NEAR-FIELD SCATTERING FROM SUBWAVELENGTH METALLIC PROTUBERANCES ON CONDUCTING FLAT SUBSTRATES

The exact electromagnetic components of the near-field wave scattered from a subwavelength metallic cylindrical protuberance located on a flat conducting substrate are calculated by applying the extinction theorem. A theoretical interpretation of the electric components of the wave is presented to separate the different contributions to the scattered wave. A comparison is made with the isolated cylinder case (no substrate) to analyze the influence of the flat substrate on the scattered wave. The effect of the incident polarization (either S or P) is also analyzed. For P-incident polarization, we show that the protuberance is able to generate surface plasmons along the flat metallic substrate. Their electromagnetic behavior (amplitude, propagation, and damping constants) is studied as a function of the imaginary part of the dielectric constant and the cylinder size. © 1995 The American Physical Society.