Tuned switching of surface waves by a liquid crystal cap layer in one-dimensional photonic crystals

In this paper, we theoretically study the electromagnetic surface waves localized at the interface between a homogeneous dielectric medium and a semi-infinite, one-dimensional photonic crystal (1D PC). The semi-infinite 1D PC is made of alternative layers of right-handed (RH) and dispersive left-handed (LH) materials in the presence of a liquid crystal (LC) cap layer. In this structure, we derive the surface waves dispersion relation with tunable switching and localization by using an analytical direct matching procedure within the Kronig-Penny model. It is shown that, for both of layer arrangements, the variation of molecules orientation of the LC cap layer acts as an effective tool to tune the type (tuned switching) and localization of the surface waves and it also can create a surface mode with maximum localization in the first frequency bandgap.