Local field distribution in random metal-dielectric films; theory and experiment

The local field properties of metal-dielectric films are investigated in terms of the probability distribution function (PDF). For metal coverage p, close to the percolation threshold we obtain a wide, lognormal PDF which for low metal concentrations gradually transforms into a scaling, power-law distribution function. Strong enhancement of the local fields in a broad spectral range is verified by an exact numerical procedure. In experimental studies, metal-dielectric films were synthesized by a pulsed laser deposition technique, and their optical properties were investigated using near-field optical microscopy. The experimentally and numerically obtained probability functions are found to be in good agreement. (C) 2003 Elsevier B.V. All rights reserved.