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

Abstract

This optical fiber sensing system comprises: an OLT (10); a plurality of ONUs (20); an optical fiber (30) connected to the OLT (10); a plurality of optical fibers (40) connected to the ONUs (20); a light output unit (12) that outputs pulse light to the optical fiber (30); a plurality of reflection parts (21) provided to the optical fibers (40); a branch part (50) that connects the optical fiber (30) to the optical fibers (40), outputs the pulse light to the optical fibers (40), and outputs reflected light of the pulse light reflected by one of the reflection parts (21) to the optical fiber (30); a light input unit (13) that receives the reflected light from the optical fiber (30); and a detection unit (14) that detects failure in an optical fiber (40) provided with the reflection part (21) that has output the reflected light through analysis of a pattern of the reflected light. The reflection parts (21) can individually switch execution of reflection of pulse light.

Description

[Technical Field]

[0001] The present disclosure relates to an optical fiber sensing system, an optical fiber sensing method, and an ONU (Optical Network Unit). [Background technology]

[0002] The PON (Passive Optical Network) system is known as one of the technologies that realizes FTTH (Fiber to the Home), which draws optical fiber transmission lines from a telecommunications station to users' homes. A typical PON system configuration is one OLT (Optical Line Terminal) on the telecommunications station side, to which multiple ONUs on the user side are connected via optical fiber transmission lines.

[0003] Furthermore, techniques for detecting faults in optical fiber transmission lines in PON systems are also known. For example, Patent Document 1 discloses a technique for detecting faults in optical fiber transmission lines in a WDM (Wavelength Division Multiplexing)-PON system.

[0004] Specifically, in Patent Document 1, the WDM-PON system is configured such that an OLT and a splitter are connected via a single common optical fiber line, and the splitter and each of multiple ONUs are connected via multiple individual optical fiber lines. The multiple individual optical fiber lines are assigned different wavelengths and have different lengths. Furthermore, the multiple ONUs are equipped with a function for total reflection of incident light using a mirror or the like during a communication outage. An optical line fault location device inputs broadband optical pulses into the WDM-PON system during a communication outage via the common optical fiber line, and the splitter separates the broadband optical pulses into individual wavelength components and outputs them to the multiple individual optical fiber lines. The optical line fault location device then receives backscattered light of each wavelength component and total reflection light from each of the multiple ONUs. In this case, in the time waveform obtained by combining the wavelength components, the total reflection components from each ONU are displayed separately at different positions because the individual optical fiber lines have different lengths. Therefore, the optical line fault detection device compares the time waveform with a reference waveform, determines which wavelengths have total reflection components that do not appear in the time waveform, and determines that a fault has occurred in the individual optical fiber line to which wavelengths have been assigned that do not have total reflection components. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-035598 Summary of the Invention [Problem to be solved by the invention]

[0006] Meanwhile, optical fiber sensing technology is also known as another technology for detecting faults in optical fiber transmission lines. Specifically, in optical fiber sensing, an optical fiber sensing device outputs pulsed light to an optical fiber transmission line and receives return light such as backscattered light and reflected light from the pulsed light. The pattern of the return light varies depending on whether or not there is a fault in the optical fiber transmission line. Therefore, the optical fiber sensing device detects faults in the optical fiber transmission line by analyzing the pattern of the return light.

[0007] Therefore, the application of optical fiber sensing technology to PON systems to detect faults in optical fiber transmission lines has been studied recently. However, because a PON system is configured with multiple ONUs connected to one OLT via optical fiber transmission lines, failures can occur in a wide variety of locations. Specifically, failures can occur not only in the optical fiber transmission line connected to the OLT, but also in the multiple optical fiber transmission lines connected to each of the multiple ONUs.

[0008] Therefore, when optical fiber sensing technology is applied to a PON system, it is necessary to individually detect faults in the multiple optical fiber transmission lines connected to each of the multiple ONUs.

[0009] The technique disclosed in Patent Document 1 makes it possible to individually detect faults in a plurality of optical fiber transmission lines connected to a plurality of ONUs. However, the technology disclosed in Patent Document 1 does not apply optical fiber sensing technology. Furthermore, the technology disclosed in Patent Document 1 has problems in that the multiple optical fiber transmission paths connected to the multiple ONUs must be different lengths, and that communication must be stopped to detect a fault.

[0010] Therefore, in view of the above-mentioned problems, the object of the present disclosure is to provide an optical fiber sensing system, an optical fiber sensing method, and an ONU that can individually detect faults in multiple optical fiber transmission paths connected to each of multiple ONUs when optical fiber sensing technology is applied to a PON system. [Means for solving the problem]

[0011] An optical fiber sensing system according to one aspect includes: OLT (Optical Line Terminal) and Multiple ONUs (Optical Network Units) and a first optical fiber transmission line connected to the OLT; a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs; an optical output unit that outputs pulsed light to the first optical fiber transmission line; a plurality of reflecting portions provided in each of the plurality of second optical fiber transmission lines; a branching section that connects the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines, outputs the pulsed light output to the first optical fiber transmission line to each of the plurality of second optical fiber transmission lines, and outputs reflected light obtained by reflecting the pulsed light at any of the plurality of reflecting sections to the first optical fiber transmission line; an optical input unit that receives the reflected light from the first optical fiber transmission line; a detection unit that detects a fault in the second optical fiber transmission line that includes the reflector that outputs the reflected light by analyzing a pattern of the reflected light, Each of the plurality of reflecting sections is capable of individually switching between reflecting the pulsed light.

