Optical branching device, optical submarine cable system, optical branching device method, and optical branching device program

Abstract

To provide an optical branching device, an optical submarine cable system, a method for optical branching, and a program for optical branching that can detect breakage of optical fibers connecting devices and activate a trunk protection function. [Solution] The optical branching device according to the present disclosure comprises an optical switch that outputs an optical signal input to an input terminal to an optical coupler or an output terminal, an optical coupler that outputs the optical signal output from the optical switch to a branching output terminal, and a photodetector that detects external scattered light input to the branching output terminal via the optical coupler, wherein the optical switch outputs the optical signal input to the input terminal to the output terminal and does not output the optical signal input to the input terminal to the optical coupler if the light intensity of the scattered light detected by the photodetector is equal to or greater than a predetermined light threshold.

Description

【Technical Field】 【0001】 The present disclosure relates to an optical branching device, an optical submarine cable system, a method for an optical branching device, and a program for an optical branching device, and particularly relates to an optical branching device, an optical submarine cable system, a method for an optical branching device, and a program that can detect a break in an optical fiber connecting devices and operate a trunk protection function. 【Background Art】 【0002】 In recent years, in an optical submarine cable system, in order to protect traffic when an optical fiber is broken, a branching device having a function (trunk protection function) of switching an optical path using an optical switch has been developed. However, in a type that operates the trunk protection function by detecting an input optical signal or a power supply current, there is a problem that when an optical fiber is broken, the break in the optical fiber cannot be detected and the trunk protection function does not operate. 【0003】 Patent Document 1 discloses an "optical branching and insertion device including a trunk-side detection and branching means that detects a failure of a trunk-side optical signal input from the trunk side and outputs it as a first detection result, and branches and transmits the trunk-side optical signal to the trunk side and the branch side; a branch-side detection means that detects a failure of a branch-side optical signal inserted from the branch side and outputs it as a second detection result, and transmits the branch-side optical signal as an insertion signal; an insertion signal adjustment means that outputs an insertion signal with an adjusted transmittance as a first adjustment signal based on the first detection result; a trunk signal adjustment means that outputs a trunk-side optical signal with an adjusted transmittance as a second adjustment signal based on the second detection result; and a multiplexing output means that outputs an optical signal obtained by multiplexing the first adjustment signal and the second adjustment signal as a trunk-side output optical signal to the outside." Patent Document 1 does not disclose an optical branching device that can detect backward scattered light due to a break in an optical fiber and operate a trunk protection function. 【0004】 Patent Document 2 discloses that "C1 station transmits a monitoring signal to the first optical fiber, the second optical multiplexer / demultiplexer passes the monitoring signal transmitted within the first optical fiber through it, the third optical multiplexer / demultiplexer passes the monitoring signal passed by the second optical multiplexer / demultiplexer through it to the second optical fiber, the optical loopback circuit transmits the monitoring signal transmitted within the second optical fiber to the second optical fiber, the fourth optical multiplexer / demultiplexer passes the monitoring signal transmitted within the first optical fiber through it, the first optical multiplexer / demultiplexer passes the monitoring signal passed by the fourth optical multiplexer / demultiplexer through it to the second optical fiber, and C1 station receives the monitoring signal transmitted within the second optical fiber." Patent Document 2 does not disclose an optical branching device capable of detecting backscattered light due to optical fiber breakage and activating a trunk protection function. 【0005】 Patent Document 3 discloses that "a trunk station is connected to a branch station via a pair of optical fiber lines, and the branch station is connected to another branch station via a pair of optical fiber lines. At the branch station, a first wavelength separation element wavelength-separates the transmitted light on the upstream line from the trunk station, a first add / drop element drops the optical signal to the branch station and adds the optical signal to be transmitted, and a first wavelength multiplexing element wavelength-multiplexes the signal light from the first add / drop element with the light of each wavelength separated by the first wavelength separation element at other wavelengths and outputs it to the upstream line. The second wavelength separation element, the second add / drop element, and the second wavelength multiplexing element operate similarly on the downstream line." Patent Document 3 does not disclose an optical branching device capable of detecting backscattered light due to optical fiber breakage and activating the trunk protection function. 【0006】 Patent Document 4 discloses a branching device inserted into a transmission line and power supply line connecting a first trunk station, a second trunk station, and a branch station, comprising: a current detection means for detecting when the current flowing through the power supply line between the branch station and the branch unit has ceased; and a switching means for controlling a switch to connect the transmission line between either the first trunk station or the second trunk station and the branch station when the first optical signal detection means detects an optical signal in the transmission line connecting the branch station and the branch unit. In other words, Patent Document 4 discloses a branching device that can protect traffic even if the transmission line (optical fiber) breaks. Patent Document 4 does not disclose an optical branching device capable of detecting backscattered light due to optical fiber breakage and activating the trunk protection function. [Prior art documents] [Patent Documents] 【0007】 [Patent Document 1] International Publication No. 2014 / 115517 [Patent Document 2] Japanese Patent Publication No. 2010-11021 [Patent Document 3] Japanese Patent Application Publication No. 10-256995 [Patent Document 4] Patent No. 7283543 [Patent Document 5] Japanese Patent Publication No. 2002-280968 [Overview of the project] [Problems that the invention aims to solve] 【0008】 As mentioned above, in types of trunk protection systems that operate by detecting input light or power supply current, there was a problem in that when the optical fiber broke, the breakage of the optical fiber could not be detected, and the trunk protection function would not operate. 