Dynamical diffraction explanation of the anomalous transmission of light through metallic gratings

In this paper, it is pointed out that the light transmission anomalies observed for thin-film metallic gratings can be explained entirely in terms of dynamical diffraction theory. Surface plasmons are an intrinsic component of the diffracted wave field and, as such, play no independent causal role in the anomalies, as has been implied by others. The dynamical scattering matrix for the Bloch-wave modes of the diffracted photon wave field (E, H) is derived for a three-dimensionally periodic medium with arbitrary dielectric constant. A new theoretical treatment and numerical results are presented for a one-dimensional array of slits. In model metallic slit arrays, with negative dielectric constant, 100% and 0% transmission is possible at different wavelengths in the zero-order beam. In slit arrays, both propagating and evanescent modes (traditional surface plasmons) are strongly excited at both the peak and the minimum transmission conditions.