WSS 32.

[0025] WSS31 separates or wavelength-multiplexes the optical signals of a specified wavelength from the optical signals input from coupler 22 and coupler 23, and outputs them to coupler 25. Coupler 25 splits the optical signals input from WSS31 into two branches, one to the optical switch 12 and the other to the photodetector 41.

[0026] The WSS32 separates or wavelength-multiplexes the optical signals of a specified wavelength from the optical signals input from coupler 22 and coupler 23, and outputs them to coupler 26. Coupler 26 splits the optical signals input from the WSS32 into two branches, one to the optical switch 12 and the other to the photodetector 42.

[0027] The photodetectors 41 and 42 are configured, for example, as photodiodes or photodetectors including photodiodes. Each of the photodetectors 41 and 42 detects the optical signals input from the couplers 25 and 26. The photodetectors 41 and 42 then output detection signals D1 and D2, respectively, indicating the detection result of the optical signals, to the control unit 50. The photodetectors 41 and 42 are also referred to as the first and second photodetectors or photodetectors, respectively.

[0028] From the above, the set consisting of WSS31, coupler 25, and photodetector 41 and the set consisting of WSS32, coupler 26, and photodetector 42 operate independently and have the same functions. Hereinafter, the set consisting of WSS31, coupler 25, and photodetector 41 will be referred to as the wavelength selection function unit 61. The set consisting of WSS32, coupler 26, and photodetector 42 will be referred to as the wavelength selection function unit 62. In other words, the optical branching and coupling device 100 has a redundant configuration that includes wavelength selection function unit 61 and wavelength selection function unit 62, which have the same functions.

[0029] In other words, the wavelength selection function unit 61 and the wavelength selection function unit 62 are capable of performing the same wavelength separation operation. Therefore, even if either the wavelength selection function unit 61 or 62 fails and becomes inoperable, the other unit, which is not malfunctioning, can take over and perform the wavelength separation operation.

[0030] Optical switch 12 complementarily switches the output destination of the optical signals input from coupler 25 and coupler 26 between optical switch 11 and optical switch 13. Optical switch 11 selectively outputs either the optical signal input from coupler 21 or the optical signal input from optical switch 12 to terminal station C 3. Optical switch 13 selectively outputs either the optical signal input from optical switch 12 or the optical signal input from coupler 24 to terminal station B 2.

[0031] In the optical branching and coupling device 100 according to this embodiment, the light detection unit of the optical branching and coupling device 100 can be used to monitor the intensity of optical signals of each wavelength without interfering with communication using optical signals.

[0032] The following describes the case where optical signal [AB] is transmitted from terminal station A 1 to terminal station B 2, and optical signal [CB] is transmitted from terminal station C 3 to terminal station B 2. The optical branching and coupling device 100 monitors the intensity of the optical signals of each wavelength without interfering with the communication between optical signals [AB] and [CB].

[0033] Figure 3 shows the transmission path of an optical signal when monitoring an optical signal in an optical branching and coupling device according to one embodiment. Figure 4 shows the main components when monitoring an optical signal in an optical branching and coupling device according to one embodiment. In this case, optical switch 11 outputs the optical signal [AB] input after branching at coupler 21 to terminal station C 3. Optical switch 12 outputs the optical signal input from coupler 26 to optical switch 11. Optical switch 13 outputs the optical signal input from optical switch 12 to terminal station B 2.

[0034] Therefore, by controlling the wavelength selection using WSS32, it is possible to transmit either the optical signal [AB] or the optical signal [CB] toward terminal station 2.

[0035] On the other hand, the wavelength selection function unit 61, which does not contribute to the transmission of optical signals to terminal station 2, controls the wavelength selection by WSS31 and sweeps the transmitted wavelength, thereby individually outputting optical signals of each wavelength set within the wavelength sweep range R0, which is defined as a predetermined wavelength range. As a result, the control unit 50 can monitor the intensity of the optical signals of each wavelength set within the wavelength sweep range R0 based on the detection signal D1 by controlling the wavelength selection of WSS31.

[0036] Next, the optical signal monitoring operation of the optical branching and coupling device 100 in Embodiment 1 will be described. Figure 5 is a flowchart of the optical signal monitoring operation in the optical branching and coupling device according to one embodiment.

[0037] Step S11 The control unit 50 controls the transmission wavelength λ of the WSS31. P The lower wavelength λ in the wavelength sweep range R0. MIN Set to this.

