Optical power supply system

Abstract

This optical power supply system comprises: a power supply light transmitter that outputs modulated light; an optical transmission path through which the light propagates; an optical element that reflects a portion of the light propagated through the optical transmission path and transmits the remainder; a photoelectric converter that converts the light transmitted through the optical element into electric power; an optical receiver that receives the light reflected by the optical element; and a control unit that executes analysis processing for determining whether an abnormality has occurred in the optical transmission path, on the basis of the intensity of the light and a timing at which the optical receiver received the light.

Description

Optical Power Feeding System

[0001] The present invention relates to an optical power feeding system.

[0002] In optical communication technology, techniques for detecting abnormalities occurring in an optical transmission line have been proposed (Patent Documents 1 and 2).

[0003] Japanese Unexamined Patent Application Publication No. 2017-85355 Japanese Unexamined Patent Application Publication No. 2009-63377

[0004] Incidentally, abnormalities in an optical transmission line may cause problems not only in optical communication technology, but also in optical power feeding technology that uses an optical transmission line.

[0005] In view of the above circumstances, an object of the present invention is to provide an optical power feeding system that detects an abnormality in an optical transmission line.

[0006] One aspect of the present invention is an optical power feeding system including: a power feeding optical transmitter that outputs modulated light; an optical transmission line through which the light propagates; an optical element that reflects part of the light propagating through the optical transmission line and transmits the remaining part; a photoelectric converter that converts the light transmitted through the optical element into electric power; an optical receiver that receives the light reflected by the optical element; and a control unit that executes analysis processing to determine whether an abnormality has occurred in the optical transmission line based on the timing at which the optical receiver receives the light and the intensity of the light.

[0007] According to the present invention, it is possible to provide an optical power feeding system that detects an abnormality in an optical transmission line.

[0008] An explanatory diagram for explaining an optical power feeding system according to an embodiment. A diagram showing an example of the hardware configuration of a terminal station device according to an embodiment. A flowchart showing a first example of a flow of processing executed by the optical power feeding system according to an embodiment. A flowchart showing a second example of a flow of processing executed by the optical power feeding system according to an embodiment. An explanatory diagram for explaining a first example of an optical signal propagating through an optical transmission line in which no abnormality has occurred in a modified example. An explanatory diagram for explaining a first example of an optical signal propagating through an optical transmission line in which an abnormality has occurred in a modified example. An explanatory diagram for explaining a second example of an optical signal propagating through an optical transmission line in which no abnormality has occurred in a modified example. An explanatory diagram for explaining a second example of an optical signal propagating through an optical transmission line in which an abnormality has occurred in a modified example.

[0009] (Embodiment) Figure 1 is an explanatory diagram illustrating an optical power supply system 100 of an embodiment. The optical power supply system 100 comprises an terminal device 1, an optical transmission line 2, and a subscriber line termination device 3, and is an optical power supply system that supplies power from the terminal device 1 to the subscriber line termination device 3.

[0010] <<Terminal Equipment>> Terminal equipment 1 is connected to one or more subscriber line termination devices 3 via an optical transmission path 2. In the example in Figure 1, for simplicity of explanation, only one subscriber line termination device 3 is shown as the destination of terminal equipment 1. The optical transmission path 2 is a transmission path that transmits optical signals. The optical transmission path 2 is, for example, an optical fiber.

[0011] The terminal device 1 comprises a power supply optical transmitter 101, an optical circulator 102, an optical receiver 103, and a control unit 11. The control unit 11 includes a processor 91 such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), or NPU (Neural Network Processing Unit) connected by a bus, and a memory 92, and executes a program.

[0012] The power supply light transmitter 101 outputs an optical signal, which is modulated light. The power supply light transmitter 101 can have any configuration as long as it is capable of outputting modulated light. In the example in Figure 1, the power supply light transmitter 101 comprises a light source 111 and a power supply light modulator 112. The light source 111 outputs light.

