Optical fiber sensing system, optical fiber sensing apparatus, and optical fiber sensing method

Abstract

To find an optical fiber laid on a same route as a communication fiber.SOLUTION: An optical fiber sensing system includes: an optical fiber cable (20) that houses an optical fiber (10AZ) connected to a first point and a second point, and houses an optical fiber (11); a communication portion (31) that transmits pulse light to and receives an optical signal from the optical fiber (10AZ) or the optical fiber (11); and a sensing portion (32) that executes first sensing for sensing vibration applied to the optical fiber cable (20) at the second point side in a state where the optical fiber (10AZ) is connected to the communication portion (31) at the first point side, and executes second sensing for sensing the vibration in a state where the optical fiber (11) is connected to the communication portion (31) at the first point side; and determination portion (33) that determines whether the optical fiber (11) is connected to the first point and the second point on the basis of results of the first and second sensing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an optical fiber sensing system, an optical fiber sensing device, and an optical fiber sensing method. [Background technology]

[0002] Optical fiber sensing, which uses optical fiber as a sensor, has the characteristic that an optical fiber sensing device (for example, a Distributed Fiber Optic Sensing (DFOS) device) can detect vibrations caused by events occurring around the optical fiber and identify the events that have occurred around the optical fiber based on the detected vibrations.

[0003] However, with optical fiber sensing, although it is possible to determine the distance of the optical fiber from the location of the optical fiber sensing device to the location where the vibration occurred, it is not possible to determine the location (latitude / longitude) where the vibration occurred, and therefore the location (latitude / longitude) where the event occurred.

[0004] For this reason, recently, a technique has been proposed for associating the distance of the optical fiber from the location of the optical fiber sensing device with the location information. For example, Patent Document 1 discloses a technique for associating the distance of the optical fiber from the location of the optical fiber sensing device with the GPS location information using a vibration generator having a vibration generating function and a GPS (Global Positioning System) function, and for identifying the optical fiber installation route based on the result of this association.

[0005] Specifically, in the technology described in Patent Document 1, vibrations generated by a vibration generator are detected by optical fiber sensing, the optical fiber distance from the location of the optical fiber sensing device to the location where the vibration occurred is identified, and the identified optical fiber distance is associated with the GPS location information of the vibration generator when the vibration was generated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2022 / 113252 Summary of the Invention [Problem to be solved by the invention]

[0007] Recently, there is a demand to identify the laying route of communication fibers, which are optical fibers used in communication lines. For example, the technology described in Patent Document 1 makes it possible to identify the laying route of communication fibers, but in order to do so, it is necessary to perform optical fiber sensing using the communication fibers.

[0008] However, because communication fibers are used in communication lines, they can only be used temporarily for optical fiber sensing during periods of low traffic, and cannot be used for long periods. In addition, there are cases where unused dark fibers, which are optical fibers housed in the same optical fiber cable as communication fibers, exist.

[0009] In light of this, in order to identify the route of a communication fiber using the technology described in Patent Document 1, it is preferable to perform optical fiber sensing using an optical fiber such as a dark fiber that is laid along the same route as the communication fiber. Therefore, it is desirable to find optical fibers laid along the same routes as communication fibers.

[0010] In view of the above-mentioned problems, an object of the present disclosure is to provide an optical fiber sensing system, an optical fiber sensing device, and an optical fiber sensing method capable of finding an optical fiber laid on the same route as a communication fiber. [Means for solving the problem]

[0011] According to one aspect, an optical fiber sensing system includes: an optical fiber cable that houses a first optical fiber connected to a first point and a second point and that houses a second optical fiber; a communication unit to which the first optical fiber or the second optical fiber is connected, which transmits pulsed light to the first optical fiber or the second optical fiber connected thereto, and receives an optical signal from the first optical fiber or the second optical fiber connected thereto; a detection unit that performs first optical fiber sensing to detect vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber in a state in which the first optical fiber is connected to the communication unit at the first location, and that performs second optical fiber sensing to detect the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber in a state in which the second optical fiber is connected to the communication unit at the first location; and a determination unit that determines whether the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing.

[0012] An optical fiber sensing device according to one aspect includes: a communication unit to which a first optical fiber connected to a first point and a second point or a second optical fiber housed in the same optical fiber cable as the first optical fiber is connected, the communication unit transmitting pulse light to the connected first optical fiber or the connected second optical fiber and receiving an optical signal from the connected first optical fiber or the connected second optical fiber; a detection unit that performs first optical fiber sensing to detect vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber in a state in which the first optical fiber is connected to the communication unit at the first location, and that performs second optical fiber sensing to detect the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber in a state in which the second optical fiber is connected to the communication unit at the first location; and a determination unit that determines whether the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing.

[0013] According to one aspect, a method for optical fiber sensing includes: An optical fiber sensing method using an optical fiber sensing device, comprising: a communication step of transmitting pulse light to a first optical fiber connected to a first point and a second point or to a second optical fiber housed in the same optical fiber cable as the first optical fiber, and receiving an optical signal from the first optical fiber or the second optical fiber; a detection step of performing a first optical fiber sensing for detecting vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber while the first optical fiber is connected to the optical fiber sensing device at the first location, and performing a second optical fiber sensing for detecting the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber while the second optical fiber is connected to the optical fiber sensing device at the first location; The method includes a determination step of determining whether the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing. Effect of the Invention

