JP2021027683A - Optical wireless power supply device and optical wireless power supply mobile object - Google Patents

Abstract

To provide an optical wireless power supply device capable of stably and efficiently supplying power by optical wireless power supply by optical beam such as laser beam to various mobile objects such as a drone existing in air, in water (especially in the sea), in space, or on lunar surface, and an optical wireless power supply mobile object.SOLUTION: An optical wireless power supply device includes: a planar reflector array 11 with a plurality of reflectors 11 arranged periodically in one direction through a transparent layer 12 with one principal surface serving as a light incident surface and another principal surface serving as a light emission surface; an asymmetrical surface optical waveguide 20 provided on the other principal surface of the reflector array 11 and composed to guide, in one direction, incident light making incident on one principal surface of the reflector mirror array 11 from outside and reflected by the reflector 11; and a power generating unit 30 composed of photoelectric convertors provided on an end on the light emission side of the asymmetrical surface optical waveguide 20. This optical wireless power supply device is installed on a mobile object such as a small sized unmanned object to be an optical wireless power supply mobile object.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical wireless power supply device and an optical wireless power supply mobile body, for example, a mobile body such as a small unmanned machine or an unmanned aircraft moving in the air, a small unmanned machine moving underwater, especially in seawater, or even on the moon surface. The present invention relates to an optical wireless power supply device and an optical wireless power supply mobile body suitable for supplying power to a moving body such as an active exploration vehicle (rover) by optical radio.

In recent years, the importance of optical wireless power supply is increasing more and more in the supply of electric power to drones and satellites staying in the air, underwater (especially underwater), and outer space. Conventionally, optical wireless power supply to such drones is generated by using microwaves or by installing a solar cell on the outer surface of the main body of the drone and irradiating the solar cell with a laser beam. (Photoelectric conversion) is generally performed (see, for example, Non-Patent Documents 1 and 2).

In addition, while small UAVs (Unmanned Aerial Vehicles) and UGVs (Unmanned Ground Vehicles) require power transmission of 10W to 1000W at a distance of 10m to 1km on order, in the future, large UAVs and disasters will occur. Power transmission of several kW to 100 kW class is also required, such as exploration / rescue equipment and power supply from the ground to satellites in outer space. In addition, thousands of low-altitude satellites will be launched as infrastructure for next-generation communication such as 5G, and power transmission and information transmission between these satellites will become more and more important in the future.

International Publication No. 2017/061448 Pamphlet International Publication No. 2019/059342 Pamphlet

Phillip P. Jenkins, et. Al., OWPT-5-064 OWPT2019, Yokohama, Japan, Apr. 23-25, 2019 Yoshihiro Masui, et. Al., OWPT-9-02 OWPT2019, Yokohama, Japan, Apr. 23-25, 2019 [Search on July 31, 1945], Internet <URL: http://www.mhgopower.com/images/Cell_Datasheet _Rev _1.2 _07-09-2019.pdf>

In order to achieve the above goals, well-controllable power transmission and communication over long distances are required. The delivery efficiency is determined by multiplying the positioning accuracy of the beam light delivered by the spatial tolerance of the light receiving unit that receives the beam light. However, in the above-mentioned conventional optical wireless power supply system, since the solar cell of the light receiving part generates electricity as it is, stable high output power transmission is difficult due to the fluctuation of the arrival point of the laser beam transmitted in the long-distance space. .. In particular, in a receiver structure in which a plurality of photoelectric conversion elements are connected in series in order to obtain a high voltage suitable for high-efficiency operation of the device, the light output is rate-determined by the minimum photoelectric conversion element, and the output efficiency is determined more and more. Highly efficient driving becomes difficult. In addition, the characteristics inherent in long-distance transmission using a laser beam have not been fully utilized.

Therefore, the problem to be solved by the present invention is stable by optical wireless power supply by an optical beam such as a laser beam to various moving objects such as drones staying in the air, underwater (especially in the sea), space or the moon surface. It is an object of the present invention to provide an optical wireless power feeding device and an optical wireless feeding mobile body capable of efficiently supplying electric power.

In order to solve the above problems, the present invention
Light receiving part and
A power generation unit composed of a photoelectric conversion element spatially separated from the light receiving unit,
It has a spatially asymmetric waveguide that connects the light receiving unit and the power generation unit and has a function of converting the traveling direction of light.
The power generation unit is an optical wireless power feeding device provided at an end of the waveguide on the light emitting side.

In this optical wireless power feeding device, since the light receiving unit and the power generation unit (photoelectric conversion unit) are spatially separated from each other, the resistance to fluctuation of the optical path can be dramatically improved. In addition, the three-dimensional propagating light is irreversibly converted into two-dimensional waveguide light by forming a spatially asymmetrical structure of the waveguide that connects the light receiving unit and the power generation unit and has a function of converting the traveling direction of light. It can be converted (just as it goes from 3D propagating light to 2D waveguide light). Preferably, the reflectance of the surface of the photoelectric conversion element constituting the power generation unit facing the end on the light emitting side of the waveguide is as low as 5% or less, particularly 1% to 2%. By doing so, it is possible to suppress the generation of a time-reversal equivalent wave due to the two-dimensional waveguide light emitted from the end of the waveguide on the light emitting side, which is waveguideed in the waveguide and reflected on the surface of the photoelectric conversion element. can do.

In contrast to the above invention of the optical wireless power feeding device, there are the following inventions as more specific subordinate inventions. That is, the present invention
A flat-plate reflector array in which a plurality of reflectors are periodically arranged in one direction via a transparent layer, one main surface constitutes a light incident surface and the other main surface constitutes a light emitting surface.
The incident light is waveguideed in one direction by being provided on the other main surface of the reflector array and incident on the one main surface of the reflector array from the outside and reflected by the reflector. With an asymmetric specular optical waveguide configured as
A power generation unit composed of a photoelectric conversion element provided at the end of the asymmetric surface optical waveguide on the light emitting side,
It is an optical wireless power supply device having.

In the invention of this optical wireless power feeding device, the reflector array and the asymmetric planar optical waveguide connect the light receiving portion and the light receiving portion and the power generating unit in the optical wireless feeding device of the invention of the above-mentioned superordinate concept, respectively, and determine the traveling direction of light. It corresponds to a spatially asymmetric waveguide that has the function of converting.

As the reflector array, for example, the one described in Patent Document 1 can be used. The cross-sectional shape and arrangement of the reflector in the reflector array is such that a light beam such as a laser beam incident from the outside does not directly hit the asymmetric planar optical waveguide (that is, it is always first incident on the reflector and reflected). ), And the light reflected by one reflector is set so as not to be incident on the adjacent reflector and scattered. The cross-sectional shape of the reflector preferably has a parabolic shape that is convex from one main surface side on which the light beam is incident to the other main surface side (the side of the asymmetrical optical waveguide). By having the cross section of the reflecting mirror having a parabolic shape in this way, the light incident on the reflecting mirror from the direction parallel to the axis of the two-fold symmetry of the parabola is reflected toward the focal point of the parabola. This allows the angle of incidence of light incident on the asymmetric planar optical waveguide to be narrowed down within a certain range. When the direction of the light beam incident on the optical wireless power feeding device is constant and the optical beam is incident on the optical wireless power feeding device from the vertical direction, the axis of the parabola is preferably selected substantially perpendicular to the asymmetric planar optical waveguide. Is done. Alternatively, when a light wave traveling direction conversion layer is further provided on the reflector array, the axis of the parabola is preferably selected to be parallel to the direction after the traveling direction conversion by the light wave traveling direction conversion layer. As the light wave traveling direction changing layer, for example, a light wave traveling direction changing sheet is used. The geometric intersection of the reflector and the asymmetric plane optical waveguide preferably has a linear or arcuate shape. When a plurality of reflectors are provided, the geometrical intersection of these reflectors and the asymmetric planar waveguide is centered on one point on the end face of the plurality of linear or asymmetric planar waveguides on the light emitting side. It has a concentric arcuate shape. In the former, a plurality of reflectors are periodically provided on the asymmetric surface optical waveguide in one direction parallel to the asymmetric surface optical waveguide to form a reflector array. The material of the reflector may be basically any material as long as it can obtain a high reflectance for light in the wavelength band targeted by this optical wireless power feeding device. Preferably, for example, a metal such as silver (Ag), a silver alloy (Ag-Pd or the like), or aluminum (Al) is used. Typically, a plurality of reflectors and transparent layers are alternately provided along one main surface of the asymmetrical optical waveguide on the asymmetrical optical waveguide, but the present invention is not limited to this. The transparent layer is preferably made of a transparent material (transparent glass, transparent resin, etc.) having a refractive index substantially equal to that of the transparent material constituting the asymmetric planar optical waveguide.

The reflector array is not limited to the above, and for example, a clad layer (clad layer 12 in FIG. 1 of Patent Document 2) in the optical waveguide device described in Patent Document 2 can be used. This clad layer functions substantially like a reflector array. That is, it has a waveguide core layer and a clad layer that discontinuously covers the waveguide core layer, and the clad layer includes an end portion of a disconnection portion that does not cover the waveguide core layer and the disconnection portion. It extends between the side of the waveguide core layer and the position opposite to the waveguide direction and away from the waveguide core layer, and is directed toward the waveguide direction of the waveguide core layer. Part of the clad layer has a structure that gradually approaches the core layer and is provided so that the tangent line at the end of the discontinuity is parallel (tangential) or substantially parallel to the waveguide core layer. The clad layer in the optical waveguide device in which the light-introducing core layer coated with the clad layer is provided so as to join the waveguide core layer can be used as a reflector array. The clad layer that discontinuously covers the waveguide core layer has discrete translational symmetry.

