Communication device, optical power supply system, and optical power supply method

Abstract

This communication device comprises: a power supply light transmission unit that transmits power supply light to a counter communication device; a measurement unit that measures an optical loss value during transmission of the power supply light from the communication device to the counter communication device; and a control unit that controls output of the power supply light to be transmitted from the power supply light transmission unit according to the optical loss value measured by the measurement unit.

Description

[Technical Field]

[0001] The present invention relates to a communication device, an optical power supply system, and an optical power supply method. This application claims priority based on PCT / JP2022 / 020497, filed in Japan on May 17, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, there is an optical communication system in which a power-supplying communication device equipped with an optical power supply light source and a power-receiving communication device equipped with an optoelectronic converter are connected to each other by wire to perform optical power supply and communication (see, for example, Non-Patent Document 1). In such an optical communication system, power is supplied to the power-receiving communication device by power supply light emitted from the optical power supply light source of the power-supplying communication device. The power-receiving communication device stores the received power in a secondary power source and is driven by the stored power. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] “2. Configuration of Wired Power Supply Access System”, ANSL R&D Times, No. 105, NTT Access Service Systems Laboratories website, December 2018, [Retrieved September 13, 2022], Internet (URL: https: / / www.rd.ntt / as / times / 105 / 02 / 02.html) [Non-patent document 2] “Basic Knowledge for OTDR Measurements,” NTT Rental Engineering Co., Ltd. website, 2015, [Retrieved September 13, 2022], Internet (URL: https: / / www.nttrec.co.jp / faq / faq-product / faq-hikarisokutei / faq-hikarisokutei05) Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional optical communication systems, the power-supplying communication device supplies power at a constant output from an optical power source regardless of the installation location of the power-receiving communication device, the amount of stored power, etc. Therefore, conventional optical communication systems have the problem of supplying excessive power depending on the status of the communication device.

[0005] In view of the above circumstances, an object of the present invention is to provide a technique that can reduce the power consumption of an optically powered light source. [Means for solving the problem]

[0006] One aspect of the present invention is a communication device comprising: a power supply light transmitting unit that transmits power supply light to a counterpart communication device; a measurement unit that measures an optical loss value in the transmission of the power supply light from the device itself to the counterpart communication device; and a control unit that controls the output of the power supply light transmitted from the power supply light transmitting unit in accordance with the optical loss value measured by the measurement unit.

[0007] Another aspect of the present invention is an optical power supply system having a first communication device and a second communication device, wherein the first communication device comprises a power supply optical transmitter that transmits power supply optical to the second communication device, a measurement unit that measures an optical loss value in transmission of the power supply optical from the first communication device to the second communication device, and a control unit that controls the output of the power supply optical transmitted from the power supply optical transmitter in accordance with the optical loss value measured by the measurement unit, and the second communication device comprises a power supply optical receiver that receives the power supply optical transmitted from the first communication device, an opto-electrical converter that converts the power supply optical received by the power supply optical receiver into electric power, and a power storage unit that stores the electric power converted by the opto-electrical converter.

[0008] Another aspect of the present invention is an optical power supply method including a power supply light transmission step of transmitting power supply light to a counterpart communication device, a measurement step of measuring an optical loss value in transmission of the power supply light from the device to the counterpart communication device, and a control step of controlling an output of the power supply light in accordance with the optical loss value measured in the measurement step.

[0009] Another aspect of the present invention is an optical power supply method in an optical power supply system having a first communication device and a second communication device, the optical power supply method including: a power supply light transmitting step in which the first communication device transmits power supply light to the second communication device; a measurement step in which the first communication device measures an optical loss value in the transmission of the power supply light from the first communication device to the second communication device; a control step in which the first communication device controls an output of the power supply light in accordance with the optical loss value measured in the measurement step; a power supply light receiving step in which the second communication device receives the power supply light transmitted from the first communication device; an opto-electrical conversion step in which the second communication device converts the power supply light received in the power supply light receiving step into electric power; and a storage step in which the second communication device stores the electric power converted in the opto-electrical conversion step. [Effects of the Invention]

[0010] The present invention makes it possible to reduce the power consumption of an optically powered light source. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing the overall configuration of an optical communication system 8. FIG. [Figure 2] 1 is a block diagram showing the overall configuration of an optical communication system 1 according to a first embodiment of the present invention. [Figure 3] 3 is a flowchart showing the operation of the optical communication system 1 in the first embodiment of the present invention. [Figure 4] FIG. 10 is a block diagram showing the overall configuration of an optical communication system 1a according to a second embodiment of the present invention. [Figure 5]10 is a flowchart showing the operation of the optical communication system 1a in the second embodiment of the present invention. [Figure 6] FIG. 10 is a block diagram showing the overall configuration of an optical communication system 1b according to a third embodiment of the present invention. [Figure 7] FIG. 10 is a block diagram showing the overall configuration of an optical communication system 1c according to a fourth embodiment of the present invention. [Figure 8] FIG. 10 is a block diagram showing the overall configuration of an optical communication system 1d according to a fifth embodiment of the present invention. [Figure 9] 11 is a flowchart showing the operation of a communication device 11d in the fifth embodiment of the present invention. [Figure 10] 11 is a flowchart showing the operation of a communication device 11d in the fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a communication device, an optical power supply system, and an optical power supply method according to the present invention will be described with reference to the drawings.

[0013] To make it easier to understand the features of the optical power supply system and optical power supply method of the present invention, we will first explain the configuration of a general optical power supply system as a comparative example. Fig. 1 is a block diagram showing the overall configuration of an optical communication system 8. The optical communication system 8 is an example of an optical power supply system as a comparative example. As shown in Fig. 1, the optical communication system 8 is configured to include a communication device 81 and a communication device 82. The communication devices 81 and 82 are connected by wire and can transmit and receive data by transmitting and receiving communication light to and from each other.

[0014] Furthermore, the communication device 81 and the communication device 82 are connected by a wire, and the power supply light output from the communication device 81 is input to the communication device 82. That is, the communication device 81 is a power supplying communication device equipped with an optical power supply light source, and the communication device 82 is a power receiving communication device equipped with an opto-electric converter.

[0015] As shown in FIG. 1, the communication device 81 includes a power supply unit 811, a power supply optical transmitter 812, a transceiver 813, and a communication circuit 814.

[0016] The power supply unit 811 is a light source power source for generating the power supply light transmitted from the power supply light transmitting unit 812. The power supply light transmitting unit 812 transmits the power supply light toward the communication device 82. The transceiver 813 is a transmitter / receiver that transmits and receives communication light between the device itself and the communication device 82. The communication circuit 814 controls the transceiver 813 and transmits and receives data between the device itself and the communication device 82 using communication light.

[0017] As shown in FIG. 1, the communication device 82 includes a photoelectric conversion unit 821, a secondary power source 822, a transceiver 823, and a communication circuit 824.

[0018] The photoelectric conversion unit 821 receives the power supply light transmitted from the communication device 81. The photoelectric conversion unit 821 converts the received power supply light into electric power. The secondary power source 822 stores the electric power converted by the photoelectric conversion unit 821. Each functional unit of the communication device 82 is driven by the electric power stored in the secondary power source 822. The transceiver 823 is a transmitter / receiver that transmits and receives communication light between the device itself and the communication device 81. The communication circuit 824 controls the transceiver 823 and transmits and receives data between the device itself and the communication device 81 using communication light.

[0019] With this configuration, the conventional optical communication system 8 can drive the communication device 82 with the power supply light transmitted from the communication device 81 to the communication device 82, and can also realize data communication between the communication device 81 and the communication device 82. However, in the conventional optical communication system 8, the communication device 81 sends out power supply light at a constant output from the power supply light transmitter 812 to supply power to the communication device 82. Therefore, depending on the installation location and stored power amount of the power receiving communication device 82, for example, excessive power may be supplied.

[0020] First Embodiment An optical communication system 1 according to a first embodiment of the present invention will be described below. The optical communication system 1 is an example of an optical power supply system according to the present invention.

[0021] The optical communication system 1 is a system in which a power-supplying communication device equipped with an optical power supply light source and a power-receiving communication device equipped with an opto-electric converter are connected to each other by wire, enabling optical power supply and communication. The optical communication system 1 measures the optical loss value of the power supply light transmitted from the power-supplying communication device to the power-receiving communication device. In general, the optical loss value varies depending on the installation location and other conditions of the power-receiving communication device equipped with an opto-electric converter (e.g., the distance from the power-supplying communication device).

[0022] The optical communication system 1 is characterized by controlling the power of the power supply light output from the optical power supply light source of the power supplying communication device based on the measured optical loss value. At this time, the optical communication system 1 controls the power intensity of the power supply light emitted from the optical power supply light source so that the power of the power supply light input to the photoelectric converter of the power receiving communication device does not exceed a predetermined value. Furthermore, the optical communication system 1 controls the on / off switching of the output of the power supply light emitted from the optical power supply light source depending on the charging state of the secondary power source of the power receiving communication device. With these characteristics, the optical communication system 1 in the first embodiment can reduce the power consumption of the optical power supply light source.

[0023] [Configuration of optical communication system] The configuration of the optical communication system 1 will be described in more detail below. Fig. 2 is a block diagram showing the overall configuration of the optical communication system 1 in the first embodiment of the present invention. As shown in Fig. 2, the optical communication system 1 is configured to include a communication device 11 and a communication device 12. The communication devices 11 and 12 are connected by a wire, and transmit and receive communication light to and from each other to transmit and receive data. The communication devices 11 and 12 are connected by, for example, a communication optical fiber cable, and the communication light is transmitted via the communication optical fiber cable.

[0024] The communication cable may be a cable other than an optical fiber cable. Furthermore, the communication device 11 and the communication device 12 may be configured to be connected for communication wirelessly.

[0025] Furthermore, communication device 11 and communication device 12 are connected by a wire, and power supply light output from communication device 11 is input to communication device 12. That is, communication device 11 is a power supplying communication device equipped with an optical power supply light source, and communication device 12 is a power receiving communication device equipped with an opto-electric converter. Communication device 11 and communication device 12 are connected by a power supply optical fiber cable that is separate from the above-mentioned communication optical fiber cable, and power supply light is transmitted via this power supply optical fiber cable.

[0026] 2, the communication device 11 includes a power supply unit 111, a power supply optical transmitter unit 112, a transceiver 113, a communication circuit 114, a loss measurement unit 115, and a power supply optical power control unit 116. The communication device 11 is, for example, an optical line terminal (OLT) installed on the central office side of a communication company in a subscriber line network (public line network) of a PON (Passive Optical Network) system using optical fiber. The communication device 11 is an example of a communication device of the present invention.

