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Thermal radiation light source NEW

外国特許コード F210010342
整理番号 J1017-14US-2
掲載日 2021年2月2日
出願国 アメリカ合衆国
出願番号 202016998182
公報番号 20200382048
出願日 令和2年8月20日(2020.8.20)
公報発行日 令和2年12月3日(2020.12.3)
優先権データ
  • 特願2013-047281 (2013.3.8) JP
  • 201514773663 (2015.9.8) US
  • 2014JP55056 (2014.2.28) WO
発明の名称 (英語) Thermal radiation light source NEW
発明の概要(英語) The present invention provides a thermal radiation light source that allows a wider range of material choices than those of conventional techniques, so that light having a desired peak wavelength can easily be obtained. A thermal radiation light source 10 includes a thermo-optical converter made of an optical structure in which a refractive index distribution is formed in a member 11 made of an intrinsic semiconductor so as to resonate with light of a shorter wavelength than a wavelength corresponding to a bandgap of the intrinsic semiconductor. When heat is externally supplied to the thermo-optical converter, light having a spectrum in a band of shorter wavelengths than a cutoff wavelength is produced by interband absorption in the intrinsic semiconductor, and light of a resonant wavelength λr in the wavelength band, the light causing resonance in the optical structure, is selectively intensified and emitted as thermal radiation light. In the present invention, an intrinsic semiconductor that provides a wide range of material choices is used, so that a thermal radiation light source that produces narrow-band light having a desired peak wavelength can easily be obtained.
従来技術、競合技術の概要(英語) BACKGROUND ART
In general, heating an object causes thermal radiation which is a radiation of light (electromagnetic waves) having a spectrum that depends on substances constituting the object and the temperature of the object. Thermal radiation generated from an ideal object that completely absorbs light given externally is called a blackbody radiation, and the object is called a blackbody. Blackbody radiation has an intensity distribution over a wide wavelength range, and light having a wavelength spectrum whose distribution is determined only by the temperature is generated. When an ordinary object is heated, it also generates light having a wavelength spectrum distribution over a wide wavelength range; however, it is known that the wavelength spectrum of ordinary object cannot exceed that of a blackbody at a same temperature. Using such thermal radiation, light with a spectrum having an intensity distribution over a wide wavelength range is emitted. That is, a light source (thermal radiation light source) that provides a wide wavelength spectrum can be obtained by a combination of an object and a heat source.
Meanwhile, instead of light having such wide wavelength spectrum, there has also been a demand for a thermal radiation light source that emits light having a large intensity in a particular wavelength band. Demand of such light source can be found, for example, in the field of solar cells. In solar cells that are currently in practical use, only light in a particular wavelength band in a wide wavelength range of sunlight contributes to photoelectric conversion, and energy of light of other wavelengths is wasted.
Non-Patent Literatures 1 and 2 each describe a thermal radiation light source including a two-dimensional photonic crystal made of a plate member having a quantum well structure, which is formed by alternately stacking layers of AlGaAs and layers of GaAs, including a plurality of holes formed on a triangular grid in the plate member. When the plate member is heated, thermal excitation of electrons between energy levels in the quantum well causes emission of light having a plurality of wavelengths corresponding to respective differences between the energy levels, where the wavelength spectrum of the emission of light is narrower than those of common thermal radiation light sources. The two-dimensional photonic crystal can resonate with light having a predetermined wavelength determined by a periodicity of holes, and selectively intensify the light of that wavelength. The combination of the quantum well and the two-dimensional photonic crystal provides a wavelength spectrum having a narrow bandwidth around the predetermined wavelength and having a large peak intensity.
特許請求の範囲(英語) [claim1]
1. A power generation device comprising:
a thermo-optical converter having an optical structure in which a refractive index distribution is formed in a member made of an intrinsic semiconductor configured to resonate with light of a shorter wavelength than a wavelength corresponding to a bandgap of the intrinsic semiconductor; and
a solar cell configured to perform photoelectric conversion by receiving light produced by the thermo-optical converter and using the light having a wavelength band including a resonant wavelength that causes resonance in the optical structure.

