Excitation of surface plasmon polaritons along the sinusoidal boundary of a metamaterial

Abstract

We present a detailed analysis about the excitation of surface polaritons (SPs) at the sinusoidally corrugated interface between a conventional dielectric medium and a metamaterial (MM) with arbitrary values of dielectric permittivity and magnetic permeability. The strong impact of SPs on the optical response of the interface is demonstrated by numerical examples obtained with a rigorous electromagnetic code. Conditions leading to total absorption of the incident power and to near-field enhancements are explored in new SP regimes provided by the emergence of MMs. In those regimes where waves incident on the surface without corrugation suffer reactive attenuation, we find SP effects very similar to those occurring for metallic gratings, where the introduction of a weak corrugation in an otherwise highly reflecting surface can turn its reflectivity to zero. New SP effects are identified in regimes corresponding to ideally transparent MMs with a negative index of refraction. In these regimes, contrary to the case of metallic gratings, the introduction of a weak corrugation in an otherwise poorly reflecting surface produces high reflectivities in angular regions corresponding to SP excitation. Moreover, maximal absorption of incident waves and maximal intensity of the excited SP do not occur under the same conditions in these regimes. The complex propagation constants of the SPs supported by the corrugated interface are approximately obtained by fitting a phenomenological expression to our numerical results.