[0014] According to the above-mentioned aspects, it is possible to provide an optical fiber sensing system, an optical fiber sensing device, and an optical fiber sensing method that are capable of finding an optical fiber laid on the same route as a communication fiber. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating an example of a configuration of an optical fiber sensing system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the first embodiment. [Diagram 3] FIG. 2 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the first embodiment. [Figure 4] FIG. 2 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the first embodiment. [Diagram 5] FIG. 4 is a flow diagram illustrating an example of a schematic operation flow of the optical fiber sensing device according to the first embodiment. [Figure 6] FIG. 11 is a diagram illustrating a configuration example of an optical fiber sensing system according to a second embodiment. [Figure 7] 10A to 10C are diagrams illustrating an example of a schematic operation of the optical fiber sensing device according to the second embodiment. [Figure 8] FIG. 11 is a diagram illustrating a configuration example of an optical fiber sensing system according to a third embodiment. [Figure 9] 11 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the third embodiment. FIG. [Figure 10] 11 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the third embodiment. FIG. [Figure 11] 11 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the third embodiment. FIG. [Figure 12] FIG. 13 is a diagram illustrating a configuration example of an optical fiber sensing system according to a fourth embodiment. [Figure 13] FIG. 13 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the fourth embodiment. [Figure 14] FIG. 13 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the fourth embodiment. [Figure 15] FIG. 13 is a diagram for explaining an example of a schematic operation of the optical fiber sensing device according to the fourth embodiment. [Figure 16] FIG. 2 is a block diagram showing an example of a hardware configuration of a computer that realizes the optical fiber sensing device according to each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that the following description and drawings are omitted and simplified as appropriate for clarity of explanation. In addition, in each of the following drawings, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0017] <Embodiment 1> First, with reference to FIG. 1, a configuration example of an optical fiber sensing system according to the first embodiment will be described.

[0018] As shown in FIG. 1, the optical fiber sensing system according to the first embodiment includes an optical fiber cable 20 and an optical fiber sensing device 30. The optical fiber sensing system according to the first embodiment includes an optical fiber cable 20 and an optical fiber sensing device 30. 1, the optical fiber cable 20 accommodates a communication fiber 10AZ (first optical fiber) that is an optical fiber used for a communication line. The communication fiber 10AZ is connected to a communication station 40A and a communication station 40Z.

[0019] The optical fiber cable 20 also accommodates dark fibers 11AZ, 11A (second optical fiber) that are unused optical fibers. The dark fiber 11AZ is connected to the communication station 40A and the communication station 40Z, similar to the communication fiber 10AZ. On the other hand, the dark fiber 11A is connected to the communication station 40A, but is disconnected between the communication station 40A and the communication station 40Z, and is not connected to the communication station 40Z. Hereinafter, when it is not necessary to specify which of the dark fibers 11AZ and 11A it is, it will be simply referred to as the "dark fiber 11". In the example of FIG. 1, the number of optical fibers accommodated in the optical fiber cable 20 is three, and the number of dark fibers 11 among them is two, but this is just an example, and the number of optical fibers accommodated in the optical fiber cable 20 and the number of dark fibers 11 among them may be arbitrary (the same applies to the following FIG. 6, FIG. 8, and FIG. 12).

[0020] The optical fiber sensing device 30 includes a communication unit 31, a detection unit 32, and a determination unit 33. The optical fiber sensing device 30 is realized by a DFOS device such as a Distributed Vibration Sensing (DVS) device or a Distributed Acoustic Sensing (DAS) device. In the example of Fig. 1, the optical fiber sensing device 30 is placed in a communication station 40A. However, the optical fiber sensing device 30 is movable by a user and can be placed in any location.

[0021] The communication unit 31 is connected to one of the communication fiber 10AZ or the dark fiber 11 on the communication station 40A side. The communication unit 31 transmits pulsed light to the connected communication fiber 10AZ or dark fiber 11. Then, as the pulsed light is transmitted through the communication fiber 10AZ or the dark fiber 11, backscattered light is generated. The communication unit 31 receives the backscattered light from the connected communication fiber 10AZ or dark fiber 11 as an optical signal.

[0022] In the first embodiment, first, the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side. With the communication fiber 10AZ connected to the communication unit 31 of the optical fiber sensing device 30, a user applies vibration to the optical fiber cable 20 on the communication station 40Z side. Note that the method of applying vibration to the optical fiber cable 20 may be any method, such as hitting it with a stick. In this state, the detection unit 32 executes a first optical fiber sensing to detect the vibration applied to the optical fiber cable 20 on the communication station 40Z side, based on the optical signal received from the communication fiber 10AZ.

[0023] Next, the dark fibers 11 are sequentially connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side. Each time the connection is made, with the dark fiber 11 connected to the communication unit 31 of the optical fiber sensing device 30, the user applies vibration to the optical fiber cable 20 on the communication station 40Z side, and the detection unit 32 performs second optical fiber sensing to detect the vibration applied to the optical fiber cable 20 on the communication station 40Z side based on the optical signal received from the dark fiber 11. Also, the determination unit 33 determines whether the dark fiber 11 on which the second optical fiber sensing has been performed is connected to the communication station 40A and the communication station 40Z based on the results of the first optical fiber sensing and the second optical fiber sensing.

[0024] Next, the operation of the optical fiber sensing device 30 according to the first embodiment will be described in more detail below with reference to FIGS.

[0025] First, as shown in FIG. 2, the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, and the first optical fiber sensing is executed. The above-mentioned operations will now be described in detail.

[0026] In a state where the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, the communication unit 31 transmits pulsed light to the communication fiber 10AZ. The communication unit 31 also receives backscattered light as an optical signal from the communication fiber 10AZ. Here, the communication fiber 10AZ is used for a communication line, and therefore cannot be used for a long time. Therefore, the above operation is performed by temporarily using the communication fiber 10AZ during a time period when the communication volume is low. At this time, the above operation may be performed while the communication fiber 10AZ is temporarily stopped from providing the communication line service. Alternatively, the above operation may be performed while the communication fiber 10AZ is continuing to provide the communication line service. However, while the communication line service is continuing, a signal for the communication line is also transmitted to the communication fiber 10AZ. Therefore, while the communication line service is continuing, the communication unit 31 may transmit pulsed light to the communication fiber 10AZ by using a method of wavelength multiplexing the pulsed light on the signal for the communication line, or the like.

[0027] In this state, the user applies vibration to the optical fiber cable 20 on the communication station 40Z side. Therefore, in the example of Fig. 2, the communication station 40A becomes the first point, and the communication station 40Z becomes the second point (the same applies to the following Figs. 3 and 4).

[0028] In this state, the detector 32 executes the first optical fiber sensing to detect the vibration applied to the optical fiber cable 20 on the communication station 40Z side, based on the optical signal received from the communication fiber 10AZ.

