Submarine Optical Communication System

Abstract

In order to be able to check a submarine optical cable in use while improving reliability, this submarine optical communication system has a loopback means included in a second path, and the loopback means comprises: a first input port that receives a first optical signal output by a first switching means; a branching means that causes the first optical signal input from the first input port to branch; a first output port that outputs, to a second switching means, one of the first optical signals branched by the branching means; and a second output port that outputs, to a first optical receiving means, at least a portion of the other of the first optical signals branched by the branching means.

Description

[Technical Field]

[0001] The present invention relates to a submarine optical communication system that is capable of identifying, for example, the submarine optical cable in use. [Background technology]

[0002] In a submarine optical communication system, terminal stations installed on land perform optical communication via submarine optical cables laid on the seabed. In this case, in order to improve the reliability of the submarine optical communication system, the submarine optical cables may have a redundant configuration. For example, a redundant configuration of submarine optical cables may include multiple submarine cables for transmission and multiple submarine cables for reception. For example, Patent Document 1 discloses a submarine optical communication system including multiple submarine cables for transmission and multiple submarine cables for reception.

[0003] In this submarine optical communication system, when multiple submarine cables for transmission and multiple submarine cables for reception are used, for example, a terminal station switches the submarine optical cable to be used by using an optical switch or the like provided in the submarine optical cable. At this time, the submarine optical communication system may communicate with the terminal station from a communication device provided in the optical switch or the like to confirm that the appropriate submarine optical cable is being used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 07-087013 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since repairing submarine optical cables is extremely expensive, there is a demand for improving reliability of submarine optical cables by reducing the number of parts and moving parts, etc. Therefore, the configuration in which communication devices are provided in optical switches, etc., as described above, is not preferable from the viewpoint of improving reliability.

[0006] In view of the above-mentioned problems, an object of the present invention is to provide a submarine optical communication system that can improve reliability and can check the submarine optical cable being used. [Means for solving the problem]

[0007] The present invention provides a submarine optical communication system comprising a first terminal station, a first branching unit, a second branching unit, and a second terminal station, The submarine optical communication system includes: the first terminal station including a first optical transmitting means for outputting a first optical signal to the first branching device and a first optical receiving means; the first branching device including a first switching means for outputting a first optical signal from the first optical transmitting means to the second branching device via a first path or a second path; the second branching device including a second switching means for outputting the first optical signal output from the first switching means via the first path or the second path toward the second terminal station; the second terminal station including second optical receiving means for receiving the first optical signal from the second switching means; Equipped with the second path includes a turning means; The folding means a first input port that receives the first optical signal output from the first switching means; a branching means for branching the first optical signal input from the first input port; a first output port that outputs one of the first optical signals branched by the branching means to the second switching means; a second output port that outputs at least a portion of the other of the first optical signals branched by the branching means to the first optical receiving means; Equipped with. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a submarine optical communication system that can improve reliability and can confirm that an appropriate submarine optical cable is being used. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of the configuration of a submarine optical communication system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram for explaining details of the submarine optical communication system according to the first embodiment of the present invention. [Figure 3] FIG. 2 is a diagram for explaining details of the submarine optical communication system according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram for explaining details of the submarine optical communication system according to the first embodiment of the present invention. [Figure 5] FIG. 10 is a block diagram showing an example of the configuration of a submarine optical communication system according to a second embodiment of the present invention. [Figure 6] FIG. 4 is a diagram for explaining details of a submarine optical communication system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment A submarine optical communication system 1 in a first embodiment will be described with reference to Figures 1, 2, 3, 4, and 5. Figure 1 is a block diagram showing an example of the configuration of the submarine optical communication system 1. Figures 2, 3, 4, and 5 are diagrams for explaining the details of the submarine optical communication system 1. Figure 6 is a flowchart for explaining an example of the operation of the submarine optical communication system 1.

[0011] As shown in Fig. 1, the submarine optical communication system 1 comprises a first terminal station 10, a first branching device 20, a second branching device 30, a second terminal station 40, and a return means 50. As shown in Fig. 1, the components of the submarine optical communication system 1 are connected by submarine optical cables 101, 102, 103, 104, 105, 106, 107, and 108. The submarine optical cables 101 to 108 are cables including optical fibers and are laid on the seabed. The submarine optical cables 101 to 108 may further comprise optical components such as optical amplifiers and gain equalizers.

[0012] The first terminal station 10 is a landing station provided on land. The first terminal station 10 includes a first optical transmitting means 11 and a first optical receiving means 12.

