Scattering and absorption of electromagnetic radiation by a semi-infinite medium in the presence of surface roughness

Abstract

In this paper, we present a theoretical description of the scattering and absorption of electromagnetic radiation induced by roughness on the surface of a semi-infinite medium. We approach the problem by the use of scattering theory applied to the classical Maxwell equations. We obtain formulas for the roughness-induced scattering from the surface of an isotropic dielectric for both $s$- and $p$-polarized waves incident on the surface at a general angle of incidence. When the real part of the dielectric constant of the material is negative and its imaginary part small (as in a simple nearly-free-electron metal), we extract from the expressions for the total absorption rate that portion which describes roughness-induced absorption by surface polaritons (surface plasmons). We compare our results with those recently published by Ritchie and collaborators for the case of normal incidence, and we present a series of numerical studies of the roughness-induced scattering and absorption rates in aluminum.