Electromagnetic Characterization of Metasurfaces

Abstract

Electromagnetic characterization of metasurfaces (MSs), electrically/optically thin sheet metamaterials (MMs), is the subject of the current study. Briefly, a MM is a composite material with unusual electromagnetic properties offered by specific response of its constituents and their arrangement. The main goal in this work is to attribute some macroscopic characteristic parameters to MSs.

We first discuss the definitions and present a brief review of the electromagnetic characterization of MMs and MSs. We explain the failures of the traditional characterization approach when applied to MSs. We discuss two known approaches especially suggested for the characterization of MSs in 1990s-2000s.

We continue to introduce a heuristic homogenization model of MSs located on a dielectric interface. Indeed, we derive the general boundary conditions invariant on the polarization of the excitation field. Then, we present the most general algorithm to retrieve the characteristic macroscopic parameters through two-dimensional reflection and transmission dyadics.

We next present two explicit examples of MSs in order to prove the applicability of our theory. The first one is a periodic array of plasmonic nano-spheres while the second one is an array of coupled plasmonic nano-patches positioned in a disordered fashion on a flat surface. We show that our approach works for for both random and periodic MSs. Indeed, the restriction of our theory is a sufficiently small electrical/optical size of a unit cell (area per one particle).

We finally present the main results of the thesis through functional MSs. We theoretically reveal and discuss novel physical effects and various functionalities. We present some discussions on the intrinsically bianisotropic and intrinsically magnetic MSs operating in the visible range. We also discuss the microscopic effect of substrate-induced bianisotropy for a substrated array of plasmonic nano-spheres. Moreover, we reveal the magnetic response within the framework of our homogenization model; i.e., retrieving some magnetic parameters. Furthermore, we obtain the perfect absorbance conditions for different topologies and discuss them in this chapter. Finally, we present a model which explains the different behavior of electric and magnetic resonant modes of MSs in transition from periodic to amorphous arrangements.