RESONANCE EFFECTS IN MULTIPLE LIGHT-SCATTERING FROM STATISTICALLY ROUGH METALLIC SURFACES

Multiple scattering of light from one-dimensional random rough metallic surfaces is numerically studied by means of a Monte Carlo simulation method based on the extinction-theorem boundary conditions. Angular and integrated distributions of the mean scattered intensity are computed for several values of the angle of incidence, state of polarization, surface statistical parameters, and dielectric permittivity. Two main regimes are addressed, depending on whether the surface correlation length T is larger or smaller than the wavelength-lambda. In the first case, we observe enhanced backscattering both for s and p waves, whereas in the latter situation there exist substantial absorption effects under p polarization, linked to the excitation of surface polaritons. In addition, calculations are made of field enhancements on the surface, owing either to surface-polariton excitation in the small-correlation-length case (T < lambda), or to multiple scattering and generation of other kinds of surface wave in the large-correlation-length case (T > lambda).