Study on the near-field coupling of resonators in metamaterial for electromagnetic-wave absorption

Abstract

Recently, metamaterial perfect absorber (MPA) has been the interested topic in physics and materials science since the first demonstration in 2008. By controlling the geometrical design of MPA, it is possible to manipulate the electric and the magnetic responses of structure, leading to the perfect absorption at desired frequency. Since then, many efforts to obtain narrow- and multi-band MPAs have been proposed. However, there are still obstacles which should be overcome. In this thesis, I studied another way, based on the near-field coupling of resonators in metamaterial for narrow- and multi-band electromagnetic-wave absorption. Firstly, a reversible-propagation narrow-band MPA is proposed. By controlling the near-field coupling between two identical resonators in structure, the perfection absorption can be achieved by exploiting the oblique incidence. Furthermore, the capability of MPA to be applied in sensor is also numerically studied, exhibiting a promising result. Secondly, the dual-band and the multi-band MPAs are presented by exploiting the near-field coupling of resonators. Here, both bright-dark and bright-bright couplings are investigated, which are possible to induce the dual-band and the multi-band absorptions working under wide range of incident angle. In the detailed comparison, the latter coupling is more advantageous owing to the symmetric structure, which makes the MPA polarization-insensitive. The approach in the thesis contributes another way to realize narrow- and multi-band MPAs, which might be easier to be fabricated in reality and be useful to be applied in practical devices, such as sensors, multi-frequency filters and single/multi-mode switches, and in stealth technology.