Optical fiber power supply system, optical fiber power supply method, and terminal device

Abstract

This invention provides an optical fiber power supply system, an optical fiber power supply method, and a terminal device that enable efficient communication within the limited power available through optical fiber power supply. [Solution] In an optical fiber power supply system 1 having an optical fiber 30 connecting a station side 10 that transmits a first wavelength power supply light and a second wavelength communication light, a power supply light source 11 that outputs power supply light and a communication light source 12 that outputs communication light are located on the station side 10, and modulation devices 23 and 24 located on the terminal side 20 modulate the communication light to generate an uplink signal when returning the communication light to the station side via the optical fiber.

Description

Technical Field

[0001] The present disclosure relates to an optical fiber power feeding system, an optical fiber power feeding method, and a terminal device.

Background Art

[0002] Power feeding technology using optical fibers is a technology that enables non-inductive power supply to terminals arranged in areas where no power is supplied or places where commercial power supply is difficult to use. In this technology, high-power light is transmitted through an optical fiber, and is converted into electric power using a photoelectric conversion element on the receiving side, thereby realizing power supply.

[0003] Non-Patent Document 1 discloses a technology related to a communication system using optical fiber power feeding, which drives a communication device with transmitted optical power. According to this technology, it is possible to operate a communication device installed in a place where power supply is difficult.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] According to the technology described in Non-Patent Document 1, the power that can be used by optical fiber power feeding is limited due to the conversion efficiency of the photoelectric conversion element, the input power limit to the optical fiber, and the like. Therefore, it has been difficult to operate the terminal using the limited power obtained by optical fiber power feeding and further perform uplink communication.

[0006] In particular, communication methods in which the terminal generates and transmits signal light consume a lot of power to operate active optical communication devices such as light sources and modulators. As a result, a large portion of the limited optical power supply is used for communication, making it difficult to supply sufficient power to other functions of the terminal.

[0007] This disclosure has been made in view of the above-mentioned problems. Its purpose is to provide an optical fiber power supply system, an optical fiber power supply method, and a terminal device that can realize efficient communication within the limited power obtained by optical fiber power supply. [Means for solving the problem]

[0008] To solve the above-mentioned problems, an optical fiber power supply system, an optical fiber power supply method, and a terminal device according to one aspect of the present disclosure relate to an optical fiber connecting a central office and a terminal office that transmits a first wavelength power supply light and a second wavelength communication light, and a power supply light source that outputs power supply light and a communication light source that outputs communication light are located on the central office side, and a modulation device located on the terminal office side modulates the communication light to generate an uplink signal when returning the communication light to the central office via the optical fiber. [Effects of the Invention]

[0009] According to this disclosure, it is possible to reduce power consumption on the terminal side and achieve efficient communication within the limited power available through optical fiber power supply. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the configuration of an optical fiber power supply system according to an embodiment of the present disclosure. [Figure 2A] This is a schematic diagram of a wavelength multiplexer / demultiplexer. [Figure 2B] This figure shows an example of the output characteristics of a wavelength multiplexer / demultiplexer. [Figure 3A]This figure shows an example of the wavelength shift amount due to a fiber Bragg grating. [Figure 3B] This figure shows an example of a reflection spectrum obtained using a fiber Bragg grating. [Figure 4] This is a schematic diagram showing a modified example of an optical fiber power supply system according to the present disclosure. [Modes for carrying out the invention]

[0011] Next, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description, identical components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0012] [Configuration of the fiber optic power supply system] Figure 1 is a schematic diagram showing the configuration of an optical fiber power supply system according to an embodiment of this disclosure.

[0013] Hereinafter, in this disclosure, "modulation device" refers to a terminal-side component that modulates communication light to generate an uplink signal. The modulation device can take various forms depending on the embodiment. For example, it may be a configuration combining a fiber Bragg grating (FBG) and a stress application unit, a loop configuration including an optical circulator and a modulator, or a configuration including various modulators such as a lithium niobate modulator, an electro-absorption modulator, an acousto-optic modulator, or a phase shifter. In any case, the modulation device is driven by power converted from the power supply light and has the function of modulating the communication light sent from the station to the terminal and returning it to the station as an uplink signal. The terminal-side battery may also be charged by the power converted from the power supply light. Furthermore, the modulation device may be driven by power supplied from the terminal-side battery. "Driving the modulation device by power" converted from the power supply light also includes cases where the power converted from the power supply light is first stored in a battery, and power is supplied from the battery to the modulation device to drive the modulation device.