【0009】 The purpose of this disclosure is to provide an optical branching device, an optical submarine cable system, a method for an optical branching device, and a program for an optical branching device that can detect breakage of optical fibers connecting devices and activate a trunk protection function, in order to solve the above-mentioned problems. [Means for solving the problem] 【0010】 The optical branching device relating to this disclosure is An optical switch that outputs an optical signal input to an input terminal to an optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to a branch output terminal, A photodetector that detects external scattered light input to the branch output terminal via the optical coupler, Equipped with, The optical switch outputs the optical signal input to the input terminal to the output terminal, and does not output the optical signal input to the input terminal to the optical coupler, when the light intensity of the scattered light detected by the photodetector is equal to or greater than a predetermined light threshold. 【0011】 The optical submarine cable system related to this disclosure is The system comprises an optical branching device, a first optical repeater connected to the optical branching device, and a second optical repeater connected to the first optical repeater. The aforementioned optical branching device, A first optical switch that outputs a first optical signal input to a first input terminal to a first optical coupler or a first output terminal, The first optical coupler outputs the first optical signal output from the first optical switch to a branch output terminal, A first photodetector detects external scattered light input to the branch output terminal via the first optical coupler, The first optical signal output from the branch output terminal is relayed back by the second optical repeater via the first optical repeater and input to the branch input terminal of the device via the first optical repeater, and the second optical coupler outputs the first optical signal input to the branch input terminal to the second optical switch, A second optical switch that outputs the first optical signal output from the second optical coupler or the second optical signal input from the second input terminal to the second output terminal, The system includes a second photodetector that detects a first optical signal input to the branch input terminal via the second optical coupler and an optical filter, The first optical switch outputs the first optical signal input to the first input terminal to the first output terminal when the light intensity detected by the first photodetector is equal to or greater than a predetermined optical threshold, and does not output the first optical signal input to the first input terminal to the first optical coupler. The second optical switch outputs the second optical signal input to the second input terminal to the second output terminal if the light intensity of the monitoring light signal included in the first optical signal detected by the second photodetector is less than a predetermined monitoring light threshold, and does not output the first optical signal output from the second optical coupler to the second output terminal. The first optical repeater is, A first optical repeater amplifier that outputs the first optical signal output from the branch output terminal to the second optical repeater, The second optical repeater has a second optical repeater amplifier that outputs the first optical signal folded back by the second optical repeater to the branch input terminal, The second optical repeater is, The system includes a monitoring optical folding circuit that folds back the first optical signal input from the first optical repeater and outputs it back to the first optical repeater. 【0012】 The method for the optical branching device relating to this disclosure is: The optical switch outputs the optical signal input to the input terminal to the optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to the branch output terminal, The photodetector detects the external scattered light input to the branch output terminal via the optical coupler, The optical switch outputs the optical signal input to the input terminal to the output terminal when the light intensity detected by the photodetector is equal to or greater than a predetermined light threshold. It is equipped with. 【0013】 The program of the optical branching device according to the present disclosure causes the optical switch to output an optical signal input to the input terminal to an optical coupler or an output terminal, the optical coupler to output the optical signal output from the optical switch to a branched output terminal, the photodetector to detect external scattered light input to the branched output terminal via the optical coupler, and the optical switch to output the optical signal input to the input terminal to the output terminal when the light intensity detected by the photodetector is equal to or greater than a predetermined optical threshold value, to be executed by a computer. 【Advantages of the Invention】 【0014】 According to the present disclosure, it is possible to provide an optical branching device, an optical submarine cable system, a method of an optical branching device, and a program of an optical branching device that can detect a break in an optical fiber connecting devices and operate a trunk protection function. 【Brief Description of the Drawings】 【0015】 [Figure 1] It is a block diagram illustrating an optical branching device according to the present disclosure. [Figure 2] It is a block diagram illustrating an optical branching device according to the present disclosure. [Figure 3] It is a block diagram illustrating an optical submarine cable system according to the present disclosure. [Figure 4] It is a block diagram illustrating a monitoring optical feedback circuit according to the present disclosure. [Figure 5] It is a block diagram illustrating the operation of an optical submarine cable system according to the present disclosure. [Figure 6] It is a block diagram illustrating the operation of an optical submarine cable system according to the present disclosure. [Figure 7] It is a block diagram illustrating the hardware configuration of an optical submarine cable system according to the present disclosure. [Modes for carrying out the invention] 【0016】 Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations will be omitted as necessary for clarity of the description. 【0017】 [Embodiment 1] <Device configuration> The following describes an example configuration of an optical branching device using Figures 1 and 2. Figure 1 is a block diagram illustrating an optical branching device according to this disclosure. 