The asymmetric planar optical waveguide typically has a wedge-shaped (or tapered) shape in which the cross-sectional area gradually increases toward the end face on the light emitting side. In such a wedge-shaped asymmetrical optical waveguide, the light incident inside from the light incident surface of the asymmetrical planar optical waveguide has a cross-sectional area while being alternately reflected by the two main surfaces of the asymmetrical planar optical waveguide. It is waveguide in a larger direction and finally incident on a power generation unit provided at an end on the light emitting side of the asymmetric planar optical waveguide. The asymmetric planar optical waveguide may be a planar optical waveguide or a curved optical waveguide. Further, the planar shape of the asymmetric planar optical waveguide is selected as necessary, but typically has a quadrangular shape, for example, a rectangular shape or a square shape. In this case, if necessary, the end face of the asymmetric surface optical waveguide excluding the light emitting end surface, for example, the asymmetric surface optical waveguide has a quadrangular shape, and at least one of a pair of opposite sides thereof. When all or part of the end face of the asymmetrical optical waveguide corresponding to the side is the light emitting end face, it corresponds to at least one side of the pair of sides different from the above-mentioned pair of opposite sides of this quadrangle. A light reflection mechanism is provided at the end of the asymmetrical optical waveguide. In this case, when the light incident on the main surface of the asymmetric specular optical waveguide is directed in the asymmetric specular optical waveguide, it is reflected when it enters the light reflection mechanism, and the optical path is bent in the direction toward the light emitting end surface. As a result, the amount of light that can be extracted from the light emitting end face is increased. In this light reflection mechanism, for example, a light reflection film provided on the side surface of the asymmetric surface optical waveguide or the side surface of the asymmetric surface optical waveguide is formed as a mirror surface.

As the configuration of the power generation unit (photoelectric conversion unit) composed of the photoelectric conversion element, the one described in Patent Document 1 can be used. The power generation unit has a semiconductor layer for photoelectric conversion provided at an end on the light emitting side of the asymmetric planar optical waveguide. A first electrode and a second electrode are provided on a pair of upper and lower surfaces of the semiconductor layer facing each other, respectively. One of these first and second electrodes is used as an anode electrode and the other as a cathode electrode. When the semiconductor layer has a pn junction, the pn junction surface is perpendicular or parallel to one main surface of the asymmetric planar waveguide. In the case of parallel, it is typically generated in the semiconductor layer by the net direction of travel of the light guided inside the asymmetric planar waveguide and the light incident on the semiconductor layer from the end face of the asymmetric planar waveguide. The angle Θ formed by the net moving direction of the carrier to be made is approximately a right angle. Specifically, Θ is selected, for example, π / 2-δ ≦ Θ ≦ π / 2 + δ. However, although δ is used as the anode electrode among the first electrode and the second electrode, the ratio of the thickness of the semiconductor layer to the width (electrode width) in the direction parallel to the traveling direction of light in the semiconductor layer. Corresponding to δ to the thickness / electrode width of the semiconductor layer. Typically, the asymmetric planar optical waveguide and the semiconductor layer are provided integrally with each other, and for example, their ends are joined and integrated.

Preferably, when the light is incident on the optical wireless power feeding device, the light is not directly incident on the semiconductor layer. In other words, when light is incident on the optical wireless power feeding device, the light is incident on the reflector array, but the light is not directly incident on the surface of the semiconductor layer. By doing so, it is possible to prevent the semiconductor layer from being heated by the light directly incident on the semiconductor layer and the temperature from rising, so that it is possible to prevent deterioration of the characteristics of the semiconductor layer and, by extension, dissipate as heat. Coupled with the small amount of energy, it is possible to prevent a decrease in the photoelectric conversion efficiency of the power generation unit, and it is possible to obtain a high photoelectric conversion efficiency.

The semiconductor layer is a pn junction composed of an inorganic semiconductor or an organic semiconductor, typically a p-type semiconductor layer and an n-type semiconductor layer, and the pn junction surface is mainly the asymmetric planar optical waveguide as described above. Parallel or perpendicular to the plane. The thickness of the semiconductor layer is appropriately selected in consideration of the function of the diffusion length of the carriers in the semiconductor layer, but when the pn junction surface is parallel to the main surface of the asymmetric planar optical waveguide, it is preferably 100 nm or more and 100 μm. Hereinafter, when the pn junction surface is perpendicular to the main surface of the asymmetric planar optical waveguide, it is preferably 1 μm or more and 500 μm or less. The semiconductor constituting the semiconductor layer may be in any form of amorphous, polycrystalline, or single crystal.

Examples of the inorganic semiconductor include II-VI compound semiconductors such as CdSe, PbS, PbSe, and PbTe, III-V compound semiconductors such as GaSb, InAs, InN, AlInN, GaInN, GaN, AlGaN, GaAsN, and GaPN, and Si and SiGe. group IV semiconductors such _{as, Si x Ge y Sn 1-} xy O, SiN x, SiO x, CIS (CuInSe), CIGS (CuInGaSe), or the like can be used CuInGaSeTe. These semiconductors are characterized in that the band gap can be controlled by, for example, controlling the composition ratio of group III elements such as In and Ga and mixing sulfur (S). The semiconductor layer can also be composed of fine particles made of these inorganic semiconductors.

As the organic semiconductor, all materials generally reported as materials for organic solar cells can be used, but specifically, polyacetylene such as pentacene, polyacetylene (preferably disubstituted polyacetylene), and poly (p). -Phenylene vinylene), poly (2,5-thienylene vinylene), polypyrrole, poly (3-methylthiophene), polyaniline, poly (9,9-dialkylfluorene) (PDAF), poly (9,9-dioctylfluorene)- co-bithiophene) (F8T2), poly (1-hexyl-2-phenylacetylene) (PH _X PA) (shows blue luminescence as a luminescent material), poly (diphenylacetylene) derivative (PDPA-nBu) (luminescent material) (Shows green luminescence), poly (pyridine) (PPy), poly (pyridylbinylene) (PPyV), cyano-substituted poly (p-phenylene vinylene) (CNPPV), poly (3,9-di-tert- Butyl indeno [1,2-b] fluorene (PIF) and the like can be used. For the dopants of these organic semiconductors, alkali metals (Li, Na, K, Cs) can be used as donors, and as acceptors. Are halogens (Br ₂ , I ₂ , CI ₂ ), Lewis acids (BF ₃ , PF ₅ , AsF ₅ , SbF ₅ , SO ₃ ), transition metal halides (FeCl ₃ , MoCl ₅ , WCl ₅ , SnCl ₄ ). TCNE and TCNNQ can be used as the organic acceptor molecule, and the dopant ions used for electrochemical doping are tetraethylammonium ion (TEA ⁺ ), tetrabutylammonium ion (TBA ⁺ ), and Li ^{+ as cations. , Na +, K +, ClO} 4 as the anion ^{_{-, BF 4 -, PF 6}} -, AsF 6 -, SbF 6 -. or the like can be used further as the organic semiconductor, also possible to use a polymer electrolyte Specific examples of this polymer electrolyte include polycations such as sulphonate polyaniline, poly (thiophene-3-acetic acid), sulphonate polystyrene, and poly (3-thiophene alkansulfonate). Examples include polyallylamine, poly (p-phenylene-vinylene) precursor polymer, poly (p-methylpyridinium vinylene), and protonated poly (p-pyridylbinile). , Poloton (2-N-methylpyridinium acetylene) and the like can be used. When an organic semiconductor layer doped with a low impurity concentration is used as the semiconductor layer, the organic semiconductor layer can have a heterojunction type or bulk heterojunction type structure. In the organic semiconductor layer having a heterojunction structure, the p-type organic semiconductor film and the n-type organic semiconductor film are bonded so as to be in contact with the first electrode and the second electrode. The organic semiconductor layer having a bulk heterojunction structure is composed of a mixture of a p-type organic semiconductor molecule and an n-type organic semiconductor molecule, and has a microstructure in which the p-type organic semiconductor and the n-type organic semiconductor are intertwined with each other and are in contact with each other.

As the semiconductor constituting the semiconductor layer, an organic-inorganic hybrid semiconductor may be used in addition to the inorganic semiconductor and the organic semiconductor. As such an organic-inorganic hybrid semiconductor, for example, a perovskite-based semiconductor can be used.

Preferably, the first electrode and the second electrode are in ohmic contact with the semiconductor layer. When an organic semiconductor is used as the semiconductor layer, the first electrode and the second electrode do not have to be in ohmic contact with the semiconductor layer. As the first electrode and the second electrode, in addition to metals such as gold (Au), nickel (Ni), and aluminum (Al), Al may be used for p-type Si and Ag may be used for n-type Si. It is effective, and various transparent conductive oxides such as indium-tin oxide (ITO), zinc oxide (ZnO), and tin oxide (SnO) can be used, and chromium, titanium, molybdenum, and the like are also used. It can, but is not limited to. Further, when the transparent electrode is used as an electrode of a semiconductor layer which is a photoelectric conversion layer, it has a low refractive index property and a wide gap property, so that it has a high waveguide characteristic of an ingress photon into the semiconductor layer and a generated photocarrier. It also has the effect of leading to a low surface recombination rate and, as a result, enabling high photoelectric conversion efficiency. Increasing the band gap of the semiconductor layer itself as it approaches the first electrode and the second electrode is also effective in suppressing the surface recombination of minority carriers, and at the same time, it is also effective in confining light. It is doubly effective. The transparent electrodes correspond to regions having a refractive index lower than the refractive index of the semiconductor layer provided at both ends in the direction of passing the semiconductor layer in the direction perpendicular to the main surface of the asymmetric planar optical waveguide.

