Optical power feeding system and optical power feeding method

Abstract

To provide an optical power feeding system and an optical power feeding method that are applicable even to a higher power laser beam.SOLUTION: An optical power feeding system related to one viewpoint of the present invention comprises: a laser device 1 for emitting a laser beam L with a wavelength range of 420 nm or more and 980 nm or less; a hollow-core fiber 2 for transmitting the laser beam L; and a photovoltaic element 3 for converting a light energy of the laser beam L into an electric energy. An optical power feeding method related to another viewpoint of the present invention includes the steps of: emitting the laser beam with the wavelength range of 420 nm or more and 980 nm or less; transmitting the laser beam using the hollow-core fiber; and converting the light energy of the laser beam into the electric energy using the photovoltaic element.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical power supply system and an optical power supply method. [Background technology]

[0002] 2. Description of the Related Art Various mechanical devices used in modern society are capable of operating by receiving an external supply of electricity and converting the electrical energy into mechanical energy, such as a motor.

[0003] Electricity can generally be supplied by connecting conductive conductors (electric wires) to the power devices of mechanical devices. However, the electric wires must be constantly connected to the power source and the machine body to be driven, and if the machine body moves freely, this can significantly restrict its movement.

[0004] Recently, techniques for converting optical energy into electrical energy have been studied. For example, Patent Document 1 below discloses a technique for transmitting high-power optical signals using photonic crystals. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6578017 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology described in Patent Document 1 uses a quartz core, and has the problem that it is not suitable for laser light of short wavelengths of less than 1000 nm, which is expected to have higher output, due to the problem of Rayleigh scattering loss in quartz.

[0007] In view of the above, an object of the present invention is to provide an optical power supply system and an optical power supply method that are applicable to higher-power laser light. [Means for solving the problem]

[0008] As a result of extensive research by the present inventors, they discovered that the above problems could be solved by using a hollow-core fiber and applying ingenuity thereto, which led to the completion of the present invention.

[0009] That is, an optical power supply system according to one aspect of the present invention that solves the above-mentioned problems includes a laser device that emits laser light in a wavelength range of 420 nm or more and 980 nm or less, a hollow core fiber that propagates the laser light, and a photovoltaic element that converts the optical energy of the laser light into electrical energy.

[0010] Further, in this respect, although not limited thereto, it is preferable that the beam parameter product (BPP) of the laser light is 8 mm·mrad or less.

[0011] In addition, in this respect, although not limited thereto, it is preferable that the output of the laser light is 100 W or more.

[0012] In addition, although not limited in this respect, the effective core area of ​​the hollow core fiber is 300 μm 2 More preferably, it is equal to or greater than this.

[0013] In addition, although not limited to this aspect, it is preferable that the laser device performs multi-mode oscillation.

[0014] In addition, in this aspect, although not limited thereto, the laser device and the hollow core fiber are provided in an energy supplying device, The photovoltaic element is preferably provided in an energy receiving device that is provided separately from the energy supplying device.

[0015] In addition, in this respect, although this is not a limitation, it is preferable to have a beam steering device that controls the optical axis of the laser light.

[0016] In addition, in this respect, although not limited thereto, it is preferable that the wavelength of the laser light is in the range of 420 nm or more and 540 nm or less.

[0017] In addition, in this respect, the photovoltaic element is not limited to In x Ga y N (1-x-y) (x is 0 or more, and x / y is 0.2 or less).

[0018] In addition, in this respect, although not limited thereto, it is preferable to provide an optical rotary joint between the laser device and the hollow core fiber.

[0019] Also, in this respect, although not limited thereto, it is preferable that the optical rotary joint includes a quartz prism.

[0020] In addition, in this respect, although not limited thereto, it is preferable that the effective core cross-sectional area of ​​the optical fiber output from the optical rotary joint is 1.5 times or more the effective core cross-sectional area of ​​the laser light beam input to the optical rotary joint.

