Patent Description:
Recently, an optical power supply system has been studied that converts electric power into light (called feed light), transmits the feed light, converts the feed light into electric energy, and uses the electric energy as electric power.

PTL <NUM> discloses an optical communication device including an optical transmitter, an optical fiber, and an optical receiver. The optical transmitter transmits signal light modulated based on an electric signal and feed light for supplying electric power. The optical fiber includes a core, a first cladding surrounding the core, and a second cladding surrounding the first cladding. The core transmits the signal light. The first cladding has a refractive index lower than that of the core and transmits the feed light. The second cladding has a refractive index lower than that of the first cladding. The optical receiver operates with electric power obtained by converting the feed light transmitted through the first cladding of the optical fiber and converts the signal light transmitted through the core of the optical fiber into the electric signal.

<CIT> discloses an optical fiber energy supply system based on a multi-junction concentrating photovoltaic battery comprising a laser module, an optical fiber coupling module, a light splitting module, and photovoltaic conversion modules, wherein the laser module uses a multiband laser module and laser beams output by the multiband laser module are incident to an energy transmission optical fiber after being merged through the optical fiber coupling module.

<CIT> discloses an optical power supply system wherein energy is transmitted from a center station including a plurality of different light sources.

<CIT> discloses an optical transmission system, wherein electrical power from a parent device is transmitted to a child device via an optical transmission line, the parent device comprising an optical amplifier for amplifying main signal light and electrical power supplying light.

If a spectrum of feed light spreads beyond a conversion wavelength range of a photoelectric conversion element, the feed light outside the conversion wavelength range is not converted into electric power. Consequently, the power supply efficiency problematically decreases.

The present invention provides an optical power supply system according to claim <NUM>. Preferred embodiments are described in the dependent claims.

In the one aspect of the present disclosure, the powered device of the optical power supply system can perform photoelectric conversion on the feed light without the feed light becoming out of the conversion wavelength ranges of the photoelectric conversion elements and thus can maintain a high power supply efficiency.

One embodiment of the present disclosure is described below with reference to the drawings.

As illustrated in <FIG>, a power-over-fiber (PoF) system 1A according to the present embodiment includes power sourcing equipment (PSE) <NUM>, an optical fiber cable 200A, and a powered device (PD) <NUM>.

In the present disclosure, the power sourcing equipment <NUM> is equipment that converts electric power into optical energy and supplies the optical energy, and the powered device <NUM> is a device that receives the supplied optical energy and converts the optical energy into electric power.

The power sourcing equipment <NUM> includes a semiconductor laser <NUM> for power supply.

The optical fiber cable 200A includes an optical fiber 250A that forms a channel of feed light.

The powered device <NUM> includes a photoelectric conversion element <NUM>.

The power sourcing equipment <NUM> is connected to a power source, which electrically drives the semiconductor laser <NUM> for power supply and so on.

The semiconductor laser <NUM> for power supply oscillates with electric power supplied from the power source to output feed light <NUM>.

The optical fiber cable 200A has one end 201A connectable to the power sourcing equipment <NUM> and an other end 202A connectable to the powered device <NUM>, and transmits the feed light <NUM>.

The feed light <NUM> from the power sourcing equipment <NUM> is input to the one end 201A of the optical fiber cable 200A. The feed light <NUM> propagates through the optical fiber 250A and is output from the other end 202A to the powered device <NUM>.

The photoelectric conversion element <NUM> converts the feed light <NUM> transmitted through the optical fiber cable 200A into electric power. The electric power obtained by the photoelectric conversion element <NUM> through the conversion is used as driving electric power needed in the powered device <NUM>. The powered device <NUM> is capable of outputting, for an external device, the electric power obtained by the photoelectric conversion element <NUM> through the conversion.

Semiconductor materials comprise semiconductor regions that exhibit a photoelectric effect of the semiconductor laser <NUM> for power supply and the photoelectric conversion element <NUM> are semiconductors having a short laser wavelength of <NUM> or shorter.

Semiconductors having a short laser wavelength have a large band gap and a high photoelectric conversion efficiency. Thus, the photoelectric conversion efficiency on the power-generating side and the powered side of optical power supply improves, and consequently the optical power supply efficiency improves.

Therefore, the semiconductor materials to be used may be, for example, semiconductor materials that are laser media having a laser wavelength (fundamental wave) of <NUM> to <NUM> such as diamond, gallium oxide, aluminum nitride, and gallium nitride.