[0013] The power supply optical modulator 112 modulates the light output by the light source 111. Therefore, the power supply optical modulator 112 outputs modulated light (i.e., an optical signal). As will be described later, the modulation method is not limited to intensity modulation, but may also be frequency modulation, phase modulation, or a combination of these. The optical signal output by the power supply optical transmitter 101 is incident on the optical circulator 102.

[0014] The optical circulator 102 outputs the optical signal (hereinafter referred to as the "power supply optical signal") output by the power supply optical transmitter 101 and incident on the optical circulator 102 to the optical transmission line 2. Therefore, the terminal device 1 outputs the power supply optical signal to the optical transmission line 2.

[0015] The optical circulator 102 outputs the optical signal (hereinafter referred to as the "reflected optical signal") that has propagated through the optical transmission path 2 and entered the optical circulator 102 to the optical receiver 103. This reflected optical signal is an optical signal that has been reflected due to an abnormality that occurred in the optical transmission path 2, such as the optical element 301 or a fractured surface.

[0016] The optical receiver 103 receives the optical signal. As described above, the optical circulator 102 outputs the reflected light signal to the optical receiver 103. Therefore, more specifically, the optical receiver 103 receives the reflected light signal.

[0017] The control unit 11 performs analysis processing and transmission stop processing. The analysis processing determines whether or not an abnormality has occurred in the optical transmission path 2 based on the results of reception by the optical receiver 103. More specifically, the reception results are the intensity of the received optical signal and the time from when the modulated optical signal was transmitted until it was received, i.e., the reception timing.

[0018] The abnormality occurring in the optical transmission line 2 may be, for example, a break in the optical transmission line 2, a bending problem, or a loosening or disconnection of a connection part such as an adapter.

[0019] The transmission stop process is executed when the analysis process determines that an abnormality has occurred in the optical transmission path 2. The transmission stop process controls the operation of the power supply optical transmitter 101 to stop the output of an optical signal to the power supply optical transmitter 101. If the power supply optical transmitter 101 is equipped with a light source 111 and a power supply optical modulator 112, the transmission stop process stops the operation of the light source 111, thereby stopping the output of an optical signal to the power supply optical transmitter 101. In other words, the transmission stop process is the process of stopping optical power supply.

[0020] <<Subscriber Line Termination Equipment>> The subscriber line termination equipment 3 comprises an optical element 301 and a photonic power converter 302.

[0021] The optical element 301 receives an optical signal (i.e., a power supply optical signal) that has been output by the terminal device 1 and propagated through the optical transmission path 2. At the optical element 301, a portion of the incident optical signal (i.e., the power supply optical signal) is reflected, and the rest is transmitted. The transmitted optical signal is then incident on the photoelectric converter 302.

[0022] Furthermore, the optical element 301 reflects, for example, 1% of the incident light signal and transmits 99%.

[0023] The photoelectric converter 302 receives the light signal that has passed through the optical element 301 and is incident on it, and converts it into electricity.

[0024] <More specific examples of information flow and learning> Here, we will explain information flow and anomaly detection.

[0025] If there is no abnormality in the optical transmission path 2 (normal operation), the optical receiver 103 acquires the information modulated by the power supply optical transmitter 101 after a time corresponding to the length of the optical transmission path 2 has elapsed. Incidentally, the information modulated by the power supply optical transmitter 101 is retained by the reflection by the optical element 301. Therefore, the optical signal received by the optical receiver 103 includes the information modulated by the power supply optical transmitter 101. Furthermore, if an abnormality occurs in the optical transmission path 2, the optical signal received by the optical receiver 103 will be different from the case when there is no abnormality in the optical transmission path 2.

[0026] Therefore, in the analysis process, for example, the intensity and timing of the optical signal received by the optical receiver 103 are compared with the intensity and timing of the optical signal received when there is no abnormality in the optical transmission path 2 to determine whether or not an abnormality has occurred in the optical transmission path 2.

