Attenuation of surface polaritons by surface roughness

Abstract

This paper presents a theoretical description of the attenuation of surface polaritons by roughness on the surface. In the presence of surface roughness, and in a frequency region where the dielectric constant is negative, the surface polariton is attenuated by two processes. It may lose energy by radiating into the vacuum, or by scattering into other surface-polariton states. Through application of a formalism developed recently to describe roughness-induced scattering and absorption of a plane electromagnetic wave incident on a surface, we obtain expressions for the contribution to the attenuation rate of the surface polariton from the two processes described above. We examine the relative importance of the two processes for surface polaritons on semiconductor surfaces, and on a nearly-free-electron metal at infrared frequencies.