【0018】 As shown in Figure 1, the optical branching device 11 according to this disclosure comprises an optical switch 111, an optical coupler 112, and a photodetector 113. 【0019】 The optical switch 111 outputs the optical signal input to the input terminal to the optical coupler 112 or to the output terminal. 【0020】 The optical coupler 112 outputs the optical signal output from the optical switch 111 to the branch output terminal. 【0021】 The photodetector 113 detects external scattered light input to the branch output terminal via an optical coupler. When a break occurs in the optical fiber between the optical branching device 11 and the first optical repeater 12a, the optical signal is scattered backward from the break (in the opposite direction of propagation), generating "backscattered light." That is, comparing before and after the break in the optical fiber, the amount of backscattered light increases after the break. The backscattered light generated by the break in the optical fiber is input to the branch output terminal of the optical branching device 11 from an external point of origin. The optical coupler 112 outputs the optical signal input to the branch output terminal to the photodetector 113. The photodetector 113 monitors (detects) the backscattered light input to the branch output terminal via the optical coupler 112. The photodetector 113 includes a photodiode. Note that optical fibers are sometimes referred to as optical cables. 【0022】 The optical switch 111 determines that the optical fiber connected to the branch output terminal has broken if the light intensity detected by the photodetector 113 is above a predetermined light threshold. 【0023】 The optical switch 111 outputs the optical signal input to the input terminal to the output terminal and does not output the optical signal input to the input terminal to the optical coupler 112 when the light intensity of the scattered light (backscattered light) detected by the photodetector 113 is above a predetermined light threshold. In this way, when the light intensity of the backscattered light is above a predetermined light threshold, the optical switch 111 can be set to the trunk side (output terminal side), thereby maintaining traffic on the trunk side. Note that the "photodetector" may also be referred to as the "light receiving unit" or "light detection circuit". 【0024】 <Effects> In this embodiment, the trunk protection function is not activated by detecting input light or power supply current. In this embodiment, the first photodetector 113 detects an increase in the light intensity of backscattered light and determines that the optical fiber between the optical branching device 11 and the first optical repeater 12a has broken. As a result, the trunk protection function is activated. That is, the backscattered light generated when the optical fiber connecting the optical branching device 11 and the first optical repeater 12a breaks is detected, and the trunk protection function is activated. As a result, it is possible to provide an optical branching device, an optical submarine cable system, an optical branching device method, and an optical branching device program that can detect the breakage of optical fibers connecting devices and activate the trunk protection function. 【0025】 In this embodiment, the optical switch 111 is switched when the photodetector 113 detects backscattered light, so the switching time can be shortened compared to, for example, the case where the photodetector is located on the terminal (trunk) side. 【0026】 Figure 2 is a block diagram illustrating an optical branching device according to this disclosure. Figure 2 differs from Figure 1 in that terminal numbers have been added to the optical switch and terminal names have been added to the optical coupler. 【0027】 As shown in Figure 2, the first terminal of the optical switch 111 is connected to the input terminal of the optical splitter 11. The second terminal of the optical switch 111 is connected to the output terminal of the optical splitter 11. The third terminal of the optical switch 111 is connected to the input terminal of the optical coupler 112. The output terminal of the optical coupler 112 is connected to the branch output terminal of the optical splitter 11. The monitor terminal of the optical coupler 112 is connected to the photodetector 113. 【0028】 When the optical fiber breaks and scattered light is generated, and the light intensity of the scattered light detected by the photodetector 113 is above a predetermined light threshold, the optical switch 111 connects the first terminal of the optical switch 111 to the second terminal of the optical switch 111, but does not connect the first terminal of the optical switch 111 to the third terminal of the optical switch 111. 【0029】 If the optical fiber is not broken and no scattered light is generated, and the light intensity of the scattered light detected by the photodetector 113 is below a predetermined light threshold, the optical switch 111 connects its first terminal to its third terminal, but does not connect its first terminal to its second terminal. 【0030】 This operation ensures that the trunk protection function works correctly and protects traffic in the event of a fiber optic cable break. 【0031】 [Embodiment 2] <System Configuration> The following describes an example configuration of a submarine optical cable system using Figure 3. Figure 3 is a block diagram illustrating an example of a submarine optical cable system according to this disclosure. Figure 4 is a block diagram illustrating an example of a monitoring light folding circuit according to this disclosure. The monitoring light folding circuit shown in Figure 4 is the circuit described in Patent Document 5. In the embodiment, the monitoring light folding circuit is not limited to this. 【0032】 As shown in Figure 3, the optical submarine cable system 10 according to this disclosure comprises an optical branching device 11, a first optical repeater 12a connected to the optical branching device 11, and a second optical repeater 12b connected to the first optical repeater 12a. The optical submarine cable system 10 also comprises an end station A connected to the first input terminal and the second output terminal of the optical branching device 11 via an optical repeater. The optical submarine cable system 10 also comprises an end station B connected to the second input terminal and the first output terminal of the optical branching device 11 via an optical repeater. The optical submarine cable system 10 also comprises an end station C connected to the second optical repeater 12b. 