[0027] For example, if a fracture occurs, the reflectivity will differ depending on the shape of the fracture surface, so the intensity of the reflected light will change from the moment the fracture occurs. Furthermore, even if the reflectivity of the fracture surface is the same as that of the optical element 301 of the subscriber line termination device 3, it is possible to determine whether or not an abnormality has occurred in the optical transmission line 2 based on the timing at which the optical receiver 103 receives the optical signal. This is because the distance from the terminal device 1 to the position where the optical signal is reflected differs between the fracture surface and the optical element 301, so the time it takes from when the terminal device 1 transmits until the reflected light returns depends on the factor that caused the reflection.

[0028] <Effects Produced> The optical power supply system 100 includes a subscriber line termination device 3. The subscriber line termination device 3 receives the optical signal transmitted by the terminal device 1 and propagated through the optical transmission line 2, and the photoelectric converter 302 converts the received optical signal into electricity. Therefore, the optical power supply system 100 is an optical power supply technology using an optical transmission line.

[0029] In this optical power supply system 100, the terminal device 1 performs analysis processing to determine whether or not an abnormality has occurred in the optical transmission path 2. Therefore, the optical power supply system 100 configured in this way is an optical power supply system that detects abnormalities in the optical transmission path.

[0030] Incidentally, unlike the technology described in Patent Document 1, the optical power supply system 100 is a power supply technology, not a communication technology. Furthermore, unlike Patent Document 1, the optical power supply system 100 does not require the subscriber line termination device 3 to be equipped with a mechanism for determining the occurrence of an abnormality in the optical transmission path 2.

[0031] Furthermore, as a technology to incorporate a mechanism for determining the occurrence of abnormalities in the optical transmission path into an optical power supply system, it is conceivable to also implement the technology described in Patent Document 2 within the optical power supply system. That is, in an optical power supply system, a technology is conceivable in which an optical signal for determining the occurrence of abnormalities in the optical transmission path 2 is sent to the optical transmission path 2 separately from the power supply.

[0032] However, in order to implement such technology, it is necessary to prepare an optical signal for determining the occurrence of an abnormality in the optical transmission path 2, separate from the power supply. On the other hand, in the case of the optical power supply system 100, the light used for power supply itself is modulated by the power supply optical transmitter 101, so it is not necessary to prepare an optical signal for determining the occurrence of an abnormality, separate from the power supply.

[0033] Therefore, the optical power supply system 100 is an optical power supply system that can determine the occurrence of an abnormality in the optical transmission path 2 with a simpler configuration than optical power supply technology that sends an optical signal to the optical transmission path 2 to determine the occurrence of an abnormality in the optical transmission path 2 separately from power supply.

[0034] Furthermore, the optical power supply system 100 determines whether or not an abnormality has occurred in the optical transmission path 2, and if it is determined that an abnormality has occurred in the optical transmission path 2, it stops the output of the optical signal, i.e., optical power supply. Continuing optical power supply despite an abnormality occurring is undesirable as it could lead to disasters such as fires. Therefore, the optical power supply system 100 has a higher level of safety than an optical power supply system 100 that cannot detect the occurrence of an abnormality, or an optical power supply system 100 that does not stop optical power supply even when an abnormality is detected.

[0035] <Example of Hardware Configuration of Terminal Device 1> Figure 2 shows an example of the hardware configuration of terminal device 1 in the embodiment. Terminal device 1 includes a control unit 11 and executes a program. By executing the program, terminal device 1 functions as a device comprising a control unit 11, an interface unit 12, a storage unit 13, a power supply optical transmitter 101, an optical circulator 102, and an optical receiver 103.

[0036] More specifically, the processor 91 reads the program stored in the storage unit 13 and stores the read program in the memory 92. By executing the program stored in the memory 92, the terminal device 1 functions as a device comprising a control unit 11, an interface unit 12, a storage unit 13, a power supply optical transmitter 101, an optical circulator 102, and an optical receiver 103.

[0037] The control unit 11 controls the operation of each functional unit of the terminal device 1. The control unit 11 performs, for example, analysis processing. The control unit 11 performs, for example, transmission stop processing. The control unit 11 retrieves, for example, information stored in the storage unit 13. Specifically, the process of retrieving information stored in the storage unit 13 is read.