[0029] At this time, since the communication fiber 10AZ extends to the communication station 40Z, the vibration applied to the optical fiber cable 20 is propagated to the communication fiber 10AZ. As a result, the characteristics (for example, wavelength) of the optical signal transmitted through the communication fiber 10AZ change.

[0030] Therefore, the detector 32 can detect the vibration applied to the optical fiber cable 20 on the communication station 40Z side based on the optical signal received from the communication fiber 10AZ. Furthermore, since the detection unit 32 was able to detect the vibration applied to the optical fiber cable 20, it identifies the distance of the communication fiber 10AZ from the location of the optical fiber sensing device 30 (communication unit 31) to the location where the vibration occurred (i.e., the location where the characteristics of the optical signal changed). For example, the detection unit 32 identifies the above-mentioned distance based on the time difference between the time when the communication unit 31 transmits pulsed light to the communication fiber 10AZ and the time when the communication unit 31 receives the optical signal with the changed characteristics from the communication fiber 10AZ.

[0031] Next, as shown in Figures 3 and 4, on the communication station 40A side, the dark fiber 11 housed in the same optical fiber cable 20 as the communication fiber 10AZ is sequentially connected to the communication unit 31 of the optical fiber sensing device 30, and each time the connection is made, a second optical fiber sensing is executed to determine whether the connected dark fiber 11 is connected to the communication station 40A and the communication station 40Z. The above-mentioned operation will be described in detail below. Here, it is assumed that the dark fiber 11AZ is first connected to the communication unit 31 of the optical fiber sensing device 30, and then the dark fiber 11A is connected to the communication unit 31.

[0032] First, with reference to FIG. 3, an operation performed in a state where the dark fiber 11AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side will be described. 3, in a state where the dark fiber 11AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, the communication unit 31 transmits pulsed light to the dark fiber 11AZ and receives backscattered light as an optical signal from the dark fiber 11AZ. In this state, the user applies vibration to the optical fiber cable 20 on the communication station 40Z side.

[0033] In this state, the detector 32 executes second optical fiber sensing to detect vibrations applied to the optical fiber cable 20 on the communication station 40Z side, based on the optical signal received from the dark fiber 11AZ.

[0034] At this time, the dark fiber 11AZ extends to the communication station 40Z. Therefore, the detector 32 can detect the vibration applied to the optical fiber cable 20 on the communication station 40Z side based on the optical signal received from the dark fiber 11AZ. Furthermore, since the detection unit 32 was able to detect the vibration applied to the optical fiber cable 20, it identifies the distance of the dark fiber 11AZ from the location of the optical fiber sensing device 30 (communication unit 31) to the location where the vibration occurred.

[0035] Here, the vibration applied to the optical fiber cable 20 on the communication station 40Z side can be detected both in the first optical fiber sensing performed with the communication fiber 10AZ connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, and in the second optical fiber sensing performed with the dark fiber 11AZ connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side.

[0036] Therefore, the determination unit 33 calculates the difference between the distance of the communication fiber 10AZ identified by the first optical fiber sensing and the distance of the dark fiber 11AZ identified by the second optical fiber sensing, and determines whether the calculated difference is within a predetermined range. Here, it is assumed that the difference is within the predetermined range, and the determination unit 33 determines that the dark fiber 11AZ is connected to the communication station 40A and the communication station 40Z.

[0037] Next, with reference to FIG. 4, an operation performed in a state where the dark fiber 11A is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side will be described. 4, in a state where the dark fiber 11A is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, the communication unit 31 transmits pulsed light to the dark fiber 11A and receives backscattered light as an optical signal from the dark fiber 11A. In this state, the user applies vibration to the optical fiber cable 20 on the communication station 40Z side.

[0038] In this state, the detector 32 executes second optical fiber sensing to detect vibrations applied to the optical fiber cable 20 on the communication station 40Z side, based on the optical signal received from the dark fiber 11A.

[0039] At this time, the dark fiber 11A is disconnected between the communication office 40A and the communication office 40Z, and does not extend to the communication office 40Z. Therefore, the vibration applied to the optical fiber cable 20 on the communication office 40Z side is not propagated to the dark fiber 11A, and the characteristics of the optical signal transmitted through the dark fiber 11A do not change.

[0040] Therefore, the detector 32 cannot detect the vibrations applied to the optical fiber cable 20 . Therefore, the determining unit 33 determines that the dark fiber 11A is disconnected between the communication station 40A and the communication station 40Z.

[0041] Next, an example of a schematic operation flow of the optical fiber sensing device 30 according to the first embodiment will be described below with reference to FIG.

[0042] As shown in FIG. 5, first, with the communication fiber 10AZ connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, the detection unit 32 performs a first optical fiber sensing to detect vibrations applied to the optical fiber cable 20 on the communication station 40Z side based on an optical signal received from the communication fiber 10AZ (step S11).

[0043] Specifically, in the first optical fiber sensing, vibrations applied to the optical fiber cable 20 are detected on the communication station 40Z side, and if vibrations are detected, the distance of the communication fiber 10AZ from the location of the optical fiber sensing device 30 (communication unit 31) to the location where the vibration occurred is determined.

[0044] Next, with the dark fiber 11 housed in the same optical fiber cable 20 as the communication fiber 10AZ connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, the detection unit 32 performs a second optical fiber sensing to detect vibrations applied to the optical fiber cable 20 on the communication station 40Z side based on the optical signal received from the dark fiber 11 (step S12).

[0045] Specifically, in the second optical fiber sensing, vibrations applied to the optical fiber cable 20 are detected on the communication station 40Z side, and if vibrations are detected, the distance of the dark fiber 11 from the location of the optical fiber sensing device 30 (communication unit 31) to the location where the vibration occurred is determined.

[0046] Thereafter, the judgment unit 33 judges whether or not the dark fiber 11 is connected to the communication station 40A and the communication station 40Z based on the result of the first optical fiber sensing in step S11 and the result of the second optical fiber sensing in step S12 (step S13).