[0012] An optical fiber sensing method according to one aspect includes: An optical fiber sensing method using an optical fiber sensing system, comprising: The optical fiber sensing system includes: OLT (Optical Line Terminal) and Multiple ONUs (Optical Network Units) and a first optical fiber transmission line connected to the OLT; a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs; a branching section that connects the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines; a plurality of reflectors provided in the plurality of second optical fiber transmission lines, each of which can individually switch between reflection of pulsed light from the second optical fiber transmission lines; The optical fiber sensing method includes: a switching step of switching the plurality of reflecting units one by one in sequence to reflect the pulsed light; an optical output step of outputting the pulsed light from the first optical fiber transmission line to each of the plurality of second optical fiber transmission lines via the branching unit; a reflecting step of outputting reflected light obtained by reflecting the pulsed light at one of the reflecting units, which is switched to reflect the pulsed light, to the first optical fiber transmission line; an optical receiving step of receiving the reflected light from the first optical fiber transmission line; a detection step of detecting a fault in the second optical fiber transmission line provided with one of the reflecting portions by analyzing a pattern of the reflected light; Includes:

[0013] According to one aspect, the ONU comprises: In an optical fiber sensing system including an OLT (Optical Line Terminal), a plurality of ONUs (Optical Network Units), a first optical fiber transmission line connected to the OLT, a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs, and a branching section connecting the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines, one of the plurality of ONUs, A reflective portion is provided, The reflecting sections are capable of individually switching between reflecting pulsed light from the second optical fiber transmission line.

[0014] According to the above-described aspects, when optical fiber sensing technology is applied to a PON system, it is possible to provide an optical fiber sensing system, an optical fiber sensing method, and an ONU that are capable of individually detecting faults in multiple optical fiber transmission paths connected to each of multiple ONUs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating a configuration example of an optical fiber sensing system according to a first embodiment. [Figure 2] 5A and 5B are diagrams illustrating an example of acoustic data acquired from returned light by a detection unit according to the first embodiment. [Figure 3] FIG. 10 is a diagram illustrating a modified configuration example of the optical fiber sensing system according to the first embodiment. [Figure 4] 3 is a flowchart showing an example of a schematic operation flow of the optical fiber sensing system according to the first embodiment. FIG. [Figure 5] FIG. 10 is a diagram illustrating another modified configuration example of the optical fiber sensing system according to the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating a configuration example of an optical fiber sensing system according to a second embodiment. [Figure 7] 1 is a block diagram showing an example of the hardware configuration of a computer that realizes an OLT and an ONU according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

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

[0018] 1, the optical fiber sensing system according to the first embodiment includes an OLT 10, a plurality of ONUs 20-1 to 20-N (N is an integer of 2 or more), an optical fiber transmission line 30, a plurality of optical fiber transmission lines 40-1 to 40-N, and a branching unit 50. Hereinafter, when it is not necessary to specify which ONUs 20-1 to 20-N are involved, they will be referred to as "ONUs 20" as appropriate. Similarly, the optical fiber transmission lines 40-1 to 40-N will be referred to as "optical fiber transmission lines 40" as appropriate.

[0019] The OLT 10 and the plurality of ONUs 20-1 to 20-N are components that make up a PON system. In the first embodiment, the OLT 10 functions as an optical fiber sensing device.

[0020] The optical fiber transmission line 30 is connected to the OLT 10. The optical fiber transmission line 30 is made of an optical fiber. The optical fiber transmission line 30 is an example of a first optical fiber transmission line.

[0021] The plurality of optical fiber transmission lines 40-1 to 40-N are connected to the plurality of ONUs 20-1 to 20-N, respectively. The optical fiber transmission line 40 is made of an optical fiber. The optical fiber transmission line 40 is an example of a second optical fiber transmission line.

[0022] The branching unit 50 connects the optical fiber transmission line 30 to the plurality of optical fiber transmission lines 40-1 to 40-N. The branching unit 50 is configured by a coupler, an optical filter, and the like.

[0023] The OLT 10 includes a DAS (Distributed Acoustic Sensing) interrogator 11 and a detection unit 14. The DAS interrogator 11 also includes an optical output unit 12 and an optical input unit 13.

[0024] However, it is sufficient that the DAS interrogator 11 and the detection unit 14 are provided on the OLT 10 side when viewed from the branching unit 50. In other words, the DAS interrogator 11 and the detection unit 14 may be provided either inside or outside the OLT 10 as long as they are provided on the OLT 10 side.

[0025] The optical output unit 12 outputs pulsed light to the optical fiber transmission line 30. The pulsed light is used to detect faults in the optical fiber transmission lines 30, 40-1 to 40-N. It is preferable to use pulsed light in a band that is not used for the main signal of the PON system. This makes it possible to detect faults in the optical fiber transmission lines 30, 40-1 to 40-N even during transmission of the main signal, i.e., while the PON system is in operation. The operations of the light input unit 13 and the detection unit 14 will be described later.