[0038] The interface unit 12 includes input devices such as a mouse, keyboard, touch panel, and microphone. The interface unit 12 may also be configured as an interface for connecting these input devices to the terminal device 1. In this way, the input devices of the interface unit 12 receive various information or signals to the terminal device 1 via wired or wireless connections.

[0039] The interface unit 12 outputs various types of information, for example. The interface unit 12 includes, for example, a display device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, or an organic EL (Electro-Luminescence) display, as well as a speaker. The interface unit 12 may be configured as an interface for connecting these display devices or speakers to the terminal device 1. Therefore, the interface unit 12 may output information indicated by information or signals input to the input device of the interface unit 12 as an image or sound.

[0040] The storage unit 13 is configured using a computer-readable recording medium such as a magnetic hard disk drive or a semiconductor memory device. The storage unit 13 stores various information related to the terminal device 1. The storage unit 13 stores various information generated by the operation of the control unit 11, for example. The storage unit 13 may reside, for example, on the cloud.

[0041] <Example of the processing flow executed in the optical power supply system 100> Figure 3 is a flowchart showing a first example of the processing flow executed in the optical power supply system 100 of this embodiment. The power supply optical transmitter 101 outputs an optical signal (step S101).

[0042] Next, part of the incident light is reflected by the optical element 301, propagates to the optical receiver 103 via the optical transmission line 2 and the optical circulator 102, and is received by the optical receiver 103 (step S102). Next, based on the timing at which the optical receiver 103 receives an optical signal and the intensity of the optical signal received by the optical receiver 103, the control unit 11 determines whether an abnormality has occurred in the optical transmission line 2 (step S103). That is, the control unit 11 executes analysis processing.

[0043] When an abnormality has occurred in the optical transmission line 2 (step S103: YES), the control unit 11 controls the operation of the feeding optical transmitter 101 to stop power feeding (step S104). That is, the control unit 11 executes transmission stop processing.

[0044] On the other hand, when no abnormality has occurred in the optical transmission line 2 (step S103: NO), the process returns to step S101.

[0045] FIG. 4 is a flowchart showing a second example of the flow of processing executed by the optical power feeding system 100 according to the embodiment. Description of the same processing as that described in FIG. 3 is omitted by assigning the same reference numerals as in FIG. 3.

[0046] Step S101 is executed. Of the optical signals incident on the optical element 301, the remainder that is not reflected by the optical element 301 passes through the optical element 301, is incident on the photoelectric converter 302, and is converted into electric power by the photoelectric converter 302 (step S201).

[0047] The optical power feeding system 100 configured as described above executes analysis processing. Therefore, as described in the above <Effects>, an abnormality in the optical transmission line can be detected.

[0048] Furthermore, in the optical power feeding system 100 configured as described above, the light used for power feeding itself is modulated. Therefore, as described in the above <Effects>, the optical power feeding system 100 can determine the occurrence of an abnormality in an optical transmission line with a simpler configuration.

[0049] (Modification) As described above, the analysis process determines whether or not an abnormality has occurred in the optical transmission path 2 based on the intensity of the optical signal received by the optical receiver 103 and the timing at which the optical signal was received by the optical receiver 103. For example, as described above, the analysis process may determine whether or not an abnormality has occurred in the optical transmission path 2 by comparing the intensity and timing of reception of the optical signal received by the optical receiver 103 with the intensity and timing of reception when no abnormality has occurred in the optical transmission path 2. However, the analysis process is not necessarily limited to this type of process.

[0050] The analysis process may be, for example, a process that executes an analysis model. The analysis model may be, for example, a mathematical model obtained by machine learning techniques. More specifically, the analysis model is the result of training a pre-training analysis model, which is a mathematical model that determines whether or not an abnormality has occurred in the optical transmission path 2 based on the results of reception by the optical receiver 103, until predetermined conditions for the termination of training (hereinafter referred to as "training termination conditions") are met, and is the pre-training analysis model at the time when the training termination conditions are met.