[0021] In addition, an optical power supply method according to another aspect of the present invention includes the steps of emitting laser light in a wavelength range of 420 nm or more and 980 nm or less, propagating the laser light through a hollow core fiber, and converting the optical energy of the laser light into electrical energy by a photovoltaic element. Effect of the Invention

[0022] As described above, the present invention can provide an optical power supply system and an optical power supply method that can be applied to higher-power laser light. [Brief description of the drawings]

[0023] [Figure 1]1 is a diagram illustrating an outline of an optical power supply system according to an embodiment. [Diagram 2] 3 is a conceptual diagram of a cross section of a hollow optical fiber used in the optical power supply system according to the embodiment. FIG. [Diagram 3] FIG. 13 is a diagram illustrating an outline of another example of an optical power supply system according to an embodiment. [Figure 4] FIG. 13 is a diagram illustrating an outline of another example of an optical power supply system according to an embodiment. BEST MODE FOR CARRYING OUT THEINVENTION

[0024] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be embodied in many different forms, and is not limited to the specific examples described in the following embodiments and examples.

[0025] (Embodiment 1) 1 is a diagram showing an outline of an optical power supply system (hereinafter referred to as "this system") S according to this embodiment. As shown in this diagram, this system S includes a laser device 1 that emits laser light L, a hollow core fiber 2 that propagates the laser light, and a photovoltaic element 3 that converts the optical energy of the laser light L into electrical energy. The effect of this system S will become clear from the description below, but by converting the optical energy of the laser light L emitted by the laser device 1 into electrical energy by the photovoltaic element 3, it becomes possible to supply electrical energy to a power unit M of a mechanical device to which the photovoltaic element 3 is connected.

[0026] Furthermore, this system S may be used in the atmosphere on land, but it is more preferable to use it underwater. Power is normally supplied underwater using copper wires, but because copper wires are thick and heavy, the supply cable is greatly affected by the stress of tidal currents, and therefore a large power unit M is required for the machinery. However, when this system S is used, power is supplied via optical fiber, which has the advantage that the cable can be made thinner and power consumption can be significantly reduced.

[0027] In the present system S, as described above, the laser device 1 can emit laser light L, the wavelength range of which is 420 nm or more and 980 nm or less. By setting the range of the laser light L to 420 nm or more, it is possible for the light to propagate in water, and by setting the range to 980 nm or less, there is an advantage that the energy to be supplied can be increased.

[0028] The laser device 1 of the present system S is not limited as long as it can emit the above-mentioned laser light L, and a commercially available laser device can be used. It may be a solid-state laser device in which the oscillation medium is a solid, or a liquid laser device in which the oscillation medium is a liquid, and is not limited thereto.

[0029] Furthermore, in this system S, although not limited thereto, it is preferable that the output of the laser light L is 100 W or more. As an example of an underwater power unit M, even a small ROV (remotely operated submersible) constantly consumes several tens of watts of power, and a medium to large one constantly consumes several hundred watts of power, so by making the output 100 W or more, it becomes possible to apply the laser light L to the above-mentioned ROVs and the like.

[0030] In addition, although not limited thereto, it is preferable for the laser device 1 to perform multi-mode oscillation in the present system S. By performing multi-mode oscillation, the efficiency of conversion from electric power to light is increased compared to a laser device that oscillates in a single mode, which has the advantage of increasing the efficiency of the entire system.

[0031] In addition, in the present system S, although not limited thereto, when the photovoltaic element 3 is separated from the power supply device and power is supplied through water, it is preferable that the wavelength of the laser light L is in the range of 420 nm to 540 nm, which is a wavelength range with little attenuation in water. By setting it in this range, as described above, it becomes possible to supply power more efficiently underwater.

[0032] Furthermore, in this system S, although not limited thereto, the beam parameter product (BPP) of the laser light L is preferably 8 mm mrad or less, and more preferably 5 mm mrad or less. By setting it to 8 mm mrad, there is an effect that the laser light L can be efficiently input into the hollow core fiber 2 and propagated within the fiber, thereby increasing the coupling efficiency to the hollow core fiber 2, and this effect becomes more remarkable by setting it to 5 mm mrad or less.

