OPTICAL STRUCTURES WITH REDUCED DIFFRACTION AND METHODS OF MAKING AND USING

摘要

An optical device that includes a metal film defining an aperture through the metal film, a plurality of first concentric ridges formed around the aperture on a first side of the metal film. Each pair of adjacent first concentric ridges are spaced apart by a first period, p1, and each pair of adjacent ones of the plurality of second concentric ridges are spaced apart by a second period, p2. In at least some instances, n1p1 is within 10% of n2p2, where n1 is an index of refraction of the material adjacent the first side of the metal film and n2 is an index of refraction of the material adjacent the second side of the metal film. The optical device optionally includes a plurality of apertures. In some instances, two or more, or even all, of the apertures have a plurality of concentric ridges formed around each of those apertures. In some instances, the metal film may be used as a polarizer or wavelength filter.