Extraordinary optical transmission through a conducting film with a nanometric inhomogeneity in the evanescent wave region

Abstract

In this paper, using mathematical simulation, we establish that extraordinary light transmission arises not only in a hole but also in other inhomogeneities present in metallic films. It is shown that this effect is most pronounced at those wavelengths for which the scattering cross section in the spectral domain is maximal. Moreover, the effect depends considerably on the material of the film. The mechanism of this phenomenon is established using simulation results. Consider a mathematical model of an inhomogeneity in a metallic film deposited on a glass prism. Suppose that the entire space is divided into three parts: air (domain D 0 ), the film ( D f ), and the glass prism ( D 1 ). Let the film and the air be separated by the plane Ξ 0 ; and the prism and the film, by the plane Ξ 1 . A local cylindrical inhomogeneity occupying the domain D i with a smooth boundary ∂ D i lies entirely inside the metallic film of thickness d . Assume that the symmetry axis of the inhomogeneity is aligned with the outward normal to Ξ 1 . We introduce a rectangular coordinate system such that its origin lies in Ξ 1 ( z = 0) and the Oz axis is directed along the inhomogeneity’s axis of symmetry. As an external excitation, we use a linearly polar