[claim2]
2. The power generation device according to claim 1, wherein the optical structure has asymmetry in a direction in which thermal radiation light is emitted from the thermo-optical converter.

[claim3]
3. The power generation device according to claim 1, wherein the optical structure has such a structure that, on a surface of a base made of material having a refractive index lower than that of the intrinsic semiconductor, members made of the intrinsic semiconductor are two-dimensionally arranged.

[claim4]
4. The power generation device according to claim 1, wherein the optical structure is a two-dimensional photonic crystal structure formed by periodically providing, in a plate member made of an intrinsic semiconductor, different refractive index areas having refractive index different from the plate member, wherein the different refractive index areas have an asymmetric shape in a direction perpendicular to the plate member.

[claim5]
5. The power generation device according to claim 4, wherein the different refractive index areas are formed so as to open in a surface of the plate member and not to open in the other surface of the plate member.

[claim6]
6. The power generation device according to claim 1, wherein the optical structure is a three-dimensional photonic crystal structure having a three-dimensional periodic refractive index distribution.

[claim7]
7. The power generation device according to claim 1, wherein the intrinsic semiconductor is Si, and the resonant wavelength is 1000 nm or shorter.

[claim8]
8. The power generation device according to claim 1, wherein the intrinsic semiconductor is 3C-SiC, and the resonant wavelength is 750 nm or shorter.

[claim9]
9. The power generation device according to claim 3, wherein the base includes a plate heater having a three-layer structure including a layer including Ti, a layer including Pt and a layer including Ti in this order from a side close to the base.

[claim10]
10. A power generation method comprising:
emitting, to an outside of a thermo-optical converter having an optical structure in which a refractive index distribution is formed in a member made of an intrinsic semiconductor configured to resonate with light of a shorter wavelength than a wavelength corresponding to a bandgap of the intrinsic semiconductor, a light with a resonant wavelength that causes resonance in the optical structure by supplying heat;
receiving the light emitted from the thermo-optical converter by a solar cell; and
performing, by the solar cell, photoelectric conversion using a light having a wavelength band including the resonant wavelength.

[claim11]
11. The power generation method according to claim 10, wherein the optical structure has asymmetry in a direction in which thermal radiation light is emitted from the thermo-optical converter.

[claim12]
12. The power generation method according to claim 10, wherein the optical structure has such a structure that, on a surface of a base made of material having a refractive index lower than that of the intrinsic semiconductor, members made of the intrinsic semiconductor are two-dimensionally arranged.

[claim13]
13. The power generation method according to claim 10, wherein the optical structure is a two-dimensional photonic crystal structure formed by periodically providing, in a plate member made of an intrinsic semiconductor, different refractive index areas having refractive index different from the plate member, wherein the different refractive index areas have an asymmetric shape in a direction perpendicular to the plate member.

[claim14]
14. The power generation method according to claim 13, wherein the different refractive index areas are formed so as to open in a surface of the plate member and not to open in the other surface of the plate member.

[claim15]
15. The power generation method according to claim 10, wherein the optical structure is a three-dimensional photonic crystal structure having a three-dimensional periodic refractive index distribution.

[claim16]
16. The power generation method according to claim 10, wherein the intrinsic semiconductor is Si, and the resonant wavelength is 1000 nm or shorter.

[claim17]
17. The power generation method according to claim 10, wherein the intrinsic semiconductor is 3C-SiC, and the resonant wavelength is 750 nm or shorter.

[claim18]
18. The power generation method according to claim 12, wherein the base includes a plate heater having a three-layer structure including a layer including Ti, a layer including Pt and a layer including Ti in this order from a side close to the base.
  • 発明者/出願人(英語)
  • NODA SUSUMU
  • SHIBAHARA TATSUYA
  • DE ZOYSA MENAKA
  • ASANO TAKASHI
  • KITANO KEISUKE
  • SUZUKI KATSUYOSHI
  • INOUE TAKUYA
  • ISHIZAKI KENJI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
国際特許分類(IPC)
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