Light transmission through a subwavelength hole

We use a recently developed electromagnetic theory to get some insight of the physics that governs the extraordinary transmission of light by a hole pierced in a metallic screen. When the film thickness increases, a comparison is made between the decay of the total field and the decay of the field of the evanescent mode in the corresponding infinite hollow metallic waveguide. The decay behavior and the comparison between their field maps demonstrates that the transmission through the hole is determined by this guided mode. The near field maps below the hole shows small oscillations around a decaying mean value, when the observation points moves away from the hole ridge. The study of the plasmon excited at the bottom interface of the screen allows interpreting all the fine phenomena in terms of simple concepts.