[0014] In the system 1 shown in Figure 1, the station side 10 and the terminal side 20 are connected via an optical fiber 30. The system 1 is a system that performs power supply and communication by propagating high-power light using the optical fiber 30. In particular, the configuration is such that the signal light for the terminal side 20 is prepared on the station side 10, light for signal transmission is propagated from the station side 10 to the terminal side 20, and the light is modulated when reflected to perform signal transmission.

[0015] The station side 10 includes a power supply light source 11 and a communication light source 12. The power supply light source 11 outputs light of wavelength λ1 (for example, 1550 nm) as power supply light. The communication light source 12 outputs light of wavelength λ2 (for example, 1310 nm) as communication light. The power supply light is input to the wavelength multiplexer / demultiplexer 14 via the optical isolator 13. The communication light is input to the wavelength multiplexer / demultiplexer 14 via the optical circulator 15. The wavelength multiplexer / demultiplexer 14 multiplexes the power supply light and the communication light and inputs the resulting light to the optical fiber 30.

[0016] The terminal side 20 includes a wavelength multiplexer / demultiplexer 21, a power supply converter 22, and a reflector 23. The wavelength multiplexer / demultiplexer 21 demultiplexes the power supply light and the communication light transmitted through the optical fiber 30. The demultiplexed power supply light λ1 is converted into electric power by the power supply converter 22. This converted electric power is used to operate each component on the terminal side 20.

[0017] The demultiplexed communication light λ2 is processed by a modulation device including a reflector 23 such as a fiber Bragg grating (FBG) and a stress applying unit 24. The reflector 23 of this modulation device reflects the communication light λ2, and the stress applying unit 24 shifts the center wavelength of the reflection spectrum by applying stress to the FBG using a piezoelectric element or the like. As a result, the intensity of the reflected light changes, and intensity modulation is realized. The communication light modulated in this way is re-input to the optical fiber 30 via the wavelength multiplexer / demultiplexer 21 and transmitted toward the station side 10.

[0018] At the station side 10, modulated communication light input from the optical fiber 30 is demultiplexed by the wavelength multiplexer / demultiplexer 14, and input to the receiver 16 via the optical circulator 15. The receiver 16 detects the input modulated light as a signal, and acquires information from the terminal side 20.

[0019] With such a configuration, all the light sources (power supply light source 11 and communication light source 12) are arranged on the station side 10, and the terminal side 20 performs modulation at the time of reflection of the communication light with a simple configuration, whereby upstream signal transmission is enabled. This makes it possible to efficiently perform communication using the limited power obtained by optical fiber power feeding while minimizing power consumption on the terminal side 20. The power converted by the power feeding converter 22 is used to drive the modulation device including the stress applying unit 24. This makes it possible to efficiently generate an upstream signal using the limited power obtained by optical fiber power feeding. Note that the power of the battery on the terminal side 20 may be charged with the power converted by the power feeding converter 22. Then, the modulation device may be driven by the power supplied from the battery.

[0020] FIG. 2A is a schematic diagram of a wavelength multiplexer / demultiplexer. FIG. 2B is a diagram illustrating an example of output characteristics of the wavelength multiplexer / demultiplexer. In particular, FIG. 2B shows transmission characteristics of a fiber coupler in a case where general single-mode fibers are arranged in parallel with a core interval of 5 μm and a coupling length of 2.15 mm.

[0021] In FIG. 2B, the solid line indicates the transmission characteristic of light input to Port 1 in FIG. 2A, and the broken line indicates the transmission characteristic of light input to Port 2 in FIG. 2A. The horizontal axis represents wavelength (nm), and the vertical axis represents transmittance (%).