[0038] Step S12 The control unit 50 detects the transmission wavelength λ transmitted through the WSS31. P The intensity of the optical signal is observed based on the detection signal D1 output by the photodetector 41.

[0039] Step S13 After observing the intensity of the optical signal, the control unit 50 determines whether the transmission wavelength λ set in the WSS 31 P is the upper limit wavelength λ in the wavelength sweep range R0 MAX . If the transmission wavelength λ set in the WSS 31 P is the upper limit wavelength λ MAX , the control unit 50 ends the optical signal monitoring operation.

[0040] Step S14 If the transmission wavelength λ set in the WSS 31 P is not the upper limit wavelength λ MAX , the control unit 50 updates the transmission wavelength λ P to a wavelength increased by Δλ. Thereafter, the control unit 50 returns the process to step S12.

[0041] From the above, the optical branching and coupling apparatus 100 can monitor the intensity of the optical signal of each wavelength included in the wavelength multiplexed signal input to the optical branching and coupling apparatus 100 without inhibiting the output of the optical signal by the wavelength selection function unit 62.

[0042] Like the optical branching and coupling apparatus 100 described above, the redundant configuration including the wavelength selection function units 61 and 62 and the light detection units in the wavelength selection function units 61 and 62 are originally provided in a general optical branching and coupling apparatus. In contrast, according to the optical signal monitoring operation according to the present embodiment, the above-described optical signal monitoring operation can be easily realized by using the original configuration without adding dedicated components or the like.

[0043] Therefore, by controlling the optical branching and coupling apparatus, the intensity of the optical signal of each wavelength separated by the WSS can be monitored without changing the configuration. Accordingly, the optical signal monitoring operation according to the present embodiment can be introduced into a general optical branching and coupling apparatus at low cost and easily.

[0044] Embodiment 2 In Embodiment 1, the operation described was one in which the wavelength selection function unit 61 performs optical signal monitoring and the wavelength selection function unit 62 outputs an optical signal of a desired wavelength, thereby achieving both optical signal monitoring and coupling of the optical signal to the optical transmission path. However, in the optical branching and coupling device 100, it is conceivable that one of the redundant wavelength selection function units 61 and 62 may fail and become unusable. Therefore, in this embodiment, the case in which the optical signal monitoring operation is performed by the other wavelength selection function unit even if one of the wavelength selection function units 61 and 62 fails will be described.

[0045] Figure 6 shows the optical signal transmission path when monitoring an optical signal in an optical branching and coupling device according to one embodiment. In this embodiment, the optical signal transmission path is the same as in Embodiment 1, but the wavelength selection function unit 61 is inoperable due to a malfunction, and the optical signal monitoring operation is performed by the wavelength selection function unit 62.

[0046] Next, the optical signal monitoring operation of the optical branching and coupling device 100 in Embodiment 2 will be described. Figure 7 is a flowchart of the optical signal monitoring operation in the optical branching and coupling device according to one embodiment.

[0047] Step S21 The control unit 50 controls the transmission wavelength λ of the WSS32. P The lower wavelength λ in the wavelength sweep range R0. MIN Set to this.

[0048] Step S22 The control unit 50 detects the transmission wavelength λ transmitted through the WSS32. P The intensity of the optical signal is observed based on the detection signal D2 output by the photodetector 42.

[0049] Step S23 After observing the intensity of the optical signal, the control unit 50 sets the transmission wavelength λ in WSS32. P However, the upper limit wavelength λ in the wavelength sweep range R0 MAX Determine whether or not this is the case. Transmission wavelength λ set in WSS32 P The upper limit wavelength λ MAXIf this is the case, the control unit 50 terminates the optical signal monitoring operation.

[0050] Step S24 The transmission wavelength λ set in WSS32 P The upper limit wavelength λ MAX If not, the control unit 50 will transmit wavelength λ P The wavelength is updated by increasing it by Δλ. Then, the control unit 50 returns the process to step S22.

[0051] As described above, even if the wavelength selection function unit 61 of the optical branching and coupling device 100 fails, the wavelength selection function unit 62 can monitor the intensity of the optical signals of each wavelength included in the wavelength multiplexed signal input to the optical branching and coupling device 100, similar to the wavelength selection function unit 61 in Embodiment 1.

[0052] Although this explanation describes the case where the wavelength selection function unit 61 is malfunctioning, it goes without saying that even if the wavelength selection function unit 61 is functioning correctly, the wavelength selection function unit 62 can still perform optical signal monitoring.

