Abstract:

We report a thorough theoretical study of the optical response of two- and three-dimensional periodic assemblies of metallic nanorods by means of full-electrodynamic calculations using the extended layer-multiple-scattering method. We show that these systems support various types of resonant- and bound-collective plasmon modes, which are tunable over a broad spectral range, and provide a consistent interpretation of the underlying physics. In particular, we reveal the existence of slab plasmon modes with zero group velocity, which can cause evanescent-wave enhancement and enable subwavelength imaging. We discuss extinction spectra of single-layer and multilayer slabs of nanorods in conjunction with relevant complex band-structure diagrams and present a rigorous analysis of the results using group theory. Moreover, we explain some peculiar spectral features which are due to the existence of surface resonances. These can modify the optical response of the system in a controllable manner by using a supporting substrate.