Optimal Design Using Stratified Bianisotropic Media: Application To Anti-Reflection Coatings

Abstract

A frequency-domain optimal design problem using a stratified bianisotropic slab is considered. An optimization approach is used to determine the constitutive parameters as functions of the position so that a certain desired reflection- and transmission-pattern are achieved. It is based on a gradient method, where the gradients are calculated explicitly. To control the spatial variation of the attained parameter profiles, parameters and gradients are expanded in a truncated set of orthogonal basis functions with support over the entire width of the slab. The design algorithm is tested numerically on a minimal reflection problem, where stratified uniaxial chiral-omega slabs coated on perfect conductors are optimized to minimize the reflected power in a certain frequency-band. Numerical results indicate that uniaxial omega media is an appropriate choice for anti-reflection coatings.