[0022] According to the characteristics of this wavelength multiplexer / demultiplexer, by inputting light with a wavelength of 1550 nm (power supply light λ1) to Port 1 and inputting light with a wavelength of 1310 nm (communication light λ2) to Port 2, these lights can be multiplexed to Port 3. As shown in FIG. 2B, the light with a wavelength of 1550 nm is transmitted from Port 1 to Port 3 at a high transmittance, and the light with a wavelength of 1310 nm is transmitted from Port 2 to Port 3 at a high transmittance.

[0023] Furthermore, in the case of wave splitting, the same symmetrical relationship is utilized. That is, by inputting light with wavelengths of 1550 nm and 1310 nm into Port 3, the 1550 nm light is split to Port 1 and the 1310 nm light is split to Port 2.

[0024] Furthermore, the wavelength multiplexer / demultiplexer 14 on the station side 10 and the wavelength multiplexer / demultiplexer 21 on the terminal side 20 shown in Figure 1 can be realized using fiber couplers having such wavelength characteristics. In addition, by appropriately adjusting the core spacing and coupling length of the wavelength multiplexer / demultiplexer, it is possible to shift the center wavelength and perform wavelength multiplexing / demultiplexing of wavelengths other than those exemplified in this embodiment (1550 nm, 1310 nm).

[0025] By using such a wavelength multiplexer / demultiplexer, it becomes possible to efficiently combine and separate the power supply light and the communication light, enabling both power supply and communication through a single optical fiber. When supporting multiple terminals, it is also possible to prepare and transmit different wavelengths for each terminal, allowing for appropriate selection depending on the system configuration.

[0026] Figure 3A shows an example of the wavelength shift amount due to a fiber Bragg grating. Figure 3B shows an example of the reflection spectrum due to a fiber Bragg grating. A fiber Bragg grating (FBG) can be used as a reflector 23 provided on the terminal side 20 in Figure 1.

[0027] In particular, Figure 3A is a graph showing the wavelength shift amount as a function of strain in an FBG at a wavelength of 1310 nm, and Figure 3B is a graph showing the change in the reflection spectrum of the FBG.

[0028] In Figure 3A, the horizontal axis represents the amount of strain (%), and the vertical axis represents the wavelength shift (nm). As shown in the figure, it can be seen that the wavelength shift increases linearly as the amount of strain increases. This wavelength shift is calculated using the following equation 1.

[0029]

number

[0030] Here, p 11 ,p 12 ν is the photoelastic constant, ν is Poisson's ratio, ε is the strain, n is the refractive index, λ B This represents the Bragg wavelength. According to the results calculated from the above formula, a shift of 5 nm can be obtained by adding approximately 0.5% strain.

[0031] In Figure 3B, the horizontal axis represents wavelength (nm), and the vertical axis represents reflectance (%). The solid line shows the reflection spectrum of the FBG without distortion, and the dashed line shows the reflection spectrum of the FBG with 0.5% distortion. As shown in the figure, it can be seen that by applying 0.5% distortion to an FBG with a center wavelength of 1310 nm and a full width at half maximum of 0.8 nm, the center wavelength of the reflection spectrum shifts by approximately 5 nm.

[0032] Since the full width at half maximum (FWHM) of a typical FBG is less than 1 nm, as shown in Figure 3B, the amount of reflected light can be sufficiently reduced by shifting the center wavelength by 3 nm or more, thereby enabling intensity modulation. As can be seen from Figure 3B, even with a FWHM of 0.8 nm, intensity modulation is sufficiently possible with a shift of 5 nm.

[0033] By utilizing these characteristics, the reflector 23 on the terminal side 20 shown in Figure 1 can control the amount of reflected light of the communication light λ2 and perform intensity modulation by applying stress to the FBG using the stress application unit 24. The power required for this intensity modulation is supplied by using a portion of the power converted from the feed light λ1 by the power converter 22.

[0034] Regarding the communication light, it is preferable to use a light source with a linewidth that fits within the half-width of the FBG used, but this method can be applied as long as the light source does not have an extremely wide linewidth.

[0035] [Modified examples of fiber optic power supply systems] Figure 4 is a schematic diagram showing a modified example of the optical fiber power supply system according to the present disclosure. The configuration when performing phase modulation or analog modulation will be described with reference to Figure 4.