[0027] The power supply unit 111 is a light source power source for generating the power supply light transmitted from the power supply light transmitting unit 112. The power supply light transmitting unit 112 transmits the power supply light toward the communication device 12. The power supply light transmitting unit 112 is, for example, a laser diode. The transceiver 113 is a transmitter / receiver that transmits and receives communication light between the device itself and the communication device 12. The communication circuit 114 controls the transceiver 113 and transmits and receives data between the device itself and the communication device 12 using the communication light.

[0028] The loss measurement unit 115 measures the optical loss value of the power supply light transmitted from the communication device 11 to the communication device 12. The loss measurement unit 115 outputs information indicating the measured optical loss value to the power supply light power control unit 116. For example, the loss measurement unit 115 measures the optical loss value of the power supply light when the communication device 11 and the communication device 12 are connected. Alternatively, for example, the loss measurement unit 115 measures the optical loss value of the power supply light at predetermined intervals (for example, every hour or every day).

[0029] Any existing technology can be used to measure the optical loss value of the power supply light. For example, the loss measurement unit 115 measures the optical loss value using an optical pulse tester (OTDR: Optical Time Domain Reflectometer). For example, the technology described in Non-Patent Document 2 can be used as a method for measuring the optical loss value using an OTDR.

[0030] For example, the loss measurement unit 115 measures the distance from the power-supplying communication device 11 to the power-receiving communication device 12 using an OTDR. Then, the loss measurement unit 115 calculates the optical loss value by multiplying the measured distance by the optical loss per unit. Alternatively, for example, the loss measurement unit 115 directly measures the optical loss value of the power-supply light between the communication device 11 and the communication device 12 using an OTDR.

[0031] The power supply optical power control unit 116 acquires information indicating the optical loss value output from the loss measurement unit 115. The power supply optical power control unit 116 controls the power supply unit 111 according to the acquired optical loss value, thereby controlling the power of the power supply optical signal transmitted from the power supply optical signal transmitting unit 112. At this time, the power supply optical power control unit 116 suppresses the power of the power supply optical signal transmitted from the power supply optical signal transmitting unit 112 so that the power of the power supply optical signal input to the power-receiving communication device 12 does not exceed a predetermined value.

[0032] For example, it is considered that the larger the optical loss value of the power supply light between the communication devices 11 and 12, the farther the installation location of the power-receiving communication device 12 is from the location of the power-supplying communication device 11. Therefore, the power supply light power control unit 116 controls the power supply unit 111 so that the power of the power supply light transmitted from the power supply light transmitting unit 112 increases as the acquired optical loss value increases. Conversely, the power supply light power control unit 116 controls the power supply unit 111 so that the power of the power supply light transmitted from the power supply light transmitting unit 112 decreases as the acquired optical loss value decreases.

[0033] The power value of the power supply light transmitted from the power supply light transmitter 112 for each optical loss value is determined in advance. For example, a table in which optical loss values ​​correspond to power values ​​of the power supply light is stored in advance in a storage medium (not shown) provided in the communication device 11. The power supply light power control unit 116 refers to the table and obtains the power value of the power supply light corresponding to the obtained optical loss value. Then, the power supply light power control unit 116 controls the power supply unit 111 so that the power of the power supply light transmitted from the power supply light transmitter 112 becomes the obtained value.

[0034] 2, the communication device 12 includes a photoelectric conversion unit 121, a secondary power supply 122, a transceiver 123, and a communication circuit 124. The communication device 12 is, for example, an optical line terminal device (ONU: Optical Network Unit) installed in a subscriber's home in a PON subscriber line network (public line network) using optical fiber.

[0035] The photoelectric conversion unit 121 receives the power supply light transmitted from the communication device 11. The photoelectric conversion unit 121 converts the received power supply light into electric power. The photoelectric conversion unit 121 is, for example, a photodiode. The secondary power source 122 stores the electric power converted by the photoelectric conversion unit 121. Each functional unit of the communication device 12 is driven by the electric power stored in the secondary power source 122. The secondary power source 122 includes, for example, a battery. The transceiver 123 is a transmitter / receiver that transmits and receives communication light between the device itself and the communication device 11. The communication circuit 124 controls the transceiver 123 and transmits and receives data between the device itself and the communication device 11 using communication light.

[0036] Furthermore, the secondary power source 122 periodically (for example, every minute or every hour) outputs information indicating its own charging state to the communication circuit 124. Note that the communication circuit 124 may be configured to periodically detect the charging state of the secondary power source 122.

[0037] When the secondary power source 122 is fully charged, it outputs information indicating that it has been fully charged to the communication circuit 124. Then, the communication circuit 124 notifies the communication device 11 that the secondary power source 122 is fully charged. Specifically, the communication circuit 124 transmits information indicating that the secondary power source 122 is fully charged (hereinafter referred to as a "full charge notification") to the communication device 11 via the transceiver 123 using communication light.

[0038] The communication circuit 114 of the communication device 11 receives the full charge notification transmitted from the power receiving communication device 12 via the transceiver 113. Upon receiving the full charge notification, the communication circuit 114 outputs the full charge notification to the power supply optical power control unit 116. The power supply optical power control unit 116 receives the full charge notification output from the communication circuit 114. Upon receiving the full charge notification, the power supply optical power control unit 116 controls the power source unit 111 to stop the power supply optical transmitter 112 from transmitting power supply optical light to the communication device 12. This stops power supply to the communication device 12.

[0039] Furthermore, when the remaining charge of the secondary power source 122 falls below a predetermined value, the secondary power source 122 outputs information indicating that the remaining charge has fallen below the predetermined value to the communication circuit 124. The communication circuit 124 notifies the communication device 11 that the remaining charge of the secondary power source 122 has fallen below the predetermined value. Specifically, the communication circuit 124 transmits information indicating that the remaining charge of the secondary power source 122 has fallen below the predetermined value (hereinafter referred to as a "remaining charge low notification") to the communication device 11 via the transceiver 123 using communication light.

[0040] The communication circuit 114 of the communication device 11 receives a low charge notification transmitted from the power receiving communication device 12 via the transceiver 113. Upon receiving the low charge notification, the communication circuit 114 outputs the low charge notification to the power supply optical power control unit 116. The power supply optical power control unit 116 receives the low charge notification output from the communication circuit 114. Upon receiving the low charge notification, the power supply optical power control unit 116 controls the power source unit 111 to resume transmission of power supply optical light to the communication device 12 by the power supply optical transmitter 112. This resumes power supply to the communication device 12.

[0041] [Operation of optical communication system] The following describes an example of the operation of the optical communication system 1. Fig. 3 is a flowchart showing the operation of the optical communication system 1 in the first embodiment of the present invention. The operation of the optical communication system 1 shown in the flowchart of Fig. 3 is started, for example, when the communication device 11 and the communication device 12 are connected.

[0042] The loss measurement unit 115 of the communication device 11 on the power supply side measures the optical loss value of the power supply light transmitted from the communication device 11 to the communication device 12 (step S001). The loss measurement unit 115 outputs information indicating the measured optical loss value to the power supply optical power control unit 116. The power supply optical power control unit 116 controls the power supply unit 111 according to the acquired optical loss value, thereby controlling the power supply light transmitter 112 to transmit power according to the optical loss value (step S002).

[0043] The photoelectric conversion unit 121 of the power-receiving communication device 12 receives the power supply light transmitted from the communication device 11. The photoelectric conversion unit 121 converts the received power supply light into electric power. The secondary power source 122 stores the electric power converted by the photoelectric conversion unit 121 (step S003).

[0044] When the secondary power source 122 is fully charged (step S004), it outputs information indicating that the secondary power source 122 is fully charged to the communication circuit 124. The communication circuit 124 transmits a full charge notification to the communication device 11 by communication light via the transceiver 123 (step S005).

[0045] The communication circuit 114 of the power-supplying communication device 11 receives the full-charge notification transmitted from the power-receiving communication device 12 via the transceiver 113 (step S006). The communication circuit 114 outputs the full-charge notification to the power-supply optical power control unit 116. Upon receiving the full-charge notification, the power-supply optical power control unit 116 controls the power supply unit 111 to stop the power-supply optical transmitter 112 from transmitting power to the communication device 12 (step S007).

[0046] Furthermore, when the remaining charge amount falls below a predetermined value (step S008: YES), the secondary power source 122 of the power-receiving communication device 12 outputs information indicating that the remaining charge amount has fallen below the predetermined value to the communication circuit 124. The communication circuit 124 transmits a notification of low remaining charge to the communication device 11 via the transceiver 123 by communication light (step S009).

[0047] The communication circuit 114 of the power supplying communication device 11 receives the remaining charge low notification transmitted from the power receiving communication device 12 via the transceiver 113 (step S010). The communication circuit 114 outputs the remaining charge low notification to the power supply optical power control unit 116. Upon receiving the remaining charge low notification, the power supply optical power control unit 116 controls the power supply unit 111 to resume transmission of power supply light by the power supply optical transmitter 112 (step S011).

[0048] The operation of the optical communication system 1 shown in the flowchart of FIG. 3 ends when, for example, communication between the communication device 11 and the communication device 12 ends.

[0049] As described above, in the optical communication system 1 according to the first embodiment, a power-supplying communication device 11 equipped with an optical power supply light source and a power-receiving communication device 12 equipped with an opto-electrical converter are connected to each other by wire, and optical power supply and communication are performed. The optical communication system 1 measures the optical loss value of the power supply light transmitted from the communication device 11 to the communication device 12. Then, the optical communication system 1 controls the power of the power supply light output from the optical power supply light source of the communication device 11 based on the measured optical loss value. At this time, the optical communication system 1 controls the power intensity of the power supply light emitted from the optical power supply light source so that the power of the power supply light input to the opto-electrical converter of the power-receiving communication device does not exceed a predetermined value.

[0050] As described above, in the optical communication system 1 according to the first embodiment, the communication device 12 notifies the communication device 11 of the charging state of the secondary power source 122 of the communication device 12 using communication light. Then, the optical communication system 1 controls the switching on and off of the output of power supply light emitted from the optical power supply light source according to the charging state of the secondary power source 122 of the communication device 12.

[0051] With such features, the optical communication system 1 in the first embodiment can reduce the power consumption of the optically powered light source.