[0033] As described above, the system S is also provided with the hollow core fiber 2 that propagates the laser light L. Here, the term "optical fiber" refers to an optical waveguide for propagating light, which is made up of a core that propagates light and a cladding surrounding the core, and by utilizing the difference in refractive index between the core and the cladding, the light can be confined within the core and guided to the tip of the optical fiber.

[0034] In addition, the present system S uses a hollow core fiber 2 as an optical fiber. Here, the term "hollow core fiber" refers to an optical fiber in which the core of the optical fiber is an air hole, and light is confined in the core by Bragg reflection and propagates. An image of the cross section is shown in FIG. 2. The present system S uses a hollow core fiber 2. Since the hollow core fiber 2 propagates in a hollow gas, it can transmit laser light L with low loss compared to a quartz core or other materials, even at wavelengths of 980 nm or less, and is therefore suitable for light propagation and power transmission at short wavelengths. In addition, when considering the transmission of laser light L underwater, it is preferable that the wavelength is in the range of 420 nm to 540 nm inclusive, taking into account its absorption. In particular, in the case of an optical fiber using a normal quartz core, it is considered that there is a large loss of 50 dB / km or more, but by using the hollow core fiber 2 in this wavelength range, it is possible to reduce the loss to 1 dB / km or less.

[0035] In the present system S, the effective core area of ​​the hollow core fiber 2 is 300 μm 2 It is preferably equal to or greater than 600 μm, and more preferably 600 μm. 2That's it. 300μm 2 By setting the wavelength to 600 μm or more, there is an advantage that the coupling efficiency between the laser and the hollow-core fiber 2 is increased. 2 By setting it as below, there is an advantage that the coupling efficiency between the laser and the optical fiber is increased and the generation of heat caused by coupling loss at the coupling point between the laser and the hollow core fiber 2 is suppressed.

[0036] The length of the hollow core fiber 2 in the present system S can be adjusted as appropriate, but the longer the distance, the more effective it is compared to other fibers, and for example, 100 m or more, preferably 200 m or more is possible. On the other hand, it is not preferable to make it too long, so the length is preferably 5000 m or less, more preferably 2000 m or less.

[0037] In the present system S, the output from the hollow core fiber 2 is preferably irradiated onto the photovoltaic element 3 via an optical system 4 such as a lens. In this case, it is also preferable to provide the optical system 4 between the laser device 1 and the hollow core fiber 2. By providing the optical system 4, the light can be appropriately converged and diffused, enabling efficient light transmission.

[0038] The system S also has a photovoltaic element 3 that converts the optical energy of the laser light L into electrical energy. Here, the "photovoltaic element" refers to an element that converts the received laser light L into electricity, and specific examples thereof include, but are not limited to, an element made of indium gallium nitride and an element having a perovskite structure.

[0039] In addition, in the present system S, although not limited thereto, the photovoltaic element 3 preferably has a band gap energy of 1.65 eV or more, more preferably 2.29 eV or more. The band gap energy is inversely proportional to the wavelength, the smaller the band gap energy is, the higher the energy is. Using a photovoltaic element 3 of 1.65 eV or more has the advantage that the photoelectric conversion efficiency is high, for example, at 980 nm or less, and using one of 2.29 eV or more has the further advantage that the photoelectric conversion efficiency is high, for example, at 540 nm or less.

[0040] In addition, the specific structure of the photovoltaic element 3 is not limited, but in order to obtain the above-mentioned band gap energy, for example, a semiconductor containing gallium and nitrogen, preferably a semiconductor containing indium, gallium, and nitrogen, specifically, In x Ga y N (1-x-y) (x is 0 or more), and in this case, the molar ratio of indium / gallium is preferably 0% or more and 20% or less (x / y is 0 or more and 0.1 or less). By using such a composition, a photovoltaic element 3 having high photoelectric conversion efficiency at 540 nm or less can be realized.

[0041] Furthermore, the light receiving efficiency can be increased by adopting a large effective area for the area of ​​the photovoltaic element 3, and it is preferable that the photovoltaic element 3 has a planar shape with an effective area of, for example, 100 mm×100 mm.