The semiconductor materials to be used may be semiconductors having a band gap of <NUM> eV or greater.

For example, semiconductor materials that are laser media having a band gap of <NUM> to <NUM> eV such as diamond, gallium oxide, aluminum nitride, and gallium nitride may be used.

Laser light having a longer wavelength tends to have a higher transmission efficiency. Laser light having a shorter wavelength tends to have a higher photoelectric conversion efficiency. Thus, in the case of long-distance transmission, a semiconductor material that is a laser medium having a laser wavelength (fundamental wave) longer than <NUM> may be used. When the photoelectric conversion efficiency is prioritized, a semiconductor material that is a laser medium having a laser wavelength (fundamental wave) shorter than <NUM> may be used.

These semiconductor materials may be used in either the semiconductor laser <NUM> for power supply or the photoelectric conversion element <NUM>. The photoelectric conversion efficiency is improved on the power-sourcing side or the powered side, and consequently the optical power supply efficiency improves.

As illustrated in <FIG>, a power-over-fiber (PoF) system <NUM> according to the present embodiment is a system including a power supply system and an optical communication system with an optical fiber. Specifically, the power-over-fiber system <NUM> includes a first data communication device <NUM> including power sourcing equipment (PSE) <NUM>, an optical fiber cable <NUM>, and a second data communication device <NUM> including a powered device (PD) <NUM>.

The power sourcing equipment <NUM> includes a semiconductor laser <NUM> for power supply. The first data communication device <NUM> includes, in addition to the power sourcing equipment <NUM>, a transmitter <NUM> and a receiver <NUM> that perform data communication. The first data communication device <NUM> corresponds to data terminal equipment (DTE), a repeater, or the like. The transmitter <NUM> includes a semiconductor laser <NUM> for signals and a modulator <NUM>. The receiver <NUM> includes a photodiode <NUM> for signals.

The optical fiber cable <NUM> includes an optical fiber <NUM> including a core <NUM> and a cladding <NUM>. The core <NUM> forms a channel of signal light. The cladding <NUM> is arranged to surround the core <NUM> and forms a channel of feed light.

The powered device <NUM> includes a photoelectric conversion element <NUM>. The second data communication device <NUM> includes, in addition to the powered device <NUM>, a transmitter <NUM>, a receiver <NUM>, and a data processor <NUM>. The second data communication device <NUM> corresponds to a power end station or the like. The transmitter <NUM> includes a semiconductor laser <NUM> for signals and a modulator <NUM>. The receiver <NUM> includes a photodiode <NUM> for signals. The data processor <NUM> is a unit that processes a received signal. The second data communication device <NUM> is a node in a communication network. Alternatively, the second data communication device <NUM> may be a node that communicates with another node.

The first data communication device <NUM> is connected to a power source, which electrically drives the semiconductor laser <NUM> for power supply, the semiconductor laser <NUM> for signals, the modulator <NUM>, the photodiode <NUM> for signals, and so on. The first data communication device <NUM> is a node in the communication network. Alternatively, the first data communication device <NUM> may be a node that communicates with another node.

The photoelectric conversion element <NUM> converts the feed light <NUM> transmitted through the optical fiber cable <NUM> into electric power. The electric power obtained by the photoelectric conversion element <NUM> through the conversion is used as driving electric power for the transmitter <NUM>, the receiver <NUM>, and the data processor <NUM> and as other driving electric power needed in the second data communication device <NUM>. The second data communication device <NUM> may be capable of outputting, for an external device, the electric power obtained by the photoelectric conversion element <NUM> through the conversion.

On the other hand, the modulator <NUM> of the transmitter <NUM> modulates laser light <NUM> output from the semiconductor laser <NUM> for signals into signal light <NUM> on the basis of transmission data <NUM>, and outputs the signal light <NUM>.

The photodiode <NUM> for signals of the receiver <NUM> demodulates the signal light <NUM> transmitted through the optical fiber cable <NUM> into an electric signal, and outputs the electric signal to the data processor <NUM>. The data processor <NUM> transmits data based on the electric signal to a node. The data processor <NUM> also receives data from the node, and outputs, as transmission data <NUM>, the data to the modulator <NUM>.

The modulator <NUM> of the transmitter <NUM> modulates laser light <NUM> output from the semiconductor laser <NUM> for signals into signal light <NUM> on the basis of the transmission data <NUM>, and outputs the signal light <NUM>.

