Abstract: A polarizing element includes fine metal particles formed in numerous regions that were occupied by respective substantially needle-like metal halide fine particles before reduction that are oriented and dispersed in a glass substrate such that the lengthwise directions thereof are almost the same, the fine metal particles being produced by heat-treating the glass substrate in a reducing atmosphere to reduce the substantially needle-like metal halide fine particles. The number of fine metal particles present in at least some of the numerous regions is two or more in each region, 90% or more of the regions each have a volume of 2,500 to 2,500,000 nm3, and the individual volumes of the fine metal particles present in each region are 4 to 40% of the volume of the region in 90% or more of the total number of the regions.

Abstract: Disclosed is a polarization element which, by utilizing the fact that the plasmon resonance frequency of a metal piece varies according to the polarization direction of a light irradiated on the metal piece, is constituted by a polarizer comprising such an aggregate of metal pieces that the plasmon resonance frequency in a predetermined direction of a metal piece is substantially equal to the frequency of light irradiated on a polarization element, and the real part and the imaginary part of permittivity at the plasmon resonance frequency of a metal material constituting the metal piece and the refractive index (na) of a dielectric layer satisfy a particular relation.

Abstract: Provided is a polarizing element, which is made into an assembly of metal elements by utilizing the fact that the plasmon resonance wavelengths of metal elements are different for the polarization direction of a light to irradiate the metal elements. The sum of the geometrically sectional areas of the metal elements in a plane substantially normal to the propagation direction of the irradiating light is smaller than the area of the irradiated region of the light, and the sum of the absorbing sectional areas of the metal elements in the plasmon resonance wavelengths is five times or more as large as the area of the irradiated region.