[0047] Specifically, when vibrations are detected by the first optical fiber sensing and the second optical fiber sensing, the determination unit 33 calculates the difference between the distance of the communication fiber 10AZ determined by the first optical fiber sensing and the distance of the dark fiber 11 determined by the second optical fiber sensing. Then, when vibrations are detected by the first optical fiber sensing and the second optical fiber sensing and the difference is within a predetermined range, the determination unit 33 determines that the dark fiber 11 is connected to the communication station 40A and the communication station 40Z. On the other hand, when vibrations are not detected by the second optical fiber sensing, the determination unit 33 determines that the dark fiber 11 is disconnected between the communication station 40A and the communication station 40Z.

[0048] In the example of Fig. 1, two dark fibers 11AZ and 11A are housed in the same optical fiber cable 20 as the communication fiber 10AZ. Therefore, in the example of Fig. 5, the processes of steps S12 and S13 may be performed for each of the dark fibers 11AZ and 11A.

[0049] As described above, according to the first embodiment, first, the detection unit 32 performs a first optical fiber sensing to detect vibrations given to the optical fiber cable 20 on the communication station 40Z side based on an optical signal received from the communication fiber 10AZ in a state where the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side. Next, the detection unit 32 performs a second optical fiber sensing to detect vibrations given to the optical fiber cable 20 on the communication station 40Z side based on an optical signal received from the dark fiber 11 in a state where the dark fiber 11 is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side. After that, the determination unit 33 determines whether the dark fiber 11 is connected to the communication station 40A and the communication station 40Z based on the results of the first optical fiber sensing and the second optical fiber sensing. This makes it possible to find the dark fiber 11AZ laid on the same route as the communication fiber 10AZ connected to the communication station 40A and the communication station 40Z. Therefore, by performing optical fiber sensing using the dark fiber 11AZ, it is possible to identify the laying route of the communication fiber 10AZ.

[0050] <Embodiment 2> First, with reference to FIG. 6, a configuration example of an optical fiber sensing system according to the second embodiment will be described. As shown in Figure 6, the optical fiber sensing system of this embodiment 2 differs from the configuration of Figure 1 of the above-mentioned embodiment 1 in that a closure 50 is interposed between communication station 40A and communication station 40Z.

[0051] 6, the optical fiber cable 20A is interposed between the communication station 40A and the closure 50, and houses a communication fiber 10AZ (first optical fiber). The communication fiber 10AZ is connected to the communication station 40A and the communication station 40Z via the closure 50.

[0052] The optical fiber cable 20A also accommodates dark fibers 11AZ and 11A (second optical fiber). The dark fiber 11AZ, like the communication fiber 10AZ, is connected to the communication station 40A and the communication station 40Z via the closure 50. On the other hand, the dark fiber 11A is connected to the communication station 40A and the closure 50, but does not extend to the communication station 40Z.

[0053] The optical fiber cable 20Z is interposed between the closure 50 and the communication station 40Z, and accommodates the above-mentioned communication fiber 10AZ and dark fiber 11AZ.

[0054] Next, the operation of the optical fiber sensing device 30 according to the second embodiment will be described below with reference to FIG. As shown in FIG. 7, first, the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, and a first optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20Z by a user on the communication station 40Z side. Next, the dark fibers 11AZ, 11A housed in the same optical fiber cable 20A as the communication fiber 10AZ are connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side in random order, and a second optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20Z by a user on the communication station 40Z side each time the connection is made. Also, each time the connection is made, it is determined whether the connected dark fibers 11AZ, 11A are connected to the communication station 40A and the communication station 40Z. Therefore, in the example of FIG. 7, the communication station 40A is the first point, and the communication station 40Z is the second point. In the example of FIG. 7, the specific operations of the above-mentioned first and second optical fiber sensing and the above-mentioned determination are similar to those in the above-mentioned first embodiment, and therefore description thereof will be omitted.

[0055] 7, the determination unit 33 determines that the dark fiber 11AZ is connected to the communication office 40A and the communication office 40Z. On the other hand, the determination unit 33 determines that the dark fiber 11A is disconnected between the communication office 40A and the communication office 40Z.

[0056] As described above, according to the second embodiment, even if a closure 50 is interposed between the communication office 40A and the communication office 40Z, it is possible to find the dark fiber 11AZ that is laid along the same route as the communication fiber 10AZ that is connected between the communication office 40A and the communication office 40Z. Therefore, by performing optical fiber sensing using the dark fiber 11AZ, it is possible to identify the laying route of the communication fiber 10AZ.

[0057] <Embodiment 3> First, with reference to FIG. 8, a configuration example of an optical fiber sensing system according to the third embodiment will be described. As shown in FIG. 8, the optical fiber sensing system of the third embodiment differs from the configuration of the second embodiment shown in FIG. 6 in that the dark fibers connected to each of the communication stations 40A, 40Z extend only to the closure 50.

[0058] 8, the optical fiber cable 20A is interposed between the communication station 40A and the closure 50, and houses a communication fiber 10AZ (first optical fiber). The communication fiber 10AZ is connected to the communication station 40A and the communication station 40Z via the closure 50.

[0059] The optical fiber cable 20A also accommodates dark fibers 11A-1 and 11A-2 (second optical fibers). The dark fibers 11A-1 and 11A-2 are connected to the communication station 40A and the closure 50, but do not extend to the communication station 40Z.

[0060] The optical fiber cable 20Z is interposed between the closure 50 and the communication station 40Z, and houses the above-mentioned communication fiber 10AZ. The optical fiber cable 20Z also accommodates a dark fiber 11Z (second optical fiber). The dark fiber 11Z is connected to the closure 50 and the communication station 40Z, but does not extend to the communication station 40A.

[0061] Next, the operation of the optical fiber sensing device 30 according to the third embodiment will be described below with reference to Fig. 9 to Fig. 11. Note that the order of the operations performed in Fig. 9 and Fig. 10 is not limited.

[0062] As shown in FIG. 9, first, the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, and a first optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20A on the closure 50 side by a user. Next, the dark fibers 11A-1 and 11A-2 housed in the same optical fiber cable 20A as the communication fiber 10AZ are connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side in random order, and a second optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20A on the closure 50 side by a user each time the connection is made. Also, each time the connection is made, it is determined whether the connected dark fibers 11A-1 and 11A-2 are connected to the communication station 40A and the closure 50. Therefore, in the example of FIG. 9, the communication station 40A is the first point, and the closure 50 is the second point. In the example of FIG. 9, the specific operations of the above-mentioned first and second optical fiber sensing and the above-mentioned determination are similar to those in the above-mentioned first embodiment, and therefore description thereof will be omitted.