Preferably, the bandgap of the semiconductor layer, or the HOMO (highest occupied molecular orbital) -LUMO (lowest unoccupied molecular orbital) gap when the semiconductor layer is made of an organic semiconductor, is stepwise and / in the direction of light travel. Or try to decrease continuously. By doing so, for example, when sunlight is incident on the main surface of the semiconductor layer of the photoelectric conversion device, the sunlight is wavelengthed in the asymmetric planar optical waveguide and when it is incident on the semiconductor layer, the band gap or HOMO -The semiconductor with the largest LUMO gap is first incident, and finally the semiconductor with the smallest band gap is incident. In this process, light with a short wavelength to light with a long wavelength in the solar spectrum is incident. Is absorbed sequentially, and the amount of absorption is maximized. Therefore, depending on how the band gap or HOMO-LUMO gap of the semiconductor layer is changed and the type of semiconductor used, the main part or substantially all of the light in the sunlight spectrum can be photoelectrically converted, and ultimately. Can bring the photoelectric conversion efficiency closer to the theoretical maximum efficiency. Typically, the semiconductor layer consists of a plurality of regions in which the band gap or HOMO-LUMO gap gradually decreases in the traveling direction of light, and the first electrode and the first electrode and the first electrode and the first electrode are on a pair of opposite surfaces of each region. Two electrodes are provided, and at least one of these first and second electrodes is provided separately from each other between the regions.

Preferably, the semiconductor layer is composed of a plurality of regions in which the band gap or HOMO-LUMO gap gradually decreases in the light traveling direction, and the width of the light traveling direction in each region is the band gap or HOMO of each region. It is greater than or equal to the reciprocal of the absorption coefficient in each region of light having an energy equal to the −LUMO gap.

When the semiconductor layer consists of a plurality of regions in which the band gap or the HOMO-LUMO gap gradually decreases in the traveling direction of light, for example, Si _x C _{1 in the traveling direction of light. A} region consisting of -x (0 <x <1), a region consisting of Si and a region consisting of Si _y Ge _1-y (0 <y <1), or a region consisting of Si _x C _1-x , consisting of Si. A region consisting of a region and microcrystal Si _y Ge _1-y , or a region containing at least one semiconductor selected from the group consisting of AlGaN, GaN and IGZO (oxides of In, Ga, Zn), Si _x C _{1 A} region consisting of -x, a region consisting of Si and a region consisting of Si _y Ge _1-y , or a region consisting of Si _x C _1-x , a region consisting of Si, a region consisting of Si _y Ge _1-y and a region consisting of Ge. Area.

As the photoelectric conversion element, a flat element in which several to several tens or several hundred layers of Si elements are connected in series is also effective (see Non-Patent Document 3).

Moreover, this invention
With a mobile body
It has an optical wireless power feeding device that is integrally provided with the moving body and supplies power to the moving body.
The above optical wireless power supply device
A flat-plate reflector array in which a plurality of reflectors are periodically arranged in one direction via a transparent layer, one main surface constitutes a light incident surface and the other main surface constitutes a light emitting surface.
The incident light is waveguideed in one direction by being provided on the other main surface of the reflector array and incident on the one main surface of the reflector array from the outside and reflected by the reflector. With an asymmetric specular optical waveguide configured as
A power generation unit composed of a photoelectric conversion element provided at the end of the asymmetric surface optical waveguide on the light emitting side,
It is an optical wireless power supply mobile body having.

The moving body may be basically any, but for example, a small unmanned aerial vehicle, an unmanned aerial vehicle, an aircraft, an artificial satellite, an unmanned ship, a ship, an underwater moving body, an exploration vehicle (rover), or an unmanned vehicle. , Automobiles, etc. Small unmanned or unmanned aerial vehicles include, for example, drones, radio-controlled aircraft, pesticide spraying helicopters, and the like.

In the invention of the optical wireless power feeding mobile body, the matters other than the above have been described in relation to the invention of the optical wireless power feeding device, unless the property is contrary to the above.

According to the present invention, since one main surface of the reflector array is a light incident surface, a drone or an unmanned person who receives optical radiopower and stays in the air, underwater (especially underwater), on the ground, in space, on the moon, etc. Even if there are fluctuations in the location of moving objects such as aircraft, or moving objects such as artificial satellites and exploration vehicles, the optical beam used for optical radio power supply can be reliably incident on the light incident surface, and the reflector array After the light beam is reflected by the reflector and incident on the asymmetric planar optical waveguide, the inside of the asymmetric planar optical waveguide can be made to waveguide toward the power generation unit due to the asymmetry of the asymmetric planar optical waveguide. Finally, the waveguide light can be incident on the power generation unit to generate power (photoelectric conversion). Therefore, it is possible to stably and efficiently supply electric power to various moving objects such as drones staying in the air by optical wireless power supply using an optical beam.

It is sectional drawing which shows the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is a top view which shows an example of the plan shape of the optical wireless power feeding device by 1st Embodiment of this invention. It is a top view which shows the specific example of the reflector array of the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is a top view which shows the other specific example of the reflector array of the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is sectional drawing which enlarges and shows the structure of the vicinity of the power generation part of the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is sectional drawing which shows the structural example of the power generation part of the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is a schematic diagram which shows the specific example of the manufacturing method of the reflector array of the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is a schematic diagram which shows another specific example of the manufacturing method of the reflector array of the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is sectional drawing for demonstrating the operation of the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is a top view for demonstrating the operation of the optical wireless power feeding apparatus by 1st Embodiment of this invention. In the optical wireless power feeding device according to the first embodiment of the present invention, a simulation performed to verify the performance of converting light incident from the outside into two-dimensional space-propagated light guided in an asymmetric specular optical waveguide. It is a schematic diagram which shows the result of. In the optical wireless power feeding device according to the first embodiment of the present invention, the location dependence of the waveguide state when the light beam incident from the outside is incident on the coupling system of the reflector array and the asymmetric plane optical waveguide is verified. It is a schematic diagram which shows the result of the simulation performed for this purpose. In the optical wireless power feeding device according to the first embodiment of the present invention, the location dependence of the waveguide state when the diluted light incident from the outside is incident on the coupling system of the reflector array and the asymmetric planar optical waveguide. It is a schematic diagram which shows the result of the simulation performed for verification. In the optical wireless power feeding device according to the first embodiment of the present invention, when the beam light and the diluted light incident from the outside are incident on the coupling system of the reflector array and the asymmetric plane optical waveguide, they are derived from the space propagating light. It is a schematic diagram which shows the light incident position dependence of the efficiency of conversion into light propagating in a waveguide. It is a schematic diagram which shows the result of having actually manufactured the reflector array shown in FIG. 3 and evaluated the optical performance. It is a drawing substitute photograph which shows the example which actually manufactured the reflector array shown in FIG. It is a schematic diagram which shows the result of having evaluated the optical performance of the reflector array shown in FIG. It is a schematic diagram which shows the method of making the reflector array invisible with respect to the incident light beam by designing the reflector array in the optical wireless power feeding apparatus by 1st Embodiment of this invention. It is a drawing substitute photograph which shows the light intensity distribution in the light emission end face of the asymmetric plane optical waveguide when a light beam is incident on the reflector array shown in FIG. It is a schematic diagram which shows the voltage-current characteristic of the general commercial solar cell. The abbreviation showing the voltage-current characteristics of a solar cell when a commercially available general solar cell is coupled as a power generation unit to the light emitting end surface of the asymmetric planar optical waveguide of the optical wireless power feeding device according to the first embodiment of the present invention. It is a diagram. It is sectional drawing which shows the optical wireless power feeding apparatus by 2nd Embodiment of this invention. It is sectional drawing which enlarges and shows a part of the asymmetric plane optical waveguide of the optical wireless power feeding apparatus by 2nd Embodiment of this invention. It is a schematic diagram which shows the optical wireless power supply drone by the 3rd Embodiment of this invention.

Hereinafter, embodiments for carrying out the invention (hereinafter, referred to as “embodiments”) will be described with reference to the drawings. In the following embodiments, the same or corresponding parts are designated by the same reference numerals.

<First Embodiment>
[Optical wireless power supply device]
FIG. 1 shows an optical wireless power feeding device according to the first embodiment. As shown in FIG. 1, in this optical wireless power feeding device, a flat plate-shaped reflector array 10 and a reflector array 10 in which one main surface constitutes a light incident surface and the other main surface constitutes a light emitting surface. An asymmetric surface-shaped optical waveguide 20 having a wedge-shaped shape provided on the other main surface of the above, and a power generation unit 30 composed of a photoelectric conversion element provided at an end portion of the asymmetric surface-shaped optical waveguide 20 on the light emitting side. Has. The planar shape of the reflector array 10 and the asymmetrical optical waveguide 20 is not particularly limited and is appropriately selected depending on the optical wireless power feeding device and the like, and is, for example, a rectangle or a square. FIG. 2 shows a case where the planar shape of the reflector array 10 and the asymmetric planar optical waveguide 20 is rectangular as an example.