[0036] In the system 1 shown in Figure 4, the terminal side 20 includes a wavelength multiplexer / demultiplexer 21, a power converter 22, and a modulation device 323. The wavelength multiplexer / demultiplexer 21 separates the power supply light λ1 and the communication light λ2 transmitted through the optical fiber 30. The separated power supply light λ1 is converted into power by the power converter 22. This converted power is used to operate each component of the terminal side 20.

[0037] The separated communication light λ2 is input to the modulator 323. The modulator 323 has a loop configuration that includes an optical circulator 324 and a modulator 325. This loop configuration restricts the propagation direction of the light passing through the modulator 325 to one direction.

[0038] Specifically, the communication light λ2 output from the wavelength multiplexer / demultiplexer 21 is input from the first port of the optical circulator 324, output from the second port, and input to the modulator 325. The communication light modulated by the modulator 325 returns to the third port of the optical circulator 324, is output from the first port, and input to the wavelength multiplexer / demultiplexer 21. The wavelength multiplexer / demultiplexer 21 re-inputs the modulated communication light into the optical fiber 30, and the modulated communication light is transmitted toward the station side 10.

[0039] Various types of modulators can be used as modulator 325. For phase modulation, LN (Lithium Niobate) modulators or phase shifters can be used. For analog modulation, LN modulators, EA (Electro-Absorption) modulators, AOM (Acousto-Optic Modulators), etc., can be used. Furthermore, for modulation that changes amplitude, intensity modulators commonly used in optical fiber communication may be used.

[0040] In addition to the intensity modulation method using FBG shown in Figure 1, the configuration shown in Figure 4 enables more advanced modulation methods such as phase modulation and analog modulation. This allows for improvements in communication quality and information transmission capacity. Furthermore, the loop configuration using an optical circulator has the advantage of stabilizing the operation of the modulator.

[0041] The power required for modulation in the modulation device 323 is supplied by power converted from the power supply light λ1 by the power supply converter 22. The modulation device 323 is driven by this converted power. Similar to system 1 in Figure 1, the terminal side 20 does not have a light source and only modulates the communication light λ2 sent from the station side 10, so that power consumption can be minimized and signal transmission can be performed efficiently. The power converted from the power supply light λ1 may also be used to charge the battery of the terminal side 20. The power required for modulation in the modulation device 323 may then be supplied by the power supplied from the battery of the terminal side 20.

[0042] [Configuration for two-way communication] As another variation, a configuration may be adopted that performs bidirectional communication, simultaneously realizing both downlink communication from the central office 10 to the terminal 20 and uplink communication from the terminal 20 to the central office 10.

[0043] For example, at the central office 10, in addition to the power supply light source 11, two types of communication light sources 12 may be provided, one for uplink communication and one for downlink communication, each outputting light of different wavelengths (e.g., wavelengths λ2 and λ3). These three types of light may be combined by a wavelength multiplexer / demultiplexer and transmitted to the terminal side through the optical fiber 30. In other words, a dedicated light source for downlink signal transmission from the central office 10 to the terminal side 20 may be added.

[0044] On the terminal side 20, the power supply light, uplink communication light, and downlink communication light are separated by a wavelength multiplexer / demultiplexer, and the power supply light is converted into power by a power converter. The uplink communication light and downlink communication light may also be separated by a configuration using an optical circulator and a reflector.

[0045] Specifically, the downlink communication light may be directly received by the receiver on the terminal side, and only the uplink communication light may be selectively reflected. During this reflection, intensity modulation or phase modulation may be performed to generate an uplink signal, which may then be sent back to the station. Compared to the one-way communication shown in Figures 1 and 4, bidirectional information transmission can be achieved over the same optical fiber.

[0046] Furthermore, in a bidirectional communication configuration, if the wavelengths of the uplink and downlink optical signals are sufficiently far apart, it is possible to separate them using only a wavelength multiplexer / demultiplexer without using an optical circulator. Also, various modulation methods can be applied to the terminal 20, such as intensity modulation using FBG as shown in Figure 1, or phase modulation / analog modulation using a loop configuration as shown in Figure 4. This configuration makes it possible to simultaneously provide power and bidirectional communication with terminals installed in locations where commercial power is difficult to access.