[0063] As a result of the operation of FIG. 9, the determining unit 33 determines that the dark fibers 11A-1 and 11A-2 are connected to the communication office 40A and the closure 50.

[0064] Also, as shown in FIG. 10, first, the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the closure 50 side, and a first optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20Z on the communication station 40Z side by a user. Next, the dark fiber 11Z housed in the same optical fiber cable 20Z as the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the closure 50 side, and a second optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20Z on the communication station 40Z side by a user. Also, it is determined whether the connected dark fiber 11Z is connected to the closure 50 and the communication station 40Z. Therefore, in the example of FIG. 10, the closure 50 is the first point, and the communication station 40Z is the second point. However, conversely, the closure 50 may be the second point, and the communication station 40Z may be the first point. That is, the communication fiber 10AZ and the dark fiber 11Z may be connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40Z side, and vibration may be applied to the optical fiber cable 20Z on the closure 50 side. Note that, in Fig. 10, the specific operations of the above-mentioned first and second optical fiber sensing and the above-mentioned determination are similar to those in the above-mentioned first embodiment, and therefore description thereof will be omitted.

[0065] As a result of the operation of FIG. 10, the determining unit 33 determines that the dark fiber 11Z is connected to the closure 50 and the communication station 40Z.

[0066] As described above, the determination unit 33 determines that the dark fibers 11A-1 and 11A-2 are connected to the communication office 40A and the closure 50, and also determines that the dark fiber 11Z is connected to the closure 50 and the communication office 40Z.

[0067] Therefore, when the dark fiber 11A-1 or 11A-2 and the dark fiber 11Z are spliced ​​together at the closure 50, the obtained optical fiber is connected to the communication station 40A and the communication station 40Z, similar to the communication fiber 10AZ. Therefore, when identifying the laying route of the communication fiber 10AZ, optical fiber sensing can be performed using the optical fiber in which the dark fiber 11A-1 or 11A-2 and the dark fiber 11Z are spliced ​​together. FIG. 11 shows an example in which the dark fiber 11A-1 and the dark fiber 11Z are spliced ​​together at the closure 50.

[0068] As described above, according to the third embodiment, even if the dark fibers connected to each of the communication offices 40A and 40Z extend only to the closure 50, the dark fibers 11A-1 and 11A-2 connected to the communication office 40A and the closure 50 can be found. Also, the dark fiber 11Z connected to the closure 50 and the communication office 40Z can be found. Therefore, by splicing the dark fiber 11A-1 or 11A-2 and the dark fiber 11Z at the closure 50, an optical fiber laid in the same route as the communication fiber 10AZ connected to the communication office 40A and the communication office 40Z can be obtained. Therefore, by performing optical fiber sensing using the obtained optical fiber, the laying route of the communication fiber 10AZ can be specified.

[0069] <Fourth embodiment> First, with reference to FIG. 12, a configuration example of an optical fiber sensing system according to the fourth embodiment will be described. As shown in Figure 12, the optical fiber sensing system of this embodiment 4 differs from the configuration of Figure 8 of the above-mentioned embodiment 3 in that communication station 40A is connected in a one-to-multiple manner to communication stations 40Y and 40Z.

[0070] 12, the optical fiber cable 20A is interposed between the communication station 40A and the closure 50, and accommodates the communication fibers 10AY and 10AZ (first optical fibers). The communication fiber 10AY is connected to the communication station 40A and the communication station 40Y via the closure 50. The communication fiber 10AZ is connected to the communication station 40A and the communication station 40Z via the closure 50.

[0071] The optical fiber cable 20A also accommodates a dark fiber 11A (second optical fiber). The dark fiber 11A is connected to the communication station 40A and the closure 50, but does not extend to the communication stations 40Y and 40Z.

[0072] The optical fiber cable 20Y is interposed between the closure 50 and the communication station 40Y, and houses the above-mentioned communication fiber 10AY. The optical fiber cable 20Y also accommodates dark fibers 11Y-1 and 11Y-2 (second optical fibers). The dark fibers 11Y-1 and 11Y-2 are connected to the closure 50 and the communication station 40Y, but do not extend to the communication station 40A.

[0073] The optical fiber cable 20Z is interposed between the closure 50 and the communication station 40Z, and houses the above-mentioned communication fiber 10AZ. The optical fiber cable 20Z also accommodates a dark fiber 11Z (second optical fiber). The dark fiber 11Z is connected to the closure 50 and the communication station 40Z, but does not extend to the communication station 40A.

[0074] Next, the operation of the optical fiber sensing device 30 according to the fourth embodiment will be described below with reference to Figs. 13 to 15. In the fourth embodiment, in addition to the operations shown in Figs. 13 and 14, the operation shown in Fig. 10 is also performed. There is no limitation on the order in which the operations shown in Figs. 13, 14, and 10 are performed.

[0075] As shown in FIG. 13, first, the communication fiber 10AY is connected to the communication unit 31 of the optical fiber sensing device 30 on the closure 50 side, and a first optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20Y by a user on the communication station 40Y side. Next, the dark fibers 11Y-1 and 11Y-2 housed in the same optical fiber cable 20Y as the communication fiber 10AY are connected to the communication unit 31 of the optical fiber sensing device 30 on the closure 50 side in random order, and a second optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20Y by a user on the communication station 40Y side each time the connection is made. Also, each time the connection is made, it is determined whether the connected dark fibers 11Y-1 and 11Y-2 are connected to the closure 50 and the communication station 40Y. Therefore, in the example of FIG. 13, the closure 50 is the first point, and the communication station 40Y is the second point. However, conversely, the closure 50 may be the second point and the communication station 40Y may be the first point. That is, the communication fiber 10AZ and the dark fibers 11Y-1 and 11Y-2 may be connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40Y side, and vibration may be applied to the optical fiber cable 20Y on the closure 50 side. Note that in Fig. 13, the specific operations of the above-mentioned first and second optical fiber sensing and the above-mentioned determination are similar to those in the above-mentioned first embodiment, and therefore description thereof will be omitted.