The photodiode <NUM> for signals of the receiver <NUM> demodulates the signal light <NUM> transmitted through the optical fiber cable <NUM> into an electric signal, and outputs the electric signal. Data based on the electric signal is transmitted to a node. On the other hand, data from the node is treated as the transmission data <NUM>.

The feed light <NUM> and the signal light <NUM> output from the first data communication device <NUM> are input to one end <NUM> of the optical fiber cable <NUM>. The feed light <NUM> and the signal light <NUM> propagate through the cladding <NUM> and the core <NUM>, respectively, and are output from an other end <NUM> of the optical fiber cable <NUM> to the second data communication device <NUM>.

The signal light <NUM> output from the second data communication device <NUM> is input to the other end <NUM> of the optical fiber cable <NUM>, propagates through the core <NUM>, and is output from the one end <NUM> of the optical fiber cable <NUM> to the first data communication device <NUM>.

As illustrated in <FIG>, the first data communication device <NUM> includes a light input/output part <NUM> and an optical connector <NUM> attached to the light input/output part <NUM>. The second data communication device <NUM> includes a light input/output part <NUM> and an optical connector <NUM> attached to the light input/output part <NUM>. An optical connector <NUM> at the one end <NUM> of the optical fiber cable <NUM> is connected to the optical connector <NUM>. An optical connector <NUM> at the other end <NUM> of the optical fiber cable <NUM> is connected to the optical connector <NUM>. The light input/output part <NUM> guides the feed light <NUM> to the cladding <NUM>, guides the signal light <NUM> to the core <NUM>, and guides the signal light <NUM> to the receiver <NUM>. The light input/output part <NUM> guides the feed light <NUM> to the powered device <NUM>, guides the signal light <NUM> to the receiver <NUM>, and guides the signal light <NUM> to the core <NUM>.

As described above, the optical fiber cable <NUM> has the one end <NUM> connectable to the first data communication device <NUM> and the other end <NUM> connectable to the second data communication device <NUM>, and transmits the feed light <NUM>. In the present embodiment, the optical fiber cable <NUM> transmits the signal light <NUM> and the signal light <NUM> bidirectionally.

As semiconductor materials of semiconductor regions that exhibit a photoelectric effect of the semiconductor laser <NUM> for power supply and the photoelectric conversion element <NUM>, same and/or similar materials as those mentioned in the first embodiment may be used, so that a high optical power supply efficiency is implemented.

As in an optical fiber cable 200B of a power-over-fiber system 1B illustrated in <FIG>, an optical fiber <NUM> that transmits signal light and an optical fiber <NUM> that transmits feed light may be provided separately. The optical fiber cable 200B may include a plurality of optical fiber cables.

Power sourcing equipment 110A illustrated in <FIG> is used instead of the power sourcing equipment <NUM> of the power-over-fiber systems 1A, <NUM>, and 1B described above, and a powered device 310A illustrated in <FIG> is used instead of the powered device <NUM> of the power-over-fiber systems 1A, <NUM>, and 1B described above.

<FIG> is based on <FIG> and also illustrates a spectrum of feed light. <FIG> illustrates a power-over-fiber system 1C according to the present invention.

The power sourcing equipment 110A includes a fiber laser 111A as a laser light source. The fiber laser 111A can achieve high output and thus is suitable for optical power supply of large electric power. However, feed light 112W output by the fiber laser 111A has a spread spectrum as illustrated in <FIG>.

The powered device 310A includes a plurality of photoelectric conversion elements 311a, 311b, and 311c. In this example, three photoelectric conversion elements are used.

The powered device 310A also includes a beam splitter <NUM>.

The beam splitter <NUM> receives the wide-band feed light 112W output from the fiber laser 111A and transmitted through the optical fiber <NUM>.

The beam splitter <NUM> splits the feed light 112W into a plurality of feed light and outputs the plurality feed light to the respective photoelectric conversion elements 311a, 311b, and 311c. That is, the beam splitter <NUM> outputs the plurality of feed light 112a, 112b, and 112c in a plurality of wavelength bands obtained through division of the feed light 112W by wavelength, to the plurality of photoelectric conversion elements 311a, 311b, and 311c respectively in a distributed manner. The feed light 112a is input to the photoelectric conversion element 311a. The feed light 112b is input to the photoelectric conversion element 311b. The feed light 112c is input to the photoelectric conversion element 311c.

<FIG> illustrates divisional wavelength ranges (assigned the same reference signs as the respective feed light 112a, 112b, and 112c) and conversion wavelength ranges (assigned the same reference signs as the respective photoelectric conversion elements 311a, 311b, and 311c) of the respective photoelectric conversion elements over the spectrum of the wide-band feed light 112W.