The reflector array 10 has a structure in which the reflector 11 and the transparent layer 12 are periodically and alternately provided in one direction parallel to the reflector array 10. The reflector 11 and the transparent layer 12 are made of, for example, the materials already mentioned. The thickness of the transparent layer 12 in one direction parallel to the reflector array 10 is selected as needed, and is, for example, several μm to several tens of μm. Also, the period of repetition of the reflector 11 and the transparent layer 12, that is, the reflector for the total thickness of one reflector 11 and the transparent layer 12 adjacent thereto in one direction parallel to the reflector array 10. The thickness ratio of 11 is preferably small, and is selected to be at least 5% or less, preferably 1% or less and 1 nm or more. The reflector 11 is provided so that the incident light does not escape (the incident light is not reflected by the reflector 11 and directly shines on the asymmetric planar optical waveguide 20), and the two reflectors adjacent to each other in FIG. 1 When focusing on 11, the structure and arrangement are set so that the light reflected by the reflector 11 on the right side is not reflected (scattered) by the back surface of the reflector 11 on the left side. The distance between the reflecting mirrors 11 and the number of repetitions between the reflecting mirror 11 and the transparent layer 12 are appropriately selected depending on the application of the optical wireless power feeding device and the like. The reflector 11 is configured to reflect a light beam incident from the outside of the optical radio feeding device so that it can be incident on the light incident surface of the asymmetric planar optical waveguide 20. Preferably, the cross-sectional shape of the reflector 11 is selected so that the light beam incident on the optical wireless power feeding device from a certain direction can be reflected and incident on the asymmetric plane optical waveguide 20 at an incident angle within a certain range. Is done. In FIG. 1, as a typical example, the shape of the reflector 11 in the cross section of the reflector array 10 perpendicular to the main surface of the asymmetric planar optical waveguide 20 may form a part of one side of the axis of the parabola. It is shown. When three-dimensional space propagating light is incident on the reflector array 10 from a substantially vertical direction, the axis of this parabola is ensured that as much light as possible is finally incident on the asymmetric planar optical waveguide 20. Is preferably set within ± 10 ° with respect to the normal line erected on the main surface of the asymmetric planar optical waveguide 20, and most preferably near 0 °, that is, on the main surface of the asymmetrical planar optical waveguide 20. Set vertically. Since the light incident parallel to the axis of the parabola has the property of concentrating at the focal point of the parabola, by setting the axis of the parabola perpendicular to the main surface of the asymmetric planar optical waveguide 20, it is substantially perpendicular to the reflector array 10. When three-dimensional space propagating light is incident on the light, the directions of the light reflected by the reflector 11 are substantially the same. In order to allow as much incident light incident on the optical wireless power feeding device to enter the asymmetrical optical waveguide 20, preferably, the reflector 11 extends from end to end of the asymmetrical optical waveguide 20. However, it is not limited to this. The planar shape of each reflector 11 is not particularly limited and is selected as necessary, but is typically reflected by the reflector 11 and incident inside the asymmetric planar optical waveguide 20 to be guided. At least most of the dimensional space propagating light is chosen to go in one direction. Specific examples of the reflector array 10 are shown in FIGS. 3 and 4. It should be noted that, as shown in FIGS. 3 and 4, the geometric intersections (sets) of the asymmetric planar optical waveguide 20 and the reflector 11 have geometric symmetry. FIG. 3 shows a case where the reflector array 10 and the asymmetric plane optical waveguide 20 have a rectangular planar shape, and each reflector 11 has a shape extending linearly in the direction of the short side of the reflector array 10. , Has translational symmetry. In this case, the light reflected by each reflector 11 is guided inside the asymmetric planar optical waveguide 20 in a direction perpendicular to each reflector 11. FIG. 4 shows that when the reflector array 10 and the asymmetric planar optical waveguide 20 have a rectangular planar shape, each reflector 11 is curved in a concentric arc shape centered on the midpoint of one short side of the reflector array 10. It has a rectangular shape and has partial rotational symmetry and directional symmetry. In this case, the light reflected by each reflector 11 is guided inside the asymmetric planar optical waveguide 20 toward the midpoint of one short side of the reflector array 10.

The wedge-shaped asymmetric planar optical waveguide 20 has an elongated right-angled triangular cross-sectional shape, the long side (bottom) sandwiching the right-angled corner coincides with the light emitting surface of the reflector array 10, and the short side is asymmetric. It coincides with the light emitting surface of the planar optical waveguide 20.

It is desirable that the substance constituting the asymmetric planar optical waveguide 20 is a substance that is as transparent as possible with respect to light having a wavelength in the range targeted by this optical wireless power feeding device. The substance constituting the asymmetric planar optical waveguide 20 is generally transparent glass, high refractive index glass, transparent plastic, or the like. Examples of transparent plastics include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyethylene, polypropylene, polyphenylene sulfide, polyvinylidene fluoride, acetylcellulose, brominated phenoxy, aramids, polyimides, polystyrenes, polyarylates, etc. Examples thereof include polysulfones and polyolefins. As the substance constituting the asymmetric planar optical waveguide 20, a fluorine-based material used for plastic optical fiber (POF) or the like is particularly suitable due to its low light loss property. The thickness of the asymmetric planar optical waveguide 20 is selected as needed, and is, for example, 1 to 1000 μm. The size (length and width) of the asymmetric plane optical waveguide 20 is appropriately selected depending on the location where the optical wireless power feeding device is installed, but is generally, for example, (1 cm to 1 m) × (1 cm to 1 m). ).

Details of the power generation unit 30 are shown in FIG. 5A. As shown in FIG. 5A, in the power generation unit 30, a semiconductor layer 40 for photoelectric conversion is provided in contact with the end surface of the asymmetric planar optical waveguide 20 on the light emitting side. The semiconductor layer 40 has a pn junction, and the pn junction surface is parallel to the main surface of the asymmetric planar optical waveguide 20 on the reflector array 10 side. Further, as shown in FIG. 5B, a plurality of semiconductor layers 40 (for example, MH GoPower element “5S1010.4”) connected in series with the electrode 501 sandwiched between them may be used, and by doing so, high output voltage operation is possible. Become. The semiconductor layer 40 is provided so as to cover all or a part of the light emitting end face of the asymmetric planar optical waveguide 20, but is preferably suitable when light is emitted from the entire light emitting end face of the asymmetric planar optical waveguide 20. Is provided so as to cover the entire surface of the light emitting end face, at least almost the entire surface, and when light is emitted from a part of the light emitting end face, it is provided so as to cover at least that part. The asymmetric planar optical waveguide 20 and the semiconductor layer 40 are provided integrally with each other, and have a planar shape as a whole.

The first electrode 50 and the second electrode 60 are provided on a pair of surfaces (upper surface and lower surface) facing each other on the upper and lower sides (the light incident side is the upper side) of the semiconductor layer 40, respectively. One of these first electrode 50 and the second electrode 60 is used as an anode electrode, and the other is used as a cathode electrode. For example, the first electrode 50 is used as an anode electrode, and the second electrode 60 is used as a cathode electrode. When the semiconductor layer 40 is divided into a plurality of regions made of different semiconductors, the first electrode 50 and the second electrode 60 may be provided for each region, or one of them may be provided on all the regions. It may be a full-face electrode extending to. A photoelectric conversion element is composed of a semiconductor layer 40, a first electrode 50, and a second electrode 60.

In this optical wireless power feeding device, the light beam (three-dimensional space-propagated light) incident on the reflector array 10 enters the inside of the asymmetric planar optical waveguide 20 and is converted into two-dimensional space-propagated light and guided. After that, it is configured to be emitted from the end surface of the asymmetric planar optical waveguide 20 and incident on the semiconductor layer 40 of the power generation unit 30. In this case, the carrier generated in the semiconductor layer 40 by the net traveling direction of the light guided inside the asymmetric optical waveguide 20 and the light incident on the semiconductor layer 40 from the end face of the asymmetric planar optical waveguide 20. The angle Θ formed by the net moving direction of the (photocarrier) (the direction connecting the first electrode 50 and the second electrode 60 at the shortest distance) is substantially perpendicular. Specifically, the angle Θ is divided into a plurality of regions in which the width of the light traveling direction of the first electrode 50 or the semiconductor layer 40 is made of semiconductors different from each other, and the first electrode 50 is provided for each region. If this is the case, assuming that the width of the first electrode 50 provided for each region in the traveling direction of light is W'and the thickness of the semiconductor layer 40 is d, π / 2-δ ≤ Θ ≤ π / 2 + δ (however, , Δ to d / W ′), typically 80 ° ≦ Θ ≦ 100 °, and most preferably 90 °. The reflectance of the surface of the semiconductor layer 40 facing the light emitting end face of the asymmetric plane optical waveguide 20 is due to the light emitted from the light emitting end face of the asymmetric plane optical waveguide 20 being reflected by the surface of the semiconductor layer 40. In order to suppress the generation of the time reversal equivalent wave, it is preferably set to several% or less, for example, 1% to 2%, which is almost 0. For this purpose, for example, an antireflection film is provided on the joint surface between the asymmetric planar optical waveguide 20 and the semiconductor layer 40.

In this optical wireless power feeding device, preferably, when light is incident from the outside, the light is not directly incident on the semiconductor layer 40. In other words, when light is incident on the optical wireless power feeding device, the light is incident on the reflector array 10, but the light is not directly incident on the surface of the semiconductor layer 40. For this purpose, for example, the following is performed. For example, a light-shielding layer (not shown) is provided above the semiconductor layer 40 so as to cover the first electrode 50. A conventionally known light-shielding layer can be used and is selected as needed. For example, an aluminum laminate film in which plastic films are formed on both sides of an aluminum foil is used. With this light-shielding layer, it is possible to prevent light from directly incident on the semiconductor layer 40.

