Interaction ofS-polarized beams with infinitely conducting grooves: Enhanced fields and dips in the reflectivity

Field enhancement and reflectivty of S-polarized Hermite-Gaussian beams from a rectangular groove ruled on a planar, perfectly conducting surface are analyzed by use of a modal theory. We show a novel effect in which S resonances are manifested by the appearance of sharp dips in the scattered intensity. We propose a relationship for the location of these minima in the scattered intensity with a precision better than 10^-3.