[0052] <Second embodiment> An optical communication system 1a according to a second embodiment of the present invention will be described below. The optical communication system 1a is an example of an optical power supply system according to the present invention. Unlike the optical communication system 1 according to the first embodiment described above, the optical communication system 1a uses reflected light of power supply light instead of communication light to notify the power supply communication device of the charging state of the secondary power source from the power receiving communication device.

[0053] However, when power supply light is not transmitted from the power supplying communication device to the power receiving communication device, there is also no reflected light of the power supply light. As a result, the power receiving communication device cannot use the reflected light to notify the power supplying communication device of the charging state of the secondary power source. Therefore, in this case, the optical communication system 1a in the second embodiment notifies the power supplying communication device of the charging state of the secondary power source using communication light, as in the optical communication system 1 in the first embodiment described above. With these characteristics, the optical communication system 1a in the second embodiment can reduce the power consumption of the optical power supply light source.

[0054] [Configuration of optical communication system] The configuration of the optical communication system 1 will be described in more detail below. Fig. 4 is a block diagram showing the overall configuration of an optical communication system 1a according to a second embodiment of the present invention. As shown in Fig. 4, the optical communication system 1a includes a communication device 11a and a communication device 12a. The communication devices 11a and 12a are connected by a wire, and transmit and receive communication light to and from each other to transmit and receive data. The communication devices 11a and 12a are connected by, for example, a communication optical fiber cable, and the communication light is transmitted via the communication optical fiber cable.

[0055] The communication cable may be a cable other than an optical fiber cable. Also, the communication device 11a and the communication device 12a may be configured to be connected for communication wirelessly.

[0056] Furthermore, the communication device 11a and the communication device 12a are connected by a wire, and the power supply light output from the communication device 11a is input to the communication device 12a. That is, the communication device 11a is a power supplying communication device equipped with an optical power supply light source, and the communication device 12a is a power receiving communication device equipped with an opto-electric converter. The communication devices 11a and 12a are connected by a power supply optical fiber cable that is separate from the above-mentioned communication optical fiber cable, and the power supply light is transmitted via the power supply optical fiber cable.

[0057] In the following description, among the functional parts of the optical communication system 1a in the second embodiment, those having the same functions as those of the functional parts of the optical communication system 1 in the first embodiment described above will be given the same symbols and their descriptions may be omitted.

[0058] 4, the communication device 11a includes a power supply unit 111, a power supply optical transmitter 112, a transceiver 113, a communication circuit 114a, a loss measurement unit 115, a power supply optical power controller 116a, and a reflected light receiver 117. The communication device 11a is, for example, an optical line terminal (OLT). The communication device 11a is an example of a communication device of the present invention.

[0059] The power supply unit 111 is a light source power source for generating the power supply light transmitted from the power supply light transmitting unit 112. The power supply light transmitting unit 112 transmits the power supply light toward the communication device 12a. The transceiver 113 is a transmitter / receiver that transmits and receives communication light between the device itself and the communication device 12a. The communication circuit 114a controls the transceiver 113 and transmits and receives data between the device itself and the communication device 12a using the communication light.

[0060] The loss measurement unit 115 measures the optical loss value of the power supply light transmitted from the communication device 11a to the communication device 12a. The loss measurement unit 115 outputs information indicating the measured optical loss value to the power supply light power control unit 116a. For example, the loss measurement unit 115 measures the optical loss value of the power supply light when the communication device 11a and the communication device 12a are connected. Alternatively, for example, the loss measurement unit 115 measures the optical loss value of the power supply light at predetermined intervals (for example, every hour or every day). Note that any existing technology can be used as a method for measuring the optical loss value of the power supply light.

[0061] The power supply optical power control unit 116a acquires information indicating the optical loss value output from the loss measurement unit 115. The power supply optical power control unit 116a controls the power supply unit 111 according to the acquired optical loss value, thereby controlling the power of the power supply optical signal transmitted from the power supply optical signal transmitting unit 112. The power supply optical power control unit 116a suppresses the power of the power supply optical signal transmitted from the power supply optical signal transmitting unit 112 so that the power of the power supply optical signal input to the power-receiving communication device 12a does not exceed a predetermined value.

[0062] The reflected light receiving unit 117 receives reflected light of the power supply light transmitted from the power supply light transmitting unit 112. As described above, the reflected light is light reflected from the power supply light transmitted from the power supply light transmitting unit 112 to the communication device 12a. A notification regarding the charging state of the secondary power source 122 of the communication device 12a is superimposed on the reflected light. The reflected light receiving unit 117 demodulates the reflected light and acquires the notification regarding the charging state of the secondary power source 122a. The reflected light receiving unit 117 is configured to include, for example, a demodulator, and is installed next to the power supply light transmitting unit 112. The reflected light receiving unit 117 outputs the acquired notification regarding the charging state of the secondary power source 122a to the power supply light power control unit 116a.

[0063] An example of the type of notification regarding the charging state of secondary power source 122a superimposed on the reflected light is a full charge notification. Note that the full charge notification does not necessarily have to be information indicating that secondary power source 122 is actually fully charged, but may be, for example, information indicating that the remaining charge of secondary power source 122 is equal to or greater than a predetermined value (i.e., information indicating that the remaining charge is sufficient). Note that an example of the type of notification regarding the charging state of secondary power source 122a superimposed on the reflected light may be a low remaining charge notification.

[0064] The power supply optical power control unit 116a acquires a notification regarding the charging state of the secondary power source 122a output from the reflected light receiving unit 117. The power supply optical power control unit 116a controls the power supply unit 111 in accordance with the acquired notification regarding the charging state of the secondary power source 122a, thereby controlling the power of the power supply optical power transmitted from the power supply optical transmitting unit 112.

[0065] The feeding optical power control unit 116a receives the full charge notification output from the reflected light receiving unit 117. When the feeding optical power control unit 116a receives the full charge notification, it controls the power supply unit 111 to stop the feeding optical power transmission unit 112 from transmitting feeding optical power to the communication device 12a. This stops the feeding of power to the communication device 12a.

[0066] The power supply optical power control unit 116a may receive a notification of low remaining charge output from the reflected light receiving unit 117. When receiving the notification of low remaining charge, the power supply optical power control unit 116a may control the power supply unit 111 to increase the power of the power supply optical signal transmitted to the communication device 12a by the power supply optical transmitter 112. This allows for more appropriate power supply to the communication device 12a.

[0067] 4, the communication device 12a includes a photoelectric conversion unit 121, a secondary power supply 122a, a transceiver 123, a communication circuit 124a, and a superimposing unit 125. The communication device 12a is, for example, an ONU.

[0068] The photoelectric conversion unit 121 receives the power supply light transmitted from the communication device 11a. The photoelectric conversion unit 121 converts the received power supply light into electric power. The secondary power source 122a stores the electric power converted by the photoelectric conversion unit 121. The transceiver 123 is a transmitter / receiver that transmits and receives communication light between the device itself and the communication device 11a. The communication circuit 124 controls the transceiver 123 and transmits and receives data between the device itself and the communication device 11a via communication light.

[0069] Furthermore, the secondary power source 122a periodically (for example, every minute or every hour) outputs information indicating its own charging state to the superimposing unit 125. Note that the superimposing unit 125 may be configured to periodically detect the charging state of the secondary power source 122a.

[0070] The superimposing unit 125 acquires information indicating the charging state of the secondary power source 122a from the secondary power source 122a. The superimposing unit 125 modulates a portion of the power supply light received by the photoelectric conversion unit 121, thereby superimposing the notification regarding the charging state of the secondary power source 122a on the reflected light of the power supply light. The superimposing unit 125 is configured to include, for example, a reflective modulator, and is provided next to the photoelectric conversion unit 121. The superimposing unit 125 transmits the reflected light on which the notification regarding the charging state of the secondary power source 122a has been superimposed to the communication device 11a.

[0071] For example, when the secondary power source 122a is fully charged, it outputs information indicating that it has been fully charged to the superimposing unit 125. Then, the superimposing unit 125 modulates a full charge notification indicating that the secondary power source 122a has been fully charged to superimpose the full charge notification on the reflected light of the power supply light. The superimposing unit 125 transmits the reflected light on which the full charge notification of the secondary power source 122a has been superimposed to the communication device 11a.

[0072] Furthermore, when the secondary power source 122a has run out of charge (zero), it outputs information indicating that the remaining charge has run out to the communication circuit 124a. Note that the communication circuit 124a may be configured to detect that the remaining charge of the secondary power source 122a has run out.

[0073] The communication circuit 124a notifies the communication device 11a that the remaining charge of the secondary power source 122a has become empty. Specifically, the communication circuit 124 transmits information indicating that the remaining charge of the secondary power source 122a has become empty (hereinafter referred to as "over-discharge notification") to the communication device 11a by communication light via the transceiver 123.

[0074] The over-discharge notification does not necessarily have to be information indicating that the secondary power source 122 has actually become empty, but may be information indicating that the remaining charge of the secondary power source 122 has become equal to or less than a predetermined value (i.e., information indicating that the remaining charge has become insufficient).

[0075] The communication circuit 114a of the power-supplying communication device 11a receives the over-discharge notification transmitted from the power-receiving communication device 12a via the transceiver 113. The communication circuit 114a outputs the over-discharge notification to the power-supply optical power control unit 116a. When the power-supply optical power control unit 116a receives the over-discharge notification, it controls the power supply unit 111 to resume the transmission of power-supply optical light to the communication device 12a from the power-supply optical transmitter 112. This resumes power supply to the communication device 12a.

[0076] It is assumed that the secondary power source 122a of the communication device 12a becomes empty when the communication device 11a is not supplying power to the communication device 12a. When the communication device 11a does not transmit power supply light to the communication device 12a, there is no reflected light of the power supply light, and therefore the over-discharge notification cannot be superimposed on the reflected light and transmitted from the communication device 12a to the communication device 11a. Therefore, the over-discharge notification is transmitted from the communication device 12a to the communication device 11a using communication light.

[0077] [Operation of optical communication system] An example of the operation of the optical communication system 1a will be described below. Fig. 5 is a flowchart showing the operation of the optical communication system 1a in the second embodiment of the present invention. The operation of the optical communication system 1a shown in the flowchart of Fig. 5 starts, for example, when the communication device 11a and the communication device 12a are connected.

[0078] The loss measurement unit 115 of the power-supplying communication device 11a measures an optical loss value of the power supply light transmitted from the communication device 11a to the communication device 12a (step S101). The loss measurement unit 115 outputs information indicating the measured optical loss value to the power supply optical power control unit 116a. The power supply optical power control unit 116a controls the power source unit 111 according to the acquired optical loss value, thereby controlling the power supply light transmitter 112 to transmit power supply light according to the optical loss value (step S102).

