Local dielectric resonance and collective response of randomly ordered metallic cells in composites

We investigate the dielectric resonance, local field distribution and optical response of randomly ordered nanometre metallic cells in two-dimensional composites using the Green's function formalism. It is found that the microstructure of a single cell determines the bandgap profiles of dielectric resonances, showing that these metallic cells have locally resonant structures. One or several defect bonds are introduced into each cell, expressed as the difference admittance ratio η (ε2-ε0)/(ε1-ε0). With varying η, the resonance bandgaps and effective optical absorption spectra are modified according to the single cell response, or local resonance structure. However, near resonances, the local field distributions from the localized modes to extended modes are shown to be the collective response of the whole material, rather than a single cell response. The results will be beneficial to the study of surface plasmon resonances in nanometre metallic clusters