[0047] [Configuration where the transmission path is branched] As another variation, a configuration in which the transmission line is branched in the transmission path up to the terminal receiving the power supply light may be adopted.

[0048] For example, while Figures 1-4 show that the station combines the power supply light (wavelength λ1) and multiple communication lights (wavelengths λ2, λ3, etc.) and inputs them into a single optical fiber, a wavelength demultiplexer may be installed in the middle of the transmission path to separate a portion of the power supply light and communication light of a specific wavelength and distribute them to multiple terminals.

[0049] Specifically, the transmission path may be configured such that a portion of the power supply light and the communication light λ2 are separated for the first terminal at a first location, and the remaining portion of the power supply light and the communication light λ3 are separated for the second terminal at a second location. While the embodiments shown in Figures 1-4 dealt only with power supply and communication to a single terminal, this configuration enables simultaneous power supply and individual communication to multiple terminals.

[0050] At each terminal, the decoupled power supply light and communication light are further separated by an internal wavelength multiplexer / demultiplexer, and the power supply light is converted into power by a power converter. For the communication light, any modulation method can be applied, such as reflection and intensity modulation by FBG as explained in Figure 1, or modulation by loop configuration as explained in Figure 4. The modulated communication light is returned to the optical fiber via a wavelength demultiplexer and transmitted to the station side 10. At the station side 10, information from multiple terminals can be acquired individually by detecting the modulated communication light of different wavelengths from each terminal with a receiver. This makes it possible to communicate efficiently with multiple terminals using a single optical fiber.

[0051] A practical advantage of this multi-terminal branching configuration is that by adding wavelength demultiplexers and communication light sources for the required number of terminals and appropriately configuring the wavelength multiplexers and demultiplexers, optical power can be supplied to any distance, enabling data transmission from terminals installed in multiple distant locations. For example, it becomes possible to efficiently supply power to sensor groups installed in environments such as mountainous areas, oceans, or underground where commercial power is unavailable, and to collect data from them using a single optical fiber. Furthermore, by appropriately branching the power supply optical fiber at different points along the transmission path, it becomes possible to place multiple terminals at distances beyond the limits of the power supply distance.

[0052] Furthermore, the above-mentioned configurations may be implemented in combination. A configuration for unidirectional communication may be combined with a configuration that branches in the transmission line, and a configuration for bidirectional communication may be combined with a configuration that branches in the transmission line. As for the modulation method of the terminal side 20, various modulation methods can be applied, such as intensity modulation by FBG, and phase modulation / analog modulation by loop configuration.

[0053] [Effects of the Embodiment] As described in detail above, the optical fiber power supply system according to this embodiment comprises an optical fiber connecting the station side and the terminal side, which transmits a first wavelength power supply light and a second wavelength communication light; a power supply light source and a communication light source, both located on the station side, which output the power supply light; and a modulation device, both located on the terminal side. The modulation device modulates the communication light to generate an uplink signal when returning the communication light to the station side via the optical fiber.

[0054] This reduces power consumption on the terminal side and enables efficient communication within the limited power available through fiber optic power supply.

[0055] By eliminating the need for a light source on the terminal side and consolidating all light sources (power supply light source and communication light source) on the central office side, the terminal only needs to drive the modulation device using the limited power obtained from the power supply light via a photoelectric conversion element. As a result, power consumption can be significantly reduced. In this disclosure, an uplink signal can be generated simply by modulating the communication light when it is reflected or circulated, making it possible to achieve stable communication with limited power supply even in terminals installed in locations where it is difficult to use commercial power.

[0056] Furthermore, it has the effect of simplifying the configuration on the terminal side. Since the terminal side does not require a light source or related control circuit, it is possible to achieve miniaturization, cost reduction, and high reliability of the terminal device. In particular, for terminal devices installed in harsh environments, the reduction of components leads to a reduction in the risk of failure, enabling long-term maintenance-free operation. In addition, since all light sources can be centrally managed at the station side, monitoring and control of the entire system becomes easier, and it also has excellent expandability, as it can flexibly handle various communication forms such as communication with multiple terminals and bidirectional communication by using communication light of different wavelengths.

