Identity of the cross-reflection coefficients for symmetric surface-relief gratings

Abstract

The zeroth-order cross-reflection coefficients of a surface-relief grating are shown to be equal from experimental evidence and numerical evidence by use of rigorous coupled-wave analysis simulations. This result is valid for any range of grating parameters as well as for anisotropic media that have the optic axis in the surface plane. This result is corroborated by effective-medium theory, which models the gratings as thin layers of uniaxial anisotropic media that have the optic axis in the surface plane. For asymmetric grating profiles the zeroth-order reflection coefficients are no longer identical. This property has potential for scatterometry applications.