# Laboratoire Collisions Agrégats Réactivité - UMR5589

Université Paul Sabatier - Bat. 3R4 - 118 route de Narbonne 31062 Toulouse Cedex 09, France

## Quantitative determination of optical transmission through subwavelength slit arrays in Ag films : Role of surface wave interference and local coupling between adjacent slits

Measurement of the transmitted intensity from a coherent monomode light source through a series of subwavelength slit arrays in Ag films, with varying array pitch and number of slits, demonstrates enhancement (suppression) by factors of as much as 6 (9) when normalized to the transmission efficiency of an isolated slit. Pronounced minima in the transmitted intensity are observed at array pitches corresponding to lambdaSPP, 2lambdaSPP, and 3lambdaSPP, where lambdaSPP is the wavelength of the surface plasmon polariton (SPP). The position of these minima arises from destructive interference between incident propagating waves and pi-phase-shifted SPP waves. Increasing the number of slits to four or more does not increase appreciably the per-slit transmission intensity. A simple interference model fits well the measured transmitted intensity profile.

Voir en ligne : Phys. Rev. B 77, 115411 (2008)