[0026] The branching unit 50 outputs the pulsed light output from the optical output unit 12 to the optical fiber transmission line 30 to each of the plurality of optical fiber transmission lines 40-1 to 40-N. Furthermore, when a main signal for communication is output from the optical output unit 12 to the optical fiber transmission line 30, the branching unit 50 also outputs this main signal to each of the plurality of optical fiber transmission lines 40-1 to 40-N.

[0027] The branching unit 50 may be configured by a branching unit of a WDM-PON system. In a WDM-PON system, different wavelengths are assigned to each of the multiple optical fiber transmission lines 40-1 to 40-N. Therefore, the branching unit of a WDM-PON system has a filter function for extracting pulsed light of each wavelength. Therefore, when the branching unit 50 is configured by a branching unit of a WDM-PON system, the filter function of the branching unit is set so that pulsed light output to the optical fiber transmission line 30 is output to all of the multiple optical fiber transmission lines 40-1 to 40-N regardless of its wavelength.

[0028] Each of the plurality of ONUs 20-1 to 20-N includes a reflecting section 21. However, it is sufficient that the reflecting unit 21 is provided on the ONU 20 side when viewed from the splitter 50. In other words, the reflecting unit 21 may be provided either inside or outside the ONU 20 as long as it is provided on the ONU 20 side.

[0029] The reflecting unit 21 has a function of reflecting pulsed light from the optical fiber transmission line 40. The reflecting unit 21 is configured by a reflective amplifier (reflective gain element) or the like. When the reflecting unit 21 is configured by a reflective amplifier, it reflects the pulsed light, amplifies the reflected light, and outputs it.

[0030] Each of the plurality of reflecting sections 21 in the plurality of ONUs 20-1 to 20-N can individually switch between reflecting and not reflecting pulsed light. In the first embodiment, the plurality of reflectors 21 are switched one by one in order to reflect pulsed light. After the switching, as will be described later, the reflected light of pulsed light reflected by the reflector 21 that is reflecting the pulsed light is used to detect a fault in the optical fiber transmission line 40 connected to the ONU 20 in which the reflector 21 is provided, and when the fault detection is completed, another reflector 21 is switched to reflect pulsed light. The method of switching between reflection of pulsed light by the reflector 21 will be described later.

[0031] As the pulsed light is transmitted through the optical fiber transmission line 30, backscattered light is generated in the optical fiber transmission line 30. This backscattered light is received by the optical input unit 13. Furthermore, as the pulsed light is transmitted through each of the optical fiber transmission lines 40-1 to 40-N, backscattered light is also generated in each of the optical fiber transmission lines 40-1 to 40-N. These backscattered lights are combined by the branching unit 50 and output to the optical fiber transmission line 30, and received by the optical input unit 13. Furthermore, reflected light, in which the pulsed light is reflected by any of the plurality of reflecting units 21, is output by the branching unit 50 to the optical fiber transmission line 30, and received by the optical input unit 13.

[0032] In this way, the light input unit 13 receives, as return light, the backscattered light generated in the optical fiber transmission line 30, the backscattered light generated and combined in each of the optical fiber transmission lines 40-1 to 40-N, and the reflected light in which the pulsed light is reflected at any of the multiple reflecting units 21.

[0033] The detection unit 14 can identify the position (distance from the OLT 10) where the returned light originates based on the time difference between the time when the pulsed light is output by the optical output unit 12 and the time when the returned light is received by the optical input unit 13.

[0034] Furthermore, the detection unit 14 can identify whether the returned light is one of the following types based on the position where the returned light is generated. Backscattered light generated in the optical fiber transmission line 30 Backscattered light generated and combined in each of the optical fiber transmission lines 40-1 to 40-N Reflected light obtained by reflecting the pulsed light at any one of the plurality of reflecting portions 21

[0035] Furthermore, for example, if the returned light is reflected light resulting from reflection of pulsed light at the reflecting section 21 within the ONU 20-1, sound generated around the optical fiber transmission line 40-1 connected to the ONU 20-1 is transmitted to the optical fiber transmission line 40-1, and as a result, the characteristics (e.g., wavelength) of the returned light change. Therefore, the detector 14 can calculate the acoustic intensity of the sound generated around the optical fiber transmission line 40-1 based on the degree of change in the characteristics of the returned light.

[0036] The detection unit 14 can similarly calculate the acoustic intensity when the returned light is backscattered light generated in the optical fiber transmission line 30, or when the returned light is backscattered light generated in each of the optical fiber transmission lines 40-1 to 40-N and combined.

[0037] Therefore, the detector 14 can acquire acoustic data such as that shown in Fig. 2 based on the returned light received by the optical input unit 13. Fig. 2 shows an example of acoustic data at an arbitrary time in a situation where only the reflector 21 in the ONU 20-1 is performing reflection. In Fig. 2, the horizontal axis indicates the position where the returned light is generated (the distance from the OLT 10), and the vertical axis indicates acoustic intensity.

[0038] 2, acoustic data D1 is acoustic data of backscattered light generated in the optical fiber transmission line 30. An acoustic pattern appears in the acoustic data D1, and this acoustic pattern changes depending on whether or not there is a fault in the optical fiber transmission line 30. Therefore, the detector 14 can detect a fault in the optical fiber transmission line 30 by analyzing the acoustic pattern that appears in the acoustic data D1.