The semiconductor layer 40 is, for example, selected from those already mentioned as needed. The semiconductor layer 40 is typically a pn junction composed of a p-type semiconductor layer and an n-type semiconductor layer. Preferably, the portion of the semiconductor layer 40 in which the first electrode 50 and the second electrode 60 come into contact is doped with a high impurity concentration, and these first electrode 50 and the second electrode 60 are the semiconductor layer 40. Make ohmic contact with. The length of one side of the semiconductor layer 40 is typically selected to be the same as the length of the side of the asymmetrical optical waveguide 20 on which the semiconductor layer 40 is provided, but the length of the side perpendicular to this side is typical. It is 0.5 μm to 5 mm, preferably 2 μm to 1 mm. Since the size of the asymmetric planar optical waveguide 20 is, for example, (1 cm to 1 m) × (1 cm to 1 m) as described above, the area of the semiconductor layer 40 is generally larger than the area of the asymmetric planar optical waveguide 20. It can be much smaller. That is, in this optical wireless power feeding device, the asymmetric planar optical waveguide 20 occupies most of the device, and the semiconductor layer 40 occupies only a small part of the end. For example, assuming that the size of the asymmetric planar optical waveguide 20 is 10 cm × 10 cm and the size of the semiconductor layer 40 is 1 mm × 10 cm, the semiconductor layer 40 occupies the total area of the asymmetric planar optical waveguide 20 and the semiconductor layer 40. The ratio of the area is only 0.1 × 10 / 10.1 × 10 = 0.0099≈1%. In addition to this, since the thickness of the semiconductor layer 40 is generally as small as several tens of μm or less, the volume of the semiconductor layer 40 is also extremely small. That is, the amount of the semiconductor layer 40 used can be extremely small. Therefore, the manufacturing cost of the optical wireless power feeding device can be reduced.

The band gap or HOMO-LUMO gap E _g of the semiconductor layer 40 gradually decreases in N steps (N ≧ 2) in the traveling direction of light in the semiconductor layer 40, and E _g1 , E _g2 , ..., It is E _gN (E _g1 > E _g2 >...> E _gN ). FIG. 6 shows the case of N = 4 as an example, but the present invention is not limited to this. As shown in FIG. 6, the semiconductor layer 40 includes regions 41, 42, 43, and 44 having _{band gaps or HOMO-LUMO gaps E g} of E _g1 , E _g2 , E _g3 , and E _{g4, respectively.} Each region 41, 42, 43, 44 has an elongated striped shape extending in a direction parallel to the side provided with the semiconductor layer 40 of the asymmetric planar optical waveguide 20. In FIG. 6, the first electrodes 51, 52, 53, and 54 are provided on the regions 41, 42, 43, and 44 separately from each other. The second electrode 60 is a full surface electrode and is a common electrode of each region 41, 42, 44, 44. (The width in the traveling direction of light, the length of the lateral direction in FIG. 6) the width of each E _gi region constituting the semiconductor layer 40, the photoelectric conversion target photons (bandgap E of the E _gi region of the E _gi region _If the absorption coefficient _{of this E gi} region for the photon with the lowest energy among photons with energy of _{gi or more is α i} , it is 1 / α _i or more.

E _gi can be set as follows. For example, the wavelength is divided into N sections in the entire wavelength range of the AM1.5 sunlight spectrum or its main wavelength range (the range including the portion having high incident energy). Then, these sections are numbered in order from the short wavelength side (high energy side) such as 1, 2, ..., N, and E _gi is selected equal to the minimum photon energy of the i-th section. By doing so, when a photon having photon energy in the kth section _{is incident on the Egi} region, an electron-hole pair is generated and photoelectric conversion is performed. Further, in this case, the E is formed from the junction surface between the asymmetrical optical waveguide 20 and the semiconductor layer 40 so that the _{photon having the photon energy in the kth section reaches each Egi region and is sufficiently absorbed.} Select the distance to the _{gi area.} As a result, the sunlight that is waveguideed inside the asymmetric planar optical waveguide 20 and enters the semiconductor layer 40 first enters the E _g1 region, and the spectrum whose photon energy is E _g1 or higher is absorbed. It is photoelectrically converted, then _{incident on the E g2} region, and the spectrum whose photon energy is E _g2 or more and _{smaller than E g1} is absorbed and photoelectrically converted, and finally _{incident on the E gN} region and the spectrum of the spectrum. Of these, those with photon energies of E _gN or more and _{less than E gN-1} are absorbed and photoelectrically converted. As a result, even if the wavelength of the light beam incident on the optical wireless power feeding device is distributed in a certain wavelength band, the light in almost the entire range or the main wavelength range can be used for photoelectric conversion.

The thickness d of each E _gi region is selected as needed, and is, for example, several μm to several tens of μm. The width of each _Egi region (width in the traveling direction of light in the semiconductor layer 40) is also selected as necessary, and is, for example, several tens of μm to several hundreds of μm. To give a specific example, the thickness d of each region 41 to 44 in FIG. 6 is several μm to several tens of μm, and the width w _{1 to w 4} of each region 41 to 44 is several tens μm to several hundred μm, for example, to 100 μm. Choose to.

In a typical case, each region 41 to 44 is composed of a pn junction composed of a p-type semiconductor layer and an n-type semiconductor layer.

[Manufacturing method of optical wireless power supply device]
This optical wireless power feeding device can be easily manufactured by using a conventionally known technique. That is, for example, an asymmetric planar optical waveguide 20 is prepared, and a power generation unit 30 is formed on the light emitting end surface thereof. Next, the reflector array 10 is formed on the bottom surface of the asymmetric planar optical waveguide 20. For example, the reflector array 10 is attached to the bottom surface of the asymmetric surface optical waveguide 20. In this way, the optical wireless power feeding device shown in FIG. 1 is manufactured.

[Manufacturing method of reflector array 10]
The reflector array 10 can be easily manufactured by, for example, the following method. That is, first, as shown in FIG. 3, a case where the reflector array 10 in which the reflector 11 extends straight in a straight line is manufactured will be described. 7A and 7B are front views and side views of the vacuum chamber 150 of the vacuum vapor deposition apparatus, and FIG. 7C is an enlarged view of a portion surrounded by a broken line in FIG. 7B. As shown in FIGS. 7A and 7B, a flat tape-shaped transparent resin base film 152 having a narrow and thin width is wound around a flat roller 151 having a square cross-sectional shape with rounded corners. After the metal 154 of the vapor deposition source 153 is evaporated on one surface of the film 152 to form a thin metal film 155, the base film 152 with the metal film 155 is wound up by a take-up roller 156. As shown in FIGS. 7B and 7C, the take-up surface of the take-up roller 156 has the same cross-sectional shape as the reflector 11 of the reflector array 10, for example, a parabolic shape. The cross-sectional shape of the outer peripheral surface of the roller 151 may be the same as the cross-sectional shape of the take-up surface of the take-up roller 156.

As described above, the base film 152 with the metal film 155 is wound by the take-up roller 156 to form a spiral structure in which the base film 152 and the metal film 155 are alternately laminated. FIG. 7C is an enlarged view of a part of FIG. 7B. The reflector array 10 can be manufactured by cutting out from this spiral structure as shown by the broken line in FIG. 7A. Here, the metal film 155 corresponds to the reflector 11, and the base film 152 corresponds to the transparent layer 12.

A reflector array 10 similar to the above can also be manufactured using a 3D printing or imprinting technique. That is, first, a flat film having the same properties as the base film 152 is prepared, and with respect to this flat film, a curved surface portion having a shape similar to the shape of the reflector 11 in the cross section of the reflector array 10 and a curved portion connected to the curved surface portion are perpendicular to the flat film. After pressing a mold having a sawtooth cross section having a straight portion, the mold is pulled away from the flat film. The pressing depth of the mold should be smaller than the thickness of the flat film so that it does not penetrate the flat film when the mold is pressed. Next, for example, a metal such as Ag is deposited on a surface embossed from a direction perpendicular to the flat film by a vacuum vapor deposition method. Metal is not deposited on the embossed surface perpendicular to the flat film, and metal is deposited only on the curved surface to form the metal film. After that, both sides of the flat film are polished so that the metal film is exposed on both sides. This metal film corresponds to the reflector 11, and the flat film corresponds to the transparent layer 12.

Next, as shown in FIG. 4, a case where the reflector array 10 in which the reflector 11 extends in a concentric arc shape is manufactured will be described. 8A and 8B are a front view and a side view of the vacuum chamber 150 of the vacuum vapor deposition apparatus. As shown in FIGS. 8A and 8B, for example, a narrow and thin flat tape-shaped transparent resin base film 152 is wound around a columnar roller 151, and an evaporation source is wound on one surface of the base film 152. After the metal 154 of 153 is evaporated to form a thin metal film 155, the base film 152 with the metal film 155 is wound up by a winding roller 156. As described above, the base film 152 with the metal film 155 is wound by the take-up roller 156 to form a spiral structure in which the base film 152 and the metal film 155 are alternately laminated. FIG. 8C is an enlarged view of the portion shown by the broken line in FIG. 8B. The reflector array 10 can be manufactured by cutting out from this spiral structure as shown by the broken line in FIG. 8A.