【0033】 The first optical signal output from terminal A is input to the first input terminal of the optical branching device 11 via an optical repeater. The first optical signal output from the first output terminal of the optical branching device 11 is input to terminal B via an optical repeater. The first optical signal output from the branch output terminal of the optical branching device 11 is input to terminal C via the first optical repeater 12a and the second optical repeater 12b. The flow of the second optical signal shown in Figure 3 is in the opposite direction to the flow of the first optical signal, and its explanation is omitted. 【0034】 The optical branching device 11 includes a first optical switch 111, a first optical coupler 112, a first photodetector 113, a second optical switch 114, a second optical coupler 115, an optical filter 116, and a second photodetector 117. 【0035】 The first optical switch 111 outputs the first optical signal input to the first input terminal of the optical branching device 11 to the first optical coupler 112 or the first output terminal of the optical branching device 11. 【0036】 The first optical coupler 112 outputs the first optical signal output from the first optical switch 111 to the branch output terminal. 【0037】 The first photodetector 113 detects the external scattered light input to the branch output terminal via the first optical coupler 112. Regarding "backscattered light" due to the break of the optical fiber between the optical branching device 11 and the first optical repeater 12a, please refer to Figure 1, and the explanation is omitted here. "Backscattered light" is also omitted in Figure 3. 【0038】 The first optical signal output from the branch output terminal of the optical branching device 11 is folded back by the second optical repeater 12b via the first optical repeater 12a. The folded first optical signal is input to the branch input terminal of the optical branching device 11 via the first optical repeater 12a. The second optical coupler 115 outputs the first optical signal input to the branch input terminal of the optical branching device 11 to the second optical switch 114. 【0039】 The second optical switch 114 outputs the first optical signal output from the second optical coupler 115 or the second optical signal input from the second input terminal of the optical branching device 11 to the second output terminal of the optical branching device 11. 【0040】 The second photodetector 117 detects the first optical signal input to the branch input terminal of the optical branching device 11 via the second optical coupler 115 and the optical filter 116. 【0041】 If the light intensity detected by the first photodetector 113 is above a predetermined light threshold, the first optical switch 111 outputs the first optical signal input to the first input terminal of the optical branching device 11 to the first output terminal of the optical branching device 11, but does not output the first optical signal input to the first input terminal to the first optical coupler 112. In other words, if the light intensity detected by the first photodetector 113 is above a predetermined light threshold, the first optical switch 111 connects the first terminal and the second terminal, but does not connect the first terminal and the third terminal of the first optical switch 111. 【0042】 If the light intensity detected by the first photodetector 113 is less than a predetermined light threshold, the first optical switch 111 outputs the first optical signal input to the first input terminal of the optical splitter 11 to the first optical coupler 112, but does not output the first optical signal input to the first input terminal of the optical splitter 11 to the first output terminal of the optical splitter 11. In other words, if the light intensity detected by the first photodetector 113 is less than a predetermined light threshold, the first optical switch 111 connects the first terminal and the third terminal, but does not connect the first terminal and the second terminal. 【0043】 If the light intensity of the monitoring light signal included in the first optical signal detected by the second photodetector 117 is less than a predetermined monitoring light threshold, the second optical switch 114 outputs the second optical signal input to the second input terminal of the optical branching device 11 to the second output terminal of the optical branching device 11, but does not output the first optical signal output from the second optical coupler to the second output terminal of the optical branching device 11. In other words, if the light intensity of the monitoring light signal detected by the second photodetector 117 is less than a predetermined monitoring light threshold, the second optical switch 114 connects its first terminal to its second terminal, but does not connect its first terminal to its third terminal. 【0044】 If the light intensity of the monitoring light signal included in the first optical signal detected by the second photodetector 117 is above a predetermined monitoring light threshold, the second optical switch 114 does not output the second optical signal input to the second input terminal of the optical branching device 11 to the second output terminal of the optical branching device 11, but instead outputs the first optical signal output from the second optical coupler to the second output terminal of the optical branching device 11. In other words, if the light intensity of the monitoring light signal detected by the second photodetector 117 is above a predetermined monitoring light threshold, the second optical switch 114 connects its first terminal to its third terminal, but does not connect its first terminal to its second terminal. 【0045】 The first optical repeater 12a includes a first optical repeater amplifier 12a1 and a second optical repeater amplifier 12a2. The first optical repeater amplifier 12a1 outputs the first optical signal output from the branch output terminal of the optical branching device 11 to the second optical repeater 12b. 【0046】 The second optical repeater amplifier 12a2 outputs the first optical signal, which has been folded back by the second optical repeater 12b, to the branch input terminal of the optical branching device 11. 【0047】 The second optical repeater 12b has a monitoring optical folding circuit 12b3 that folds back the first optical signal input from the first optical repeater 12a and outputs it to the first optical repeater 12a. In Figure 3, the side of terminal A and / or terminal B as seen from the optical branching device 11 is referred to as the trunk side, and the side of the first repeater 12 is referred to as the branch side. 【0048】 The following describes an example of the configuration of a monitoring light folding circuit using Figure 4. As shown in Figure 4, the monitoring optical folding circuit 12b3 includes an optical amplifier 2a, an optical coupler 3a, a fixed attenuator 7, and an optical coupler 3b, etc. The first optical signal input from the first input of the second optical repeater 12b is amplified by the optical amplifier 2a, partially branched by the optical coupler 3a, the optical intensity is adjusted by the fixed attenuator 7, and output from the second output of the second optical repeater 12b via the optical coupler 3b. 