[0053] Embodiment 3 This embodiment describes a monitoring method that shortens the time required for optical signal monitoring. For example, if photodiodes are used in the optical detection unit 41 and optical detection unit 42, the reduction of the time required for optical signal detection may be limited. Generally, a certain time called the response time or rise time is required from the time light is incident on the photodiode until the output signal of the photodiode stabilizes. Hereinafter, the time from the time light is incident on the photodiode until the output signal of the photodiode stabilizes will be referred to as the response time of the photodiode.

[0054] Therefore, in order to accurately observe the intensity of the optical signal incident on the photodetector, the transmission wavelength λ of the WSS during the optical signal monitoring operation is required. PEach time the wavelength is switched, an observation time longer than the response time is required. However, if the wavelength sweep range R0 by WSS is wide, the number of measurements performed while switching the transmission wavelength increases, and the total time required for the photodetector to detect the optical signal is extended accordingly. Therefore, when performing optical signal monitoring using either the photodetector of the wavelength selection function unit 61 or 62, a time longer than the above-mentioned total time is required.

[0055] Therefore, in this embodiment, we will describe an operation that uses both the wavelength selection function units 61 and 62 to perform optical signal monitoring more quickly.

[0056] Figure 8 shows the optical signal transmission path when monitoring an optical signal in an optical branching and coupling device according to one embodiment. In this embodiment, the optical signal transmission path is the same as in Embodiment 1, but the wavelength sweep range R0 is divided into a wavelength range handled by the wavelength selection function unit 61 and a range handled by the wavelength selection function unit 62.

[0057] lower limit wavelength λ of the wavelength sweep range R0 MIN and upper limit wavelength λ MAX The central wavelength between the two is the central wavelength λ MID The wavelength sweep range R0 is defined as the lower wavelength λ. MIN and the central wavelength λ MID The short wavelength range R1 between and the central wavelength λ MID and upper limit wavelength λ MAX The wavelength is divided into a long-wavelength range R2 and a short-wavelength range R2. Hereinafter, the wavelength selection function unit 61 performs optical signal monitoring in the short-wavelength range R1. The wavelength selection function unit 62 performs optical signal monitoring in the long-wavelength range R2. One of the short-wavelength range R1 and the long-wavelength range R2 will also be referred to as the first wavelength range, and the other as the second wavelength range.

[0058] Next, the optical signal monitoring operation of the optical branching and coupling device 100 in Embodiment 3 will be described. Figure 9 is a flowchart of the optical signal monitoring operation in the optical branching and coupling device according to one embodiment.

[0059] Step S31 The control unit 50, similar to step S11 in Figure 5, controls the transmission wavelength λ of the WSS31. P The lower wavelength λ in the wavelength sweep range R0. MIN Set to this.

[0060] Step S32 The control unit 50, similar to step S12 in Figure 5, receives the transmitted wavelength λ transmitted through the WSS31. P The intensity of the optical signal is observed based on the detection signal D1 output by the photodetector 41.

[0061] Step S33 After observing the intensity of the optical signal, the control unit 50 sets the transmission wavelength λ in WSS31. P However, the central wavelength λ in the wavelength sweep range R0 MID Determine whether or not this is the case. Transmission wavelength λ set in WSS31 P The central wavelength λ MID If this is the case, the control unit 50 terminates the optical signal monitoring operation by the wavelength selection function unit 61.

[0062] Step S34 The transmission wavelength λ set in WSS31 P The central wavelength λ MID If not, the control unit 50 will transmit wavelength λ P The wavelength is updated by increasing it by Δλ. Then, the control unit 50 returns the process to step S32.

[0063] Step S35 The control unit 50 controls the transmission wavelength λ of the WSS32. P The upper limit wavelength λ in the wavelength sweep range R0. MAX Set to this.

[0064] Step S36 The control unit 50, similar to step S22 in Figure 7, receives the transmitted wavelength λ transmitted through the WSS32. P The intensity of the optical signal is observed based on the detection signal D2 output by the photodetector 42.

[0065] Step S37 After observing the intensity of the optical signal, the control unit 50 sets the transmission wavelength λ in WSS32. P However, the central wavelength λ in the wavelength sweep range R0 MID Determine whether or not this is the case. Transmission wavelength λ set in WSS32 P The central wavelength λ MID If this is the case, the control unit 50 terminates the optical signal monitoring operation by the wavelength selection function unit 62.

