Showing papers by "A. A. Maradudin published in 1975"

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.

Surface roughness and the optical properties of a semi-infinite material; the effect of a dielectric overlayer

Abstract: We derive expressions for the rate at which radiation is scattered and absorbed because of surface roughness on a semi-infinite material, in the presence of a dielectric overlayer. We confine our attention to the case of normal incidence. A formalism developed in an earlier paper by the present authors is utilized in the discussion. We also present a series of numerical calculations which explore the roughness-induced scattering and absorption of electromagnetic radiation for aluminum overcoated by aluminum oxide, in the ultraviolet region of the spectrum. The position of the reflectivity dip produced by roughness-induced coupling to the surface plasmon is found to shift toward the visible as the thickness of the oxide layer increases. The size of the dip is controlled strongly by the degree of correlation between the roughness on the vacuum-oxide interface, and that on the oxide-substrate interface. Under conditions discussed in the text of the paper, the presence of the oxide layer can greatly enhance the coupling between the incident radiation and surface plasmons.