Patent ID: 8130447

Claim:
A polarization element comprising: a substrate that transmits light with a predetermined wavelength; a plurality of metal pieces, each having a length and a width on a plane, coplanar with a top surface of the substrate, and a height orthogonal to the top surface, arranged upon the top surface of the substrate such that no metal piece contacts another metal piece; and a dielectric layer that contacts and coats each piece of the plurality of metal pieces, sandwiching them between the dielectric layer and the substrate, wherein: polarization characteristics of the polarization element change with a variation in plasmon resonance frequency of each piece of the plurality of metal pieces and a polarization direction of light irradiated onto each piece of the plurality of metal pieces: the plasmon resonance frequency of each piece of the plurality of metal pieces in a predetermined direction is substantially equal to a frequency of light irradiated onto the polarization element; and a real part (ε′) and an imaginary part (ε″) of a permittivity of a metal material comprises in each piece of the plurality of metal pieces at the plasmon resonance frequency, and the refractive index (n a ) of the dielectric layer have a relationship: {(ε′−n a 2 ) 2 +ε″ 2 }≧80*n a *ε″.