Optical response of gold hemispheroidal lattices on transparent substrates
Résumé
tSquare arrays of gold (Au) hemispheroids deposited on a UV-transparent glass substrate reveal a richoptical response when investigated by spectroscopic Mueller Matrix Ellipsometry. Two samples werestudied; the first consisted of hemispheroids of parallel radius of 58 nm and height 30 nm with lat-tice constant 210 nm; the corresponding parameters for the second sample were 38 nm, 20 nm and125 nm, respectively. By a full azimuthal rotation of the samples, we observe all the Rayleigh anoma-lies corresponding to grazing diffracted waves, with strong resonances for co-polarization scattered lightnear the high symmetry points and cross-polarization scattered light around the Localized Surface Plas-mon Resonance. Polarization-conversion becomes particularly important at grazing incidence, and thecross-polarization follows the Rayleigh lines. The optical response (neglecting polarization conversion) ismodelled in the quasi-static approximation using the so-called Bedeaux-Vlieger formalism, and the FiniteElement Method using COMSOL....