[0066] Step S38 The transmission wavelength λ set in WSS32 P The central wavelength λ MID If not, the control unit 50 will transmit wavelength λ P The wavelength is updated to one that is reduced by Δλ. After that, the control unit 50 returns the process to step S36.

[0067] In this embodiment, steps S31 to S34 by the wavelength selection function unit 61 and steps S35 to S38 by the wavelength selection function unit 62 can be performed independently and simultaneously. Furthermore, the optical signal monitoring operation performed by each of the wavelength selection function units 61 and 62 is performed over a wavelength range of half the wavelength sweep range R0. Therefore, the time required for the optical signal monitoring operation performed by each of the wavelength selection function units 61 and 62 can be halved compared to the time required for the optical signal monitoring operation in embodiments 1 and 2.

[0068] As a result, the optical signal monitoring operation according to this embodiment can significantly reduce the time required for optical signal monitoring that performs a wavelength sweep within the same range, compared to optical signal monitoring operations using only one of the wavelength selection functions 61 and 62, as in Embodiments 1 and 2.

[0069] Embodiment 4 In this embodiment, we will describe a case in which both the wavelength selection function units 61 and 62 are used, similar to Embodiment 3, to perform optical signal monitoring with higher wavelength resolution. Figure 10 is a diagram showing the optical signal transmission path when an optical signal is monitored in an optical branching and coupling device according to one embodiment. In this embodiment, the optical signal transmission path and the wavelength sweep range handled by the wavelength selection function units 61 and 62 are the same as in Embodiment 3. However, while the wavelength sweep resolution in Embodiment 3 was Δλ, in this embodiment, the wavelength sweep resolution is Δλ / 2, which is half of Δλ. Therefore, in this embodiment, optical signal monitoring is performed with twice the wavelength resolution compared to Embodiment 3.

[0070] Next, the optical signal monitoring operation of the optical branching and coupling device 100 in Embodiment 4 will be described. Figure 11 is a flowchart of the optical signal monitoring operation in the optical branching and coupling device according to one embodiment.

[0071] Steps S41-S43 Steps S41 to S43 in Figure 11 are the same as steps S31 to S33 in Figure 9, so redundant explanations are omitted.

[0072] Step S44 The transmission wavelength λ set in WSS31 P The central wavelength λ MID If not, the control unit 50 will transmit wavelength λ P The wavelength is updated by increasing it by Δλ / 2. After that, the control unit 50 returns the process to step S42.

[0073] Steps S45-S47 Steps S45 to S47 in Figure 11 are the same as steps S35 to S37 in Figure 9, so redundant explanations are omitted.

[0074] Step S48 The transmission wavelength λ set in WSS32 P The central wavelength λ MID If not, the control unit 50 will transmit wavelength λ PThe wavelength is updated to one that is reduced by Δλ / 2. After that, the control unit 50 returns the process to step S46.

[0075] In this embodiment, each of the wavelength selection function units 61 and 62 takes approximately twice as long to perform optical signal monitoring in a wavelength range of half the wavelength sweep range R0 compared to Embodiment 3. In other words, the time required for optical signal monitoring in this embodiment is equivalent to the time required for optical signal monitoring in Embodiments 1 and 2.

[0076] Therefore, according to the optical signal monitoring operation in this embodiment, it is possible to perform optical signal monitoring with twice the wavelength resolution in approximately the same amount of time as in embodiments 1 and 2.

[0077] Embodiment 5 In this embodiment, we will describe a case in which both the wavelength selection function units 61 and 62 are used, similar to Embodiment 3, to perform optical signal monitoring with higher precision.

[0078] Figure 12 shows the transmission path of an optical signal when monitoring the intensity of an optical signal in an optical branching and coupling device according to one embodiment. In this embodiment, the wavelength selection function unit 61 monitors the intensity of the optical signal in the same way as in Embodiment 1. The wavelength selection function unit 62 also monitors the intensity of the optical signal in the same way as in Embodiment 2. As a result, the control unit 50 can obtain two monitoring results from the wavelength selection function units 61 and 62 based on the detection signals D1 and D2 for the intensity of the optical signal at each wavelength in the wavelength sweep range R0.

[0079] The control unit 50 calculates the average value of the two monitoring results obtained from the wavelength selection function units 61 and 62, thereby acquiring the intensity of the optical signal at each wavelength with higher accuracy compared to the embodiment described above.

[0080] Next, the optical signal monitoring operation of the optical branching and coupling device 100 in Embodiment 5 will be described. Figure 13 is a flowchart of the optical signal monitoring operation in the optical branching and coupling device according to one embodiment.