[Operation of optical wireless power supply device]
The operation of the optical wireless power supply device will be described. As shown in FIGS. 9 and 10, consider a case where a light beam 200 such as a laser beam is incident from the outside somewhere on the light incident surface of the reflector array 10 of the optical wireless power feeding device from a substantially vertical direction. The incident light beam 200 is reflected by each reflector 11 of the reflector array 10 and then enters the inside of the asymmetric planar optical waveguide 20. The light that has entered the inside of the asymmetric planar optical waveguide 20 is repeatedly totally reflected at the interface between the bottom surface of the asymmetric planar optical waveguide 20 and the asymmetric planar optical waveguide 20 and the air layer, and the asymmetric planar optical waveguide 20 has a tapered shape. Since the cross-sectional area gradually increases toward the power generation unit 30, the inside of the asymmetric planar optical waveguide 20 is guided in the direction of the arrow, and the light is emitted from the light emitting end surface of the asymmetric planar optical waveguide 20. The light is incident on the end face of the semiconductor layer 40 of the power generation unit 30 to generate power (photoelectric conversion). Electron-hole pairs are generated in the semiconductor layer 40 in the process of the waveguide light traveling in the semiconductor layer 40. Then, the electrons and holes thus generated move in the semiconductor layer 40 by drift or diffusion, and are collected on one and the other of the first electrode 50 and the second electrode 60. In this way, photoelectric conversion is performed in the semiconductor layer 40, and a current (photocurrent) is taken out from the first electrode 50 and the second electrode 60.

[Verification experiment of optical wireless power supply device]
A computer simulation was used to verify the performance of the optical wireless power supply device. FIG. 11 shows the results of a computer simulation of a light wave tracking experiment performed assuming a two-layer structure of an asymmetric planar optical waveguide 20 and a reflector array 10. This structure does not have spatial inversion symmetry (that is, the scenery seen by light when propagating in the asymmetric planar optical waveguide 20 is the same when the time is reversed and when it is rotating forward. By setting the surface reflectance of the semiconductor layer 40 of the photoelectric conversion element provided at the end of the asymmetric planar optical waveguide 20 to several percent or less, it is possible to suppress the generation of time-reversal equivalent waves. That is, it is possible to prevent the light once converted into waveguide light in the asymmetric planar optical waveguide 20 from being converted into three-dimensional space (free space) propagating light again. The thickness direction of these asymmetric planar optical waveguides 20 and the reflector array 10 is the z-axis, and the direction parallel to these asymmetric planar optical waveguides 20 and the reflector array 10 is the x-axis, and these x-axis and z-axis. The vertical direction was defined as the y-axis. Hereinafter, directional light, that is, beam light when the light beam is narrowed down to a diameter of several mm or less, and diluted light when the light beam is controlled to 10 mm or more (directivity but narrow). It is defined as light that spreads spatially at a constant density rather than in the form of a beam). FIG. 11 shows the distribution of the magnitude (intensity) of _{the amplitude E y in} the y-axis direction of the electric field of the light wave in the xz plane. The conditions of the simulation are as follows. The inclination angle of the slope with respect to the bottom surface of the asymmetric planar optical waveguide 20 was 7 °. The refractive index of the asymmetric planar optical waveguide 20 was set to n = 1.585. The material of the reflector 11 made of a parabolic mirror constituting the reflector array 10 was Ag, and the refractive index of the transparent layer 12 was n = 1.35. It was set that light was incident on the reflector array 10 from the negative direction of the z-axis. From FIG. 11, incident light is reflected by the reflector 11 of the reflector array 10 in the optical path as shown in FIG. 9, enters the inside of the asymmetric planar optical waveguide 20, and efficiently enters the asymmetric planar waveguide 20 without leaking to the outside. It can be clearly seen that the inside of the optical waveguide 20 is guided in the x-axis direction. FIG. 12 shows the results of a simulation performed to verify the location dependence of the waveguide state when the beam light incident from the outside enters the coupling system of the reflector array 10 and the asymmetric planar optical waveguide 20. It is a schematic diagram. In FIG. 12, the reflector of the reflector array 10 is described as a parabolic mirror, and the asymmetric plane optical waveguide 20 is described as a tapered waveguide (the same applies to FIG. 13). FIG. 13 shows a similar result when the light incident from the outside is diluted light. It was shown that diluted light is more efficient in converting spatially propagating light to intrawaveduct propagating light. This information is useful for optimizing the spatial distribution of light during power beaming. Diluted light can reduce the spatial energy density compared to beam light, so in the unlikely event that a person or object accidentally invades the beaming path, the damage can be minimized. The significance of the present invention is further enhanced. FIG. 14 shows a waveguide from three-dimensional (3D) space propagating light when light (beam light and diluted light) incident from the outside enters the coupling system of the reflector array 10 and the asymmetric planar optical waveguide 20. It shows the light incident position dependence of the efficiency of conversion to inner two-dimensional space (2D) propagating light. In FIG. 14, the origin of the horizontal axis is the asymmetric plane optical waveguide 20 (tapered waveguide) in FIG. 11 (in this calculation, the refractive index of the waveguide portion is 1.58 and the refractive index of the portion where the parabola is embedded is 1.35. It is the tip (with a corresponding taper angle of 7 °), and the opposite end is 100 μm from it. Since the state of waveguide is a function of only the angle, the results of FIGS. 12 and 13 show that the spread size of the asymmetric planar optical waveguide 20 can be standardized by the taper thickness of the waveguide. The results shown are obtained (by utilizing such a scaling law, the waveguide structure can be designed according to the required size). Also in FIG. 14, the tip of the asymmetric planar optical waveguide 20 is at the lateral (lateral) position X = 0, and the other end of the asymmetric planar optical waveguide 20 is X = 11 (that is, the thickness of the asymmetric planar optical waveguide 20 is 11). It exists at twice the distance). It can be seen that the efficiency of converting the three-dimensional space-propagating light to the light propagating in the waveguide is almost constant regardless of the landing point of the light. Assuming that the taper thickness of the asymmetric planar optical waveguide 20 is about 10 mm, the size of the light receiving portion of the coupling system between the reflector array 10 (concentric periodic array parabolic mirror) shown in FIG. 4 and the asymmetric planar optical waveguide 20 is 10 cm. It can be set to about the corner. This is because in the prior art shown in Non-Patent Documents 1 and 2, the output is reduced from a fraction to a few tenths caused by the beam landing point swaying by about several centimeters. (Since the location dependence can be made very small as shown in FIG. 14), it is shown that it can be suppressed almost completely. The location independence is more pronounced for beam light, but fairly good results are also obtained for diluted light. In this optical wireless power feeding device, for example, a commercially available photoelectric conversion element (MH GoPower element “5S1010.4”) is attached to the light emitting end surface of the asymmetric planar optical waveguide 20 (the element is 10 mm × 10 mm). It has a size and thickness of 400 μm, and has an efficiency of 40.5% at an incident light power of 1463.3 mW with respect to a laser beam having a wavelength of 915 nm (see Non-Patent Document 3), and at this relatively high efficiency (beam light). This means that stable optical wireless power supply can be performed (regardless of the landing location) even if the wobbling of the landing point extends over several centimeters.

As shown in the insertion view at the lower right of FIG. 15, the reflector array shown in FIG. 3 was prototyped. The lower left insertion view of FIG. 15 is a perspective view of the reflector array shown in FIG. From FIG. 15, it can be seen that the focus is set to Z = 6 mm as set. The focal line width is about 0.8 ± 0.1 mm in the observed value, and considering that the thickness of the screen that received the light is about 0.16 mm and that it is obliquely incident, it is an effective focal line. The width is estimated to be about 0.6 mm. By arranging the focal point so as to come inside the asymmetric surface optical waveguide 20 provided under the reflector array, the light is completely reflected and efficiently guided to the waveguide end as shown in FIG. ..

As shown in FIG. 16, the reflector array shown in FIG. 4 was prototyped. The trial production was performed using a 3D printer. In this reflector array, when the beam light is incident as shown by the broken arrow in FIG. 16, it converges toward the center of the end face on the light emitting side of the reflector array as shown by the solid arrow in FIG. Waveguided to. Therefore, sufficient photoelectric conversion can be performed by coupling the minute solar cell 300 to the center of the end face on the light emitting side of the reflector array.

FIG. 17 shows the result of evaluating the focusing performance of the reflector array having the rotational symmetry (that is, the symmetry in the φ direction in the cylindrical coordinate system) shown in FIG. 4 toward the center of the end face on the light emitting side of the reflector array. Is shown. In FIG. 17, Concentric PPM means a concentric periodic parabolic mirror, and Parallel PPM means a periodic parabolic mirror having translational symmetry. As shown in FIG. 17, a line width at a focal point almost the same as that of the data of the retroreflector array having translational symmetry shown in FIG. 14 is observed, and the reflector array composed of concentric periodic parabolic mirrors also has good optical characteristics. It was demonstrated to have.

FIG. 18 shows a method of making the reflector 11 invisible when viewed from the incident side of the beam light with respect to the reflector array 10 by designing the reflector 11 of the reflector array 10. That is, the light incident on the right end of the right reflecting mirror 11 facing the two adjacent reflecting mirrors 11 is reflected by the reflecting mirror 11 and exists underneath the root of the left adjacent reflecting mirror 11. It is incident on the asymmetric planar optical waveguide 20. On the other hand, the light incident on the left end of the right reflecting mirror 11 facing the two adjacent reflecting mirrors 11 is reflected by the portion and is directly incident on the asymmetric plane optical waveguide 20. In this way, all of the light coming from above is incident on the asymmetric planar optical waveguide 20 without being scattered by the reflector array 10 made of a periodic parabolic mirror. 19A and 19B show the light intensity distribution on the end face of the reflector array 10 and the light intensity distribution on the light emitting end face of the asymmetric planar optical waveguide 20 when the beam light is incident on the reflector array 10, respectively. FIG. 19A shows the case where the refractive index matching is not performed (refractive index n = 1.58 of the asymmetric planar optical waveguide 20 and the refractive index n = 1 of the transparent layer 12), and FIG. 19B shows the case where matching is performed (asymmetric planar light). The refractive index n of the waveguide 20 is 1.58, the refractive index of the transparent layer 12 is n = 1.35), and the refractive index matching that matches the setting of the simulation of FIG. 11 is established, and the light is an asymmetric surface as calculated. Experiments have demonstrated that the light is confined in the optical waveguide 20 and is waveguideed.

