  We study light diffraction in the periodically modulated ultrathin metal
films both analytically and numerically. Without modulation these films are
almost transparent. The periodicity results in the anomalous effects, such as
suppression of the transmittance accompanied by a strong enhancement of the
absorptivity and specular reflectivity, due to excitation of the surface
plasmon polaritons. These phenomena are opposite to the widely known enhanced
transparency of periodically modulated optically thick metal films. Our
theoretical analysis can be a starting point for the experimental investigation
of these intriguing phenomena.
