Forbidden Spatial Frequencies in Periodic Structures Composed of Subwavelength Nano Conducting Layers

Recently, electromagnetic slow wave propagation in Kronig-Penny photonic crystals composed of conducting interfaces constituted of extremely thin charge layers has been studied, where analytic expressions for Bloch wave numbers in terms of normalized frequency were derived, asymptotic behavior of electromagnetic slow wave propagation in these structures was investigated at different regimes, and the possibility of observing forbidden spatial frequencies was numerically demonstrated. In this manuscript, the existence and electromagnetic behavior of such waves together with the possibility of having forbidden spatial frequency are investigated by taking the finiteness of charge layer thickness into account. The asymptotic behavior of such periodic structures toward conducting interfaces, where the thin charge layer of finite thickness is modeled via a surface conductivity sigma_s, is thoroughly studied for the first time.