[0039] 2, acoustic data D3 is acoustic data of reflected light when pulsed light is reflected by reflector 21 in ONU 20-1. The acoustic pattern appearing in acoustic data D3 also differs depending on whether or not there is a fault in optical fiber transmission line 40-1 connected to ONU 20-1. Therefore, the detector 14 can detect a fault in the optical fiber transmission line 40-1 by analyzing the acoustic pattern that appears in the acoustic data D3.

[0040] 2, the acoustic data D2 is acoustic data of backscattered light generated and combined in each of the optical fiber transmission lines 40-1 to 40-N. Therefore, even if the acoustic pattern appearing in the acoustic data D2 is the acoustic pattern when a fault occurs, it is not possible to identify in which optical fiber transmission line 40 the fault occurred. Therefore, the detector 14 does not use the acoustic data D2 for fault detection.

[0041] Here, we will explain a specific method by which the detection unit 14 detects a fault in the optical fiber transmission lines 30 and 40. Here, we will explain an example of a method for detecting a fault in the optical fiber transmission line 40-1 connected to ONU 21-1 when the reflector 21 in ONU 21-1 is performing reflection.

[0042] (A1) Method A1 The detector 14 stores in advance in a memory (not shown) or the like, an acoustic pattern that appeared in the acoustic data when a fault occurred in the optical fiber transmission line 40-1 as a matching pattern. The matching pattern may be an individual pattern for each of the optical fiber transmission lines 40-1 to 40-N, or may be a pattern common to the optical fiber transmission lines 40-1 to 40-N.

[0043] First, the detector 14 acquires acoustic data of the reflected light, based on the reflected light reflected by the reflector 21 in the ONU 21-1 out of the return light received by the optical input unit 13. Next, the detection unit 14 compares the acoustic pattern included in the acquired acoustic data with the matching pattern. If the matching rate between the acoustic pattern and the matching pattern is equal to or greater than a threshold, the detection unit 14 determines that a fault has occurred in the optical fiber transmission line 40-1.

[0044] (A2) Method A2 The detection unit 14 prepares pairs of teacher data indicating the presence or absence of a fault in the optical fiber transmission line 40-1 and the acoustic pattern that appeared in the acoustic data at that time, and inputs each prepared pair to construct a learning model using a convolutional neural network (CNN) in advance, which is then stored in a memory (not shown) or the like. Note that the learning model may be an individual learning model for each of the optical fiber transmission lines 40-1 to 40-N, or may be a common learning model for the optical fiber transmission lines 40-1 to 40-N.

[0045] First, the detector 14 acquires acoustic data of the reflected light, based on the reflected light reflected by the reflector 21 in the ONU 21-1 out of the return light received by the optical input unit 13. Next, the detection unit 14 inputs the acoustic pattern included in the acquired acoustic data into the learning model, thereby obtaining information indicating the presence or absence of a fault in the optical fiber transmission line 40-1 as an output result of the learning model.

[0046] In addition, when detecting a fault in the optical fiber transmission line 30, the detecting unit 14 may detect the fault in the optical fiber transmission line 30 using a method substantially similar to the above-described method A1 or method A2.

[0047] The OLT 10 includes the DAS interrogator 11, but may instead include a DVS (Distributed Vibration Sensing) interrogator. In this case, the detector 14 acquires vibration data based on the return light received by the optical input unit 13, and analyzes the vibration pattern included in the acquired vibration data to detect faults in the optical fiber transmission lines 30 and 40.

[0048] The OLT 10 may also include a DTS (Distributed Temperature Sensing) interrogator instead of the DAS interrogator 11. In this case, the detector 14 acquires temperature data based on the return light received by the optical input unit 13, and analyzes the temperature pattern included in the acquired temperature data to detect a fault in the optical fiber transmission lines 30 and 40.

[0049] Furthermore, when the detection unit 14 determines that a fault has occurred in any of the optical fiber transmission lines 30, 40-1 to 40-N, it may notify the user of the optical fiber transmission line 30 or 40 in which the fault has occurred by displaying the optical fiber transmission line 30 or 40 on a display unit (not shown).

[0050] 2, the detecting unit 14 can identify not only the optical fiber transmission line 30 or 40 in which a fault has occurred, but also the location of the fault (the distance from the OLT 10) on the optical fiber transmission line 30 or 40 in which the fault has occurred. Therefore, when the detecting unit 14 determines that a fault has occurred in any of the optical fiber transmission lines 30, 40-1 to 40-N, it may notify not only the optical fiber transmission line 30 or 40 in which the fault has occurred, but also the location of the fault.

[0051] Furthermore, when the detecting unit 14 determines that a fault has occurred in any of the optical fiber transmission lines 40-1 to 40-N, it may notify the ONU 20 connected to the optical fiber transmission line 40 in which the fault has occurred.

[0052] Next, a method for switching between execution of reflection of pulsed light by the reflecting section 21 will be described in detail below. As described above, the plurality of reflecting sections 21 are switched one by one in sequence to reflect the pulsed light.

[0053] For example, first, the reflector 21 in the ONU 20-1 is made to reflect pulsed light, while the reflectors 21 in the other ONUs 20-2 to 20-N are made to stop reflecting pulsed light. In this state, the detector 14 detects a fault in the optical fiber transmission line 40-1 connected to the ONU 20-1. After the fault detection in the optical fiber transmission line 40-1 is completed, the detector 14 stops the reflection of the pulsed light by the reflector 21 in the ONU 20-1.

