Recent Advances in Nearfield Optical Analysis and Description of Amorphous Metamaterials

Abstract

Amorphous metamaterials, a system of conglomerated plasmonic atoms arranged in a nondeterministic way, is an emerging class of nanostructured plasmonic material that is easily fabricated in large quantities and over macroscopic areas. It consists of individual, nominally identical, plasmonic resonators, whose spatial arrangement is random. These elements have been studied intensely over the last decade on a single particle level. Investigations of dimers and more complex plasmonic molecules created from such elements have lead to a thorough understanding of their nearfield-mediated interactions. Adding more plasmonic particles augments the degree of control over the ensemble response. When plasmonic particles are arranged in an array, 1D, 2D or 3D, additional optical features arising from periodic arrangement of the particles appear, adding further complexity to the system. The behavior of these periodically arranged particles is relatively easily captured in exact theoretical calculations using periodic boundary condition. On the contrary, the study of amorphous plasmonics has received much less attention, at least partially due to high computational costs that severely limit an exact treatment. At the same time, successful approximate descriptions of the ensemble behavior are largely missing. In this chapter, we review studies on plasmonic near-field interaction, starting from basic system of dimers, to periodic, and to completely disordered arrangement. We briefly review various fabrication techniques, and discuss in depth the use of Apertureless Scanning Nearfield Microscopy in amorphous plasmonics. Finally, we propose a metaglass theory that provides an explicit analytical model description of a homogenized effective medium response of amorphous plasmonic systems.