[0013] The first optical transmitting means 11 outputs a first optical signal to the first branching device 20. Specifically, the first optical transmitting means 11 outputs the first optical signal to the first switching means 21 in the first branching device 20 via the submarine optical cable 101. The first optical signal is, for example, a WDM (Wavelength Division Multiplexed) optical signal. The first optical signal includes, for example, a first band and a second band. The first band is allocated to an optical signal including information addressed to the second terminal station 40. The second band is allocated to a first supervisory optical signal. The first band and the second band are different bands from each other.

[0014] The first optical receiving means 12 receives an optical signal input via the submarine optical cable 102. Specifically, the first optical receiving means 12 receives an optical signal output from the second terminal station 40.

[0015] The first branching device 20 includes a first switching means 21 and a fourth switching means 22. The first switching means 21 outputs the first optical signal from the first optical transmitting means 11 to the second branching device 30 via the submarine optical cable 103 or the submarine optical cable 105. The submarine optical cable 103 corresponds to the first route. The submarine optical cable 105 corresponds to the second route.

[0016] The optical signal output from the second terminal station 40 is input to the fourth switching means 22 via the submarine optical cable 104 or the submarine optical cable 105. The fourth switching means 22 outputs the input optical signal to the first optical receiving means 12 via the submarine optical cable 102. The first switching means 21 and the fourth switching means 22 are, for example, optical switches.

[0017] The second branching device 30 includes second switching means 31 and third switching means 32. The optical signal output from the first terminal station 10 is input to the second switching means 31 via the submarine optical cable 103 or the submarine optical cable 105. The second switching means 31 outputs the input optical signal to the second terminal station 40 via the submarine optical cable 107.

[0018] The third switching means 32 outputs the optical signal output from the second terminal station 40 toward the first branching device 20 via the submarine optical cable 104 or the submarine optical cable 106. The second switching means 31 and the third switching means 32 are, for example, optical switches.

[0019] The second terminal station 40 is a landing station provided on land. The second terminal station 40 includes a second optical transmitting means 41 and a second optical receiving means 42.

[0020] The second optical transmitting means 41 outputs the second optical signal to the second branching device 30. Specifically, the second optical transmitting means 41 outputs the second optical signal to the third switching means 32 in the second branching device 30 via the submarine optical cable 108. The second optical signal is, for example, a WDM optical signal. The second optical signal includes, for example, a third band and a fourth band. The third band is allocated to an optical signal including information addressed to the first terminal station 10. The fourth band is allocated to a second supervisory optical signal. The third band and the fourth band are different bands from each other.

[0021] The second optical receiving means 42 receives an optical signal input via the submarine optical cable 107. Specifically, the second optical receiving means 42 receives an optical signal output from the first terminal station 10.

[0022] The turning-back means 50 will be described using Fig. 2. The turning-back means 50 is included in the submarine optical cable 105 and the submarine optical cable 106. As shown in Fig. 2, the turning-back means 50 includes a first branching means 51, a first wavelength filter 52, a second branching means 53, a second wavelength filter 54, a first multiplexing means 55, and a second multiplexing means 56. The turning-back means 50 also includes optical ports P1, P2, P3, and P4 through which optical signals can be input and output.

[0023] The first optical signal output from the first switching means 21 is input to the optical port P1. The optical port P1 corresponds to the first input port. The first branching means 51 branches the first optical signal input from the optical port P1. The first branching means 51 is, for example, an optical coupler. The first branching means 51 outputs one of the branched first optical signals toward the second multiplexing means 56 and outputs the other of the branched first optical signals toward the first wavelength filter 52.

[0024] The first wavelength filter 52 is an optical filter that transmits a second band of the first optical signal that is assigned to the first supervisory optical signal. The first wavelength filter 52 may block the first band. In this case, the first band is assigned to an optical signal that includes information addressed to the second terminal station 40. As a result, the first supervisory optical signal assigned to the second band is output from the first wavelength filter 52 toward the first multiplexing means 55. Note that the first wavelength filter 52 does not necessarily have to be provided.

[0025] The second optical signal output from the third switching means 32 is input to the optical port P4. The optical port P4 corresponds to the second input port. The second branching means 53 branches the second optical signal input from the optical port P4. The second branching means 53 is, for example, an optical coupler. The second branching means 53 outputs one of the branched second optical signals toward the first multiplexing means 55 and outputs the other of the branched second optical signals toward the second wavelength filter 54.

