Electrically controlled optical bandgap in a twisted photonic liquid crystal

Abstract

We consider a one-dimensional twisted photonic liquid crystal, which consists of N nematic liquid crystal slabs in a twisted configuration alternated by N isotropic dielectric layers under the action of a dc electric field (Edc) aligned along the periodicity axis. We write and solve numerically the corresponding Euler-Lagrange equations describing the nematic layer configuration. We express Maxwell’s equations in a 4×4 matrix representation, and by using the transfer matrix formalism, we obtain the optical band structures at arbitrary incidence angles and different external electric fields. We have found that there exists a strong dependence of electric field on the transmission and reflection spectra in enhancing and extinguishing bandgaps. The analysis presented here allow us to propose an electrically shiftable universal rejection filter for incident waves of left- and right-circular polarization. It is observed that by increasing the electric field we can highly enhance the cross-polarized reflection ...