[0081] Steps S51-S54 Steps S51 to S54 in Figure 13 are the same as steps S11 to S14 in Figure 5, so redundant explanations are omitted.

[0082] Steps S55~S58 Steps S55 to S58 in Figure 13 are the same as steps S21 to S24 in Figure 7, so redundant explanations are omitted.

[0083] Step S59 The control unit 50 calculates the average value of two intensities for each wavelength belonging to the wavelength sweep range R0, obtained based on the detection signals D1 and D2. Thus, the control unit 50 obtains the average value of the intensities for each wavelength belonging to the wavelength sweep range R0.

[0084] As described above, according to the optical signal monitoring operation of this embodiment, the average value of the intensity measured by the wavelength selection function units 61 and 62 for each wavelength can be obtained as the observed value of the optical signal intensity. This averages out the measurement variations between the wavelength selection function units 61 and 62, allowing for more accurate monitoring of the optical signal intensity for each wavelength.

[0085] Other embodiments 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.

[0086] In the above-described embodiment, an example was given in which the wavelength sweep range R0 is divided into a short-wavelength range R1 and a long-wavelength range R2, but this is merely an example. The wavelength sweep range R0 may also be divided into two other wavelength ranges.

[0087] Furthermore, in the embodiments described above, the wavelength selection functions 61 and 62 were described as changing the transmission wavelength of the WSS from the lower limit wavelength to the upper limit wavelength, or from the upper limit wavelength to the lower limit wavelength, but the direction of wavelength change may be selected as appropriate. Also, the transmission wavelengths of the WSS may be selected in any order, such as randomly changing them within the wavelength range so that the wavelengths do not overlap.

[0088] In the embodiment described above, the transmission wavelength of the WSS was varied from the lower limit wavelength to the upper limit wavelength of the wavelength range at a constant wavelength interval of Δλ or Δλ / 2, but this is merely an example. The transmission wavelength of the WSS may be set to any multiple wavelengths within the wavelength sweep range R0.

[0089] In the embodiments described above, the control unit of the optical branching and coupling device according to this disclosure has been described mainly as a hardware configuration, but it is not limited thereto. It is also possible to realize the control unit of the optical branching and coupling device according to this disclosure by having a computer execute a computer program to perform any processing. These processing may be realized by having a computer, which includes at least one processor (e.g., a microprocessor, CPU, GPU, MPU, or DSP (Digital Signal Processor)), execute a program. Specifically, one or more programs including a set of instructions for having a computer perform algorithms related to these transmission signal processing or reception signal processing can be created and supplied to the computer.

[0090] Computer programs can be stored and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memory (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (random access memory)). Programs may also be supplied to a computer using various types of transient computer-readable media. Examples of transient computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable media can be supplied to a computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels.

[0091] The following shows an example of a computer configuration for realizing the control unit of the optical branching and coupling device according to the above-described embodiment. Figure 14 is a diagram showing an example of a computer configuration for realizing the control unit of the optical branching and coupling device. The information processing system can be realized by a computer 9000 such as a dedicated computer or a personal computer (PC). However, the computer does not need to be physically single; there may be multiple computers when performing distributed processing. As shown in Figure 14, the computer 9000 has, for example, a processor 9001, a ROM (Read Only Memory) 9002, a RAM (Random Access Memory) 9003, a storage unit 9004, a communication interface 9005, and a user interface 9006.

[0092] The processor 9001, ROM 9002, RAM 9003, memory unit 9004, communication interface 9005, and user interface 9006 are interconnected via bus 9007, enabling them to communicate with each other. While the operating system software necessary to run the computer is not described here, it will be implemented in the computer 9000 as appropriate.

[0093] ROM is composed of, for example, non-volatile semiconductor memory devices. ROM 9002 stores information such as various programs used by the computer 9000.

[0094] The storage unit 9004 is composed of various storage devices, such as hard disks and solid-state disks. Furthermore, the storage unit 9004 is not limited to storage devices installed in the computer 9000, but may also be external storage devices. External storage devices may include various communication means, such as cloud storage connected to the computer 9000 via a network. The storage unit 9004 stores information such as various programs and data used by the computer 9000.

[0095] RAM 9003 is composed of volatile semiconductor memory devices. Programs and data used by the processor 9001 are loaded into RAM 9003 as needed from either ROM 9002 or memory unit 9004, or both.