The power generation performance of this optical wireless power supply device was compared with the power generation performance of a general Si solar cell alone. FIG. 20 shows the voltage-current characteristics of the Si solar cell measured in the state of 1 Sun. It was found that the photoelectric conversion efficiency was a dozen percent. On the other hand, in the condensing optical system shown in FIG. 16 in which the reflector array 10 composed of the periodic array parabolic mirror shown in FIG. 16 and the asymmetric planar optical waveguide 20 are combined, the light emitting end surface of the asymmetric planar optical waveguide 20 FIG. 21 shows the results of characteristic evaluation of the same Si solar cell in a direct incident arrangement on the optical surface. Since the light receiving area of the reflector array 10 composed of the periodic parabolic mirror is larger than the area of the light emitting end face of the asymmetric planar optical waveguide 20, this system constitutes a condensing optical system. Compared to the characteristics of FIG. 20, the characteristics of FIG. 21 show a value of about four times the amount of power generated even though the same Si solar cell is used. In the solar cell 300 shown in FIG. 16, all the light incident on the region where the reflector 11 made of a parabolic mirror exists (rectangular region in FIG. 16) is collected as shown by the broken line and the solid line in FIG. Therefore, even if the light beam such as a laser beam that has propagated over a long distance fluctuates in the middle of a medium such as air or water, even if the arrival point varies, as long as it enters the rectangular area of FIG. 16, a reflector composed of the periodic parabolic mirror. It is guided to the solar cell 300 by the action of the array 10 and the asymmetrical optical waveguide 20 (in this case, having a structure obtained by cutting out a flat cone) coupled thereto. That is, the influence of the fluctuation of the landing point of the light beam is almost eliminated.

According to this first embodiment, since one main surface of the reflector array 10 is the light incident surface, there is fluctuation in the location of a moving body such as a drone that receives optical radio power supply and stays in the air. However, the light beam 200 used for optical wireless power feeding can be reliably incident on the light incident surface, and after the light beam 200 is reflected by the reflector 11 of the reflector array 10 and incident on the asymmetric planar optical waveguide 20. The inside of the asymmetric planar optical waveguide 20 can be made to waveguide toward the power generation unit 30, and finally the waveguide light can be incident on the power generation unit 30 to generate power (photoelectric conversion). Therefore, it is possible to stably and efficiently supply electric power to various moving objects such as drones staying in the air, underwater (especially under the sea), on the ground, in outer space, on the moon, etc. by optical wireless power supply by the optical beam 200. it can. In particular, as a direct result of this "stable supply of light to the photoelectric conversion element of the power generation unit", the intensity of the power transmission light [now changes only constantly or slowly due to the stability of the power transmission light [. It is possible to superimpose a high frequency component on this low vibration component], and it is possible to send not only power but also communication / control information to the unmanned machine / drive body, etc. at the same time by the power transmission light itself. This is another great advantage of this optical wireless power supply device. Furthermore, since this optical wireless power feeding device basically forms a reflection optical system, it has a small wavelength dependence and also collects light in another band, particularly light (electromagnetic wave) in a wavelength band for communication. Since it can be delivered to the power generation unit 30 (semiconductor element) composed of the photoelectric conversion element installed at the end of the asymmetric planar optical waveguide 20, the robustness of information communication with the moving body also uses the reflector array 10 as an antenna. It can be realized at the same time by the waveguide system of this optical wireless power feeding device. That is, when a signal processing element made of a semiconductor having a relatively small bandgap is placed behind the power beaming light receiving element installed at the end of the asymmetric planar optical waveguide 20, in other words, the power generation unit 30, the semiconductor has The corresponding long wavelength light can pass through the semiconductor on the front surface and reach the rear surface. In this way, the asymmetrical planar optical waveguide 20 of this optical wireless power feeding device, which changes the traveling direction of light and has good waveguide characteristics, shares this one while performing power beaming on the front side and a signal on the rear side. Processing can be performed collectively at the same time.

<Second Embodiment>
[Optical wireless power supply device]
In the optical wireless power feeding device according to the second embodiment, unlike the optical wireless power feeding device according to the first embodiment, instead of the wedge-shaped asymmetric planar optical waveguide 20, the flat plate-shaped asymmetric planar optical waveguide 20 as a whole is used. Is used. FIG. 22 shows a portion of the optical wireless power feeding device according to the second embodiment, particularly the reflector array 10 and the asymmetric planar optical waveguide 20 (see Patent Document 2). The power generation unit 30 is the same as the optical wireless power feeding device according to the first embodiment. As shown in FIG. 22, in this case, the reflector array 10 and the asymmetric plane optical waveguide 20 are flattened by the clad layer 311 and a plurality of clad layers 312 periodically arranged at intervals δ in the waveguide direction. It is formed by a structure in which the upper and lower sides of the waveguide core layer 313 are sandwiched. The clad layer 311 continuously covers one main surface (upper surface) of the waveguide core layer 313, and the clad layer 312 discontinuously covers the other main surface (lower surface) of the waveguide core layer 313. The clad layer 311 and the clad layer 312 together form a clad layer that discontinuously covers the waveguide core layer 313. That is, this clad layer has an end portion of a disconnection portion that does not cover the waveguide core layer 313 (for example, indicated by E in FIG. 22) and a waveguide direction of the waveguide core layer 313 with respect to this disconnection portion. The waveguide core layer 313 extends in the direction opposite to the waveguide and away from the waveguide core layer 313 (for example, indicated by P in FIG. 22) and toward the waveguide direction of the waveguide core layer 313. It has a structure in which the tangent line at the end of the disconnection portion is provided so as to be parallel to or substantially parallel to the waveguide core layer 313 as described later. Both side surfaces of the waveguide core layer 313 may be covered with an extension portion of the clad layer 311 or may be formed by a reflective surface. The details of the coupling portion between the clad layer 312 and the waveguide core layer 313 are shown in FIG. In FIG. 23, the clad layer 312 is represented by clad layers 312-a, 312-b, 312-c, and 312-d. A light introduction core layer 314 is provided between each clad layer 312 and the adjacent clad layer 312. In FIG. 23, the light introduction core layer 314 is shown by the light introduction core layers 314-a, 314-b, 314-c, and 314-d. The clad layer 312 and the light introduction core layer 314 extend by a predetermined distance in the vertical direction (depth direction) of FIG. The clad layer 312 has a shape that is concavely curved in the waveguide direction of the waveguide core layer 313, and the shape is selected as necessary. In FIG. 22, the clad layer 12 has a quarter circle as an example. Cases with a shape are shown. The tangent at the end of the cladding layer 312 on the waveguide core layer 313 side coincides with the plane of the waveguide core layer 313 and therefore coincides with the waveguide direction within the waveguide core layer 313. In other words, the end of the cladding layer 312 on the waveguide core layer 313 side is tangentially connected to the waveguide core layer 313. The refractive index of the clad layers 311 and 312 and the waveguide core layer 313 is clad with respect to the refractive index of the waveguide core layer 313 so that light can be confined in the waveguide core layer 311 by the clad layers 311 and 312. The refractive index of layers 311 and 312 is selected to be small. Further, the refractive index of the clad layer 312 and the light introduction core layer 314 is the clad layer 312 with respect to the refractive index of the light introduction core layer 314 so that the light can be confined in the light introduction core layer 314 by the clad layer 312. The refractive index of light is selected to be small. The refractive index of the waveguide core layer 313 and the refractive index of the light introduction core layer 314 are preferably selected equally, but are not limited thereto. In this optical wireless power feeding device, the reflector array 10 is composed of a waveguide assembly composed of a light introduction core layer 314 having a curved cross section and a clad layer 312 arranged periodically. In this case, the light incident upward from the lower surface of FIG. 22 is finally guided to the waveguide core layer 313 while repeating total reflection in the light introduction core layer 314 by the function of the clad layer 312. In this sense, it has the same function as the reflector array 10. In this way, a spatially asymmetric waveguide having a function of connecting the light receiving unit and the power generation unit and changing the traveling direction of light is formed.