【0049】 <System Operation> The operation of a fiber optic submarine cable system will be explained below using Figures 5 and 6. Figure 5 is a block diagram illustrating the operation of the optical submarine cable system according to this disclosure. Figure 5 shows the operation of the optical submarine cable system during normal operation. Figure 6 is a block diagram illustrating the operation of the optical submarine cable system according to this disclosure. Figure 6 shows the operation of the optical submarine cable system when a break in the optical fiber is detected. 【0050】 First, let's explain the operation when no fiber optic cable break has been detected. As shown in Figure 5, the first optical coupler 112 outputs the first optical signal output from the first optical switch 111 (when terminals 1 and 3 of the first optical switch 111 are connected) to the branch output terminal of the optical branching device 11. The first optical signal is output to the outside of the optical branching device 11. The first photodetector 113 detects the external scattered light input to the branch output terminal of the optical branching device 11 via the first optical coupler 112. 【0051】 The first optical switch 111 determines that the optical fiber connected to the branch output terminal of the optical branching device 11 has broken if the light intensity detected by the first photodetector 113 is above a predetermined light threshold. 【0052】 If the light intensity detected by the first photodetector 113 is greater than or equal to a predetermined light threshold, the first optical switch 111 outputs the first optical signal input to the first input terminal of the optical branching device 11 to the first output terminal of the optical branching device 11, but does not output the first optical signal input to the first input terminal to the first optical coupler 112. 【0053】 The first optical signal output from the first optical coupler 112 of the optical branching device 11 via the branch output terminal is input to the first optical repeater 12a. At this time, the first optical signal includes a first main signal λa and a monitoring optical signal λb. The first main signal λa is a bundle containing optical signals of multiple wavelengths, and data is transmitted by the first main signal. In this embodiment, the monitoring optical signal λb is used to detect breakage of the optical fiber. 【0054】 The first optical signal (first main signal λa and monitoring optical signal λb) output from the first optical repeater 12a is input to the second optical repeater 12b. The monitoring optical folding circuit 12b3 of the second optical repeater 12b folds back a portion of the first optical signal input from the first optical repeater 12a and outputs it back to the first optical repeater 12a. The first optical signal folded back by the monitoring optical folding circuit 12b3 is input to the branch input terminal of the optical branching device 11 via the first optical repeater 12a. 【0055】 The first optical signal input to the branch input terminal of the optical branching device 11 is input to the optical filter 116 via the second optical coupler 115. The optical filter 116, through its filtering function, allows only the monitoring optical signal λb of the first main signal λa to pass through, while blocking the first main signal λa. The monitoring optical signal λb that has passed through the optical filter 116 is input to the second photodetector 117. The second photodetector 117 detects the monitoring optical signal λb. 【0056】 The second optical switch 114 determines that the optical fiber connecting the first optical repeater 12a and the second optical repeater 12b is not broken if the light intensity of the monitoring optical signal λb included in the first optical signal input to the branch input terminal of the optical branching device 11 is equal to or greater than a predetermined monitoring optical threshold. 【0057】 The second optical switch 114 outputs the first optical signal output from the second optical coupler 115 to the second output terminal of the optical branching device 11 if the light intensity of the monitoring light signal λb included in the first optical signal input to the branch input terminal of the optical branching device 11 is equal to or greater than a predetermined monitoring light threshold, and does not output the second optical signal input to the second input terminal of the optical branching device 11 to the second output terminal of the optical branching device 11. 【0058】 Next, we will explain the operation when a break in the optical fiber is detected. As shown in Figure 6, if a break occurs in the optical fiber between the first optical repeater 12a and the second optical repeater 12b, the monitoring optical signal λb folded back by the monitoring optical folding circuit 12b3 of the second optical repeater 12b is interrupted, and the light intensity of the monitoring optical signal λb decreases. The second photodetector 117 detects the light intensity of the monitoring optical signal λb included in the first optical signal. Therefore, by checking the change in the light intensity of the folded monitoring optical signal λb, the break in the optical fiber can be detected and the second optical switch 114 can be switched. 【0059】 The second optical switch 114 determines that the optical fiber connecting the first optical repeater 12a and the second optical repeater 12b has broken if the light intensity of the monitoring optical signal λb included in the first optical signal input to the branch input terminal of the optical branching device 11 is less than a predetermined monitoring optical threshold. 【0060】 The second optical switch 114 outputs the second optical signal input to the second input terminal of the optical branching device 11 to the second output terminal of the optical branching device 11 when the light intensity of the monitoring light signal λb detected by the second photodetector 117 is less than a predetermined monitoring light threshold, and does not output the first optical signal output from the second optical coupler 115 to the second output terminal of the optical branching device 11. 【0061】 <Effects> In this embodiment, the second photodetector 117 detects a decrease in the light intensity of the monitoring light signal λb and determines that the optical fiber between the first optical repeater 12a and the second optical repeater 12b has broken. This then activates the trunk protection function. As a result, it is possible to provide an optical branching device, an optical submarine cable system, a method for an optical branching device, and a program for an optical branching device that can detect a decrease in light intensity due to optical fiber breakage and activate the trunk protection function. 