Full Poincaré sphere coverage with plasmonic nanoslit metamaterials at Fano resonance

Abstract

A form-birefringent plasmonic metamaterial of the subwavelength thickness is used to convert the light's polarization state in a way to cover the whole Poincar\'e sphere's surface by adjusting the experimental configuration. This optical anisotropy is induced by grating surface plasmon polaritons of a nanoslit array made in a thin golden film with the narrow spectral Fano resonance. Phase delay between linearly polarized states introduced by the sample reaches the value of $0.85\ensuremath{\pi}$ in the visible corresponding to the effective ordinary-extraordinary refractive index difference of $\ensuremath{\Delta}n\ensuremath{\simeq}10.4$.