[0076] As a result of the operation in FIG. 13, the determining unit 33 determines that the dark fibers 11Y-1 and 11Y-2 are connected to the closure 50 and the communication station 40Y.

[0077] Also, as shown in FIG. 14, first, the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, and a first optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20A on the closure 50 side by a user. However, the first optical fiber sensing may be performed by connecting the communication fiber 10AY to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side. Next, the dark fiber 11A housed in the same optical fiber cable 20A as the communication fiber 10AZ is connected to the communication unit 31 of the optical fiber sensing device 30 on the communication station 40A side, and a second optical fiber sensing is performed to detect vibrations given to the optical fiber cable 20A on the closure 50 side by a user. Also, it is determined whether the connected dark fiber 11A is connected to the communication station 40A and the closure 50. Therefore, in the example of FIG. 14, the communication station 40A is the first point, and the closure 50 is the second point. In the example of FIG. 14, the specific operations of the above-mentioned first and second optical fiber sensing and the above-mentioned determination are similar to those in the above-mentioned first embodiment, and therefore description thereof will be omitted.

[0078] As a result of the operation of FIG. 14, the determining unit 33 determines that the dark fiber 11A is connected to the communication office 40A and the closure 50. As a result of the operation of FIG. 10 described above, the determining unit 33 determines that the dark fiber 11Z is connected to the closure 50 and the communication station 40Z.

[0079] Therefore, when the dark fiber 11A and the dark fiber 11Y-1 or 11Y-2 are spliced ​​together at the closure 50, the obtained optical fiber is connected to the communication office 40A and the communication office 40Y, similar to the communication fiber 10AY. Therefore, when identifying the laying route of the communication fiber 10AY, optical fiber sensing can be performed using the optical fiber in which the dark fiber 11A and the dark fiber 11Y-1 or 11Y-2 are spliced ​​together. FIG. 15 shows an example in which the dark fiber 11A and the dark fiber 11Y-1 are spliced ​​together at the closure 50.

[0080] Furthermore, when the dark fiber 11A and the dark fiber 11Z are spliced ​​together at the closure 50, the resulting optical fiber is connected to the communication station 40A and the communication station 40Z, similar to the communication fiber 10AZ. Therefore, when identifying the laying route of the communication fiber 10AZ, optical fiber sensing can be performed using the optical fiber in which the dark fiber 11A and the dark fiber 11Z are spliced ​​together.

[0081] As described above, according to the fourth embodiment, even when the communication office 40A is connected to the communication offices 40Y and 40Z in a one-to-multiple manner, the dark fiber 11A connected to the communication office 40A and the closure 50 can be found. Also, the dark fibers 11Y-1 and 11Y-2 connected to the closure 50 and the communication office 40Y can be found. Also, the dark fiber 11Z connected to the closure 50 and the communication office 40Z can be found. Therefore, if the dark fiber 11A and the dark fiber 11Y-1 or 11Y-2 are spliced ​​together at the closure 50, an optical fiber laid in the same route as the communication fiber 10AY connected to the communication office 40A and the communication office 40Y can be obtained. Also, if the dark fiber 11A and the dark fiber 11Z are spliced ​​together at the closure 50, an optical fiber laid in the same route as the communication fiber 10AZ connected to the communication office 40A and the communication office 40Z can be obtained. Therefore, by performing optical fiber sensing using the obtained optical fiber, it is possible to identify the laying route of the communication fiber 10AY or 10AZ.

[0082] <Other embodiments> In the above-mentioned first to fourth embodiments, the communication unit 31, the detection unit 32, and the determination unit 33 are provided in the same optical fiber sensing device 30, but this is not limited thereto, and they may be arranged separately from each other. For example, the communication unit 31, the detection unit 32, and the determination unit 33 may be arranged in different devices. Furthermore, the detection unit 32 and the determination unit 33 may be arranged on the cloud.

[0083] <Hardware configuration of the optical fiber sensing device according to the embodiment> Next, with reference to FIG. 16, an example of the hardware configuration of a computer that realizes the optical fiber sensing device 30 according to the above-mentioned first to fourth embodiments will be described.

[0084] 16, a computer 90 includes a processor 91, a memory 92, a storage 93, an input / output interface (input / output I / F) 94, and a communication interface (communication I / F) 95. The processor 91, the memory 92, the storage 93, the input / output interface 94, and the communication interface 95 are connected by a data transmission path for transmitting and receiving data to and from each other.

[0085] The processor 91 is, for example, an arithmetic processing device such as a central processing unit (CPU) or a graphics processing unit (GPU). The memory 92 is, for example, a random access memory (RAM) or a read only memory (ROM). The storage 93 is, for example, a storage device such as a hard disk drive (HDD), a solid state drive (SSD), or a memory card. The storage 93 may also be a memory such as a RAM or a ROM.

[0086] The storage 93 stores programs that realize the functions of the components of the optical fiber sensing device 30. The processor 91 executes each of these programs to realize the functions of the components of the optical fiber sensing device 30. When executing each of the above programs, the processor 91 may read these programs onto the memory 92 and then execute them, or may execute them without reading them onto the memory 92. The memory 92 and the storage 93 also serve to store information and data held by the components of the optical fiber sensing device 30.

[0087] The above-mentioned program can be stored using various types of non-transitory computer readable media and can be provided to a computer (including the computer 90). The non-transitory computer readable medium includes various types of tangible storage media. Examples of the non-transitory computer readable medium include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), compact disc-ROMs (CD-ROMs), CD-recordables (CD-Rs), CD-rewritables (CD-R / Ws), and semiconductor memories (e.g., mask ROMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, and RAMs). The program can also be provided to a computer by various types of transitory computer readable media. Examples of the transitory computer readable medium include electric signals, optical signals, and electromagnetic waves. The transitory computer readable medium can provide the program to a computer via a wired communication path such as an electric wire and an optical fiber, or via a wireless communication path.

