Giant enhancement of the controllable in-plane anisotropy of biased isotropic noncentrosymmetric materials with epsilon-negative multilayers

摘要

Giant in-plane anisotropy can be exhibited by a finitely thick periodic multilayer comprisingbilayers of an isotropic noncentrosymmetric material and a non-dissipative isotropic medium ofnegative permittivity, when a dc electric field is applied in the thickness direction. Compared to ahomogeneous layer of the noncentrosymmetric material with the same thickness as the periodicmultilayer, the latter exhibits an effective in-plane anisotropy that can be three orders larger inmagnitude. This enhancement gets more substantial at higher frequencies and is electrically controllable.The incorporation of dissipation reduces the enhancement of the effective in-plane anisotropy,which nevertheless remains significant. We expect the finitely thick periodic multilayer to beuseful as a polarization transformer or a modulator in the terahertz regime fully controllable viaexternal dc bias