Photonic-crystal slab absorber and high-frequency circuit and electronic components, and transmitter, receiver and proximity wireless communication system

1. A photonic-crystal slab absorber comprising:

a two dimensional photonic crystal slab composed of semiconducting materials; and

a plurality of lattice points periodically arranged in the two dimensional photonic crystal slab, each lattice point for forming resonant-state which can capture an electromagnetic wave incident from an outside by resonating an electromagnetic wave in a band edge of a photonic band structure of the two dimensional photonic crystal slab in the plane of the two dimensional photonic crystal slab, wherein

the two dimensional photonic crystal slab is doped with impurities and can absorb the captured electromagnetic wave in the band edge resonant frequency, wherein

an amount of impurities doping level of a surface portion of the two dimensional photonic crystal slab is higher than an amount of the impurities doping level of a portion of the two dimensional photonic crystal slab other than the surface portion.

2. The photonic-crystal slab absorber according to claim 1 , wherein the lattice points for forming resonant-state comprises a vertically symmetric through-hole with respect to a principal surface of the two dimensional photonic crystal slab.

3. The photonic-crystal slab absorber according to claim 1 , wherein the lattice points for forming resonant-state comprises a vertically asymmetric non-through hole with respect to a principal surface of the two dimensional photonic crystal slab.

4. The photonic-crystal slab absorber according to claim 3 , wherein a depth of the non-through hole is formed relatively shallowly to achieve broader bandwidth for frequency characteristics of transmissivity.

5. The photonic-crystal slab absorber according to claim 4 , wherein a thickness of the two dimensional photonic crystal slab is relatively reduced to form the depth of the non-through hole to be relatively shallow.

6. The photonic-crystal slab absorber according to claim 1 , wherein adjacent two resonant points of resonant frequencies composed of a resonant frequency in an even mode and a resonant frequency in an odd mode are close to or matched with each other, in order to achieve broader bandwidth for frequency characteristics of transmissivity.

7. The photonic-crystal slab absorber according to claim 6 , wherein a lattice constant of the lattice points for forming resonant-state is kept constant, and a diameter of the lattice points for forming resonant-state is formed to be relatively large.

8. The photonic-crystal slab absorber according to claim 1 , wherein an impurities doping level to the two dimensional photonic crystal slab is set to a carrier density corresponding to a value of an imaginary part of refractive index so that absorptivity of the two dimensional photonic crystal slab becomes the maximum.

9. The photonic-crystal slab absorber according to claim 1 , wherein a lattice constant of the lattice points for forming resonant-state is equal to a wavelength of said electromagnetic wave in the medium, and scaling can be performed according to a wavelength.

10. The photonic-crystal slab absorber according to claim 1 , wherein a thickness of the two dimensional photonic crystal slab is not more than ⅕ of a wavelength of said electromagnetic wave in the medium.

11. The photonic-crystal slab absorber according to claim 1 , wherein the lattice points for forming resonant-state is arranged in any one selected from the group consisting of a square lattice, a rectangular lattice, a face-centered rectangle lattice, and a triangular lattice.

12. The photonic-crystal slab absorber according to claim 1 , comprising:

a reflecting mirror arranged at a back side surface of the two dimensional photonic crystal slab, the reflecting mirror configured to reflect an electromagnetic wave transmitted in the two dimensional photonic crystal slab, wherein

the reflected electromagnetic wave can be made incident at a back side surface of the two dimensional photonic crystal slab.

13. The photonic-crystal slab absorber according to claim 12 , wherein the reflecting mirror is formed of any one of a metallic plate, a substrate on which a metallic thin film is formed, a dielectric multilayer, or a photonic crystal.

14. The photonic-crystal slab absorber according to claim 12 , wherein the two dimensional photonic crystal slab and the reflecting mirror are arranged so as to be distanced from each other.

15. The photonic-crystal slab absorber according to claim 14 , wherein a separation distance between the two dimensional photonic crystal slab and the reflecting mirror is equal to a wavelength/4 plus or minus wavelength/8 with respect to a wavelength of the electromagnetic wave.

16. A high-frequency circuit comprising the photonic-crystal slab absorber according to claim 1 .

17. An electronic component comprising the photonic-crystal slab absorber according to claim 1 .

18. A transmitter comprising:

the photonic-crystal slab absorber according to claim 12 ; and

an antenna for transmitter disposed so as to pass through the photonic-crystal slab absorber.

19. A receiver comprising:

the photonic-crystal slab absorber according to claim 12 ; and

an antenna for receiver disposed so as to pass through the photonic-crystal slab absorber.

20. A proximity wireless communication system comprising:

the transmitter according to claim 18 ; and

the receiver according to claim 19 , wherein

the transmitter and the receiver disposed so as to be opposed with each other.