[0054] Next, the reflector 21 in another ONU 20 (for example, ONU 20-2) is caused to reflect the pulsed light. Thereafter, the above operation is repeated, and the reflectors 21 in the ONUs 20-1 to 20-N are switched one by one in order to reflect the pulsed light.

[0055] At this time, in the plurality of reflecting sections 21, specifically, execution of reflection of pulsed light is switched using one of the following methods.

[0056] (B1) Method B1 Method B1 is a method of switching over time. In method B1, the reflector 21 that reflects the pulsed light is switched for each time slot, thereby individually detecting faults in the plurality of optical fiber transmission lines 40-1 to 40-N connected to the plurality of ONUs 20-1 to 20-N, respectively.

[0057] In method B1, for example, different time slots may be set for each of the multiple reflectors 21. Then, each of the multiple reflectors 21 may reflect pulsed light in the time slot set for that reflector 21.

[0058] 3, a control unit 60 may be further provided that transmits a control signal to each of the plurality of reflectors 21 instructing whether or not to reflect pulsed light according to the time slot. Each of the plurality of reflectors 21 may then reflect pulsed light based on the control signal from the control unit 60. The control unit 60 may be provided within the OLT 10, or may be provided within an external control device (not shown).

[0059] (B2) Method B2 Method B2 is a method in which switching is performed by individual instructions. 3, for example, a control unit 60 may be further provided that transmits a control signal to each of the plurality of reflectors 21 instructing whether or not to reflect pulsed light. Each of the plurality of reflectors 21 may then reflect pulsed light based on the control signal from the control unit 60. Note that the control unit 60 may be provided within the OLT 10, or may be provided within an external control device (not shown).

[0060] (B3) Method B3 Method B3 is a method of switching based on error detection on the ONU 20 side. In method B3, for example, when an ONU 20 detects a reception error in pulsed light, the ONU 20 may cause the reflector 21 in the ONU 20 to reflect the pulsed light.

[0061] Next, an example of a schematic flow of operations of the optical fiber sensing system according to the first embodiment will be described with reference to FIG. As shown in FIG. 4, first, one of the reflecting sections 21 in the plurality of ONUs 20-1 to 20-N is switched so as to reflect pulsed light (step S11).

[0062] Next, the optical output unit 12 outputs pulsed light to the optical fiber transmission line 30 (step S12). This pulsed light is output by the branching unit 50 to each of the optical fiber transmission lines 40-1 to 40-N.

[0063] Then, the pulsed light is reflected by one of the reflecting sections 21 switched in step S11, and the reflected light is output to the optical fiber transmission line 30 by the branching section 50 and received by the light input section 13 (step S13).

[0064] Next, the detection unit 14 analyzes the acoustic pattern of the reflected light received by the optical input unit 13 to detect a fault in the optical fiber transmission path 40 connected to the ONU 20 equipped with the reflection unit 21 that output the reflected light (step S14).

[0065] After completion of step S14, if there is an optical fiber transmission line 40 for which fault detection has not been performed (Yes in step S15), the process returns to step S11. In step S11, one of the reflectors 21 in the ONU 20 connected to the optical fiber transmission line 40 for which fault detection has not been performed is switched to reflect pulsed light. On the other hand, after step S14 is completed, if there is no optical fiber transmission line 40 for which fault detection has not yet been performed (No in step S15), the process ends.

[0066] As described above, according to the first embodiment, each of the plurality of optical fiber transmission lines 40-1 to 40-N is provided with a reflecting section 21. Each of the plurality of reflecting sections 21 can individually switch between reflecting pulsed light and not reflecting pulsed light.

[0067] Therefore, for example, if only the reflector 21 provided in one optical fiber transmission line 40 of the plurality of optical fiber transmission lines 40-1 to 40-N reflects pulsed light, the reflected light from the one optical fiber transmission line 40 is received by the light input unit 13, and the detector 14 can detect a fault in the one optical fiber transmission line 40. As a result, even when optical fiber sensing technology is applied to a PON system, fault detection in the plurality of optical fiber transmission lines 40-1 to 40-N can be performed individually. Furthermore, unlike the technology disclosed in patent documents, there is no need to make the plurality of optical fiber transmission lines 40-1 to 40-N different lengths or to stop communication in order to detect a fault.

[0068] <Modification of the First Embodiment> In the above-described first embodiment, the reflecting section 21 is provided in all of the plurality of optical fiber transmission lines 40-1 to 40-N, but the present invention is not limited to this. For example, if there is an optical fiber transmission line 40 that is a target of fault detection among the plurality of optical fiber transmission lines 40-1 to 40-N, the reflector 21 may not be provided in the optical fiber transmission lines 40 that are not a target of fault detection.

[0069] 5, the optical fiber transmission line 40-3 among the plurality of optical fiber transmission lines 40-1 to 40-N is not a target for fault detection. Therefore, the reflector 21 is not provided in the ONU 20-3 connected to the optical fiber transmission line 40-3. Therefore, when pulsed light is transmitted, the ONU 20-3 terminates the pulsed light.

