Metamaterials: Definitions, properties, applications, and FDTD-based modeling and simulation (Invited paper)

In this article, we review definition, origin, terminology, fundamental properties, design concepts and procedures, basic applications, modeling, and numerical simulation of metamaterials. It is shown that metamaterial origin can be easily understood by placing metamaterials in the more general context of artificial electromagnetic materials and of the efforts performed by the scientific community working in complex materials to mimic and overcome the properties of natural materials. The basic properties of some classes of metamaterials as well as the related limitations are reviewed and discussed. A new application-oriented definition of metamaterials is given in terms of a functionalizing layer placed in between the traditional concepts of materials and devices. Metamaterial applications and the design steps of metamaterial-based and metamaterial-inspired components are also discussed, with particular emphasis on the numerical simulation of ideal metamaterials through available solvers. In this frame, finite-difference time-domain (FDTD) modeling and simulation of the electromagnetic properties of metamaterials are deeply discussed. The recently introduced virtual MTM-FDTD tool is used to simulate the interaction between the electromagnetic field and metamaterials and show some metamaterial effects, such as beam focusing, existence of negative refractive angle, and so forth, through various examples in different scenarios.