[0057] Furthermore, the optical fiber power supply system according to this embodiment may further include a power supply converter having a photoelectric conversion element located on the terminal side, wherein the power supply converter converts the power supply light into electricity, and the modulation device may be driven by the electricity. This makes the terminal side a completely independent and autonomous system. As a result, both power supply and signal transmission can be achieved with a single optical fiber even in mountainous areas where commercial power is unavailable, underwater, in hazardous areas, or in places where laying power wiring is difficult or uneconomical. Moreover, compared to conventional methods in which power lines and communication lines are laid separately, wiring is simplified, and it has high environmental resistance that is less susceptible to the effects of ambient electromagnetic noise and lightning, and is also excellent in explosion-proofness because it is electrically insulated. Furthermore, since the limited power obtained from the power supply light can be used for communication in the most efficient way, it overcomes conventional challenges such as the conversion efficiency of the photoelectric conversion element and the input power limit to the optical fiber, and can handle applications that require longer distance communication and complex control.

[0058] Furthermore, in the optical fiber power supply system according to this embodiment, the modulation device may include a fiber Bragg grating that reflects communication light, and by applying stress to the fiber Bragg grating, the central wavelength of the reflected spectrum when the communication light is reflected may be shifted. The configuration of the modulation device using an FBG has the remarkable effect of achieving particularly low power consumption and high reliability. An FBG is a simple structure in which a periodic refractive index change is formed in the optical fiber itself, and the central wavelength of the reflected spectrum can be efficiently shifted by applying only a small amount of stress by a piezoelectric element or the like. Since modulation is performed by controlling the intensity of the reflected light by this shift, complex optical components and high-power active elements are not required, and it can operate sufficiently even with the limited power converted from the power supply light.

[0059] Furthermore, because it is an integrated optical fiber device with few moving parts, it boasts excellent environmental resistance and long-term reliability, and stable operation can be expected even in environments with severe vibration and temperature changes. In addition, its small size and light weight reduce the installation space of terminal equipment, and it also contributes to improved overall system efficiency because it has low connection loss with the optical fiber and excellent optical compatibility. This makes it possible to communicate under extremely limited power environments, which was difficult to achieve with conventional methods.

[0060] Furthermore, in the optical fiber power supply system according to this embodiment, the modulation device may include a loop for circulating communication light, and modulate the communication light as it passes through the loop. One advantage of employing a loop-configured modulation device is that it enables the realization of more advanced and diverse modulation methods, such as phase modulation and analog modulation, in addition to simple intensity modulation.

[0061] By using a loop configuration with an optical circulator, the propagation direction of light passing through the modulation section is limited to one direction, improving modulation efficiency and optimizing the modulator's operation. Furthermore, the flexibility to select various types of modulators, such as lithium niobate modulators, field absorption modulators, acousto-optic modulators, and phase shifters, according to application and required specifications enables higher information transmission capacity and improved signal quality. This ensures system scalability to meet a wide range of communication needs, from simple sensor data transmission to high-speed data communication, and enables more advanced communication functions even with the limited power supplied by optical fiber.

[0062] Furthermore, in the optical fiber power supply system according to this embodiment, the modulation device may include at least one of a lithium niobate modulator, an electric field absorption modulator, an acousto-optic modulator, and a phase shifter. This has the significant advantage of enabling the realization of an optimal modulation scheme according to the application and requirements of the communication system.

[0063] Lithium niovate modulators enable wideband and high-speed modulation, making them suitable for high-quality signal transmission. Field absorption modulators feature low-voltage operation and miniaturization, making them particularly efficient in limited power environments. Acousto-optic modulators offer excellent wavelength selectivity, making them suitable for processing multi-wavelength optical signals. Phase shifters enable advanced digital modulation schemes such as QPSK, improving information transmission efficiency per unit power.

[0064] By selecting the appropriate modulator for each application, it becomes possible to build systems that meet a variety of requirements, from simple transmission of sensing data to high-speed data communication, while simultaneously optimizing the balance between transmission distance, modulation speed, signal quality, and power consumption. Furthermore, even in the limited power environment of optical fiber power supply, efficient and advanced communication can be achieved by utilizing the characteristics of these modulators, significantly expanding the range of system applications.