[0079] The photoelectric conversion unit 121 of the power-receiving communication device 12a receives the power supply light transmitted from the communication device 11a. The photoelectric conversion unit 121 converts the received power supply light into electric power. The secondary power source 122a stores the electric power converted by the photoelectric conversion unit 121 (step S103).

[0080] When the secondary power source 122a is fully charged (YES in step S104), it outputs information indicating that the secondary power source 122a is fully charged to the superimposing unit 125. The superimposing unit 125 then modulates the full charge notification to superimpose it on the reflected light of the power supply light. The superimposing unit 125 transmits the reflected light on which the full charge notification is superimposed to the communication device 11a (step S105).

[0081] The reflected light receiving unit 117 of the power supply side communication device 11a receives the reflected light of the power supply light transmitted from the power supply light transmitting unit 112. The reflected light receiving unit 117 demodulates the reflected light and acquires a full charge notification (step S106). The reflected light receiving unit 117 outputs the acquired full charge notification to the power supply light power control unit 116a. Upon acquiring the full charge notification, the power supply light power control unit 116a controls the power supply unit 111 to stop the power supply light transmitting unit 112 from transmitting the power supply light to the communication device 11a (step S107).

[0082] Furthermore, when the secondary power source 122 of the power-receiving communication device 12a is empty (YES in step S108), it outputs information indicating that the secondary power source 122 is empty to the communication circuit 124a. The communication circuit 124a then transmits an over-discharge notification to the communication device 11a via the transceiver 123 using communication light (step S109).

[0083] The communication circuit 114a of the power-supplying communication device 11a receives the over-discharge notification transmitted from the power-receiving communication device 12a via the transceiver 113 (step S110). The communication circuit 114 outputs the over-discharge notification to the power-supply optical power control unit 116a. Upon receiving the over-discharge notification, the power-supply optical power control unit 116a controls the power supply unit 111 to resume transmission of power-supply optical light from the power-supply optical transmitter 112 to the communication device 12a (step S111).

[0084] The operation of the optical communication system 1a shown in the flowchart of FIG. 5 ends when, for example, communication between the communication device 11a and the communication device 12a ends.

[0085] As described above, in the optical communication system 1a according to the second embodiment, a power-supplying communication device 11a equipped with an optical power supply light source and a power-receiving communication device 12a equipped with an opto-electrical converter are connected to each other by wire, and optical power supply and communication are performed. The optical communication system 1a measures the optical loss value of the power supply light transmitted from the communication device 11a to the communication device 12a. Then, the optical communication system 1a controls the power of the power supply light output from the optical power supply light source of the communication device 11a based on the measured optical loss value. At this time, the optical communication system 1a controls the power intensity of the power supply light transmitted from the optical power supply light source so that the power of the power supply light input to the opto-electrical converter of the power-receiving communication device does not exceed a predetermined value.

[0086] As described above, in the optical communication system 1a according to the second embodiment, the communication device 12a notifies the communication device 11a of the charge state of the secondary power source 122a of the communication device 12a using reflected light from the power supply light. The optical communication system 1a then controls the on / off switching of the power supply light emitted from the optical power supply light source according to the charge state of the secondary power source 122 of the communication device 12a. However, as described above, when the power supply light output is turned off, the reflected light also disappears, and therefore the communication device 12a can no longer notify the communication device 11a of the charge state of the secondary power source 122a. Therefore, in the optical communication system 1a according to the second embodiment, the communication device 12a transmits an over-discharge notification indicating that the secondary power source 122a has run out to the communication device 11a using communication light, rather than reflected light. This allows the communication device 11a to recognize that the secondary power source 122a has run out of charge, even without receiving reflected light.

[0087] With such features, the optical communication system 1a according to the second embodiment can reduce the power consumption of the optically powered light source.

[0088] <Third embodiment> An optical communication system 1b according to the third embodiment of the present invention will be described below. The optical communication system 1b is an example of an optical power supply system according to the present invention.

[0089] In the optical communication system 1 in the first embodiment and the optical communication system 1a in the second embodiment, the optical fiber through which the power supply light is transmitted is separate from the optical fiber through which the communication light is transmitted. In contrast, the optical communication system 1b in the third embodiment is configured to transmit the power supply light and the communication light using the same optical fiber cable. As a technology for transmitting the power supply light and the communication light using the same optical fiber cable, for example, WDM (Wavelength Division Multiplexing) can be used.

[0090] The configuration of the optical communication system 1b in the third embodiment of the present invention is a modified configuration of the optical communication system 1 in the first embodiment described above, in which the transmission of power supply light and the transmission of communication light are performed using the same optical fiber cable.

[0091] [Configuration of optical communication system] The configuration of the optical communication system 1b will be described in more detail below. Fig. 6 is a block diagram showing the overall configuration of the optical communication system 1b according to the third embodiment of the present invention. As shown in Fig. 6, the optical communication system 1b includes a communication device 11b and a communication device 12b. The communication devices 11b and 12b are connected by wire, and transmit and receive data by transmitting and receiving communication light to and from each other. The communication devices 11b and 12b are connected by an optical fiber cable that serves both for communication and power supply, and the communication light is transmitted via this optical fiber cable.

[0092] The power supply light output from the communication device 11b is transmitted through the optical fiber cable used for both communication and power supply, and is input to the communication device 12b. That is, the communication device 11b is a power supplying communication device equipped with an optical power supply light source, and the communication device 12b is a power receiving communication device equipped with an optoelectric converter.

[0093] In the following description, among the functional parts of the optical communication system 1b in the third embodiment, those having the same functions as those of the functional parts of the optical communication system 1 in the first embodiment described above will be given the same symbols and their descriptions may be omitted.

[0094] 6, the communication device 11b includes a power supply unit 111, a communication circuit 114, a loss measurement unit 115, a power supply optical power control unit 116, and a power supply optical transmitter / transceiver 118. The communication device 11b is, for example, an optical line terminal (OLT). The communication device 11b is an example of a communication device of the present invention.

[0095] The power supply unit 111 is a light source power source for generating the power supply light transmitted from the power supply light transmitter / transceiver 118. The power supply light transmitter / transceiver 118 transmits the power supply light toward the communication device 12b. The power supply light transmitter / transceiver 118 includes, for example, a laser diode. The power supply light transmitter / transceiver 118 also transmits and receives communication light between its own device and the communication device 12b. The communication circuit 114 controls the power supply light transmitter / transceiver 118 to transmit and receive data between its own device and the communication device 12b using communication light.

[0096] The loss measurement unit 115 measures the optical loss value of the power supply light transmitted from the communication device 11b to the communication device 12b. The loss measurement unit 115 outputs information indicating the measured optical loss value to the power supply light power control unit 116. For example, the loss measurement unit 115 measures the optical loss value of the power supply light when the communication device 11b and the communication device 12b are connected. Alternatively, for example, the loss measurement unit 115 measures the optical loss value of the power supply light at predetermined intervals (for example, every hour or every day).

[0097] The power supply optical power control unit 116 acquires information indicating the optical loss value output from the loss measurement unit 115. The power supply optical power control unit 116 controls the power supply unit 111 according to the acquired optical loss value, thereby controlling the power of the power supply optical signal transmitted from the power supply optical transmitter / transceiver 118. At this time, the power supply optical power control unit 116 suppresses the power of the power supply optical signal transmitted from the power supply optical transmitter / transceiver 118 so that the power of the power supply optical signal input to the power-receiving communication device 12b does not exceed a predetermined value.

[0098] 6, the communication device 12b includes a secondary power source 122, a communication circuit 124, and a photoelectric converter / transceiver 126. The communication device 12b is, for example, an ONU.

[0099] The photoelectric conversion unit and transceiver 126 receives the power supply light transmitted from the communication device 11b. The photoelectric conversion unit and transceiver 126 converts the received power supply light into electric power. The photoelectric conversion unit and transceiver 126 includes, for example, a photodiode. The secondary power source 122 stores the electric power converted by the photoelectric conversion unit and transceiver 126. Each functional unit of the communication device 12b is driven by the electric power stored in the secondary power source 122. The photoelectric conversion unit and transceiver 126 transmits and receives communication light between the communication device 12b and the communication device 11b. The communication circuit 124 controls the photoelectric conversion unit and transceiver 126 to transmit and receive data between the communication device 12b and the communication device 11b using communication light.

[0100] Furthermore, the secondary power source 122 periodically (for example, every minute or every hour) outputs information indicating its own charging state to the communication circuit 124. Note that the communication circuit 124 may be configured to periodically detect the charging state of the secondary power source 122.

[0101] When the secondary power source 122 reaches a fully charged state, it outputs information indicating that the secondary power source 122 has reached a fully charged state to the communication circuit 124. Then, the communication circuit 124 notifies the communication device 11b that the secondary power source 122 has reached a fully charged state. Specifically, the communication circuit 124 transmits a full charge notification indicating that the secondary power source 122 has reached a fully charged state to the communication device 11b via the photoelectric conversion unit / transceiver 126 using communication light.

[0102] The communication circuit 114 of the communication device 11b receives the full charge notification transmitted from the power receiving communication device 12b via the power supply optical transmitter / transceiver 118. Upon receiving the full charge notification, the communication circuit 114 outputs the full charge notification to the power supply optical power control unit 116. The power supply optical power control unit 116 receives the full charge notification output from the communication circuit 114. Upon receiving the full charge notification, the power supply optical power control unit 116 controls the power source unit 111 to stop the power supply optical transmitter / transceiver 118 from transmitting power supply optical light to the communication device 12b. This stops power supply to the communication device 12b.

[0103] Furthermore, when the remaining charge of the secondary power source 122 falls below a predetermined value, the secondary power source 122 outputs information indicating that the remaining charge has fallen below the predetermined value to the communication circuit 124. The communication circuit 124 notifies the communication device 11b that the remaining charge of the secondary power source 122 has fallen below the predetermined value. Specifically, the communication circuit 124 transmits a remaining charge low notification, indicating that the remaining charge of the secondary power source 122 has fallen below the predetermined value, to the communication device 11b via the photoelectric conversion unit / transceiver 126 using communication light.

