Electromagnetic Plane Wave Propagation through a Chiral Fresnel Zone Plate

Abstract

A methodology based on electromagnetic (EM) propagation across planar chiral slabs resulting in the computation of Fresnel coefficients (FCs), is applied to the case of a Fresnel zone plate (FZP) where the standard, clear circular zones are replaced with a magnetic, chiral material. Using appropriate amplitude transmission profiles across the zones, EM diffraction past the FZP is examined using a modified version of the Fresnel-Kirchhoff integral in near- and far-fields, and the emergence of multiple focal planes along the longitudinal axis is tracked based on both hard paraxial and also more general off-axis approximations. The resulting defocusing effects in the transverse planes at and near individual focal planes are also examined for point sources and 2D transparencies.