【0062】 Therefore, it is possible to provide an optical branching device, an optical submarine cable system, an optical branching device method, and an optical branching device program that can detect optical fiber breakage occurring between the optical branching device 11 and the first optical repeater 12a, and / or between the first optical repeater 12a and the second optical repeater 12b, and activate the trunk protection function. 【0063】 This disclosure uses a (2-input, 2-output, and 1-branch input, 1-branch output) configuration as an example (see Figures 3, 5, and 6). However, this disclosure is not limited to this configuration. This disclosure can also be applied to configurations such as (2-input, 2-output, and 2-branch input, 2-branch output). 【0064】 <Hardware Configuration> The hardware configuration of the optical submarine cable system will be explained below using Figure 7. Figure 7 is a block diagram illustrating the hardware configuration of the optical submarine cable system described herein. 【0065】 As shown in Figure 7, the optical branching device 11 may include a processor 11p and a memory 11m in addition to the first optical switch 111, the first optical coupler 112, the first photodetector 113, the second optical switch 114, the second optical coupler 115, the optical filter 116, and the second photodetector 117. The memory 11m stores control instructions related to the optical branching device 11, and the processor 11p executes these control instructions. The control instructions related to the optical branching device 11 are control instructions for the first optical switch 111, the first optical coupler 112, the first photodetector 113, the second optical switch 114, the second optical coupler 115, the optical filter 116, and the second photodetector 117. 【0066】 The processor 11p reads control instructions for the optical branching device 11 stored in memory 11m and executes these control instructions on the optical switch 111, the first optical coupler 112, the first photodetector 113, the second optical switch 114, the second optical coupler 115, the optical filter 116, and the second photodetector 117. 【0067】 The first optical repeater 12a may include a processor 12ap and a memory 12am in addition to the first optical repeater amplifier 12a1 and the second optical repeater amplifier 12a2. The memory 12am stores control instructions related to the first optical repeater 12a, and the processor 12ap executes these control instructions. The control instructions related to the first optical repeater 12a are control instructions for the first optical repeater amplifier 12a1 and the second optical repeater amplifier 12a2. 【0068】 The processor 12ap reads a control instruction for the first optical repeater 12a stored in memory 12am and executes the control instruction on the first optical repeater amplifier 12a1 and the second optical repeater amplifier 12a2. 【0069】 The second optical repeater 12b may include a processor 12bp and a memory 12bm in addition to the first optical repeater amplifier 12b1, the second optical repeater amplifier 12b2, and the monitoring optical loopback circuit 12b3. The memory 12bm stores control instructions related to the second optical repeater 12b, and the processor 12bp executes these control instructions. The control instructions related to the second optical repeater 12b are control instructions for the first optical repeater amplifier 12b1, the second optical repeater amplifier 12b2, and the monitoring optical loopback circuit 12b3. 【0070】 The processor 12bp reads a control instruction for the second optical repeater 12b stored in memory 12bm and executes the control instruction on the first optical repeater amplifier 12b1, the second optical repeater amplifier 12b2, and the monitoring optical loopback circuit 12b3. 【0071】 Although the above embodiments describe the present disclosure as a hardware configuration, the present disclosure is not limited thereto. The present disclosure can also be implemented by having a CPU (Central Processing Unit) execute a computer program to process each component. 【0072】 In the above embodiment, the program can be stored and supplied to the computer using various types of non-transitory computer-readable medium. Non-transitory computer-readable mediums include various types of tangible storage mediums. Examples of non-transitory computer-readable mediums include magnetic recording media (specifically flexible disks, magnetic tapes, and hard disk drives), magneto-optical recording media (specifically magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, semiconductor memory (specifically mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs)), flash ROMs, and RAMs (Random Access Memory). Alternatively, the program may be supplied to the computer using various types of transient computer-readable mediums. Examples of transient computer-readable mediums include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable mediums can supply the program to the computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels. 【0073】 Furthermore, although the operations are described in a specific order, this should not be understood as requiring that such operations be performed in a specific or sequential order shown, or that all shown operations be performed, in order to achieve the desired result. In certain situations, multitasking and parallel processing may be advantageous. Similarly, while details of several specific embodiments are included in the above discussion, these should be interpreted not as limitations on the scope of this disclosure, but as descriptions of features specific to those embodiments. Certain features described in the context of a separate embodiment may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may be implemented separately or in any suitable combination in multiple embodiments. 【0074】 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. 【0075】 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. 【0076】 Furthermore, this disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. 【0077】 Some or all of the above embodiments may also be described as follows, but are not limited to the following: (Note 1) An optical switch that outputs an optical signal input to an input terminal to an optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to a branch output terminal, A photodetector that detects external scattered light input to the branch output terminal via the optical coupler, Equipped with, The optical switch outputs the optical signal input to the input terminal to the output terminal and does not output the optical signal input to the input terminal to the optical coupler when the light intensity of the scattered light detected by the photodetector is equal to or greater than a predetermined light threshold. Optical branching device. (Note 2) The aforementioned photodetector includes a photodiode, The optical branching device described in Appendix 1. (Note 3) The optical switch determines that the optical fiber connected to the branch output terminal has broken if the light intensity detected by the photodetector is equal to or greater than the predetermined light threshold. The optical branching device described in