Near-Field Distribution of Optical Transmission of Periodic Subwavelength Holes in a Metal Film

Optical transmission of a two-dimensional array of subwavelength holes in a metal film has been numerically studied using a differential method. Transmission spectra have been calculated showing a significant increase of the transmission in certain spectral ranges corresponding to the excitation of the surface polariton Bloch waves on a metal surface with a periodic hole structure. Under the enhanced transmission conditions, the near-field distribution of the transmitted light reveals an intensity enhancement greater than 2 orders of magnitude in localized $\left(\sim 40\mathrm{nm}\right)$ spots resulting from the interference of the surface polaritons Bragg scattered by the holes in an array.