[0104] The communication circuit 114 of the communication device 11b receives the remaining charge low notification transmitted from the power receiving communication device 12b via the power supply optical transmitter / transceiver 118. Upon receiving the remaining charge low notification, the communication circuit 114 outputs the remaining charge low notification to the power supply optical power control unit 116. The power supply optical power control unit 116 receives the remaining charge low notification output from the communication circuit 114. Upon receiving the remaining charge low notification, the power supply optical power control unit 116 controls the power source unit 111 to resume transmission of power supply optical light to the communication device 12b from the power supply optical transmitter / transceiver 118. This resumes power supply to the communication device 12b.

[0105] As described above, the configuration of the optical communication system 1b in the third embodiment is a modified configuration of the optical communication system 1 in the first embodiment described above, in which the transmission of power supply light and the transmission of communication light are performed using the same optical fiber cable.

[0106] By having such a configuration, the optical communication system 1b can reduce, for example, the number of optical fiber cables required, thereby reducing device costs, installation costs, installation space, operation costs, etc.

[0107] <Fourth embodiment> An optical communication system 1c according to the fourth embodiment of the present invention will now be described.

[0108] The configuration of the optical communication system 1c in the fourth embodiment of the present invention is a modified configuration of the optical communication system 1a in the second embodiment described above, in which the transmission of the power supply light and the transmission of the communication light are performed using the same optical fiber cable. As a technology for performing the transmission of the power supply light and the communication light using the same optical fiber cable, for example, WDM can be used.

[0109] [Configuration of optical communication system] The configuration of the optical communication system 1c will be described in more detail below. Fig. 7 is a block diagram showing the overall configuration of the optical communication system 1c according to the fourth embodiment of the present invention. As shown in Fig. 7, the optical communication system 1c includes a communication device 11c and a communication device 12c. The communication devices 11c and 12c are connected by wire, and transmit and receive data by transmitting and receiving communication light to and from each other. The communication devices 11c and 12c are connected by an optical fiber cable that serves both for communication and power supply, and the communication light is transmitted via this optical fiber cable.

[0110] The power supply light output from the communication device 11c is transmitted through the optical fiber cable used for both communication and power supply, and is input to the communication device 12c. That is, the communication device 11c is a power supplying communication device equipped with an optical power supply light source, and the communication device 12c is a power receiving communication device equipped with an opto-electric converter.

[0111] In the following description, among the functional parts of the optical communication system 1c in the fourth embodiment, those having the same functions as those of the functional parts of the optical communication system 1a in the second embodiment described above will be given the same symbols, and their descriptions may be omitted.

[0112] 7, the communication device 11c includes a communication circuit 114a, a loss measurement unit 115, a feed optical power control unit 116a, a reflected light receiving unit 117, and a feed optical transmitting unit / transceiver 118. The communication device 11c is, for example, an optical line terminal (OLT). The communication device 11c is an example of the communication device of the present invention.

[0113] The power supply unit 111 is a light source power source for generating the power supply light transmitted from the power supply light transmitter / transceiver 118. The power supply light transmitter / transceiver 118 transmits the power supply light toward the communication device 12c. The power supply light transmitter / transceiver 118 is a transceiver that transmits and receives communication light between its own device and the communication device 12c. The communication circuit 114a controls the power supply light transmitter / transceiver 118 and transmits and receives data between its own device and the communication device 12c using communication light.

[0114] The loss measurement unit 115 measures the optical loss value of the power supply light transmitted from the communication device 11c to the communication device 12c. The loss measurement unit 115 outputs information indicating the measured optical loss value to the power supply light power control unit 116a. For example, the loss measurement unit 115 measures the optical loss value of the power supply light when the communication device 11c and the communication device 12c are connected. Alternatively, for example, the loss measurement unit 115 measures the optical loss value of the power supply light at predetermined intervals (for example, every hour or every day). Note that any existing technology can be used as a method for measuring the optical loss value of the power supply light.

[0115] The power supply optical power control unit 116a acquires information indicating the optical loss value output from the loss measurement unit 115. The power supply optical power control unit 116a controls the power supply unit 111 according to the acquired optical loss value, thereby controlling the power of the power supply optical signal transmitted from the power supply optical transmitter / transceiver 118. The power supply optical power control unit 116a suppresses the power of the power supply optical signal transmitted from the power supply optical transmitter / transceiver 118 so that the power of the power supply optical signal input to the power-receiving communication device 12c does not exceed a predetermined value.

[0116] The reflected light receiving unit 117 receives reflected light of the power supply light transmitted from the power supply light transmitting unit and transceiver 118. As described above, the reflected light is light reflected from the power supply light transmitted from the power supply light transmitting unit and transceiver 118 to the communication device 12c. A notification regarding the charging state of the secondary power source 122a of the communication device 12c is superimposed on the reflected light. The reflected light receiving unit 117 demodulates the reflected light and acquires the notification regarding the charging state of the secondary power source 122a. The reflected light receiving unit 117 is configured to include, for example, a demodulator, and is provided in addition to the power supply light transmitting unit and transceiver 118. The reflected light receiving unit 117 outputs the acquired notification regarding the charging state of the secondary power source 122a to the power supply light power control unit 116a.

[0117] An example of the type of notification regarding the charging state of secondary power source 122a superimposed on the reflected light is a full charge notification. Note that the full charge notification does not necessarily have to be information indicating that secondary power source 122a is actually fully charged, but may be, for example, information indicating that the remaining charge of secondary power source 122a is equal to or greater than a predetermined value (i.e., information indicating that the remaining charge is sufficient). Note that an example of the type of notification regarding the charging state of secondary power source 122a superimposed on the reflected light may be a low remaining charge notification.

[0118] The power supply optical power control unit 116a acquires a notification regarding the charging state of the secondary power source 122a output from the reflected light receiving unit 117. The power supply optical power control unit 116a controls the power supply unit 111 in accordance with the acquired notification regarding the charging state of the secondary power source 122a, thereby controlling the power of the power supply optical power transmitted from the power supply optical transmitter / transceiver 118.

[0119] The power supply optical power control unit 116a receives the full charge notification output from the reflected light receiving unit 117. When the power supply optical power control unit 116a receives the full charge notification, it controls the power supply unit 111 to stop the power supply optical transmitter / transceiver 118 from transmitting power supply optical light to the communication device 12c. This stops power supply to the communication device 12c.

[0120] The power supply optical power control unit 116a may receive a notification of low remaining charge output from the reflected light receiving unit 117. When receiving the notification of low remaining charge, the power supply optical power control unit 116a may control the power supply unit 111 to increase the power of the power supply optical signal transmitted to the communication device 12c by the power supply optical transmitter / transceiver 118. This allows for more appropriate power supply to the communication device 12c.

[0121] 7, the communication device 12c includes a secondary power source 122a, a communication circuit 124a, a superimposing unit 125, and an opto-electrical converter / transceiver 126. The communication device 12c is, for example, an ONU.

[0122] The photoelectric conversion unit 121 receives the power supply light transmitted from the communication device 11c. The photoelectric conversion unit and transceiver 126 converts the received power supply light into electric power. The secondary power source 122a stores the electric power converted by the photoelectric conversion unit and transceiver 126. The photoelectric conversion unit and transceiver 126 transmits and receives communication light between the device itself and the communication device 11c. The communication circuit 124 controls the photoelectric conversion unit and transceiver 126 to transmit and receive data between the device itself and the communication device 11c using communication light.

[0123] Furthermore, the secondary power source 122a periodically (for example, every minute or every hour) outputs information indicating its own charging state to the superimposing unit 125. Note that the superimposing unit 125 may be configured to periodically detect the charging state of the secondary power source 122a.

[0124] The superimposing unit 125 acquires information indicating the charging state of the secondary power source 122a from the secondary power source 122a. The superimposing unit 125 modulates a portion of the power supply light received by the photoelectric conversion unit 121, thereby superimposing the notification regarding the charging state of the secondary power source 122a on the reflected light of the power supply light. The superimposing unit 125 is configured to include, for example, a reflective modulator, and is provided in addition to the photoelectric conversion unit / transceiver 126. The superimposing unit 125 transmits the reflected light on which the notification regarding the charging state of the secondary power source 122a has been superimposed to the communication device 11c.

[0125] For example, when the secondary power source 122a is fully charged, it outputs information indicating that it has been fully charged to the superimposing unit 125. Then, the superimposing unit 125 modulates a full charge notification indicating that the secondary power source 122a has been fully charged to superimpose it on the reflected light of the power supply light. The superimposing unit 125 transmits the reflected light on which the full charge notification of the secondary power source 122a has been superimposed to the communication device 11c.

[0126] Furthermore, when the secondary power source 122a has run out of charge (zero), it outputs information indicating that the remaining charge has run out to the communication circuit 124a. Note that the communication circuit 124a may be configured to detect that the remaining charge of the secondary power source 122a has run out.

[0127] The communication circuit 124a notifies the communication device 11c that the remaining charge of the secondary power source 122a has become empty. Specifically, the communication circuit 124a transmits an over-discharge notification indicating that the remaining charge of the secondary power source 122a has become empty to the communication device 11c by communication light via the photoelectric conversion unit / transceiver 126.

[0128] The over-discharge notification does not necessarily have to be information indicating that the secondary power source 122a has actually become empty, but may be information indicating that the remaining charge of the secondary power source 122a has become equal to or less than a predetermined value (i.e., information indicating that the remaining charge has become insufficient).

[0129] The communication circuit 114a of the power-supplying communication device 11c receives the over-discharge notification transmitted from the power-receiving communication device 12c via the power-supplying optical transmitter / transceiver 118. The communication circuit 114a outputs the over-discharge notification to the power-supplying optical power control unit 116a. When the power-supplying optical power control unit 116a receives the over-discharge notification, it controls the power supply unit 111 to resume transmission of power supplying optical light to the communication device 12c from the power-supplying optical transmitter / transceiver 118. This resumes power supply to the communication device 12c.

[0130] It is assumed that the secondary power source 122a of the communication device 12c becomes empty when power is not being supplied from the communication device 11c to the communication device 12c. When the communication device 11c does not transmit power supply light to the communication device 12c, there is no reflected light of the power supply light, and therefore the over-discharge notification cannot be superimposed on the reflected light and transmitted from the communication device 12c to the communication device 11c. Therefore, the over-discharge notification is transmitted from the communication device 12c to the communication device 11c using communication light.

[0131] As described above, the configuration of the optical communication system 1c in the fourth embodiment is a modified configuration of the optical communication system 1a in the second embodiment described above, in which the transmission of power supply light and the transmission of communication light are performed using the same optical fiber cable.

[0132] By having such a configuration, the optical communication system 1c can reduce, for example, the number of optical fiber cables required, thereby reducing device costs, installation costs, installation space, operation costs, and the like.