Appendix 1. (Note 4) The first terminal of the optical switch is connected to the input terminal of the device, The second terminal of the optical switch is connected to the output terminal of the device. The third terminal of the optical switch is connected to the input terminal of the optical coupler. The output terminal of the optical coupler is connected to the branch output terminal of the device, The monitor terminal of the optical coupler is connected to the photodetector. The optical switch connects its first terminal to its second terminal and does not connect its first terminal to its third terminal when the light intensity of the scattered light detected by the photodetector is equal to or greater than the predetermined light threshold. The optical branching device described in Appendix 1. (Note 5) The system comprises an optical branching device, a first optical repeater connected to the optical branching device, and a second optical repeater connected to the first optical repeater. The aforementioned optical branching device, A first optical switch that outputs a first optical signal input to a first input terminal to a first optical coupler or a first output terminal, The first optical coupler outputs the first optical signal output from the first optical switch to a branch output terminal, A first photodetector detects external scattered light input to the branch output terminal via the first optical coupler, The first optical signal output from the branch output terminal is relayed back by the second optical repeater via the first optical repeater and input to the branch input terminal of the device via the first optical repeater, and the second optical coupler outputs the first optical signal input to the branch input terminal to the second optical switch, A second optical switch that outputs the first optical signal output from the second optical coupler or the second optical signal input from the second input terminal to the second output terminal, The system includes a second photodetector that detects a first optical signal input to the branch input terminal via the second optical coupler and an optical filter, The first optical switch outputs the first optical signal input to the first input terminal to the first output terminal when the light intensity detected by the first photodetector is equal to or greater than a predetermined optical threshold, and does not output the first optical signal input to the first input terminal to the first optical coupler. The second optical switch outputs the second optical signal input to the second input terminal to the second output terminal if the light intensity of the monitoring light signal included in the first optical signal detected by the second photodetector is less than a predetermined monitoring light threshold, and does not output the first optical signal output from the second optical coupler to the second output terminal. The first optical repeater is, A first optical repeater amplifier that outputs the first optical signal output from the branch output terminal to the second optical repeater, The second optical repeater has a second optical repeater amplifier that outputs the first optical signal folded back by the second optical repeater to the branch input terminal, The second optical repeater is, The system includes a monitoring optical folding circuit that folds back the first optical signal input from the first optical repeater and outputs it back to the first optical repeater. Optical submarine cable system. (Note 6) The first optical switch determines that the optical fiber connected to the branch output terminal has broken if the light intensity detected by the first photodetector is equal to or greater than the predetermined light threshold. The second optical switch determines that the optical fiber connecting the first optical repeater and the second optical repeater has broken if the light intensity of the monitoring optical signal included in the first optical signal input to the branch input terminal is less than or equal to the predetermined monitoring optical threshold. The optical submarine cable system described in Appendix 5. (Note 7) The first optical signal output from the branch output terminal includes a first main signal containing multiple wavelengths and the monitoring optical signal. The optical filter allows the monitoring optical signal to pass through but prevents the first main signal from passing through. The optical submarine cable system described in Appendix 5. (Note 8) The monitoring optical folding circuit folds back a portion of the first optical signal input from the first optical repeater and outputs it to the first optical repeater. The optical submarine cable system described in Appendix 5. (Note 9) The optical switch outputs the optical signal input to the input terminal to the optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to the branch output terminal, The photodetector detects the external scattered light input to the branch output terminal via the optical coupler, The optical switch outputs the optical signal input to the input terminal to the output terminal when the light intensity detected by the photodetector is equal to or greater than a predetermined light threshold. A method for an optical branching device comprising the above. (Note 10) The optical switch outputs the optical signal input to the input terminal to the optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to the branch output terminal, The photodetector detects the external scattered light input to the branch output terminal via the optical coupler, The optical switch outputs the optical signal input to the input terminal to the output terminal when the light intensity detected by the photodetector is equal to or greater than a predetermined light threshold. A program for an optical branching device that causes a computer to execute. 【0078】 Some or all of the elements (e.g., configuration and function) described in Appendices 2 to 4 that are dependent on Appendice 1 {e.g., device} may also be dependent on Appendices 9 {e.g., method} and 10 {e.g., program} in the same way as in Appendices 2 to 4. Some or all of the elements described in any appendice may be applied to various hardware, software, recording means, systems, and methods for recording software. [Explanation of Symbols] 【0079】 10… Submarine fiber optic cable systems 11… Optical branching device 111...First optical switch 112...First Optical Coupler 113...First photodetector 114...Second optical switch 115...Second Optical Coupler 116… Light filter 117...Second photodetector 12a...First optical repeater 12a1...First optical relay amplifier 12a2...Second optical relay amplifier 12b...Second optical repeater 12b1...First optical relay amplifier 12b2...Second optical relay amplifier 12b3... Monitoring light folding circuit 2a…Optical amplifier 3a, 3b... Optical couplers 11m, 12am, 12bm...memory 11p, 12ap, 12bp… processor λa... First main signal λb… Monitoring optical signal

Claims

