Some aspects of light scattering from a randomly rough metal surface

TLDR

The study investigates light scattering from randomly rough metal surfaces, focusing on the experimentally determined two‑dimensional Fourier transform of the surface correlation function. The authors aim to fit a resonant nonspecular scattering theory to experimental data to extract the surface correlation function and to analyze p‑polarized light scattering from a rough grating with normal incidence. They fit the theory to data to obtain the correlation function and employ a self‑consistent diagrammatic method that incorporates localization diagrams. The extracted correlation function is nonmonotonic with a maximum away from zero, the localization diagrams produce enhanced antispecular scattering, and surface polaritons are localized by roughness with a measurable localization length.

Abstract

Two problems involving the interaction of a volume electromagnetic wave with a randomly rough metal surface are studied. In the first part a recently constructed theory of the resonant nonspecular scattering of light from a randomly rough metal surface is fitted to experimental data in a way that permits the extraction of the two-dimensional Fourier transform g(k∥) of the two-point correlation function of the surface profile function from the experimental results. It is found that the resulting correlation function can have its first maximum away from k∥ = 0 and decays to zero with increasing k∥ in a nonmonotonic fashion. This form for g(k∥) has been obtained in recent, independent, experimental determinations of this function. In the second part the scattering of p-polarized light from a randomly rough grating is studied in a case in which the plane of incidence is normal to the grooves of the grating. A diagrammatic method that self-consistently takes into account the diagrams responsible for localization phenomena in other contexts is used in this analysis. It is shown that the contribution from these diagrams gives rise to an enhanced scattered intensity in the antispecular direction. As a by-product of this calculation, the localization of surface polaritons by surface roughness is demonstrated and their localization length is determined.