The clad layer 312 having the curved cross-sectional shape is a light incident surface and has a vertical tangent line. Various shapes are allowed as long as the curved cross-sectional shape is tangentially in contact with the waveguide core layer 313, but in particular, a vertically long ellipse and a horizontally long ellipse are guided in the vicinity of the waveguide core layer 313 (preferably from the light incident surface). A structure connected at a position close to the waveguide layer 313 enables highly efficient light propagation. At the end opposite to the light incident surface of this curved cross section, the clad layer 312 is cut off, where it has a horizontal tangent. Since the clad layer 312 is periodically arranged in the lateral direction with an interval δ, the waveguide core layer 313 (the portion having a large refractive index) is formed at the upper end of the quarter circle, as shown in FIG. It is characterized by having a geometrically open structure without being completely closed by the clad layer 312. As a result, when the x-axis is taken in the waveguide direction as shown in FIG. 23 (the z-axis is taken in the thickness direction of the waveguide core layer 313 and the y-axis is taken in the direction perpendicular to the paper surface of FIG. 23), the clad layer is taken. When the point where 312 is discontinuous is _{described as x = x i} , when x <x _i , in the vicinity of the waveguide core layer 313 and its lower portion, as shown in FIG. 23, along the waveguide direction (as a cross-sectional shape). ) There are four clad layers 312, that is, clad layers 312-a, 312-b, 312-c and 312-d. _{That is, in the region (x ≧ x i} ) after the point where the clad layer 312-a shown in FIG. 23 is cut off, the director is guided from the outside world other than the starting point (in FIG. 23, from the lower left side through the light introduction core layer 314-a). Light can penetrate the waveguide core layer 313. At a point shifted to the right by δ (2δ) from x = x _{i , that is, at x = x i} + δ (x = x _i + 2δ), the optical introduction core layer 314-b (optical introduction core layer 314-c) (tributary). ) Joins the waveguide core layer 313 (mainstream). The tangents of the clad layers 312-a, 312-b, and 312-c at the right end (discontinuity) are parallel or substantially parallel to the waveguide light traveling direction. That is, a tangier connection is formed to the waveguide core layer 313 at the end of the clad layers 312-a, 312-b, and 312-c. In this way, the waveguide core layer 313 is provided with continuous translational symmetry along the traveling method, and the cladding layer 312 is provided with discrete translational symmetry having a period δ. As a result, the waveguide core layer 313 has a quasi-open structure. The clad layer 312-a, which is _{in close contact with the waveguide core layer 313 at x i −} δ <x <x _{i , has a discontinuous structure at the terminal portion x = x i} , but is smoother and substantially parallel from below. Another clad layer 312b, which is one layer below the waveguide core layer 313, covers the disconnection of the closest clad layer and becomes the closest clad layer by itself, so that the inside of the waveguide core layer 313 is formed. Light is efficiently guided to the right as it is directed, without loss. Further, at this time, each discontinuous clad layer 312 is geometrically parallel or substantially parallel to the upper clad layer 311 at the upper end portion thereof. Since the waveguide direction is parallel to the clad layer 311 (because it is of course horizontal), the discontinuous clad layer 312 is described above with respect to the waveguide core layer 313 at its rearmost end along the waveguide direction. It has a structure that merges with the tangential. According to the Huygens principle, the light guided through the waveguide core layer 313 as a microspherical wave tries to spread from the point where the closest clad layer 312a is terminated at x = x _{i, but the above tangentiality} It is totally reflected by the cladding layer 312-b, which is one step lower than the layer that approaches from the bottom. The above-mentioned "parallel or nearly parallel" is defined as being parallel to the extent that total reflection can occur by the above process. Due to this parallelism, the light in the waveguide core layer 313 is not dissipated as described above, and is guided almost 100% efficiently. At x = x _i + δ, exactly the same thing occurs for the clad layer 312b and the clad layer 312-c.

According to this second embodiment, the same advantages as those of the first embodiment can be obtained without using the wedge-shaped asymmetric plane optical waveguide 20.

<Third embodiment>
[Optical wireless power supply drone]
FIG. 24 shows an optical wireless power supply drone according to the third embodiment. As shown in FIG. 24, in this optical wireless power supply drone, the optical wireless power supply device 500 according to the first or second embodiment is installed on the outer surface of the main body of the drone 400. The output terminal of the optical wireless power supply device 500 is connected to the input terminal of the power supply of the main body of the drone 400. At the time of power supply, the optical beam 200 is irradiated to the optical wireless power feeding device 500 from the outside.

According to the third embodiment, even if the location fluctuates while the drone 400 stays in the air, the light beam 200 used for the optical wireless power feeding device is surely incident on the light incident surface of the optical wireless power feeding device 500. Therefore, the optical wireless power feeding device 500 can stably and efficiently supply power to the drone 400.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible. In particular, the greatest feature of the present invention is the separation of the light receiving unit and the power generation unit, but the incident of light spread by this (diluted light and sunlight as the ultimate example thereof) is concerned. It has a function of surface integral of incident light (condensing property, antenna function), or has spatial beam fluctuation resistance (robustness against beam wobbling) for the beam-shaped light of the opposite electrode. In that it is possible, the range of applications can be greatly expanded. Further, regarding the conversion of the light beam incident from the oblique direction in the direction perpendicular to the light receiving surface, the parabola cross section is already shown by the same inventor as the present invention in Patent Documents 1 and 2. It is effective to use a structure having a structure or a light wave traveling direction changing layer covered with paraboloids. As a further merit, as a result of the separation of the light receiving part and the power generation part, even if the light receiving part itself is placed in a harsh environment, the light itself is charged neutral and the power generation part is in a relatively non-harsh environment. Due to the synergistic effect of being placed in, it is easy to obtain extremely good long-term reliability (on the contrary, the conventional photoelectric conversion element / solar cell basically generates electricity as it is at the point where it receives light. Therefore, due to its outdoor installation property, there is always a risk of short circuit in the long term due to precipitation, especially acid rain. It is easy to be dragged by factors that are not directly related to photoelectric conversion performance such as weather resistant passion. In contrast, it leads to higher costs). In addition, the above-mentioned harsh environment includes an environment with large radiation damage in outer space, underwater (especially saltwater environment in the sea), an external environment (compared to an in-vehicle environment) in an electric vehicle, and an indoor environment (indoor environment) in the polar region. Needless to say, it also includes outdoor environments (which have a larger temperature history amplitude than the above).

Further, the numerical values, materials, shapes, arrangements, etc. given in the above-described embodiment are merely examples, and different numerical values, materials, shapes, arrangements, etc. may be used as necessary.

10 ... Reflector array, 11 ... Reflector, 12 ... Transparent layer, 20 ... Asymmetric planar optical waveguide, 30 ... Power generation unit, 40 ... Semiconductor layer, 50 ... First electrode, 60 ... Second electrode, 200 ... Optical beam, 400 ... Drone, 500 ... Optical wireless power supply device

Claims (15)

Light receiving part and
A power generation unit composed of a photoelectric conversion element spatially separated from the light receiving unit,
It has a spatially asymmetric waveguide that connects the light receiving unit and the power generation unit and has a function of converting the traveling direction of light.
The power generation unit is an optical wireless power feeding device provided at an end of the waveguide on the light emitting side. The optical wireless power feeding device according to claim 1, wherein the reflectance of the surface of the photoelectric conversion element constituting the power generation unit facing the end of the waveguide on the light emitting side is 5% or less. A flat-plate reflector array in which a plurality of reflectors are periodically arranged in one direction via a transparent layer, one main surface constitutes a light incident surface and the other main surface constitutes a light emitting surface.
The incident light is waveguideed in one direction by being provided on the other main surface of the reflector array and incident on the one main surface of the reflector array from the outside and reflected by the reflector. With an asymmetric specular optical waveguide configured as
A power generation unit composed of a photoelectric conversion element provided at the end of the asymmetric surface optical waveguide on the light emitting side,
Optical wireless power supply device having. The optical wireless power feeding device according to claim 3, wherein the asymmetric planar optical waveguide has a wedge-shaped shape in which the cross-sectional area gradually increases toward the end surface on the light emitting side. The optical wireless power feeding device according to claim 3 or 4, wherein the cross section of the reflector has a parabolic shape having an apex on the side of the other main surface. The optical wireless power feeding device according to claim 5, wherein the axis of the parabola is substantially perpendicular to the other main surface. 3. The geometric intersection of the reflector and the asymmetric planar optical waveguide has a linear or concentric arcuate shape centered on one point on the end face of the asymmetrical planar optical waveguide on the light emitting side. The optical wireless power feeding device according to any one of items to 6. The light according to claim 9, wherein a light wave traveling direction conversion layer is further provided on one of the main surfaces of the reflector array, and the axis of the parabola is parallel to the direction after the traveling direction conversion by the light wave traveling direction conversion layer. Wireless power supply. The optical wireless power feeding device according to any one of claims 3 to 8, wherein the power generation unit has a semiconductor layer for photoelectric conversion. The optical wireless power feeding device according to claim 9, wherein a first electrode and a second electrode are provided on the first surface and the second surface of the semiconductor layer facing each other, respectively. The optical wireless power feeding device according to claim 10, wherein the semiconductor layer is a pn junction composed of a p-type semiconductor layer and an n-type semiconductor layer. The optical wireless power feeding device according to claim 11, wherein the band gap or HOMO-LUMO gap of the semiconductor layer is configured to decrease stepwise and / or continuously in the traveling direction of light. The semiconductor layer is composed of a plurality of regions in which the band gap or the HOMO-LUMO gap gradually decreases in the traveling direction of light, and at least one of the first electrode and the second electrode is between the regions. The optical wireless power feeding device according to claim 12, wherein the optical wireless power feeding devices are provided separately from each other. With a mobile body
It has an optical wireless power feeding device that is integrally provided with the moving body and supplies power to the moving body.
The above optical wireless power supply device
A flat-plate reflector array in which a plurality of reflectors are periodically arranged in one direction via a transparent layer, one main surface constitutes a light incident surface and the other main surface constitutes a light emitting surface.
The incident light is waveguideed in one direction by being provided on the other main surface of the reflector array and incident on the one main surface of the reflector array from the outside and reflected by the reflector. With an asymmetric specular optical waveguide configured as
A power generation unit composed of a photoelectric conversion element provided at the end of the asymmetric surface optical waveguide on the light emitting side,
Optical wireless power supply mobile body having. The optical wireless power supply moving body according to claim 14, wherein the moving body is a small unmanned aerial vehicle, an unmanned aerial vehicle, an aircraft, an artificial satellite, an unmanned ship, a ship, an underwater moving body, an unmanned automobile or an automobile.