[0133] <Fifth embodiment> An optical communication system 1d according to the fifth embodiment of the present invention will be described below. The optical communication system 1d is an example of an optical power feeding system according to the present invention.

[0134] In the first to fourth embodiments described above, the network configuration of the optical communication systems 1, 1a to 1c is basically assumed to be a single star configuration in which the power supplying communication device (communication devices 11, 11a to 11c) and the power receiving communication device (communication devices 12, 12a to 12c) are connected in a one-to-one relationship. The one-to-one configuration can prevent optical loss caused by branching of optical fiber, for example, and thus realize efficient optical power supply. In contrast, the optical communication system 1d in the fifth embodiment described below is assumed to be a double star configuration in which the power supplying communication device (communication device 11d) and the power receiving communication devices (communication devices 12-1 to 12-n) are connected in a one-to-multiple relationship. The one-to-multiple configuration can reduce, for example, the number of power supplying communication devices (communication device 11d) and optical fibers, etc., thereby reducing device costs, installation costs, operation costs, etc.

[0135] The optical communication system 1d in the fifth embodiment is a system in which a power supplying side communication device equipped with an optical power supply light source and a plurality of power receiving side communication devices equipped with photoelectric converters are connected to each other by wire via a branching unit such as an optical splitter, and optical power supply and communication can be performed. The optical communication system 1d measures the optical loss value of the power supply light transmitted from the power supplying side communication device to each of the plurality of power receiving side communication devices.

[0136] The optical communication system 1d is characterized by controlling the power of the optical feed light output from the optical feed light source of the power-feeding communication device based on the measured optical loss value. At this time, for example, if at least one of the measured optical loss values ​​is equal to or greater than a predetermined value, the optical communication system 1d controls the output of the optical feed light to maximize it. Also, for example, if all of the measured optical loss values ​​are less than a predetermined value, the optical communication system 1d controls the output of the optical feed light to set the output value to a preset output value obtained by adding the maximum of the measured optical loss values.

[0137] Furthermore, the optical communication system 1d controls the output of the power supply light emitted from the optical power supply light source to be switched on and off depending on the state of charge of the secondary power source of the power receiving communication device. For example, the optical communication system 1d controls the output of the power supply light to be on when the state of charge of the secondary power source of at least one power receiving communication device is not fully charged, and controls the output of the power supply light to be off when the state of charge of the secondary power sources of all power receiving communication devices is fully charged. With these features, the optical communication system 1d in the fifth embodiment can reduce the power consumption of the optical power supply light source even in a network configuration in which power supplying communication devices and power receiving communication devices are connected to each other in a one-to-multiple configuration, such as a double star configuration.

[0138] [Configuration of optical communication system] The configuration of the optical communication system 1d will be described in more detail below. Fig. 8 is a block diagram showing the overall configuration of the optical communication system 1d according to the fifth embodiment of the present invention. As shown in Fig. 8, the optical communication system 1d includes a communication device 11d and a plurality of communication devices 12 (communication devices 12-1 to 12-n). The communication device 11d and each of the communication devices 12-1 to 12-n are connected by wire, and transmit and receive communication light to and from each other to transmit and receive data. The communication device 11d and each of the communication devices 12-1 to 12-n are connected by a communication optical fiber cable that branches one-to-multiple by a branching unit such as an optical splitter 20, as shown in Fig. 8, for example, and communication light is transmitted via the communication optical fiber cable.

[0139] The communication cable may be a cable other than an optical fiber cable. Also, communication device 11d and each of communication devices 12-1 to 12-n may be connected to each other wirelessly for communication.

[0140] Furthermore, communication device 11d and each of communication devices 12-1 to 12-n are connected by wire, and power supply light output from communication device 11d is input to each of communication devices 12-1 to 12-n. That is, communication device 11d is a power supply-side communication device equipped with an optical power supply light source, and each of communication devices 12-1 to 12-n is a power receiving-side communication device equipped with an opto-electric converter. Communication device 11d and each of communication devices 12-1 to 12-n are connected by a power supply optical fiber cable that is separate from the above-mentioned communication optical fiber cable and that branches one to many by a branching unit such as optical splitter 20 as shown in FIG. 8, for example, and power supply light is transmitted via the power supply optical fiber cable.

[0141] 8, the communication device 11d includes a power supply unit 111, a power supply optical transmitter 112, a transceiver 113d, a communication circuit 114d, a loss measurement unit 115d, and a power supply optical power control unit 116d. The communication device 11d is, for example, an optical line terminal (OLT) installed on the central office side of a communication company in a PON subscriber line network (public line network) using optical fiber. The communication device 11d is an example of a communication device of the present invention.

[0142] The power supply unit 111 is a light source power source for generating the power supply light transmitted from the power supply light transmitting unit 112. The power supply light transmitting unit 112 transmits the power supply light toward the plurality of communication devices 12 (communication devices 12-1 to 12n). The power supply light transmitting unit 112 is, for example, a laser diode. The transceiver 113d is a transmitter / receiver that transmits and receives communication light between its own device and each of the plurality of communication devices 12 (communication devices 12-1 to 12n). The communication circuit 114d controls the transceiver 113d and transmits and receives data between its own device and each of the plurality of communication devices 12 (communication devices 12-1 to 12n) using communication light.

[0143] The loss measurement unit 115d measures an optical loss value of the power supply light transmitted from the communication device 11d to each of the plurality of communication devices 12 (communication devices 12-1 to 12n). The loss measurement unit 115d outputs information indicating the measured optical loss values ​​to the power supply optical power control unit 116d. For example, when the communication device 11d is connected to a new communication device 12, the loss measurement unit 115d measures an optical loss value of the power supply light transmitted from the communication device 11d to each of the plurality of communication devices 12 (communication devices 12-1 to 12n). Alternatively, for example, the loss measurement unit 115d measures an optical loss value of the power supply light transmitted from the communication device 11d to each of the plurality of communication devices 12 (communication devices 12-1 to 12n) at predetermined intervals (for example, every hour or every day).

[0144] Any existing technology can be used to measure the optical loss value of the power supply light. For example, the loss measurement unit 115d measures the optical loss value using an optical pulse tester (OTDR). For example, the technology described in Non-Patent Document 2 can be used as a method for measuring the optical loss value using an OTDR.

[0145] For example, the loss measurement unit 115d measures the distance from the power-supplying communication device 11d to each of the power-receiving communication devices 12 (communication devices 12-1 to 12n) using an OTDR. Then, the loss measurement unit 115d calculates each optical loss value by multiplying each measured distance by the optical loss per unit. Alternatively, for example, the loss measurement unit 115d directly measures the optical loss value of the power-supply light between the communication device 11d and each of the communication devices 12 (communication devices 12-1 to 12n) using an OTDR.

[0146] The power supply optical power control unit 116d acquires information indicating the plurality of optical loss values ​​output from the loss measurement unit 115d. The power supply optical power control unit 116d controls the power supply unit 111 in accordance with the acquired plurality of optical loss values, thereby controlling the power of the power supply optical signal transmitted from the power supply optical transmitter 112.

[0147] At this time, if at least one of the acquired optical loss values ​​is equal to or greater than a predetermined value, the power supply optical power control unit 116d controls the power supply unit 111 to maximize the output of the power supply optical signal transmitted from the power supply optical transmitter 112. The predetermined value here is, for example, a value that represents the maximum extent to which the power supply optical signal transmitter 112 can further increase the output of the power supply optical signal.

[0148] Furthermore, when all of the acquired optical loss values ​​are less than a predetermined value, the optical power control unit 116d controls the power supply unit 111 so that the optical power transmission unit 112 transmits optical power at an output value obtained by adding the maximum value of the acquired optical loss values ​​to a preset output value.

[0149] The power value of the power supply light transmitted from the power supply light transmitter 112 for each optical loss value is determined in advance. For example, a table in which optical loss values ​​correspond to power values ​​of the power supply light is stored in advance in a storage medium (not shown) provided in the communication device 11d. The power supply light power control unit 116d refers to the table and obtains the power value of the power supply light corresponding to the obtained optical loss value. Then, the power supply light power control unit 116d controls the power supply unit 111 so that the power of the power supply light transmitted from the power supply light transmitter 112 becomes the obtained value.

[0150] 8, each of the communication devices 12-1 to 12-n includes an opto-electrical conversion unit 121, a secondary power supply 122, a transceiver 123, and a communication circuit 124. Each of the communication devices 12-1 to 12-n is, for example, an optical line terminal device (ONU) installed in a subscriber's home in a PON subscriber line network (public line network) using optical fibers.

[0151] The photoelectric conversion unit 121 receives the power supply light sent from the communication device 11d and transmitted via the optical splitter 20. The photoelectric conversion unit 121 converts the received power supply light into electric power. The photoelectric conversion unit 121 is, for example, a photodiode. The secondary power source 122 stores the electric power converted by the photoelectric conversion unit 121. The functional units of each of the communication devices 12-1 to 12-n are driven by the electric power stored in the secondary power source 122. The secondary power source 122 includes, for example, a battery. The transceiver 123 is a transmitter / receiver that transmits and receives communication light between the communication device 11d and the communication device 11d. The communication circuit 124 controls the transceiver 123 and transmits and receives data between the communication device 11d and the communication device 11d using the communication light.

[0152] Furthermore, the secondary power source 122 periodically (for example, every minute or every hour) outputs information indicating its own charging state to the communication circuit 124. Note that the communication circuit 124 may be configured to periodically detect the charging state of the secondary power source 122.

[0153] When the secondary power source 122 is fully charged, it outputs information indicating that it has been fully charged to the communication circuit 124. Then, the communication circuit 124 notifies the communication device 11d that the secondary power source 122 is fully charged. Specifically, the communication circuit 124 transmits a full charge notification, which is information indicating that the secondary power source 122 is fully charged, to the communication device 11d via the transceiver 123 using communication light.

[0154] The communication circuit 114d of the communication device 11d acquires the full charge notification transmitted from each of the power receiving communication devices 12 (communication devices 12-1 to 12-n) via the transceiver 113d. Upon acquiring the full charge notification, the communication circuit 114d outputs the full charge notification to the supplied optical power control unit 116d. The supplied optical power control unit 116d acquires the full charge notification output from the communication circuit 114d.

[0155] Furthermore, the power supply optical power control unit 116d controls switching on and off of the power supply optical output transmitted from the power supply optical transmitter 112 according to the charge state of the secondary power source of each of the power receiving side communication devices 12 (communication devices 12-1 to 12n).

