Negative effective permeability of multilayers of ordered arrays of metal-dielectric nanosandwiches

摘要

We present a thorough theoretical study of the optical properties of periodic structures built of silver and silicananodisks in a sandwich-like configuration, by means of full electrodynamic calculations using the extendedlayer-multiple-scattering method. The strong coupling of the metallic nanoparticles and the resulting plasmonhybridization lead to collective electric and magnetic resonant modes, which can be tuned by changing thestructural parameters, such as nanoparticle size and lattice constant. We analyze the response of single- andmulti-layer architectures of ordered arrays of such nanosandwiches on a dielectric substrate to externally incidentlight and evaluate the corresponding effective permittivity and permeability functions. Our results reveal theexistence of optical magnetism, with a strong negative effective permeability over a tunable spectral range atnear-infrared and visible frequencies. We introduce the complex photonic band structure as a tool in the studyof three-dimensional metamaterials and establish additional criteria for the validity of their effective-mediumdescription. Our work demonstrates the efficiency of the recently developed extended layer-multiple-scatteringmethod in the study of metamaterials of composite metal-dielectric particles of arbitrary shape.