[0042] Moreover, it is preferable that the photovoltaic element 3 is connected to a battery to store the necessary power.

[0043] Furthermore, although this system S can be omitted, it is preferable to have a beam steering device 5 that controls the optical axis of the laser light L. By using the beam steering device 5, it is possible to control the optical axis of the laser light L, reliably direct the laser light L to the photovoltaic element 3, and perform highly efficient power supply. An image of this system S when the beam steering device 5 is provided is shown in Fig. 3.

[0044] Here, the "beam steering device" is not limited as long as it has the above-mentioned functions, but it is preferable that the power transmitting side has a light source 51 for adjusting the optical axis and the light receiving side has a photoelectric conversion element array 52 for position detection, and the light receiving side transmits an optical signal of position detection information to the power transmitting side to perform positioning. Here, the light source 51 for adjusting the optical axis can be coupled to the same optical fiber as the power supplying optical fiber, but an optical fiber different from the optical fiber for power supplying may be used. The optical signal of the position detection information on the light receiving side may be transmitted through the same optical fiber as the power supplying optical fiber or a different optical fiber.

[0045] In addition, in the present system S, although not limited thereto, it is preferable that the laser device 1 and the hollow core fiber 2 are provided in the energy supplying device A, and the photovoltaic element 3 is provided in the energy receiving device B provided separately from the energy supplying device A. In this way, it is possible to physically separate the energy supplying device A and the energy receiving device B, and the energy receiving device B can move freely without being restricted by electric wires or the like. In particular, when the present system S is used underwater, the energy receiving device B can move without being subjected to resistance and restrictions by the energy supplying device A by transmitting underwater, which is effective in reducing power consumption. In particular, in the case of an optical fiber cable, it is possible to form it with a smaller diameter than a general power supply cable, and by separating the energy supplying device A and the energy receiving device B, the power consumption can be further reduced.

[0046] Here, the operation of the present system S is clear from the above description, but a new optical power supply method can be provided by using the present system S. Specifically, the optical power supply method according to this embodiment (hereinafter referred to as "the present method") includes the steps of (1) emitting laser light in a wavelength range of 420 nm or more and 980 nm or less, (2) propagating the laser light through a hollow core fiber, and (3) converting the optical energy of the laser light into electrical energy by a photovoltaic element.

[0047] That is, in this method, by supplying laser light in the wavelength range of 420 nm to 980 nm, there is an effect that it can be used even underwater as described above, and particularly, by using light of 540 nm or less, highly efficient optical power supply with little attenuation is possible even underwater. In addition, in this method, by using a hollow core fiber, it is possible to reduce the loss of light in the above range. Then, by converting this light energy into electrical energy using a photovoltaic element, it is possible to return it as electric power.

[0048] Incidentally, in this system S, although not limited thereto, it is preferable to provide an optical rotary joint between the laser device 1 and the hollow core fiber 2. An image diagram of this case is shown in Fig. 4. Here, an "optical rotary joint" refers to a device that connects one or more fixed incident side optical waveguides to an equal number of rotatable output side optical waveguides via a prism, and providing this system S with an optical rotary joint has the effect of making it possible to continue connecting the optical fiber to the optical fiber wound on the drum while paying out the optical fiber from the fixed laser device 1.

[0049] In addition, in the present system S, although this is not a limitation, it is preferable that the prism constituting the optical rotary joint is made of quartz. By making the prism out of quartz, it has the effect of being able to withstand high-power laser light L of 100 W or more.

[0050] Furthermore, in this system S, it is preferable that the effective core cross-sectional area of ​​the optical fiber output from the optical rotary joint is 1.5 times or more the effective core cross-sectional area of ​​the beam of laser light L input to the optical rotary joint. Higher efficiency is achieved when the input beam is smaller than the output beam (core cross-sectional area of ​​the fiber receiving the beam). This has the effect of suppressing fluctuations in coupling loss with the output fiber that occur when the optical rotary joint rotates, thereby maintaining high coupling efficiency.