[0156] For example, when the secondary power source of at least one of the power receiving communication devices 12 (any of the communication devices 12-1 to 12-n) is not fully charged (i.e., when a full charge notification has not been received from at least one of the power receiving communication devices 12), the power supply optical power control unit 116d controls the power supply unit 111 to start, resume, or continue transmitting the power supply optical light from the power supply optical transmitter 112. Also, when the secondary power sources of all of the power receiving communication devices 12 (communication devices 12-1 to 12-n) are fully charged (i.e., when a full charge notification has been received from all of the power receiving communication devices 12), the power supply optical power control unit 116d controls the power supply unit 111 to stop transmitting the power supply optical light from the power supply optical transmitter 112. As a result, power supply to each of the communication devices 12 (communication devices 12-1 to 12-n) is stopped.

[0157] Furthermore, when the remaining charge of the secondary power source 122 falls below a predetermined value, the secondary power source 122 outputs information indicating that the remaining charge has fallen below the predetermined value to the communication circuit 124. The communication circuit 124 notifies the communication device 11d that the remaining charge of the secondary power source 122 has fallen below the predetermined value. Specifically, the communication circuit 124 transmits a remaining charge low notification, which is information indicating that the remaining charge of the secondary power source 122 has fallen below the predetermined value, to the communication device 11d via the transceiver 123 using communication light.

[0158] The communication circuit 114d of the communication device 11d receives a low charge notification transmitted from each of the power receiving communication devices 12 (communication devices 12-1 to 12-n) via the transceiver 113d. Upon receiving the low charge notification, the communication circuit 114d outputs the low charge notification to the supplied optical power control unit 116d. The supplied optical power control unit 116d receives the low charge notification output from the communication circuit 114d.

[0159] When receiving a notification of low remaining charge from at least one of the power receiving communication devices 12, the power supply optical power control unit 116 controls the power supply unit 111 to restart the transmission of power supply optical power to each of the communication devices 12 (communication devices 12-1 to 12n) by the power supply optical transmitter 112d. This restarts power supply to each of the communication devices 12 (communication devices 12-1 to 12n).

[0160] [Operation of optical communication system] An example of the operation of the communication device 11d will be described below. Figures 9 and 10 are flowcharts showing the operation of the communication device 11d in the fifth embodiment of the present invention.

[0161] The flowchart in Fig. 9 shows the process of controlling the output of power supply light based on the measured optical loss value. The operation of the communication device 11d shown in the flowchart in Fig. 9 is started, for example, when a power-receiving communication device 12 is newly connected to the power-supplying communication device 11d (step S201). The loss measurement unit 115d measures the optical loss value of the power supply light transmitted from the communication device 11d to each of the communication devices 12 (communication devices 12-1 to 12-n) (step S202).

[0162] The loss measurement unit 115d outputs information indicating the measured optical loss values ​​to the supplied optical power control unit 116d. The supplied optical power control unit 116d controls the power supply unit 111 according to the acquired optical loss values. The supplied optical power control unit 116d determines whether all the acquired optical loss values ​​are less than a predetermined value (step S203).

[0163] If it is determined that all optical loss values ​​are less than the predetermined value (step S203: Yes), the optical power control unit 116d controls the power supply unit 111 so that the optical power transmission unit 112 transmits optical power at an output value obtained by adding the maximum value of the measured optical loss values ​​to a preset output value (step S204).

[0164] On the other hand, if it is determined that at least one optical loss value is equal to or greater than the predetermined value (step S203: NO), the power supply unit 111 is controlled so that the power supply light is output from the power supply light transmitting unit 112 at the maximum output value (step S205).

[0165] The communication device 11d waits until a predetermined time has elapsed, and then repeatedly executes the processes from step S202 onwards.

[0166] The flowchart in Fig. 10 shows the process of controlling the output of power supply light based on the power storage state of the secondary power source 122 of each of the communication devices 12 (communication devices 12-1 to 12-n). The operation of the communication device 11d shown in the flowchart in Fig. 10 is started, for example, when optical power supply is started or resumed (step S301).

[0167] The communication circuit 114d acquires a full charge notification transmitted from one of the plurality of communication devices 12 (communication devices 12-1 to 12-n) on the power receiving side via the transceiver 113d (step S302). Upon acquiring the full charge notification, the communication circuit 114d outputs the full charge notification to the supplied optical power control unit 116d. The supplied optical power control unit 116d acquires the full charge notification output from the communication circuit 114d.

[0168] The supplied optical power control unit 116d determines whether or not there is any communication device 12 that has not received a full charge notification among the multiple communication devices 12 (communication devices 12-1 to 12n) on the power receiving side (step S303). If it is determined that there is any communication device 12 that has not received a full charge notification (step S303: YES), the supplied optical power control unit 116d controls the power supply optical transmitter 112 to continue transmitting power supply light (step S304). Then, the communication device 116d repeatedly executes the processes from step S302 onwards.

[0169] On the other hand, if it is determined that there is no communication device 12 that has not received a full charge notification (step S303: NO), the power supply light power control unit 116d controls the power supply unit 111 to stop the transmission of power supply light from the power supply light transmitting unit 112 (step S305).

[0170] Thereafter, the communication circuit 114d acquires a remaining charge low notification transmitted from one of the plurality of communication devices 12 (communication devices 12-1 to 12-n) on the power receiving side via the transceiver 113d (step S306). Upon acquiring the remaining charge low notification, the communication circuit 114d outputs the remaining charge low notification to the supplied optical power control unit 116d. The supplied optical power control unit 116d acquires the remaining charge low notification output from the communication circuit 114d.

[0171] When receiving the notification of low remaining charge, the power supply optical power control unit 116 controls the power supply unit 111 to restart the transmission of power supply optical power to each of the communication devices 12 (communication devices 12-1 to 12-n) by the power supply optical transmitter 112d (step S301). Then, the communication device 11d repeatedly executes the processes from step S302 onwards.

[0172] As described above, in the optical communication system 1d of the fifth embodiment, a power supply side communication device 11d equipped with an optical power supply light source and a plurality of power receiving side communication devices 12 (communication devices 12-1 to 12-n) equipped with photoelectric converters are connected to each other by wire, and perform optical power supply and communication. The optical communication system 1d measures the optical loss value of the power supply light transmitted from the communication device 11d to each of the communication devices 12 (communication devices 12-1 to 12-n). Then, the optical communication system 1d controls the power of the power supply light output from the optical power supply light source of the communication device 11d based on the measured optical loss value.

[0173] At this time, for example, when at least one of the plurality of measured optical loss values ​​is equal to or greater than a predetermined value, the optical communication system 1d controls the output of the power supply light to be maximized.Also, for example, when all of the plurality of measured optical loss values ​​are less than a predetermined value, the optical communication system 1d controls the output of the power supply light to be an output value obtained by adding the maximum of the plurality of measured optical loss values ​​to a preset output value.

[0174] Furthermore, the optical communication system 1d controls the output of the power supply light emitted from the optical power supply light source to be switched on and off depending on the state of charge of the secondary power source of the power receiving communication device. For example, the optical communication system 1d controls the output of the power supply light to be on when the state of charge of the secondary power source of at least one power receiving communication device is not fully charged, and controls the output of the power supply light to be off when the state of charge of the secondary power sources of all power receiving communication devices is fully charged.

[0175] With these features, the optical communication system 1d in the fifth embodiment can adjust the power of the power supply light output from the optical power supply light source so that the power of the power supply light input to the photoelectric converter does not become excessive, based on the optical loss value corresponding to the installation location of each of the multiple power-receiving-side communication devices 12 (communication devices 12-1 to 12-n) equipped with photoelectric converters, in various network configurations such as a network configuration in which communication devices are connected to each other in a one-to-multipoint configuration such as a double star configuration. This allows the optical communication system 1d to reduce the power consumption of the optical power supply light source.

[0176] Furthermore, by virtue of these features, the optical communication system 1d according to the fifth embodiment can stop optical power feeding when the secondary power source of each of the power-receiving communication devices 12 (communication devices 12-1 to 12-n) equipped with a photoelectric converter is fully charged, thereby enabling the optical communication system 1d to reduce the power consumption of the optically powered light source.

[0177] An optical communication system 1d in the fifth embodiment is based on the configuration of the optical communication system 1 in the first embodiment, and further includes control processing for controlling the output of power supply light appropriately when a power supply-side communication device and a power receiving-side communication device are connected in a one-to-many relationship. That is, in the optical communication system 1d in the fifth embodiment, the power receiving-side communication device notifies the power supply-side communication device about the charging state of the secondary power source using communication light, and the optical fiber for transmitting the power supply light and the optical fiber for transmitting the communication light are separate optical fibers. However, the optical communication system of the present invention is not limited to this configuration, and may be based on the configuration of any of the optical communication system 1a in the second embodiment, the optical communication system 1b in the third embodiment, or the optical communication system 1c in the fourth embodiment, and further includes control processing for controlling the output of power supply light appropriately when a power supply-side communication device and a power receiving-side communication device are connected in a one-to-many relationship. In other words, the optical communication system of the present invention may be configured so that the power-receiving communication device notifies the power-supplying communication device about the charging status of the secondary power source using reflected light from the power-supplying light, or may be configured so that the optical fiber transmitting the power-supply light and the optical fiber transmitting the communication light are the same optical fiber.

[0178] According to the above-described embodiment, the communication device includes a power supply optical transmitter, a measurement unit, and a control unit. For example, the communication device is the communication device 11 in the embodiment, the power supply optical transmitter is the power supply optical transmitter 112 in the embodiment, the measurement unit is the loss measurement unit 115 in the embodiment, and the control unit is the power supply optical power control unit 116 in the embodiment. The power supply optical transmitter transmits power supply optical to a counterpart communication device. For example, the counterpart communication device is the communication device 12 in the embodiment. The measurement unit measures an optical loss value in the transmission of power supply optical from the communication device to the counterpart communication device. The control unit controls the output of power supply optical power transmitted from the power supply optical transmitter in accordance with the optical loss value measured by the measurement unit.

[0179] In the above communication device, the measurement unit may measure the optical loss value using an optical pulse tester. In this case, the control unit may control the power supply light so that the output power is increased as the optical loss value increases.

