Surface Plasmon Dispersion Relation and Local Field Enhancement Distribution for a Deep Sinusoidal Grating

摘要

Two features of light scattering from a deep lossless metallic sinusoidal grating are considered in the limit g/d approaches infinity, where g and d are the height and periodicity of the grating, respectively. It is found that the surface plasmon dispersion relation is comprised of two flat bands with a frequency gap delta omega/omega sub p = (sq rt (2) -1)/2, where omega sub p is the volume plasmon frequency. For the local field enhancement distribution at the grating's surface, the results show the existence of two qualitatively distinct domains, i.e., lambda>>d and lambda<< d, where lambda denotes the radiation wavelength. In both domains, however, the local field enhancement is larger at the bottom of the troughs than at the top of the peaks. The dressed Rayleigh expansion is used throughout for the analysis.