SURFACE-PLASMON POLARITON MECHANISM FOR ENHANCED BACKSCATTERING OF LIGHT FROM ONE-DIMENSIONAL RANDOMLY ROUGH METAL-SURFACES

Recent experimental results of West and O'Donnell [J. Opt. Soc. Am. A 12, 390 (1995)] for the enhanced backscattering of p-polarized light f rom weakly rough, one-dimensional, random gold surfaces are compared w ith the predictions of two perturbative calculations of such scatterin g. The experimental surfaces were fabricated to possess power spectra that are nonzero in only a narrow range of wave numbers about the wave number of the surface plasmon polariton supported by them at the freq uency of the incident light. As a consequence, enhanced backscattering that is due to the coherent interference of time-reversed scattering sequences involving counterpropagating surface plasmon polaritons is p ossible for only a limited range of values for the angles of incidence and scattering. The perturbative calculations used in the comparisons with experiment are the infinite-order calculation of McGurn et al. [ Phys. Rev, B 31, 4866 (1985)] in the small-roughness approximation and the small-amplitude perturbation theory of Maradudin and Mendez [Appl . Opt. 32, 3335 (1993)] that is exact to fourth order in the surface-p rofile function. In both calculations the origin of enhanced backscatt ering is the coherent interference of multiply scattered surface plasm on polaritons with their time-reversed partners, The good quantitative and qualitative agreement between the theoretical and experimental re sults, with no fitting parameters, supports the conclusion of West and O'Donnell that their data demonstrate the existence of enhanced backs cattering caused by the excitation of surface plasmon polaritons on a weakly rough random metal surface. (C) 1995 Optical Society of America