JP-7856506-B2 - Optical power supply system

JP7856506B2JP 7856506 B2JP7856506 B2JP 7856506B2JP-7856506-B2

Inventors

菊池信彦
田所秀之
益子英昭
山本智裕
栗原佳弘
土橋昌郎
一色充也

Assignees

株式会社日立製作所
東京都下水道サービス株式会社
一般社団法人日本下水道光ファイバー技術協会
東京都

Dates

Publication Date: 20260511
Application Date: 20220624

Claims (12)

A light-power supply device that emits power supply light, One or more node devices that receive a portion of the aforementioned power supply light and operate using that power, Includes an optical fiber line connecting a first and second geographically separated point, and connecting to an optical power supply device at a third point which is a transit point between the first and second points, Of the section between the third point and the first point, or the section between the third point and the second point, one is a power supply section used for optical power supply, and the other is an unused section. An optical power supply system in which the power supply section and the unused section are optically connected at the third point of the optical fiber line.
The optical power supply system according to claim 1, An optical power supply system in which the optical connection between the power supply section and the unused section is used for optical circuit testing between the endpoints of optical fibers in the section of the optical fiber line including the power supply section and the unused section.
The optical power supply system according to claim 1, Including an optical splitter, The aforementioned optical splitter is Including a common optical port, a first optical port, and a second optical port, The optical signal input to the common optical port is separated and output to the first optical port and the second optical port at a constant intensity ratio. The signals input to the first optical port and the second optical port are combined and output to the common optical port. An optical power supply system in which the common optical port is connected to the power supply section side of the optical fiber line, the first optical port is connected to the optical power supply system, and the second optical port is connected to the unused section side of the optical fiber line.
The optical power supply system according to claim 3, An optical power supply system in which the unused section is downstream in the direction of propagation of the power supply light, and optical termination processing is performed at the downstream endpoint of the unused section.
The optical power supply system according to claim 3, An optical power supply system in which the optical signal branching ratio output to the second optical port is between 50% and 1%.
The optical power supply system according to claim 1, Including an optical splitter, The aforementioned optical splitter is Including a common optical port, a first optical port, and a second optical port, The optical signal input to the common optical port is separated into an optical signal in a first wavelength range used by the optical power supply device and an optical signal in a second wavelength range different from the first wavelength range, and the optical signal in the first wavelength range is output to the first optical port and the optical signal in the second wavelength range is output to the second optical port. The optical signal in the first wavelength range input to the first optical port and the optical signal in the second wavelength range input to the second optical port are combined and output to the common optical port. An optical power supply system in which the common optical port is connected to the power supply section side of the optical fiber line, the first optical port is connected to the optical power supply system, and the second optical port is connected to the unused section side of the optical fiber line.
The optical power supply system according to claim 6, The second wavelength range mentioned above is used for optical power supply systems in optical circuit testing.
The optical power supply system according to claim 6, An optical power supply system in which the first wavelength range is longer than 1.4 μm and the second wavelength range is shorter than 1.4 μm, or the first wavelength range is shorter than 1.2 μm and the second wavelength range is longer than 1.2 μm.
The optical power supply system according to claim 1, An optical power supply system comprising a ladder-type configuration in which the power supply light is sequentially branched to node devices by an optical splitter, a star-type configuration in which the power supply light is branched by an optical star coupler, or a combination thereof.
The optical power supply system according to claim 7, An optical power supply system comprising means for conducting an optical line test while the optical power supply system is in operation and for aggregating the optical line information obtained in the optical line test at a central office.
A node device included in the optical power supply system described in claim 1, comprising an optical port used for inputting and outputting optical signals used in optical line testing.
An optical power supply device included in the optical power supply system described in claim 1, comprising an optical port used for inputting and outputting optical signals used in optical line testing.

Description

This invention relates to an optical power supply system, and more particularly to an optical power supply technology that transmits power using optical fibers, and to an optical line test that verifies the integrity of an optical fiber line. Optical fibers are a medium for transmitting light through thin glass wires. Due to their extremely low transmission loss of high-frequency signals per unit length compared to electrical cables, they are widely used as signal transmission media over long distances ranging from a few meters to several thousand kilometers. The optical power supply technology discussed in this invention utilizes such communication optical fibers for power transmission. The optical power supply device, which acts as the power transmission side, is equipped with a high-power light source such as a semiconductor laser to convert power into light, which is then input into the optical fiber for transmission. The receiving device (hereinafter referred to as the node device) receives the output light from the optical fiber using a photodetector such as a photodiode, converts it back into power, and stores it as needed, allowing it to be used as operating power for the slave device. When applied to energy transmission, optical fibers have disadvantages compared to electrical cables, such as higher transmission loss and low conversion efficiency between optical and electrical signals at the receiving end (around 20-30%). Therefore, the optical power source placed within the master unit requires high output power; for example, high-power semiconductor lasers with outputs ranging from several hundred mW to over 1 W are used. However, especially in communication optical fibers, the diameter of the central core that transmits light is very small (only a few microns), and if strong light is incident, the core will melt. Therefore, the incident optical power is generally limited to a few watts or less. Due to these limitations, optical power transmission has a limited power range and is not a widely used technology. However, optical fibers have advantages such as being electrically insulated, highly explosion-proof, less susceptible to electromagnetic interference, and highly corrosion-resistant. Thus, in situations where the use of electrical cables is difficult, or in remote or isolated areas where there are no other suitable power sources, optical power transmission can be used as an effective power transmission technology. Furthermore, since optical power supply allows the use of optical fibers as a communication medium between the power supply device and multiple node devices, it is advantageous for use in remote areas where radio waves are difficult to reach and wired communication lines are difficult to secure, such as underground, inside buildings, plants, underwater, deserts, mountains, and underground. Actual examples of optical power supply technology applications include remote sensing, such as collecting sensing data from infrastructure like pipelines, plants, bridges, and railways, and remote monitoring using cameras. Figure 1 is a diagram of a conventional optical power supply system, illustrating an example of an optical power supply system that supplies power to multiple node devices, as disclosed in Figure 5 of Japanese Patent Publication No. 2021-19444, "Optical Power Supply System" (Patent Document 1). This example is a 1:4 optical power supply system in which four node devices 110-1, 110-2, 110-3, and 110-4 are connected to a single optical power supply device 100 as receiving devices via an optical fiber line 106. Inside the optical power supply device 100, a power supply light source 101 is located, which transmits power supply light 104 via the optical fiber line 106. Furthermore, a transmitting unit 102 and a receiving unit 103 are used to transmit and receive up/down communication light 105 for communication with node devices 110-1 to 110-4 via the optical fiber. Although not explicitly stated in this example, multiple optical fiber cores within the optical fiber line 106 may be used to transmit these optical signals, or, by wavelength multiplexing with wavelength differences, it is possible to connect to multiple downstream node devices using a single optical fiber core within the optical fiber line 106. At the end of the optical fiber line 106 are optical splitters (also called optical couplers) 107-1 to 107-3. Each splits the power supply light 104 transmitted from the upstream at a fixed ratio and distributes it to node devices 110-1 to 110-4. They also distribute and combine the upstream and downstream communication light 105 transmitted and received by each node device. Inside node devices 110-1 to 110-4 are power receiving units 111-1 to 111-4 that receive the power supply light 104. These units convert the received power supply light 104 into electrical energy, which is used to operate the node devices 110-1 to 110-4. On the other hand, the optical fiber line testing ha