[0051] As described above, the present system S can provide an optical power supply system and an optical power supply method that can be applied to higher-power laser light L. The effects of the present system S will be specifically described below.

[0052] Previously, quartz was mainly used as the core of optical fiber to transmit high-power laser light L of 100 W or more over long distances, and for example, in communication applications, transmission at 850 nm or the like has been used mainly for short-distance communication of about 100 m, but these have mainly been for oscillation wavelengths of 1000 nm or more. A known technology is to use photonic crystal fiber to transmit light through a fiber designed with an enlarged core diameter, thereby achieving higher power transmission, but because the core is made of quartz, it is difficult to transmit wavelengths of 980 nm or less over long distances with little loss.

[0053] In recent years, high-output lasers with wavelengths of 980 nm or less have been developed, and there is a demand for long-distance transmission of light with high power at these wavelengths. In the case of quartz cores, the transmission loss due to Rayleigh scattering is large at wavelengths of 980 nm or less, making them unsuitable for long-distance power transmission.

[0054] In contrast, the present system S includes a laser device 1, a hollow core fiber 2, and a photovoltaic element 3. The laser device 1 has an output of 100 W or more at an oscillation wavelength of 980 nm or less, thereby solving the above-mentioned problems and providing an optical power supply system and an optical power supply method that can be applied to higher-output laser light L. [Industrial Applicability]

[0055] INDUSTRIAL APPLICABILITY The present invention has industrial applicability as an optical power supply system and an optical power supply method.

Claims

1. A laser device that emits laser light in a wavelength range of 420 nm to 980 nm, a hollow core fiber for propagating the laser light; a photovoltaic element that converts the optical energy of the laser light into electrical energy, An optical power supply system, wherein a beam parameter product (BPP) of the laser light is 8 mm·mrad or less.

2. 2. The optical power supply system according to claim 1, wherein the output of the laser light is 100 W or more.

3. The effective core area of ​​the hollow core fiber is 300 μm ２ 2. The optical power supply system according to claim 1 .

4. The optical power supply system according to claim 1 , wherein the laser device performs multi-mode oscillation.

5. 2. The optical power supply system according to claim 1, further comprising a beam steering device for controlling an optical axis of the laser light.

6. 2. The optical power supply system according to claim 1, wherein the wavelength of the laser light is in the range of 420 nm to 540 nm.

7. The photovoltaic element is In ｘ G ｙ N （１－ｘ－ｙ） 2. The optical power supply system according to claim 1, further comprising a semiconductor element including: (x is 0 or more, and x / y is 0.2 or less).

8. 2. The optical power supply system according to claim 1, further comprising an optical rotary joint between the laser device and the hollow-core fiber.

9. 9. The optical power supply system according to claim 8, wherein the optical rotary joint includes a quartz prism.

10. 9. The optical power supply system according to claim 8, wherein an effective core area of ​​the optical fiber on the side exiting the optical rotary joint is 1.5 times or more an effective core area of ​​the laser light beam incident on the optical rotary joint.

11. An optical power supply system as described in claim 1, wherein the hollow core fiber has a transmission loss of 1 dB / km or less.

12. The optical power supply system according to claim 1, characterized in that the optical power supply system has at least one light source that transmits an optical signal for information communication from an energy receiving device to an energy supplying device.

13. The optical power supply system as described in claim 1, characterized in that the optical power supply system has at least one optical fiber separate from the hollow core fiber for transmitting optical signals for information and communication from an energy receiving device to an energy supplying device.

14. Emitting laser light having a wavelength range of 420 nm or more and 980 nm or less; Propagating the laser light through a hollow core fiber; A method for supplying optical power comprising: converting optical energy of the laser light into electrical energy by a photovoltaic element, The optical power supply method, wherein a beam parameter product (BPP) of the laser light is 8 mm·mrad or less.

15. The optical power supply method according to claim 14, further comprising transmitting an optical signal for information communication from an energy receiving device to an energy supplying device.

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