[0026] The second wavelength filter 54 is an optical filter that transmits a fourth band of the second optical signal that is assigned to the second supervisory optical signal. The first wavelength filter 52 may block the third band. Here, the third band is assigned to an optical signal that includes information addressed to the first terminal station 10. As a result, the second supervisory optical signal assigned to the fourth band is output from the second wavelength filter 54 toward the second multiplexing means 56. Note that the second wavelength filter 54 does not necessarily have to be provided.

[0027] The first multiplexing means 55 receives the first supervisory optical signal from the first wavelength filter 52 and the second optical signal from the second branching means 53. The first multiplexing means 55 multiplexes the input optical signals and outputs the multiplexed signal toward optical port P3. Optical port P3 corresponds to the second output port. Specifically, the first multiplexing means 55 outputs an optical signal including the second, third, and fourth bands toward optical port P3. Here, the second band is assigned to the first supervisory optical signal. The third band is assigned to an optical signal including information addressed to the first terminal station 10. The fourth band is assigned to the second supervisory optical signal. As a result, the optical signal from the first multiplexing means 55 is output to the first optical receiving means 12 via the submarine optical cable 106, the fourth switching means 22, and the submarine optical cable 102.

[0028] The second multiplexing means 56 receives the second supervisory optical signal from the second wavelength filter 54 and the first optical signal from the first branching means 51. The second multiplexing means 56 multiplexes the input optical signals and outputs the multiplexed signal toward optical port P2. The optical port P2 corresponds to the first output port. Specifically, the second multiplexing means 56 outputs an optical signal including a first band, a second band, and a fourth band toward optical port P2. Here, the first band is assigned to an optical signal including information addressed to the second terminal station 40. The second band is assigned to the first supervisory optical signal. The fourth band is assigned to the second supervisory optical signal. As a result, the optical signal from the second multiplexing means 56 is output to the second optical receiving means 42 via the submarine optical cable 105, the second switching means 31, and the submarine optical cable 107.

[0029] Next, the first switching means 21, the second switching means 31, the third switching means 32, and the fourth switching means 22 in the submarine optical communication system 1 will be described in detail. At least one of the first optical transmitting means 11 and the second optical transmitting means 41 is capable of outputting instructions to the first switching means 21, the second switching means 31, the third switching means 32, and the fourth switching means 22 via the submarine optical cable. The first switching means 21, the second switching means 31, the third switching means 32, and the fourth switching means 22 switch the connection relationship between the submarine optical cables in response to the instructions. For example, the first switching means 21 determines which of the submarine optical cables 103 and 105 to connect to the submarine optical cable 101.

[0030] The first state of the submarine optical communication system 1 will be explained using Figure 3. The solid line portions in Figure 3 indicate submarine optical cables through which light can propagate. The dotted line portions in Figure 3 indicate submarine optical cables through which light cannot propagate. In the first state, the first switching means 21 connects the submarine optical cables 101 and 103. The second switching means 31 connects the submarine optical cables 103 and 107. The third switching means 32 connects the submarine optical cables 104 and 108. The fourth switching means 22 connects the submarine optical cables 102 and 104.

[0031] The second state of the submarine optical communication system 1 will be explained using Figure 4. The solid line portions in Figure 3 indicate submarine optical cables through which light can propagate. The dotted line portions in Figure 4 indicate submarine optical cables through which light cannot propagate. In the second state, the first switching means 21 connects the submarine optical cables 101 and 105. The second switching means 31 connects the submarine optical cables 105 and 107. The third switching means 32 connects the submarine optical cables 106 and 108. The fourth switching means 22 connects the submarine optical cables 102 and 106.

[0032] In the first state, the first optical receiving means 12 receives a second optical signal output from the second optical transmitting means 41. Here, the second optical signal includes a third band and a fourth band. The third band is assigned to an optical signal including information addressed to the first terminal station 10. The fourth band is assigned to a second supervisory optical signal. Also, in the second state, the first optical receiving means 12 receives an optical signal including the second band, the third band, and the fourth band. Here, the second band is assigned to the first supervisory optical signal. The third band is assigned to an optical signal including information addressed to the first terminal station 10. The fourth band is assigned to the second supervisory optical signal. The first optical receiving means 12 detects that the submarine optical communication system 1 is in the first state when the received optical signal does not include the second band. Furthermore, the first optical receiving means 12 detects that the submarine optical communication system 1 is in the second state when the received optical signal contains the second band.