[0088] The input / output interface 94 is connected to a display device 941, an input device 942, a sound output device 943, and the like. The display device 941 is a device that displays a screen corresponding to drawing data processed by the processor 91, such as an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, or a monitor. The input device 942 is a device that accepts an operation input by an operator, and is, for example, a keyboard, a mouse, or a touch sensor. The display device 941 and the input device 942 may be integrated and realized as a touch panel. The sound output device 943 is a device that acoustically outputs a sound corresponding to the sound data processed by the processor 91, such as a speaker.

[0089] The communication interface 95 transmits and receives data to and from an external device. For example, the communication interface 95 communicates with the external device via a wired communication path or a wireless communication path.

[0090] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. For example, the above-described embodiments may be used in combination with one another in whole or in part.

[0091] Furthermore, some or all of the above-described embodiments can be described as, but are not limited to, the following supplementary notes. (Appendix 1) an optical fiber cable that houses a first optical fiber connected to a first point and a second point and that houses a second optical fiber; a communication unit to which the first optical fiber or the second optical fiber is connected, which transmits pulsed light to the first optical fiber or the second optical fiber connected thereto, and receives an optical signal from the first optical fiber or the second optical fiber connected thereto; a detection unit that performs first optical fiber sensing to detect vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber in a state in which the first optical fiber is connected to the communication unit at the first location, and that performs second optical fiber sensing to detect the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber in a state in which the second optical fiber is connected to the communication unit at the first location; and a determination unit that determines whether or not the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing. Fiber optic sensing system. (Appendix 2) The detection unit is In the first optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the first optical fiber from the location of the communication unit to the location where the vibration occurs is specified; In the second optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the second optical fiber from the location of the communication unit to the location where the vibration occurs is specified; The determination unit is When the vibration is detected by the first optical fiber sensing and the second optical fiber sensing, a difference between a distance of the first optical fiber determined by the first optical fiber sensing and a distance of the second optical fiber determined by the second optical fiber sensing is calculated; determining whether the second optical fiber is connected to the first point and the second point based on the difference; 2. The optical fiber sensing system of claim 1. (Appendix 3) the determination unit determines that the second optical fiber is connected to the first point and the second point when the vibration can be detected by the first optical fiber sensing and the second optical fiber sensing and the difference is within a predetermined range. 3. The optical fiber sensing system of claim 2. (Appendix 4) When the vibration cannot be detected by the second optical fiber sensing, the determination unit determines that the second optical fiber is broken between the first point and the second point. 3. The optical fiber sensing system of claim 2. (Appendix 5) The first optical fiber is a communication fiber used for a communication line. 2. The optical fiber sensing system of claim 1. (Appendix 6) a communication unit to which a first optical fiber connected to a first point and a second point or a second optical fiber housed in the same optical fiber cable as the first optical fiber is connected, the communication unit transmitting pulse light to the connected first optical fiber or the connected second optical fiber and receiving an optical signal from the connected first optical fiber or the connected second optical fiber; a detection unit that performs first optical fiber sensing to detect vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber in a state in which the first optical fiber is connected to the communication unit at the first location, and that performs second optical fiber sensing to detect the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber in a state in which the second optical fiber is connected to the communication unit at the first location; and a determination unit that determines whether or not the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing. Optical fiber sensing device. (Appendix 7) The detection unit is In the first optical fiber sensing, a vibration applied to the optical fiber cable is detected at the second point side, and when the vibration is detected, a distance of the first optical fiber from the location of the communication unit to the location where the vibration occurs is specified; In the second optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the second optical fiber from the location of the communication unit to the location where the vibration occurs is specified; The determination unit is When the vibration is detected by the first optical fiber sensing and the second optical fiber sensing, a difference between a distance of the first optical fiber determined by the first optical fiber sensing and a distance of the second optical fiber determined by the second optical fiber sensing is calculated; determining whether the second optical fiber is connected to the first point and the second point based on the difference; 7. The optical fiber sensing device of claim 6. (Appendix 8) the determination unit determines that the second optical fiber is connected to the first point and the second point when the vibration can be detected by the first optical fiber sensing and the second optical fiber sensing and the difference is within a predetermined range. 8. The optical fiber sensing device of claim 7. (Appendix 9) When the vibration cannot be detected by the second optical fiber sensing, the determination unit determines that the second optical fiber is broken between the first point and the second point. 8. The optical fiber sensing device of claim 7. (Appendix 10) The first optical fiber is a communication fiber used for a communication line. 7. The optical fiber sensing device of claim 6. (Appendix 11) An optical fiber sensing method using an optical fiber sensing device, comprising: a communication step of transmitting pulse light to a first optical fiber connected to a first point and a second point or to a second optical fiber housed in the same optical fiber cable as the first optical fiber, and receiving an optical signal from the first optical fiber or the second optical fiber; a detection step of performing a first optical fiber sensing for detecting vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber while the first optical fiber is connected to the optical fiber sensing device at the first location, and performing a second optical fiber sensing for detecting the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber while the second optical fiber is connected to the optical fiber sensing device at the first location; and a determining step of determining whether the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing. Fiber optic sensing methods. (Appendix 12) In the detection step, In the first optical fiber sensing, a vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the first optical fiber from the location of the optical fiber sensing device to the location where the vibration occurs is specified; In the second optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the second optical fiber from the location of the optical fiber sensing device to the location where the vibration occurs is specified; In the determination step, When the vibration is detected by the first optical fiber sensing and the second optical fiber sensing, a difference between a distance of the first optical fiber determined by the first optical fiber sensing and a distance of the second optical fiber determined by the second optical fiber sensing is calculated; determining whether the second optical fiber is connected to the first point and the second point based on the difference; 12. The optical fiber sensing method of claim 11. (Appendix 13) In the determining step, when the vibration can be detected by the first optical fiber sensing and the second optical fiber sensing and the difference is within a predetermined range, it is determined that the second optical fiber is connected to the first point and the second point. 13. The optical fiber sensing method of claim 12. (Appendix 14) In the determining step, if the vibration cannot be detected by the second optical fiber sensing, it is determined that the second optical fiber is broken between the first point and the second point. 13. The optical fiber sensing method of claim 12. (Appendix 15) The first optical fiber is a communication fiber used for a communication line. 12. The optical fiber sensing method of claim 11. [Explanation of symbols]

