Geometrical optics method for polarization correction of Luneburg lens with chiral medium

A geometric optics method for polarization correction of inhomogeneous lens antennas is applied to the Luneburg lens. The geometric optics method is based on the normalized wave fields, which are certain complex combinations of the electric and magnetic fields. To achieve the polarization rotation effect, the chirality is assumed to be small; otherwise, the chirality has an effect on the refractive index. The chirality causes a phase shift of two eigenrays, resulting in change of polarization of the combined geometric optics field. The rays in the inhomogeneous lens experience polarization rotation owing to the curvature of the rays. With a suitable distribution of chiral material along the ray, the polarization rotation due to the curvature may be eliminated. An analytic expression for the chirality distribution function is derived for the Luneburg lens antenna.<>