  In this letter we present an analytical theory of Extraordinary optical
transmission (EOT) through semi-transparent screens, such as thin metallic
plates or high permittivity dielectric slabs. Using this theory we show that
EOT appears not only for screens perforated by holes or slits, but also for
screens loaded by any defects, including opaque defects. These results widen
the scope of EOT concept, opening up the way to the study of new physical
effects.