[0051] In the learning process for obtaining the analysis model, learning is performed using the reception results of the optical receiver 103 when no abnormality occurs in the optical transmission path 2. In other words, the analysis model and the pre-learning analysis model are mathematical models that determine whether or not an abnormality has occurred in the optical transmission path 2 based on the timing and intensity of the optical signal received by the optical receiver 103.

[0052] The learning process is, for example, supervised learning. This supervised learning may involve using information indicating that no abnormality has occurred in the optical transmission path 2 as a label. In this supervised learning, the pre-learning analysis model determines whether or not an abnormality has occurred in the optical transmission path 2 based on the reception results of the optical receiver 103 when no abnormality has occurred in the optical transmission path 2. The pre-learning analysis model is then updated to minimize the difference between the result of the pre-learning analysis model's determination and the label.

[0053] Furthermore, this supervised learning may be performed using, for example, information indicating that an abnormality has occurred in the optical transmission path 2 as a label. In this supervised learning, the pre-training analysis model determines whether or not an abnormality has occurred in the optical transmission path 2 based on the reception results of the optical receiver 103 when there is no abnormality in the optical transmission path 2. The pre-training analysis model is then updated to minimize the difference between the result of the pre-training analysis model's determination and the label.

[0054] <Example of a configuration in which terminal equipment 1 is connected to one subscriber line termination device 3> Here, we will explain an example of an optical signal propagating through an optical transmission path 2 in which no abnormality has occurred, and an example of an optical signal propagating through an optical transmission path 2 in which an abnormality has occurred, in an optical power supply system 100 in which terminal equipment 1 is connected to one subscriber line termination device 3.

[0055] Figure 5 is an explanatory diagram illustrating a first example of an optical signal propagating through an optical transmission path 2 where no abnormality is occurring, in a modified example. Terminal device 1 is connected to one subscriber line termination device 3 via the optical transmission path 2. In the example in Figure 5, an intensity-modulated optical signal is output from terminal device 1 as feed light. This optical signal is reflected by the subscriber line termination device 3 and propagates back to terminal device 1 through the optical transmission path 2 as reflected light.

[0056] Figure 6 is an explanatory diagram illustrating a first example of an optical signal propagating through the optical transmission path 2 where an abnormality is occurring, in a modified example. Figure 6 shows a scenario in the optical power supply system 100 of Figure 5 where a break has occurred at position P1 on the optical transmission path 2.

[0057] Because a break has occurred at position P1 on the optical transmission path 2, at least a portion of the optical signal output from terminal device 1 is reflected at position P1 on the optical transmission path 2. The reflected optical signal then propagates as reflected light through the optical transmission path 2 to terminal device 1. In the example shown in Figure 6, the optical signal reflected at position P1 on the optical transmission path 2 has a lower intensity than the signal before reflection.

[0058] <Example of a configuration in which terminal device 1 is connected to multiple subscriber line termination devices 3> Here, we will explain an example of an optical signal propagating through an optical transmission path 2 in which no abnormality has occurred, and an example of an optical signal propagating through an optical transmission path 2 in which an abnormality has occurred, in an optical power supply system 100 in which terminal device 1 is connected to multiple subscriber line termination devices 3.

[0059] Figure 7 is an explanatory diagram illustrating a second example of an optical signal propagating through the optical transmission path 2 without any abnormalities in a modified example. Terminal device 1 is connected to two subscriber line termination devices 3 via the optical transmission path 2. In the example in Figure 7, an intensity-modulated optical signal is output from terminal device 1 as feed light. This optical signal is reflected by each subscriber line termination device 3 and propagates as reflected light through the optical transmission path 2 to terminal device 1.

[0060] However, the length of the optical transmission path 2 connecting each subscriber line termination device 3 to the terminal device 1 is different from that of the other subscriber line termination device 3. Therefore, the optical signal reflected from one of the two subscriber line termination devices 3 and the optical signal reflected from the other subscriber line termination device 3 reach the terminal device 1 at different times.

[0061] Figure 8 is an explanatory diagram illustrating a second example of an optical signal propagating through the optical transmission path 2 where an abnormality has occurred, in a modified example. Figure 8 shows a scenario in the optical power supply system 100 of Figure 7 where a break has occurred at position P2 on the optical transmission path 2.

