RESONANT SCATTERING OF ELECTROMAGNETIC-WAVES FROM A RECTANGULAR GROOVE ON A PERFECTLY CONDUCTING SURFACE

The frequencies of the electromagnetic surface shape resonances of bot h p- and s-polarizations associated with a rectangular groove on the o therwise planar surface of a perfect conductor, and the scattering of a Gaussian beam of p- and s-polarized light from the same groove, are calculated by both a modal approach and a numerical method based on Gr een's second integral identity. On the basis of the results of these c alculations we show that the dips in the frequency dependence of the i ntensity of the scattered light in s-polarization for fixed angles of incidence and scattering found in earlier work by Zuniga-Segundo and M ata-Mendez [Phys. Rev. B 46 (1992) 536], and which we find in the scat tering of p-polarized light as well, do not occur at the frequencies o f the surface shape resonances as asserted by these authors, and we gi ve the correct explanation for these features. In addition, we show th at while the dips in the frequency dependence of the intensity of the scattered light associated with s-polarized surface shape resonances a re masked by the dips found by Zuniga-Segundo and Mata-Mendez, this is not the case for dips associated with p-polarized surface shape reson ances. The latter should therefore be observable in experimental studi es of the scattering of p-polarized light from a rectangular groove on an otherwise planar surface of a highly conducting metal.