Patent ID: 7697799

Claim:
A light receiving device comprising: a first receiving structure having; a first concentric coupling periodic structure provided in a first surface of a conductive thin film formed on a substrate and configured to convert incident light to a surface plasmon; a first opening located at a center of the first concentric coupling periodic structure and penetrating the conductive thin film; and a first light receiving section located at an opening end of the first opening, the opening end being at a second surface opposite to the first surface; and a second receiving structure having: a second concentric coupling periodic structure provided in the first surface of the conductive thin film and configured to convert incident light to a surface plasmon, the second concentric coupling periodic structure having a period which is different from a period of the first concentric coupling periodic structure and overlapping the first concentric coupling periodic structure; a second opening located at a center of the second concentric coupling periodic structure and penetrating the conductive thin film, the second opening being located in a region in which the first and the second concentric coupling periodic structures overlap each other; and a second light receiving section located at an opening end of the second opening, the opening end being at the second surface, the second light receiving section being electrically isolated from the first light receiving section.