Evanescent and propagating electromagnetic waves in Bi-isotropic layers

This paper presents a theoretical study of evanescent and propagating electromagnetic waves in bi-isotropic layers. The dispersion relation, guided mode condition, and evanescent wave coupling and tunneling in a bi-isotropic slab placed in a contrast bi-isotropic ambient medium are derived. A transfer matrix model is developed to acquire the transmission and reflection coefficients across the bi-isotropic layers. The creation of discrete guided modes and the continuous interval where the discrete guided modes are conceived are determined. Additionally, the effects of the Tellegen and chirality parameters on the width of the continuous interval are explained. The field distribution reformed by evanescent wave coupling and tunneling through the bi-isotropic slab is presented. The contrast bi-isotropic structure displays an evident high-pass frequency response that is controlled by the chirality of the slab. The behavior of the transmittance response with the material parameters and the incidence angle can facilitate the possible design of future electromagnetic and optical devices.