Dispersion Engineering with Impedance-Matched Metamaterials

Abstract

Metamaterials are engineered artificial materials with electromagnetic properties that are not easily available in nature. They affect electromagnetic waves in a different manner compared to traditional materials. They consist of conventional dielectrics and metals, but get their new properties through internal structure. Perhaps the most amazing observed feature of some metamaterials is having simultaneously negative permittivity and permeability, which results in a phenomenon called negative refraction. In this thesis, we will study a metamaterial structure for using in dispersion engineering. Due to its limiting effects on bit rate and distance of data transfer, dispersion in fiber optical communications is a significant problem that has to be dealt with. Resonant metamaterials are usually highly dispersive materials. In some applications, dispersion is not a desirable characteristic. However, by properly designing the structure, we are able to determine the sign and amount of the dispersion. Our metamaterial consists of a nonradiative dielectric resonator for energy storing and wire antennae to couple incident wave to the dielectric resonator. This metamaterial exhibits normal dispersion or in other words, it has positive group velocity dispersion (GVD). We define electric and magnetic conductivities as material characteristics. It is possible to change those material characteristics by changing the positions and dimensions of the metamaterial’s constituents. According to theory that will be described, if the electric and magnetic conductivities are equal in a frequency range, we can obtain very low reflectance from the metamaterial. Simultaneously low reflectance and positive GVD make the metamaterial as a dispersion compensating system.