[0096] The processor 9001 may be composed of, for example, a CPU (Central Processing Unit). Alternatively, the processor 9001 may include not only a CPU but also a GPU (Graphics Processing Unit). A GPU is suitable for parallel processing of routine tasks, and by applying it to, for example, neural network processing, it is possible to improve processing speed compared to a CPU. The processor 9001 executes various processes as appropriate, based on various programs stored in the ROM 9002 or various programs and data held in the RAM 9003. The processor 9001 may also store the data generated by the processing in the RAM 9003 or the storage unit 9004 as appropriate.

[0097] The communication interface 9005 is an interface that connects the computer 9000 to a communication network such as the Internet or an intranet via various wired or wireless communication means. This allows the computer 9000 to communicate with other devices, systems, and sensors connected to the communication network.

[0098] The user interface 9006 includes, for example, a display unit that provides information so that the user can perceive it, such as through a display device, and an audio output unit that provides audio. The user interface 9006 also includes an input unit that allows the user to input information into the computer 9000 through user operation, such as a keyboard, mouse, and touch panel. Furthermore, the user interface 9006 may include devices such as sensors that acquire information useful to the user.

[0099] Here, the computer 9000 is described as a single device, but this is merely an example. The computer 9000 may consist of multiple physically separate devices. Some of these devices may be portable, while others may be stationary.

[0100] 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.

[0101] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0102] (Note 1) First and second wavelength separation means for separating optical signals of a specific wavelength from an input optical signal, A first branching means that branches a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength-separating means, A second branching means that branches the second wavelength-division multiplexed optical signal input from the second node to the first and second wavelength-separating means, A first photodetector for detecting the optical signals separated by the first wavelength separation means, A second optical detection means for detecting the optical signals separated by the second wavelength separation means, The system includes a control means for monitoring the intensity of optical signals at each wavelength within a predetermined wavelength range, based on one or both of the results of detecting the optical signals separated by the first wavelength separation means by the first photodetector and the results of detecting the optical signals separated by the second wavelength separation means by the second photodetector, while varying the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range. Optical branching and coupling device.

[0103] (Note 2) The control means monitors the intensity of each of the multiple wavelengths within the predetermined wavelength range, based on the result of detecting the optical signal separated by the first wavelength separation means, while changing the wavelength of the optical signal separated by the first wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower limit wavelength and the upper limit wavelength of the predetermined wavelength range. The optical branching and coupling device described in Appendix 1.

[0104] (Note 3) The control means changes the wavelength of the optical signal separated by the first wavelength separation means by a predetermined wavelength interval, from one of the lower limit wavelength and the upper limit wavelength of the predetermined wavelength range to the other. The optical branching and coupling device described in Appendix 2.

[0105] (Note 4) The control means is The wavelength of the optical signal to be separated by the second wavelength separation means is specified, The second wavelength separation means outputs the optical signal of the specified wavelength to a third node different from the first and second nodes. An optical branching and coupling device as described in Appendix 2 or 3.

[0106] (Note 5) The control means monitors the intensity of the optical signal at each wavelength within the predetermined wavelength range, based on the result of the second photodetector detecting the optical signal separated by the second wavelength separation means, while changing the wavelength of the optical signal separated by the second wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper wavelengths of the predetermined wavelength range. The optical branching and coupling device described in Appendix 1.

[0107] (Note 6) The control means changes the wavelength of the optical signal separated by the second wavelength separation means by a predetermined wavelength interval, from one of the lower limit wavelength and the upper limit wavelength of the predetermined wavelength range to the other. The optical branching and coupling device described in Appendix 5.

[0108] (Note 7) The control means, in the event of a failure of the first wavelength separation means or the first photodetector, monitors the intensity of the optical signals of each wavelength within the predetermined wavelength range based on the result of the second photodetector detecting the optical signals separated by the second wavelength separation means. An optical branching and coupling device as described in Appendix 5 or 6.

[0109] (Note 8) The predetermined wavelength range is divided into a first wavelength range and a second wavelength range. The control means is While varying the wavelength of the optical signal separated by the first wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper limits of the first wavelength range, the intensity of each of the plurality of wavelengths of the optical signal within the predetermined wavelength range is monitored based on the result of detecting the optical signal separated by the first wavelength separation means. While varying the wavelength of the optical signal separated by the second wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper limits of the second wavelength range, the intensity of each of the plurality of wavelengths of the optical signal within the predetermined wavelength range is monitored based on the result of detecting the optical signal separated by the second wavelength separation means. Monitoring of the optical signal in the first wavelength range and monitoring of the optical signal in the first wavelength range are performed in parallel. The optical branching and coupling device described in Appendix 1.

