Patent ID: 7824761

Claim:
A metal structure showing plasmon resonance absorption, comprising: a substrate and a plurality of rod-shaped metallic fine particles on a nanometer scale arranged directly on a surface of the substrate at a constant interval in a fixed direction, the substrate surface being made of transparent insulating material, wherein: variability in a major axis length or minor axis length of the plurality of rod-shaped metallic fine particles is 5 percent or less; when each of the plurality of rod-shaped metallic fine particles is viewed from a top surface perpendicular to the substrate, an aspect ratio specified by a ratio of a major axis and a minor axis of the rod-shaped metallic fine particles is in the range of 3 to 10; two absorption maxima of plasmon resonance absorption spectra corresponding to two polarization directions for incident light having the two polarization directions mutually orthogonal on a plane perpendicular to the incident light are caused; a difference between the two absorption maxima of plasmon resonance absorption spectra is in the range of 50 nm to 1000 nm; and each of the two absorption maxima of plasmon resonance absorption spectra are variable within the range of 500 nm to 1500 nm.