Surface plasmons of metallic surfaces perforated by nanohole arrays

Recent works have dealt with the optical transmission on arrays of subwavelength holes perforated in a thick metallic film. We have performed simulations which quantitatively agree with experimental results and which unambiguously provide evidence that the extraordinary transmission is due to the excitation of a surface-plasmon-polariton (SPP) mode on the metallic film interfaces. We identify this SPP mode and show that its near field possesses a hybrid character, gathering collective and localized effects which are both essential for the transmission.