Division-of-wave-front thin-film beam splitter for generating binary patterns of orthogonal elliptical polarization states

Abstract

A division-of-wave-front thin-film beam splitter is described that reflects monochromatic light at oblique incidence with orthogonal elliptical polarization states. It consists of a metallic substrate partially covered with a transparent thin film that inverts the ratio ρ of the complex p and s reflection coefficients at the principal angle of the metal. Any pattern of coated and uncoated areas of the substrate is imprinted upon the reflected wave front as a corresponding two-dimensional spatial binary polarization pattern. A specific design is given that uses a Au substrate at a wavelength of 632.8 nm. The effects of small errors in the film refractive index, the film thickness, and the angle of incidence are discussed. It is noted that a layer that inverts ρ at a certain (especially high) angle of incidence is an effective ρ-inverting layer at all angles.