[0092] 10AY, 10AZ Communication fiber 11A, 11A-1, 11A-2, 11AZ, 11Y-1, 11Y-2, 11Z dark fiber 20, 20A, 20Y, 20Z Optical fiber cable 30 Optical fiber sensing device 31 Communications Department 32 Detection unit 33 Judgment section 40A, 40Y, 40Z Communication building 50 Closure 90 Computer 91 Processor 92 Memory 93 Storage 94 Input / Output Interface 941 Display device 942 Input Device 943 Sound output device 95 Communication Interface

Claims

1. an optical fiber cable containing a first optical fiber connected to a first point and a second point and containing a second optical fiber; a communication unit to which the first optical fiber or the second optical fiber is connected, the communication unit transmitting pulsed light to the first optical fiber or the second optical fiber connected thereto, and receiving an optical signal from the first optical fiber or the second optical fiber connected thereto; a detection unit that performs a first optical fiber sensing to detect vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber while the first optical fiber is connected to the communication unit at the first location, and that performs a second optical fiber sensing to detect the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber while the second optical fiber is connected to the communication unit at the first location; a determination unit that determines whether or not the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing. Fiber optic sensing system.

2. The detection unit is In the first optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the first optical fiber from the location of the communication unit to the location where the vibration occurs is specified; In the second optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point, and if the vibration is detected, a distance of the second optical fiber from the location of the communication unit to the location where the vibration occurs is specified; The determination unit is When the vibration is detected by the first optical fiber sensing and the second optical fiber sensing, a difference between a distance of the first optical fiber determined by the first optical fiber sensing and a distance of the second optical fiber determined by the second optical fiber sensing is calculated; determining whether the second optical fiber is connected to the first point and the second point based on the difference; The optical fiber sensing system of claim 1 .

3. the determination unit determines that the second optical fiber is connected to the first point and the second point when the vibration can be detected by the first optical fiber sensing and the second optical fiber sensing and the difference is within a predetermined range. The optical fiber sensing system of claim 2 .

4. When the vibration cannot be detected by the second optical fiber sensing, the determination unit determines that the second optical fiber is broken between the first point and the second point. The optical fiber sensing system of claim 2 .

5. The first optical fiber is a communication fiber used for a communication line. The optical fiber sensing system of claim 1 .

6. a communication unit to which a first optical fiber connected to a first point and a second point or a second optical fiber housed in the same optical fiber cable as the first optical fiber is connected, the communication unit transmitting pulse light to the connected first optical fiber or the connected second optical fiber and receiving an optical signal from the connected first optical fiber or the connected second optical fiber; a detection unit that performs a first optical fiber sensing to detect vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber while the first optical fiber is connected to the communication unit at the first location, and that performs a second optical fiber sensing to detect the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber while the second optical fiber is connected to the communication unit at the first location; a determination unit that determines whether or not the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing. Optical fiber sensing device.

7. The detection unit is In the first optical fiber sensing, a vibration applied to the optical fiber cable is detected at the second point side, and when the vibration is detected, a distance of the first optical fiber from the location of the communication unit to the location where the vibration occurs is specified; In the second optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point, and if the vibration is detected, a distance of the second optical fiber from the location of the communication unit to the location where the vibration occurs is specified; The determination unit is When the vibration is detected by the first optical fiber sensing and the second optical fiber sensing, a difference between a distance of the first optical fiber determined by the first optical fiber sensing and a distance of the second optical fiber determined by the second optical fiber sensing is calculated; determining whether the second optical fiber is connected to the first point and the second point based on the difference; 7. The optical fiber sensing device according to claim 6.

8. the determination unit determines that the second optical fiber is connected to the first point and the second point when the vibration can be detected by the first optical fiber sensing and the second optical fiber sensing and the difference is within a predetermined range.

8. The optical fiber sensing device according to claim 7.

9. When the vibration cannot be detected by the second optical fiber sensing, the determination unit determines that the second optical fiber is broken between the first point and the second point.

8. The optical fiber sensing device according to claim 7.

10. The first optical fiber is a communication fiber used for a communication line.

7. The optical fiber sensing device according to claim 6.

11. An optical fiber sensing method using an optical fiber sensing device, comprising: a communication step of transmitting pulsed light to a first optical fiber connected to a first point and a second point or to a second optical fiber housed in the same optical fiber cable as the first optical fiber, and receiving an optical signal from the first optical fiber or the second optical fiber; a detection step of performing a first optical fiber sensing for detecting vibrations applied to the optical fiber cable at the second location based on an optical signal received from the first optical fiber while the first optical fiber is connected to the optical fiber sensing device at the first location, and performing a second optical fiber sensing for detecting the vibrations applied to the optical fiber cable at the second location based on an optical signal received from the second optical fiber while the second optical fiber is connected to the optical fiber sensing device at the first location; and a determining step of determining whether the second optical fiber is connected to the first point and the second point based on a result of the first optical fiber sensing and a result of the second optical fiber sensing. Fiber optic sensing methods.

12. In the detection step, In the first optical fiber sensing, a vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the first optical fiber from the location of the optical fiber sensing device to the location where the vibration occurs is specified; In the second optical fiber sensing, the vibration applied to the optical fiber cable is detected at the second point side, and if the vibration is detected, a distance of the second optical fiber from the location of the optical fiber sensing device to the location where the vibration occurs is specified; In the determination step, When the vibration is detected by the first optical fiber sensing and the second optical fiber sensing, a difference between a distance of the first optical fiber determined by the first optical fiber sensing and a distance of the second optical fiber determined by the second optical fiber sensing is calculated; determining whether the second optical fiber is connected to the first point and the second point based on the difference; The optical fiber sensing method of claim 11.

13. In the determining step, when the vibration can be detected by the first optical fiber sensing and the second optical fiber sensing and the difference is within a predetermined range, it is determined that the second optical fiber is connected to the first point and the second point. The optical fiber sensing method of claim 12.

14. In the determining step, if the vibration cannot be detected by the second optical fiber sensing, it is determined that the second optical fiber is broken between the first point and the second point. The optical fiber sensing method of claim 12.

15. The first optical fiber is a communication fiber used for a communication line. The optical fiber sensing method of claim 11.

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