Scattering of p-polarized light from Au and Ag gratings and the effect of surface polaritons

Abstract

Light (p-polarized) reflected at silver and gold gratings shows at certain angles of incidence (resonance angles) a minimum of the reflected intensity, due to the excitation of surface plasmons by coupling with the corrugation of the surface. The depth of the minimum is a sensitive function of the amplitude h of a sinusoidal profile and it can become zero which indicates the maximum excitation of surface plasmons or the maximum electro-magnetic field intensity in the surface. With increasing h the minimum displaces to higher angles and its width increases, a consequence of the influence of the corrugation of the surface on the dispersion relation. We present a theoretical description of experimental observations published in the literature. The calculations are based on the extinction theorem; it is shown that the details of the experimental results as the position of the intensity minima, its variation with the amplitude h of the sinusoidal profile, the deformation of the intensity minimum with increasing h, etc. are well reproduced. The calculations display quantitative agreement by direct comparison of observed and theoretical results.