[Claim 1] An optical switch that outputs an optical signal input to an input terminal to an optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to a branch output terminal, A photodetector that detects external scattered light input to the branch output terminal via the optical coupler, Equipped with, The optical switch outputs the optical signal input to the input terminal to the output terminal and does not output the optical signal input to the input terminal to the optical coupler when the light intensity of the scattered light detected by the photodetector is equal to or greater than a predetermined light threshold. Optical branching device. [Claim 2] The aforementioned photodetector includes a photodiode, The optical branching device according to claim 1. [Claim 3] The optical switch determines that the optical fiber connected to the branch output terminal has broken if the light intensity detected by the photodetector is equal to or greater than the predetermined light threshold. The optical branching device according to claim 1. [Claim 4] The first terminal of the optical switch is connected to the input terminal of the device. The second terminal of the optical switch is connected to the output terminal of the device. The third terminal of the optical switch is connected to the input terminal of the optical coupler. The output terminal of the optical coupler is connected to the branch output terminal of the device, The monitor terminal of the optical coupler is connected to the photodetector. The optical switch connects its first terminal to its second terminal and does not connect its first terminal to its third terminal when the light intensity of the scattered light detected by the photodetector is equal to or greater than the predetermined light threshold. The optical branching device according to claim 1. [Claim 5] The system comprises an optical branching device, a first optical repeater connected to the optical branching device, and a second optical repeater connected to the first optical repeater. The aforementioned optical branching device, A first optical switch that outputs a first optical signal input to a first input terminal to a first optical coupler or a first output terminal, The first optical coupler outputs the first optical signal output from the first optical switch to a branch output terminal, A first photodetector detects the external scattered light input to the branch output terminal via the first optical coupler, The first optical signal output from the branch output terminal is relayed back by the second optical repeater via the first optical repeater and input to the branch input terminal of the device via the first optical repeater, and the second optical coupler outputs the first optical signal input to the branch input terminal to the second optical switch, A second optical switch that outputs the first optical signal output from the second optical coupler or the second optical signal input from the second input terminal to the second output terminal, The system includes a second photodetector that detects a first optical signal input to the branch input terminal via the second optical coupler and an optical filter, The first optical switch outputs the first optical signal input to the first input terminal to the first output terminal when the light intensity detected by the first photodetector is equal to or greater than a predetermined light threshold, and does not output the first optical signal input to the first input terminal to the first optical coupler. The second optical switch outputs the second optical signal input to the second input terminal to the second output terminal, and does not output the first optical signal output from the second optical coupler to the second output terminal, if the light intensity of the monitoring light signal included in the first optical signal detected by the second photodetector is less than a predetermined monitoring light threshold. The first optical repeater is, A first optical repeater amplifier that outputs the first optical signal output from the branch output terminal to the second optical repeater, The system includes a second optical repeater amplifier that outputs the first optical signal folded back by the second optical repeater to the branch input terminal, The second optical repeater is, The system includes a monitoring optical folding circuit that folds back the first optical signal input from the first optical repeater and outputs it back to the first optical repeater. Optical submarine cable system. [Claim 6] The first optical switch determines that the optical fiber connected to the branch output terminal has broken if the light intensity detected by the first photodetector is equal to or greater than the predetermined light threshold. The second optical switch determines that the optical fiber connecting the first optical repeater and the second optical repeater has broken if the light intensity of the monitoring optical signal included in the first optical signal input to the branch input terminal is less than or equal to the predetermined monitoring optical threshold. The optical submarine cable system according to claim 5. [Claim 7] The first optical signal output from the branch output terminal includes a first main signal containing multiple wavelengths and the monitoring optical signal. The optical filter allows the monitoring optical signal to pass through but prevents the first main signal from passing through. The optical submarine cable system according to claim 5. [Claim 8] The monitoring optical folding circuit folds back a portion of the first optical signal input from the first optical repeater and outputs it to the first optical repeater. The optical submarine cable system according to claim 5. [Claim 9] The optical switch outputs the optical signal input to the input terminal to the optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to the branch output terminal, The photodetector detects the external scattered light input to the branch output terminal via the optical coupler, The optical switch outputs the optical signal input to the input terminal to the output terminal when the light intensity detected by the photodetector is equal to or greater than a predetermined light threshold. A method for an optical branching device comprising the above. [Claim 10] The optical switch outputs the optical signal input to the input terminal to the optical coupler or output terminal, The optical coupler outputs the optical signal output from the optical switch to the branch output terminal, The photodetector detects the external scattered light input to the branch output terminal via the optical coupler, The optical switch outputs the optical signal input to the input terminal to the output terminal when the light intensity detected by the photodetector is equal to or greater than a predetermined light threshold. A program for an optical branching device that causes a computer to execute.

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