[0033] Moreover, in the first state, the second optical receiving means 42 receives a first optical signal output from the first optical transmitting means 11. Here, the first optical signal includes a first band and a second band. The first band is assigned to an optical signal including information addressed to the second terminal station 40. The second band is assigned to a first supervisory optical signal. Moreover, in the second state, the second optical receiving means 42 receives an optical signal including the first band and the second band, and an optical signal including a fourth band. The first band is assigned to an optical signal including information addressed to the second terminal station 40. The second band is assigned to the first supervisory optical signal. The fourth band is assigned to the second supervisory optical signal. The second optical receiving means 42 detects that the submarine optical communication system 1 is in the first state when the received optical signal does not include the fourth band, and detects that the submarine optical communication system 1 is in the second state when the received optical signal includes the fourth band.

[0034] The above has described the submarine optical communication system 1. As described above, the submarine optical communication system 1 includes a turn-back means 50 provided on one of the first path (submarine optical cable 103) and the second path (submarine optical cable 105). The turn-back means 50 outputs at least a part of the first optical signal output from the first optical transmitting means to the first optical receiving means 12.

[0035] In this way, in the submarine optical communication system 1, when the first switching means 21 outputs the first optical signal to the first path, the first optical receiving means 12 does not receive at least a portion of the first optical signal. On the other hand, when the first switching means 21 outputs the first optical signal to the second path, the first optical receiving means 12 receives at least a portion of the first optical signal from the return means 50.

[0036] Therefore, if the first optical receiving means 12 does not receive at least a portion of the first optical signal, it can determine that the first route is being used in the submarine optical communication system 1. Also, if the first optical receiving means 12 receives at least a portion of the first optical signal, it can determine that the second route is being used in the submarine optical communication system 1. In this way, it is possible to confirm which of multiple submarine optical cables is being used in the submarine optical communication system 1. Also, since there is no need to provide communication means in the first switching means 21, the reliability of the submarine optical communication system 1 can be improved.

[0037] Furthermore, when the first optical receiving means 12 receives at least a part of the first optical signal, it detects that the first optical signal from the first switching means is being output to the second path. For example, when the first wavelength filter 52 is not provided and the first switching means 21 is outputting the first optical signal to the second path (the submarine optical cable 105), the first optical receiving means 12 receives the first optical signal.

[0038] In the above case, when the first optical receiving means 12 receives the first optical signal, it detects that the first optical signal from the first switching means 21 is being output to the second path. Also, it is assumed that the first optical transmitting means 11 outputs a first optical signal including a first band and a second band to the first branching device 20. The first band is assigned to an optical signal including information destined for the second terminal station 40. The second band is assigned to a first supervisory optical signal. Furthermore, the return means 50 further includes a wavelength filter (first wavelength filter 52) that transmits only the optical signal of the second band, out of the first optical signal branched from the branching means (first branching means 51), toward the second output port (optical port P3). In this case, when the first switching means 21 outputs the first optical signal to the second path (submarine optical cable 105), the first optical receiving means 12 receives the optical signal of the second band, which is at least a part of the first optical signal.

[0039] In the above case, when the first optical receiving means 12 receives an optical signal in the second band, it detects that the first optical signal from the first switching means is being output to the second path. <Second embodiment> A submarine optical communication system 2 according to the second embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a block diagram showing an example of the configuration of the submarine optical communication system 2. Fig. 6 is a block diagram showing the details of the submarine optical communication system 2.

[0040] 5, the submarine optical communication system 2 comprises a first terminal station 10, a first branching unit 20, a second branching unit 30, a second terminal station 40, and a return means 50. The first terminal station 10, the first branching unit 20, the second branching unit 30, the second terminal station 40, and the return means 50 of the submarine optical communication system 2 may have the same functions and connection relationships as the first terminal station 10, the first branching unit 20, the second branching unit 30, the second terminal station 40, and the return means 50 of the submarine optical communication system 2.

[0041] As shown in FIG. 5, the components of the submarine optical communication system 1 are connected by submarine optical cables 101, 102, 103, 105, 106, and 107, respectively.

[0042] The first terminal station 10 includes a first optical transmitting means 11 for outputting a first optical signal to the first branching device 20 , and a first optical receiving means 12 .

[0043] The first branching device 20 includes a first switching means 21. The first switching means 21 outputs the first optical signal from the first optical transmitting means 11 to the second branching device 30 via the first path (the submarine optical cable 103) or the second path (the submarine optical cable 104).