The plurality of photoelectric conversion elements 311a, 311b, and 311c respectively correspond to the input plurality of feed light 112a, 112b, and 112c and have the respective conversion wavelength ranges different from each other.

The conversion wavelength range of the photoelectric conversion element 311a is the same as the wavelength range of the feed light 112a. The conversion wavelength range of the photoelectric conversion element 311b is the same as the wavelength range of the feed light 112b. The conversion wavelength range of the photoelectric conversion element 311c is the same as the wavelength range of the feed light 112c.

However, the conversion wavelength range of the photoelectric conversion element (311a) may be slightly wider than the wavelength range of the input feed light (112a) and may overlap the adjacent conversion wavelength range. The conversion wavelength range of any one of the photoelectric conversion elements cannot include the wavelength range of the feed light 112W.

The photoelectric conversion element 311a converts the input feed light 112a into electric power. The photoelectric conversion element 311b converts the input feed light 112b into electric power. The photoelectric conversion element 311c converts the input feed light 112c into electric power.

<FIG> illustrates a case where the laser light source is the semiconductor laser <NUM>.

In the case of the semiconductor laser <NUM>, a spectrum is narrow. Thus, the wavelength range of the feed light <NUM> can be dealt with by the conversion wavelength range of the single photoelectric conversion element <NUM>. That is, the feed light <NUM> output by the semiconductor laser <NUM> includes almost no light that is out of the conversion wavelength range of the photoelectric conversion element <NUM>.

As illustrated in <FIG>, only the laser light source is replaced with the fiber laser 111A in such a system illustrated in <FIG>.

The feed light 112W output by the fiber laser 111A is of a wide band. Thus, light that is out of the conversion wavelength range of the photoelectric conversion element <NUM> is caused, and this light is not converted into electricity.

Thus, highly efficient photoelectric conversion cannot be performed.

On the other hand, in the power-over-fiber system 1C illustrated in <FIG>, the beam splitter <NUM> splits the wide-band feed light 112W output by the fiber laser 111A by wavelength, and the three photoelectric conversion elements 311a, 311b, and 311c perform photoelectric conversion in a distributed manner. Thus, no light that is out of the conversion wavelength ranges of the photoelectric conversion elements 311a, 311b, and 311c is caused as illustrated in <FIG>, and highly efficient photoelectric conversion can be performed.

Thus, the power-over-fiber system 1C can perform photoelectric conversion on the feed light without the feed light becoming out of the conversion wavelength ranges of the photoelectric conversion elements and thus can maintain a high power supply efficiency. Optical power supply of large electric power can be performed using high-energy feed light of the fiber laser.

While the embodiments of the present disclosure have been described above, these embodiments are merely presented as examples and can be carried out in various other forms. Each component may be omitted, replaced, or modified within a range not departing from the scope of the invention as defined by the appended claims.

In the power-over-fiber system 1C according to the embodiment described above, the powered device 310A includes three photoelectric conversion elements. However, implementation may be carried out using two photoelectric conversion elements or four or more photoelectric conversion elements.

In the power-over-fiber system 1C according to the embodiment described above, the fiber laser is used. However, the implementation is not limited to this, and the present invention can be broadly carried out in the case of a combination in which the wavelength range of the laser used in optical power supply is wider than the conversion wavelength range of a single photoelectric conversion element.

Claim 1:
An optical power supply system comprising: power sourcing equipment (110A) including a laser comprising a fiber laser (111A), the laser being configured to oscillate with electric power to output wide-band feed light (112w); and a powered device (310A) configured to receive the feed light (112w),
the powered device (310A) comprising:
a beam splitter (<NUM>) configured to
receive the feed light (112w) and
split the feed light (112w) into
a first feed light (112a) having a first wavelength band and
a second feed light (112b) having a second wavelength band different from the first wavelength band;
a first photoelectric conversion element (311a) configured to
receive the first feed light (112a) from the beam splitter (<NUM>) and
convert the first feed light (112a) into electric power by photoelectric effect; and
a second photoelectric conversion element (311b) configured to
receive the second light (112b) from the beam splitter (<NUM>) and
convert the second light (112b) into electric power by photoelectric effect,
wherein the first photoelectric conversion element (311a) and the second photoelectric conversion element (311b) respectively correspond to the received first feed light (112a) and the received second feed light (112b) and have respective conversion wavelength ranges different from each other.