Abstract:The potential of random metal-dielectric nanocomposites as constituent elements of metamaterial structures is explored. Classical effective medium theories indicate that these composites can provide a tunable negative dielectric function with small absorption losses. However, the tuning potential of real random composites is significantly lower than the one predicted by classical theories, due to the underestimation of the spectral range where topological resonances take place. This result suggests that a random mixture consisting of a metal matrix with embedded isolated dielectric inclusions is a promising design guideline for the fabrication of tunable composites for metamaterial purposes. Photonics 1(4), 224-227 (2007
Abstract. The influence of the substrate temperature on the effective optical behavior of Ag-SiO 2 composites obtained by electron beam evaporation was studied. Optical characterization of the composites was performed by means of spectroscopic ellipsometry measurements. The effective dielectric function of the composites, modeled using a multiple oscillator approach, could be widely tuned by controlling the deposition temperature. The spectral dependence of the composite absorption appeared to be better described with a Gaussian line shape than with the classical Lorentz oscillator model. The description of the effective dielectric function using standard effective medium theories failed and the experimental results could be explained only in the general framework of the Bergman spectral density theory. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
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