[0110] (Note 9) The first wavelength range is one of two wavelength ranges demarcated by a predetermined wavelength between the lower and upper wavelengths of the predetermined wavelength range. The second wavelength range is the other wavelength range of the two wavelength ranges. The optical branching and coupling device described in Appendix 8.

[0111] (Note 10) The predetermined wavelength is the midpoint wavelength between the lower limit wavelength and the upper limit wavelength of the predetermined wavelength range. The optical branching and coupling device described in Appendix 9.

[0112] (Note 11) The control means specifies the predetermined wavelength interval values ​​to the first and second wavelength separation means. The optical branching and coupling device described in Appendix 1.

[0113] (Note 12) The control means is The wavelength of the optical signal separated by the first wavelength separation means is varied among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper wavelengths of the predetermined wavelength range, and the intensity of each of the plurality of wavelengths of the optical signal within the predetermined wavelength range is monitored based on the result of detecting the optical signal separated by the first wavelength separation means. The wavelength of the optical signal separated by the second wavelength separation means is varied among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper wavelengths of the predetermined wavelength range, and the intensity of each of the plurality of wavelengths of the optical signal within the predetermined wavelength range is monitored based on the result of detecting the optical signal separated by the second wavelength separation means. The average of the monitoring results of the intensity of the optical signal at each wavelength separated by the first wavelength separation means and the monitoring results of the intensity of the optical signal at each wavelength separated by the second wavelength separation means is calculated as the intensity of the optical signal at each wavelength. The optical branching and coupling device described in Appendix 1.

[0114] (Note 13) First and second wavelength separation means for separating optical signals of a specific wavelength from an input optical signal, A first branching means that branches a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength-separating means, A second branching means that branches the second wavelength-division multiplexed optical signal input from the second node to the first and second wavelength-separating means, A first photodetector for detecting the optical signals separated by the first wavelength separation means, An optical branching and coupling device having a second optical detection means for detecting the optical signals separated by the second wavelength separation means, The wavelengths separated by the first and second wavelength separation means are changed at predetermined wavelength intervals within a predetermined wavelength range. Based on either or both of the results of detecting the optical signals separated by the first wavelength separation means using the first photodetector and the results of detecting the optical signals separated by the second wavelength separation means using the second photodetector, the intensity of the optical signals of each wavelength within the predetermined wavelength range is monitored. A method for monitoring optical signals.

[0115] (Note 14) First and second wavelength separation means for separating optical signals of a specific wavelength from an input optical signal, A first branching means that branches a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength-separating means, A second branching means that branches the second wavelength-division multiplexed optical signal input from the second node to the first and second wavelength-separating means, A first photodetector for detecting the optical signals separated by the first wavelength separation means, A computer that controls the operation of an optical branching and coupling device having a second optical detection means for detecting the optical signals separated by the second wavelength separation means, A process of changing the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range, Based on either or both of the results of detecting the optical signals separated by the first wavelength separation means using the first photodetector and the results of detecting the optical signals separated by the second wavelength separation means using the second photodetector, the system performs a process of monitoring the intensity of optical signals of each wavelength within the predetermined wavelength range. program. [Explanation of Symbols]

[0116] 1 A terminal 2 B terminal station 3 C terminal 11-13 Optical switch 21-26 Couplers 31, 32 WSS 41, 42 Light detection unit 50 Control Unit 61, 62 Wavelength selection function section 100 Optical branching and coupling device 1000 Optical Communication Networks 1010 Optical transmission path 1020 Optical transmission path 9000 Computers 9001 Processor 9002 ROM 9003 RAM 9004 Storage section 9005 Communication Interface 9006 User Interface 9007 Bus C1, C2 control signals D1, D2 detection signals R0 Wavelength sweep range R1 Short wavelength range R2 Long wavelength range

Claims

1. First and second wavelength separation means for separating optical signals of a specific wavelength from an input optical signal, A first branching means that branches a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength-separating means, A second branching means that branches the second wavelength-division multiplexed optical signal input from the second node to the first and second wavelength-separating means, The first wavelength separation means detects the optical signals separated by the first optical detection means, The second wavelength separation means detects the optical signals separated by the second wavelength separation means, The system includes a control means for monitoring the intensity of optical signals at each wavelength within a predetermined wavelength range, based on either or both of the results of detecting the optical signals separated by the first wavelength separation means by the first photodetector and the results of detecting the optical signals separated by the second wavelength separation means by the second photodetector, while changing the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range. Optical branching and coupling device.