[0070] <Embodiment 2> In the above-described first embodiment, the OLT 10 functions as an optical fiber sensing device. In contrast to this, in the second embodiment, each of the plurality of ONUs 20-1 to 20-N functions as an optical fiber sensing device.

[0071] An example of the configuration of an optical fiber sensing system according to the second embodiment will be described with reference to FIG. 6, in the optical fiber sensing system according to the second embodiment, each of a plurality of ONUs 20-1 to 20-N includes a DAS interrogator 22 and a detection unit 25, which correspond to the DAS interrogator 11 and the detection unit 14 according to the first embodiment. The DAS interrogator 22 also includes an optical output unit 23 and an optical input unit 24, which correspond to the optical output unit 12 and the optical input unit 13 according to the first embodiment.

[0072] Each of the optical output units 23 in the ONUs 20-1 to 20-N can individually switch between outputting pulsed light and not outputting pulsed light. In the second embodiment, the plurality of light output units 23 are switched one by one in sequence to execute output of pulsed light. Note that the method of switching execution of output of pulsed light by light output units 23 may be the same as that of the first embodiment described above.

[0073] For example, in a situation where only the optical output unit 23 in ONU 20-1 is outputting pulsed light, the optical input unit 24 in ONU 20-1 receives the backscattered light generated in the optical fiber transmission line 30 and the backscattered light generated in the optical fiber transmission line 40-1 as returned light.

[0074] Therefore, the detection unit 25 in ONU 20-1 can detect faults in the optical fiber transmission line 30 by analyzing the acoustic pattern of the backscattered light generated in the optical fiber transmission line 30 from the return light received by the optical input unit 24.

[0075] In addition, the detection unit 25 in the ONU 20-1 can detect a failure in the optical fiber transmission line 40-1 by analyzing the acoustic pattern of the backscattered light generated in the optical fiber transmission line 40-1 among the return light received by the optical input unit 24. Thus, in the second embodiment as well, failures in the plurality of optical fiber transmission lines 40-1 to 40-N can be individually detected.

[0076] <Hardware Configuration of OLT and ONU (Optical Fiber Sensing Device)> Subsequently, referring to FIG. 7, a hardware configuration example of a computer 70 that realizes the OLT 10 functioning as an optical fiber sensing device in the above-described first embodiment and the ONU 20 functioning as an optical fiber sensing device in the above-described second embodiment will be described.

[0077] As shown in FIG. 7, the computer 70 includes a processor 71, a memory 72, a storage 73, an input / output interface (input / output I / F) 74, a communication interface (communication I / F) 75, and the like. The processor 71, the memory 72, the storage 73, the input / output interface 74, and the communication interface 75 are connected by a data transmission path for transmitting and receiving data to each other.

[0078] The processor 71 is an arithmetic processing device such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The memory 72 is a memory such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The storage 73 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a memory card. Also, the storage 73 may be a memory such as a RAM or a ROM.

[0079] A program is stored in the storage 73. When the program is loaded into a computer, it includes a set of instructions (or software code) that causes the computer 70 to perform one or more functions of the OLT 10 and ONU 20 described above. The optical output units 12 and 23, optical input units 13 and 24, and detection units 14 and 25 in the ONU 21 described above may be realized by the processor 71 reading and executing a program stored in the storage 73. Furthermore, the storage function of the OLT 10 and ONU 20 described above may be realized by the memory 72 or the storage 73.

[0080] The above-described programs may also be stored on non-transitory computer-readable media or tangible storage media. By way of example and not limitation, computer-readable media or tangible storage media include RAM, ROM, flash memory, SSD or other memory technology, CD (Compact Disc)-ROM, DVD (Digital Versatile Disc), Blu-ray® disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The programs may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0081] The input / output interface 74 is connected to a display device 741, an input device 742, a sound output device 743, etc. The display device 741 is a device that displays a screen corresponding to drawing data processed by the processor 71, such as an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, or a monitor. The input device 742 is a device that accepts operational inputs from an operator, such as a keyboard, a mouse, or a touch sensor. The display device 741 and the input device 742 may be integrated and realized as a touch panel. The sound output device 743 is a device that outputs sound corresponding to audio data processed by the processor 71, such as a speaker.

[0082] The communication interface 75 transmits and receives data to and from an external device. For example, the communication interface 75 communicates with the external device via a wired communication path or a wireless communication path.

[0083] 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 those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

