Resonant light scattering by small coated nonmagnetic spheres: magnetic resonances, negative refraction, and prediction

摘要

Light scattering of individual coated nonmagnetic spherical particles and effective parameters for a collection of such inclusions are studied at terahertz frequencies, with the emphasis on the conditions of achieving resonant light scatterings, induced magnetic resonance, and negative refraction. Moreover, the prediciton of those critical conditions is proposed. Different core-shell combinations aiming at inducing magnetic resonances are investigated, including plasmonic metamaterials and polar crystals. It is shown that the resonant scattering is controllable with fine adjustment of the core-shell ratio, varying from enhancement to suppression in the scattering drastically. Embedding identical coated nanospheres in a matrix, the polarizability and effective medium parameters of the bulk are examined to give better understanding of unusual scatterings and their predictions. The resonances in electric and magnetic dipole approximation for such a bulk medium are presented. (C) 2008 Optical Society of America