[0062] Because a break has occurred at position P2 on the optical transmission path 2, at least a portion of the optical signal output from terminal device 1 is reflected at position P2 on the optical transmission path 2. The reflected optical signal then propagates as reflected light through the optical transmission path 2 to terminal device 1. In the example shown in Figure 8, the optical signal reflected at position P2 on the optical transmission path 2 has a lower intensity than the signal before reflection.

[0063] In the examples shown in Figures 5 to 8, the modulation method used to obtain the optical signal output by the power supply optical transmitter 101 was intensity modulation. However, the modulation method used to obtain the optical signal output by the power supply optical transmitter 101 can be any method. The modulation method is not limited to intensity modulation; it may also be frequency modulation, phase modulation, or a combination of these.

[0064] Furthermore, frequency modulation and phase modulation provide more stable power supply than intensity modulation. This is because, in the case of intensity modulation, the light intensity fluctuates, whereas in the case of frequency modulation and phase modulation, the light intensity does not fluctuate. Here, stability is defined as having a small fluctuation in the value of the power converted and extracted by the photoelectric converter 302.

[0065] Furthermore, the modulation method may also be inverse pulse intensity modulation. This improves power supply efficiency compared to pulse intensity modulation. This is because, with inverse pulse intensity modulation, the intensity of the power supply light decreases only during the time the pulse-like modulation occurs, thus allowing for a longer period of high power supply light intensity.

[0066] Furthermore, if the modulation method is inverse pulse intensity modulation, the shorter the pulse width, the shorter the time the intensity decreases, thus enabling more efficient power supply.

[0067] The predetermined pulse width affects the accuracy of anomaly detection when the reflectivity at the anomaly location is equivalent to that of the optical element. For example, to achieve a detection accuracy of 1 m, the pulse width is 10 ns.

[0068] The terminal device 1 may be implemented using multiple information processing devices that are connected to each other via a network. In this case, each process executed by the control unit 11 may be performed by multiple information processing devices in a distributed manner.

[0069] Furthermore, all or part of each function of the optical power supply system 100 may be implemented using hardware such as ASICs (Application Specific Integrated Circuits), PLDs (Programmable Logic Devices), or FPGAs (Field Programmable Gate Arrays). The program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, magnetic disks, magneto-optical disks, optical disks (CD-ROMs, DVD-ROMs, etc.), portable media such as semiconductor memory (volatile memory, non-volatile memory, etc.) (ROM, RAM, etc.), and storage devices such as hard disks built into computer systems. The program may also be transmitted via a telecommunications line.

[0070] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs and the like that do not depart from the spirit of this invention.

[0071] 100...Optical power supply system, 1...Terminal device, 2...Optical transmission line, 3...Subscriber line termination device, 101...Power supply optical transmitter, 111...Light source, 112...Power supply optical modulator, 102...Optical circulator, 103...Optical receiver, 11...Control unit, 301...Optical element, 302...Photoelectric converter, 12...Interface unit, 13...Storage unit, 91...Processor, 92...Memory

Claims

1. An optical power supply system comprising: a power supply optical transmitter that outputs modulated light; an optical transmission path through which the light propagates; an optical element that reflects a portion of the light propagating through the optical transmission path and transmits the remainder; a photoelectric converter that converts the light that has passed through the optical element into electricity; an optical receiver that receives the light reflected by the optical element; and a control unit that performs an analysis process to determine whether or not an abnormality has occurred in the optical transmission path based on the timing at which the optical receiver receives the light and the intensity of the light.

2. The optical power supply system according to claim 1, wherein the light output by the power supply optical transmitter is light modulated by frequency modulation or phase modulation.

3. The optical power supply system according to claim 1, wherein the light output by the power supply optical transmitter is light modulated using an inverse pulse type intensity modulation method.

4. The optical power supply system according to claim 1, wherein the control unit determines that an abnormality has occurred in the optical transmission path and stops the output of the light from the power supply optical transmitter.

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