[0044] The second branching device 30 includes a second switching means 31. The second switching means 31 outputs the first optical signal output from the first switching means via the first path or the second path toward the second terminal station 40.

[0045] The second terminal station 40 includes second optical receiving means for receiving the first optical signal from the second switching means 31 .

[0046] The second route (submarine optical cable 104) includes a turn-back means 50. As shown in Fig. 6, the turn-back means 50 includes a first input port IP1, a branching means 57, a first output port OP1, and a second output port OP2. The branching means 57 corresponds to the first branching means 51.

[0047] The first input port IP1 receives the first optical signal output from the first switching means 21. The first input port IP1 corresponds to the optical port P1. The branching means 57 branches the first optical signal input from the first input port IP1. The first output port OP1 outputs one of the first optical signals branched by the branching means 57 to the second switching means 31. The first output port OP1 corresponds to the optical port P2. The second output port OP2 outputs at least a portion of the other first optical signal branched by the branching means 57 to the first optical receiving means 12. The second output port OP2 corresponds to the optical port P3.

[0048] The above has described the submarine optical communication system 2. As described above, the submarine optical communication system 2 includes a turn-back means 50 provided on one of the first path (submarine optical cable 103) and the second path (submarine optical cable 105). The turn-back means 50 outputs at least a part of the first optical signal output from the first optical transmitting means to the first optical receiving means 12.

[0049] In this way, in the submarine optical communication system 2, when the first switching means 21 outputs the first optical signal to the first path, the first optical receiving means 12 does not receive at least a portion of the first optical signal. On the other hand, when the first switching means 21 outputs the first optical signal to the second path, the first optical receiving means 12 receives at least a portion of the first optical signal from the return means 50.

[0050] Therefore, if the first optical receiving means 12 does not receive at least a portion of the first optical signal, it can determine that the first route is being used in the submarine optical communication system 2. Also, if the first optical receiving means 12 receives at least a portion of the first optical signal, it can determine that the second route is being used in the submarine optical communication system 2. In this way, it is possible to confirm which of multiple routes is being used in the submarine optical communication system 2. Also, since there is no need to provide a communication means in the first switching means 21, the reliability of the submarine optical communication system 2 can be improved.

[0051] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. [Explanation of symbols]

[0052] 1, 2 Submarine optical communication system 10 First terminal 11 First optical transmitting means 12 First optical receiving means 20 First branching device 21 First switching means 22 Fourth Switching Method 30 Second branching device 31 Second switching method 32 Third switching method 40 Second Terminal Station 41 Second optical transmitting means 42 second optical receiving means 50 Return means 51 First branching means 52 First wavelength filter 53 Second branching means 54 Second wavelength filter 55 First multiplexing means 56 Second multiplexing means P1, P2, P3, P4 optical ports IP1 First input port OP1 First output port OP2 Second output port 101, 102, 103, 104, 105, 106, 107, 108 Submarine optical cables

Claims

1. A submarine optical communication system comprising a first terminal station, a first branching unit, a second branching unit, and a second terminal station, the first terminal station includes a first optical transmitting means for outputting a first optical signal to the first branching device, and a first optical receiving means; the first branching device includes a first switching means for outputting a first optical signal from the first optical transmitting means to the second branching device via a first path or a second path; the second branching device includes a second switching means that outputs the first optical signal output from the first switching means via the first path or the second path to the second terminal station; the second terminal station includes second optical receiving means for receiving the first optical signal from the second switching means, the second path includes a turning means; The folding means a first input port that receives the first optical signal output from the first switching means; a branching unit for branching the first optical signal input from the first input port; a first output port that outputs one of the first optical signals branched by the branching means to the second switching means; a second output port that outputs at least a portion of the other of the first optical signals branched by the branching means to the first optical receiving means; A submarine optical communication system comprising:

2. 2. The submarine optical communication system according to claim 1, wherein the first optical receiving means detects that the first optical signal from the first switching means is output to the second path when the first optical receiving means receives at least a portion of the first optical signal.

3. the first optical transmitting means outputs the first optical signal, which includes a first band assigned to an optical signal including information destined for the second terminal station and a second band assigned to a first supervisory optical signal, to the first branching device; the folding means further includes a wavelength filter that transmits, toward the second output port, only the optical signal in the second band out of the first optical signal branched from the branching means.

3. A submarine optical communication system according to claim 1 or 2.

4. 4. The submarine optical communication system according to claim 3, wherein the first optical receiving means detects that the first optical signal from the first switching means is output to the second path when the first optical receiving means receives an optical signal in the second band.

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