2. The control means monitors the intensity of each of the multiple wavelengths of the optical signal within the predetermined wavelength range, based on the result of detecting the optical signal separated by the first wavelength separation means, while changing the wavelength of the optical signal separated by the first wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower limit wavelength and the upper limit wavelength of the predetermined wavelength range. The optical branching and coupling device according to claim 1.

3. The control means changes the wavelength of the optical signal separated by the first wavelength separation means by a predetermined wavelength interval, from one of the lower limit wavelength and the upper limit wavelength of the predetermined wavelength range to the other. The optical branching and coupling device according to claim 2.

4. The control means is The wavelength of the optical signal to be separated by the second wavelength separation means is specified, The second wavelength separation means outputs the optical signal of the specified wavelength to a third node different from the first and second nodes. The optical branching and coupling device according to claim 2 or 3.

5. The control means monitors the intensity of the optical signal at each wavelength within the predetermined wavelength range, based on the result of the second photodetector detecting the optical signal separated by the second wavelength separation means, while changing the wavelength of the optical signal separated by the second wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper wavelengths of the predetermined wavelength range. The optical branching and coupling device according to claim 1.

6. The control means changes the wavelength of the optical signal separated by the second wavelength separation means by a predetermined wavelength interval, from one of the lower limit wavelength and the upper limit wavelength of the predetermined wavelength range to the other. The optical branching and coupling device according to claim 5.

7. The control means, in the event of a failure of the first wavelength separation means or the first photodetection means, monitors the intensity of the optical signals of each wavelength within the predetermined wavelength range based on the result of the second photodetection means detecting the optical signals separated by the second wavelength separation means. The optical branching and coupling device according to claim 5 or 6.

8. The predetermined wavelength range is divided into a first wavelength range and a second wavelength range. The control means is While varying the wavelength of the optical signal separated by the first wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper limits of the first wavelength range, the intensity of each of the plurality of wavelengths of the optical signal within the predetermined wavelength range is monitored based on the result of detecting the optical signal separated by the first wavelength separation means. While varying the wavelength of the optical signal separated by the second wavelength separation means among a plurality of wavelengths that differ by a predetermined wavelength interval between the lower and upper limits of the second wavelength range, the intensity of each of the plurality of wavelengths of the optical signal within the predetermined wavelength range is monitored based on the result of detecting the optical signal separated by the second wavelength separation means. Monitoring of the optical signal in the first wavelength range and monitoring of the optical signal in the first wavelength range are performed in parallel. The optical branching and coupling device according to claim 1.

9. First and second wavelength separation means for separating optical signals of a specific wavelength from an input optical signal, A first branching means that branches a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength-separating means, A second branching means that branches the second wavelength-division multiplexed optical signal input from the second node to the first and second wavelength-separating means, The first wavelength separation means detects the optical signals separated by the first optical detection means, An optical branching and coupling device having a second optical detection means for detecting the optical signals separated by the second wavelength separation means, The wavelengths separated by the first and second wavelength separation means are changed at predetermined wavelength intervals within a predetermined wavelength range. Based on either or both of the results of detecting the optical signals separated by the first wavelength separation means using the first photodetector and the results of detecting the optical signals separated by the second wavelength separation means using the second photodetector, the intensity of the optical signals of each wavelength within the predetermined wavelength range is monitored. A method for monitoring optical signals.

10. First and second wavelength separation means for separating optical signals of a specific wavelength from an input optical signal, A first branching means that branches a first wavelength-division multiplexed optical signal input from a first node to the first and second wavelength-separating means, A second branching means that branches the second wavelength-division multiplexed optical signal input from the second node to the first and second wavelength-separating means, The first wavelength separation means detects the optical signals separated by the first optical detection means, A computer that controls the operation of an optical branching and coupling device having a second optical detection means for detecting the optical signals separated by the second wavelength separation means, A process to change the wavelengths separated by the first and second wavelength separation means at predetermined wavelength intervals within a predetermined wavelength range, Based on either or both of the results of detecting the optical signals separated by the first wavelength separation means using the first photodetector and the results of detecting the optical signals separated by the second wavelength separation means using the second photodetector, the system performs a process of monitoring the intensity of optical signals of each wavelength within the predetermined wavelength range. program.

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