Extraordinary Transmission Through Slit Arrays In Metal Films

Extraordinary transmission of electromagnetic wave through an array of subwavelength slits in a metal film is considered. Probable mechanisms responsible for this effect are analyzed. Comparison of theoretical model, semi-analytical model based on Fabry-Perot formula and results of numerical simulation of Maxwell equations in time-dependent form for silver with various geometric parameters is presented. It is concluded from numerical results the validity of single-mode approximation described by Fabry-Perot formula. All characteristics of extraordinary transmission are completely described by single-mode approximation. Surface plasmon coupling with propagative eigenmode of slit leads to zero in transmittance for certain wavelength, i.e. plays negative role in extraordinary transmission.