[0180] In the above-described communication device, the power supply light transmitted from the power supply light transmitter may be transmitted to each of a plurality of opposing communication devices via a branching unit. In this case, the measurement unit may measure an optical loss value in the transmission of the power supply light from the device itself to each of the opposing communication devices. In this case, the control unit may control the output of the power supply light in accordance with the plurality of optical loss values ​​measured by the measurement unit. For example, the communication device is the communication device 11d in the embodiment, the branching unit is the optical splitter 20 in the embodiment, the plurality of opposing communication devices are the communication devices 12-1 to 12-n in the embodiment, the measurement unit is the loss measurement unit 115d in the embodiment, and the control unit is the power supply light power control unit 116d in the embodiment.

[0181] In the above communication device, the control unit may be configured to control the output of the power supply light to be maximized when at least one of the multiple optical loss values ​​measured by the measurement unit is equal to or greater than a predetermined value.Also, when all of the multiple optical loss values ​​measured by the measurement unit are less than a predetermined value, the control unit may be configured to control the output of the power supply light to be an output value obtained by adding the maximum of the multiple optical loss values ​​to a preset output value.

[0182] Furthermore, according to the above-described embodiment, the optical power supply system includes a first communication device and a second communication device. For example, the optical power supply system is the optical communication system 1 in the embodiment, the first communication device is the communication device 11 in the embodiment, and the second communication device is the communication device 12 in the embodiment. The first communication device includes a power supply optical transmitter, a measurement unit, and a control unit. For example, the power supply optical transmitter is the power supply optical transmitter 112 in the embodiment, the measurement unit is the loss measurement unit 115 in the embodiment, and the control unit is the power supply optical power control unit 116 in the embodiment. The power supply optical transmitter transmits power supply optical to the second communication device. The measurement unit measures an optical loss value in the transmission of the power supply optical from the first communication device to the second communication device. The control unit controls the output of the power supply optical transmitted from the power supply optical transmitter in accordance with the optical loss value measured by the measurement unit. The second communication device includes a power supply optical receiver, an opto-electrical conversion unit, and a power storage unit. For example, the power supply light receiving unit and the photoelectric conversion unit correspond to the photoelectric conversion unit 121 in the embodiment, and the power storage unit corresponds to the secondary power source 122 in the embodiment. The power supply light receiving unit receives the power supply light transmitted from the first communication device. The photoelectric conversion unit converts the power supply light received by the power supply light receiving unit into electric power. The power storage unit stores the electric power converted by the photoelectric conversion unit.

[0183] In the above optical power supply system, the second communication device may further include a power storage state information transmitting unit. For example, the power storage state information transmitting unit is the communication circuit 124 and the transceiver 123 in the embodiment. The power storage state information transmitting unit may transmit first power storage state information indicating the power storage state of the power storage unit to the first communication device. In this case, the first communication device may further include a power storage state information acquiring unit. For example, the power storage state information acquiring unit is the communication circuit 114 and the transceiver 113 in the embodiment. The power storage state information acquiring unit may acquire the first power storage state information transmitted from the power storage state information transmitting unit. In this case, the control unit may control the output of the power supply light transmitted from the power supply light transmitting unit in accordance with the first power storage state information acquired by the power storage state information acquiring unit.

[0184] In the optical power supply system described above, the power storage state information transmitter may transmit the first power storage state information by superimposing it on reflected light of the power supply light. For example, the optical power supply system is the optical communication system 1a in the embodiment, and the power storage state information transmitter is the superimposing unit 125 in the embodiment.

[0185] In the optical power supply system described above, the second communication device may further include a communication optical transmitter. For example, the optical power supply system is the optical communication system 1a in the embodiment, and the communication optical transmitter is the communication circuit 124 and the transceiver 123 in the embodiment. The communication optical transmitter may transmit the second power storage state information to the first communication device by communication light. In this case, the first communication device may further include a communication optical receiver. For example, the communication optical receiver is the transceiver 113 and the communication circuit 114 in the embodiment. The communication optical receiver may receive the second power storage state information transmitted from the second communication device. When the power supply light receiver is receiving power supply light, the power storage state information transmitter may transmit the first power storage state information to the first communication device. When the power supply light receiver is not receiving power supply light, the communication optical transmitter may transmit the second power storage state information to the first communication device. In this case, the control unit may control the output of the power supply light in accordance with the power storage state information acquired by the power storage state information acquisition unit or the communication light receiving unit.

[0186] In the optical power supply system described above, the power supply light transmitted from the power supply light transmitter may be transmitted to each of the plurality of second communication devices via a branching unit. In this case, the measurement unit may measure an optical loss value in transmission of the power supply light from the first communication device to each of the plurality of second communication devices. In this case, the control unit may control the output of the power supply light in accordance with the plurality of optical loss values ​​measured by the measurement unit. For example, the optical power supply system is the optical communication system 1d in the embodiment, the first communication device is the communication device 11d in the embodiment, the branching unit is the optical splitter 20 in the embodiment, the plurality of second communication devices are the communication devices 12-1 to 12-n in the embodiment, the measurement unit is the loss measurement unit 115d in the embodiment, and the control unit is the power supply light power control unit 116d in the embodiment.

[0187] In the optical power supply system, the control unit may be configured to control the output of the power supply light to a maximum when the maximum of the optical loss values ​​measured by the measurement unit is equal to or greater than a predetermined value, or to control the output of the power supply light to a value obtained by adding the maximum value to the predetermined output value when the maximum value is less than the predetermined value.

[0188] The communication devices 11, 11a to 11c and the communication devices 12, 12a to 12c in the above-described embodiments may be implemented by a computer. In this case, a program for implementing the functions may be recorded on a computer-readable recording medium, and the program may be read and executed by a computer system. Note that the term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system.

[0189] Furthermore, the term "computer-readable recording medium" may include a medium that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or a medium that stores a program for a fixed period of time, such as a volatile memory within a computer system that serves as a server or client in such a case. The program may also be one that realizes part of the above-mentioned functions, or one that can realize the above-mentioned functions in combination with a program already stored in the computer system, or one that can be realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0190] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Explanation of symbols]

[0191] 1,1a,1b,1c,1d,8...Optical communication system,11,11a,11b,11c,11d,12,12a,12b,12c,12-1~12-n,81,82...Communication equipment,111...Power supply Section, 112...Power supply optical transmitter, 113...Transceiver, 114, 114a...Communication circuit, 115, 115d...Loss measurement unit, 116, 116a, 116d...Power supply control unit, 117...Reflected light reception unit, 118... power supply optical transmitter and transceiver, 121... photoelectric conversion unit, 122, 122a... secondary power supply, 123... transceiver, 124, 124a... communication circuit, 125... superimposing unit, 126... photoelectric conversion unit and transceiver, 811... power supply unit, 812... power supply optical transmitter, 813... transceiver, 814... communication circuit, 821... photoelectric conversion unit, 822... secondary power supply, 823... transceiver, 824... communication circuit

Claims

1. a power supply light transmitting unit that transmits power supply light to each of a plurality of opposing communication devices via a branching unit; a measurement unit that measures optical loss values ​​in transmission of the power supply light from the own device to each of the plurality of opposite communication devices; a control unit that controls the output of the power supply light to be maximized when at least one of the plurality of optical loss values ​​measured by the measurement unit is equal to or greater than a predetermined value, and that controls the output of the power supply light transmitted from the power supply light transmitter unit to be an output value obtained by adding the maximum value of the plurality of optical loss values ​​to a preset output value when all of the plurality of optical loss values ​​measured by the measurement unit are less than the predetermined value; A communication device comprising:

2. the measurement unit measures the optical loss value using an optical pulse tester; The control unit controls the output of the power supply light so that the output is increased as the optical loss value increases. The communication device according to claim 1 .

3. An optical power supply system having a first communication device and a second communication device, the first communication device, a power supply light transmitter that transmits power supply light to the second communication device; a measurement unit that measures an optical loss value in transmission of the power supply light from the first communication device to the second communication device; a power storage state information acquisition unit that acquires first power storage state information transmitted from the second communication device; a control unit that controls the output of the power supply light transmitted from the power supply light transmitter in accordance with the optical loss value measured by the measurement unit and the first power storage state information acquired by the power storage state information acquisition unit; Equipped with the second communication device, a power supply light receiving unit that receives the power supply light transmitted from the first communication device; a photoelectric conversion unit that converts the power supply light received by the power supply light receiving unit into electric power; a power storage unit that stores the power converted by the photoelectric conversion unit; a power storage state information transmitting unit that transmits the first power storage state information indicating a power storage state of the power storage unit to the first communication device by superimposing the first power storage state information on reflected light of the power supply light; Equipped with Optical power supply system.

4. the second communication device, a communication light transmitter that transmits second power storage state information to the first communication device by communication light; Furthermore, the first communication device, a communication light receiving unit that receives the second power storage state information transmitted from the second communication device; Furthermore, When the power supply light receiving unit receives the power supply light, the power storage state information transmitting unit transmits the first power storage state information to the first communication device; When the power supply light receiving unit does not receive the power supply light, the communication light transmitting unit transmits the second power storage state information to the first communication device; The control unit controls the output of the power supply light in accordance with the power storage state information acquired by the power storage state information acquisition unit or the communication light receiving unit. The optical power supply system according to claim 3 .

5. a power supply light transmitting step of transmitting the power supply light to each of the plurality of opposing communication devices via the branching portion; a measuring step of measuring an optical loss value in transmission of the power supply light from the own device to each of the plurality of opposite communication devices; a control step of controlling the output of the power supply light to maximize it when at least one of the plurality of optical loss values ​​measured in the measuring step is equal to or greater than a predetermined value, and controlling the output of the power supply light to set an output value obtained by adding the maximum value of the plurality of optical loss values ​​to a preset output value when all of the plurality of optical loss values ​​measured in the measuring step are less than the predetermined value; An optical power supply method comprising:

6. An optical power supply method in an optical power supply system having a first communication device and a second communication device, comprising: a power supply light transmitting step in which the first communication device transmits power supply light to the second communication device; a measuring step in which the first communication device measures an optical loss value in transmission of the power supply light from the first communication device to the second communication device; a power supply light receiving step in which the second communication device receives the power supply light transmitted from the first communication device; a photoelectric conversion step in which the second communication device converts the power supply light received in the power supply light receiving step into electric power; a power storage step in which the second communication device stores the power converted by the photoelectric conversion step; a power storage state information transmitting step in which the second communication device transmits power storage state information indicating a power storage state to the first communication device by superimposing the power storage state information on reflected light of the power supply light; a power storage state information acquisition step in which the first communication device acquires power storage state information transmitted from the second communication device; a control step in which the first communication device controls an output of the power supply light in accordance with the optical loss value measured in the measuring step and the power storage state information acquired in the power storage state information acquiring step; An optical power supply method comprising:

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