[0065] Furthermore, the optical fiber power supply method according to this embodiment relates to an optical fiber connecting a central office and a terminal, which transmits a first wavelength power supply light and a second wavelength communication light. Power supply light is output from a power supply light source located on the central office side, communication light is output from a communication light source located on the central office side, and a modulation device located on the terminal side modulates the communication light to generate an uplink signal when returning the communication light to the central office side via the optical fiber. Similar to an optical fiber power supply system, it is possible to suppress power consumption on the terminal side and realize efficient communication within the limited power obtained by optical fiber power supply.

[0066] Furthermore, the terminal device according to this embodiment is connected to the central office via an optical fiber that transmits a first wavelength power supply light and a second wavelength communication light. It includes a wavelength multiplexer / demultiplexer that separates the power supply light and the communication light, and a modulation device that modulates the communication light to generate an uplink signal when returning the communication light to the central office via the optical fiber. Similar to an optical fiber power supply system, it is possible to reduce power consumption on the terminal side and achieve efficient communication within the limited power obtained by optical fiber power supply.

[0067] While the contents of this disclosure have been described above in accordance with the embodiments, it will be obvious to those skilled in the art that this disclosure is not limited to these descriptions and that various modifications and improvements are possible. The discussions and drawings that constitute part of this disclosure should not be understood as limiting this disclosure. Various alternative embodiments, examples and operational techniques will become apparent to those skilled in the art from this disclosure.

[0068] This disclosure naturally includes various embodiments and other features not described herein. Therefore, the technical scope of this disclosure is determined solely by the inventive features relating to the claims that are reasonable given the above description. [Explanation of symbols]

[0069] 1. System (Fiber Optic Power Supply System) 10 station side 11 Power supply light source 12 Communication light source 13 Optical Isolator 14,21 Wavelength multiplexer / demultiplexer 15,324 Light Circulator 20. Terminal side 22 Power converter 23 Reflector 24 Stress application section 30 optical fibers 323 Modulator 325 Modulator

Claims

1. An optical fiber connecting the station and the terminal side transmits a first wavelength power supply light and a second wavelength communication light, Located on the aforementioned station side A power supply light source that outputs the aforementioned power supply light, and A communication light source that outputs the aforementioned communication light, A modulation device located on the terminal side, Equipped with, The modulation device is an optical fiber power supply system that modulates the communication light to generate an uplink signal when returning the communication light to the station side via the optical fiber.

2. The terminal side further comprises a power supply converter having a photoelectric conversion element, The power converter converts the power supply light into electricity, The modulation device is driven by the power, The optical fiber power supply system according to claim 1.

3. The modulation device is The system includes a fiber Bragg grating that reflects the aforementioned communication light, By applying stress to the aforementioned fiber Bragg grating, the central wavelength of the reflection spectrum when the communication light is reflected is shifted. The optical fiber power supply system according to claim 1.

4. The modulation device is The system includes a loop for circulating the aforementioned communication light, When the communication light passes through the loop, the communication light is modulated. The optical fiber power supply system according to claim 1.

5. The modulation device includes at least one of a lithium niobate modulator, an electro-absorption modulator, an acousto-optic modulator, and a phase shifter. The optical fiber power supply system according to any one of claims 1 to 4.

6. A method for supplying power to an optical fiber that connects a central office side and a terminal side, which transmits a first wavelength power supply light and a second wavelength communication light, The power supply light is output from the power supply light source located on the station side. The communication light is output from the communication light source located on the station side. A method for supplying power to an optical fiber, wherein a modulation device located on the terminal side modulates the communication light to generate an uplink signal when returning the communication light to the station side via the optical fiber.

7. A terminal device connected to the central office via an optical fiber that transmits a first wavelength power supply light and a second wavelength communication light, A wavelength multiplexer / demultiplexer that separates the power supply light and the communication light, A modulation device that modulates the communication light to generate an uplink signal when returning the communication light to the station side via the optical fiber, A terminal device equipped with the following features.

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