Inhomogeneous fields for surface plasmon excitation

摘要

Point sources of polarized light generate inhomogeneous fields at the surface of a metallic slab localized at its vicinity. It is found that the associated ^-spectrum contains wave vectors larger than those corresponding to free oscillations. Consequently evanescent fields are available and surface plasmons can be excited. With FDTD calculations we prove in detail this effect using a point source of cylindrical symmetry placed near a silver film. In addition, the interaction of the cylindrical wave and the metallic surface is analytically described by writing the incident wave in terms of a plane wave basis. Images of the surface plasmon excited by this source and the field distribution in the vicinity of the surface are shown.