[0084] Furthermore, some or all of the above-described embodiments can be described as, but are not limited to, the following supplementary notes. (Appendix 1) OLT (Optical Line Terminal) and Multiple ONUs (Optical Network Units) and a first optical fiber transmission line connected to the OLT; a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs; an optical output unit that outputs pulsed light to the first optical fiber transmission line; a plurality of reflecting portions provided in each of the plurality of second optical fiber transmission lines; a branching section that connects the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines, outputs the pulsed light output to the first optical fiber transmission line to each of the plurality of second optical fiber transmission lines, and outputs reflected light obtained by reflecting the pulsed light at any of the plurality of reflecting sections to the first optical fiber transmission line; an optical input unit that receives the reflected light from the first optical fiber transmission line; a detection unit that detects a fault in the second optical fiber transmission line that includes the reflector that outputs the reflected light by analyzing a pattern of the reflected light, Each of the plurality of reflecting units is capable of individually switching between reflecting the pulsed light. Fiber optic sensing system. (Appendix 2) The plurality of reflecting units are switched to reflect the pulsed light one by one in sequence. 10. The optical fiber sensing system of claim 1. (Appendix 3) a time slot different from each other is set for each of the plurality of reflecting portions, each of the plurality of reflectors reflects the pulsed light in a time slot set for the reflector; 10. The optical fiber sensing system of claim 2. (Appendix 4) a control unit that transmits a control signal to each of the plurality of reflectors to instruct whether or not to reflect the pulsed light, each of the plurality of reflectors reflects the pulsed light based on the control signal; 10. The optical fiber sensing system of claim 2. (Appendix 5) when determining that a fault has occurred in any of the plurality of second optical fiber transmission lines, the detection unit notifies the second optical fiber transmission line in which the fault has occurred. 5. The optical fiber sensing system of any one of appendices 1 to 4. (Appendix 6) The detection unit When it is determined that a fault has occurred in any of the plurality of second optical fiber transmission lines, a location of the fault on the second optical fiber transmission line where the fault has occurred is identified; notifying the second optical fiber transmission line where a failure has occurred and the location of the failure; 5. The optical fiber sensing system of any one of appendices 1 to 4. (Appendix 7) When the detection unit determines that a fault has occurred in any of the plurality of second optical fiber transmission lines, it notifies the ONU connected to the second optical fiber transmission line in which the fault has occurred. 5. The optical fiber sensing system of any one of appendices 1 to 4. (Appendix 8) the optical input unit receives, from the first optical fiber transmission line, backscattered light generated as the pulsed light is transmitted through the first optical fiber transmission line; the detection unit detects a fault in the first optical fiber transmission line by analyzing a pattern of the backscattered light. 8. The optical fiber sensing system of any one of appendices 1 to 7. (Appendix 9) the optical output unit, the optical input unit, and the detection unit are provided in the OLT. 9. The optical fiber sensing system of any one of appendices 1 to 8. (Appendix 10) The plurality of reflectors are provided in each of the plurality of ONUs. 10. The optical fiber sensing system of any one of appendices 1 to 9. (Appendix 11) An optical fiber sensing method using an optical fiber sensing system, comprising: The optical fiber sensing system includes: OLT (Optical Line Terminal) and Multiple ONUs (Optical Network Units) and a first optical fiber transmission line connected to the OLT; a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs; a branching section that connects the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines; a plurality of reflectors provided in the plurality of second optical fiber transmission lines, each of which can individually switch between reflection of pulsed light from the second optical fiber transmission lines; The optical fiber sensing method includes: a switching step of switching the plurality of reflecting units one by one in sequence to reflect the pulsed light; an optical output step of outputting the pulsed light from the first optical fiber transmission line to each of the plurality of second optical fiber transmission lines via the branching unit; a reflecting step of outputting reflected light obtained by reflecting the pulsed light at one of the reflecting units, which is switched to reflect the pulsed light, to the first optical fiber transmission line; an optical receiving step of receiving the reflected light from the first optical fiber transmission line; a detection step of detecting a fault in the second optical fiber transmission line provided with one of the reflecting portions by analyzing a pattern of the reflected light; Including, Fiber optic sensing methods. (Appendix 12) a time slot different from each other is set for each of the plurality of reflecting portions, In the switching step, each of the plurality of reflectors reflects the pulsed light in a time slot set for the reflector. 12. The optical fiber sensing method of claim 11. (Appendix 13) In the switching step, transmitting a control signal to each of the plurality of reflectors, the control signal instructing whether or not to reflect the pulsed light; each of the plurality of reflectors reflects the pulsed light based on the control signal; 12. The optical fiber sensing method of claim 11. (Appendix 14) further comprising a step of notifying the second optical fiber transmission line in which a fault has occurred when it is determined that a fault has occurred in any of the plurality of second optical fiber transmission lines; 14. An optical fiber sensing method according to any one of appendices 11 to 13. (Appendix 15) when it is determined that a fault has occurred in any of the plurality of second optical fiber transmission lines, identifying a location of the fault on the second optical fiber transmission line where the fault has occurred; and notifying the second optical fiber transmission line where a failure has occurred and the location of the failure. 14. An optical fiber sensing method according to any one of appendices 11 to 13. (Appendix 16) further comprising a step of notifying the ONU connected to the second optical fiber transmission line in which a fault has occurred when it is determined that a fault has occurred in any of the plurality of second optical fiber transmission lines. 14. An optical fiber sensing method according to any one of appendices 11 to 13. (Appendix 17) the light receiving step further receives backscattered light from the first optical fiber transmission line, the backscattered light being generated as the pulsed light is transmitted through the first optical fiber transmission line; In the detecting step, a fault in the first optical fiber transmission line is further detected by analyzing a pattern of the backscattered light. 17. An optical fiber sensing method according to any one of appendices 11 to 16. (Appendix 18) In an optical fiber sensing system including an OLT (Optical Line Terminal), a plurality of ONUs (Optical Network Units), a first optical fiber transmission line connected to the OLT, a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs, and a branching section connecting the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines, one of the plurality of ONUs, A reflective portion is provided, the reflecting unit is capable of individually switching between reflection of the pulsed light from the second optical fiber transmission line. ONU. (Appendix 19) Each of the plurality of ONUs includes the reflector, The plurality of reflectors provided in each of the plurality of ONUs are switched one by one in sequence to reflect the pulsed light. ONUs as described in Appendix 18. (Appendix 20) a time slot different from each other is set for each of the plurality of reflecting portions, the reflector reflects the pulsed light in a time slot set for the reflector. ONUs as described in Appendix 19. (Appendix 21) the reflector reflects the pulsed light based on a control signal instructing whether or not to reflect the pulsed light. ONUs as described in Appendix 19. [Explanation of symbols]

