Reflective thin-film device for generating spatial binary patterns of orthogonal circular polarization states

A novel device is described that generates, by reflection, polarized optical wavefronts of juxtaposed fields of alternating orthogonal circular polarization states. It consists of a dielectric substrate coated by a transparent thin film of certain refractive index and of thickness that alternates between two discrete values over adjacent areas of the substrate, in a pattern that corresponds to the desired binary polarization pattern of the reflected wave. Devices that use Ge and Si substrates at wavelengths of 10.6 and 0.6328 μm, respectively, are presented as examples.