An effective-medium theory (EMT) is developed to predict the effective permittivity ε eff of dense random dispersions of high optical-conductivity metals such as Ag, Au, and Cu. Dependence of εeff on the volume fraction ø, a microstructure parameter-related to the static structure factor and particle radius a, is studied. In the electrostatic limit, the upper and lower bounds of k correspond to Maxwell-Garnett and Bruggeman EMTs, respectively. Finite size effects are significant when jβ2(ka/n)3 becomes O(1), where β, k, and n denote the nanoparticle polarizability, wavenumber, and matrix refractive index, respectively. The coupling between the particle and effective medium results in a red-shift in the resonance peak, a nonlinear dependence of εeff on ø, and Fano resonance in εeff .
|Original language||English (US)|
|Number of pages||13|
|Journal||Journal of the Optical Society of America B: Optical Physics|
|State||Published - Jun 2012|
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Atomic and Molecular Physics, and Optics