[0085] 10 OLT 11 DAS Interrogator 12 Optical output section 13 Optical input section 14 Detector 20-1~20-N ONU 21 Reflector 22 DAS Interrogator 23 Optical output section 24 Optical input section 25 Detector 30 Optical fiber transmission line 40-1 to 40-N Optical fiber transmission line 50 Branch 60 Control Unit 70 Computer 71 processors 72 memory 73 Storage 74 Input / Output Interface 741 Display device 742 Input Device 743 Sound Output Device 75 Communication Interface

Claims

1. OLT (Optical Line Terminal) and A plurality of ONUs (Optical Network Units); a first optical fiber transmission line connected to the OLT; a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs; an optical output unit that outputs pulsed light to the first optical fiber transmission line; a plurality of reflectors provided in the plurality of second optical fiber transmission lines, each of which is capable of individually switching between reflection of pulsed light from the second optical fiber transmission lines; a branching section that connects the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines, outputs the pulsed light output to the first optical fiber transmission line to each of the plurality of second optical fiber transmission lines, and outputs reflected light obtained by reflecting the pulsed light at any of the plurality of reflecting sections to the first optical fiber transmission line; an optical input unit that receives the reflected light from the first optical fiber transmission line; a detection unit that detects a fault in the second optical fiber transmission line that includes the reflector that outputs the reflected light by analyzing a pattern of the reflected light, a time slot different from each other is set for each of the plurality of reflecting portions, each of the plurality of reflectors reflects the pulsed light in a time slot set for the reflector; Fiber optic sensing system.

2. the plurality of reflecting units are switched one by one in sequence to reflect the pulsed light; The optical fiber sensing system of claim 1 .

3. when determining that a fault has occurred in any of the plurality of second optical fiber transmission lines, the detection unit notifies the second optical fiber transmission line in which the fault has occurred.

3. The optical fiber sensing system according to claim 1 or 2.

4. The detection unit When it is determined that a fault has occurred in any of the plurality of second optical fiber transmission lines, a location of the fault on the second optical fiber transmission line where the fault has occurred is identified; notifying the second optical fiber transmission line where a failure has occurred and the location of the failure; 3. The optical fiber sensing system according to claim 1 or 2.

5. When the detection unit determines that a fault has occurred in any of the plurality of second optical fiber transmission lines, the detection unit notifies the ONU connected to the second optical fiber transmission line in which the fault has occurred.

3. The optical fiber sensing system according to claim 1 or 2.

6. the optical input unit receives, from the first optical fiber transmission line, backscattered light generated as the pulsed light is transmitted through the first optical fiber transmission line; the detection unit detects a fault in the first optical fiber transmission line by analyzing a pattern of the backscattered light. The optical fiber sensing system according to any one of claims 1 to 5.

7. An optical fiber sensing method using an optical fiber sensing system, comprising: The optical fiber sensing system includes: OLT (Optical Line Terminal) and A plurality of ONUs (Optical Network Units); a first optical fiber transmission line connected to the OLT; a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs; a branching section that connects the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines; a plurality of reflectors provided in the plurality of second optical fiber transmission lines, each of which is capable of individually switching between reflection of pulsed light from the second optical fiber transmission lines; The optical fiber sensing method includes: a switching step of switching the plurality of reflecting units one by one in sequence to reflect the pulsed light; an optical output step of outputting the pulsed light from the first optical fiber transmission line to each of the plurality of second optical fiber transmission lines via the branching unit; a reflecting step of outputting reflected light obtained by reflecting the pulsed light at one of the reflecting units, which is switched to reflect the pulsed light, to the first optical fiber transmission line; an optical receiving step of receiving the reflected light from the first optical fiber transmission line; a detection step of detecting a fault in the second optical fiber transmission line provided with one of the reflecting portions by analyzing a pattern of the reflected light; Including, a time slot different from each other is set for each of the plurality of reflecting portions, each of the plurality of reflectors reflects the pulsed light in a time slot set for the reflector; Fiber optic sensing methods.

8. In an optical fiber sensing system including an OLT (Optical Line Terminal), a plurality of ONUs (Optical Network Units), a first optical fiber transmission line connected to the OLT, a plurality of second optical fiber transmission lines connected to each of the plurality of ONUs, and a branching unit connecting the first optical fiber transmission line and each of the plurality of second optical fiber transmission lines, one of the plurality of ONUs, a reflector that can individually switch between reflection of pulsed light from the second optical fiber transmission line, a plurality of reflecting units provided in each of the plurality of ONUs are set with different time slots, each of the plurality of reflectors reflects the pulsed light in a time slot set for the reflector; ONU.

Images