Surface electromagnetic waves in 1D optically active photonic crystals

Abstract

Surface electromagnetic waves at the interface of a semi-infinite isotropic medium and aone-dimensional photonic crystal consisting of alternating optically active layers of a planar3m,4mm, or6mm symmetry class are considered. The layers differ only in the sign of the antisymmetricmagnetoelectric pseudotensor that describes the optical activity, and their rotationsymmetry axes are perpendicular to the layer boundaries. It is shown that the surfacewaves are either TE (transverse electrically) or TM (transverse magnetically) polarized andcan be excited in the photonic crystal with arbitrarily small activity of the layers. Thedispersion equations for surface TE and TM modes are obtained in closed form. The phasevelocities of the surface electromagnetic waves are numerically calculated for thecase where one of the crystal lattice parameters (crystal period, optical activityparameter, or relative layer thickness) is varied. Depending on the sign of the activityparameter, in photonic crystals with the layers of the same thickness only oneof the polarization types (either TE or TM) is allowed for the surface modes.