Controlling the electromagnetic fields with simple structures

Determining the operation of an electromagnetic structure by employing the proper media and components is one of the most intriguing and general issues posed in electronics and optics. In fact, it constitutes a great challenge to manage to tailor the functionality a device in a way that can vary at will, simply by choosing and calibrating the constituent materials, dimensions and shapes. Due to its generality, numerous works with the same purpose have been published from the distant past till nowadays, when it remains a hotly debated issue. Our aim is to achieve this goal by employing conventional media and simple structures which could lead to the discovery of new physics governing the corresponding phenomena and to the modeling of more complicated configurations.

• Simple Cloaks: Claddings of suitable electromagnetic properties and dimensions are used in order to diminish substantially the scattering effect of an object either posed alone into free space or located on PEC planes. We have performed an optimization technique that led to the effective modelling of the "carpet cloak" shown below for arbitrary-shaped bumps. Numerous other structures have been investigated and are ongoingly considered. Indicative papers on this topic: UniformCloak, PECScatteringCancellation, ExperimentalCloakA, ExperimentalCloakB.

• Simple Absorbers: Modelling of balanced cylindrical and electrically small particles becomes feasible by employing media of high permittivity contrast. In this way, the magnetic dipoles get amplified and effective absorption of the electromagnetic illumination is achieved as demonstrated below. Similar structures are being currently examined by aiming at increasing the electrical path of the rays into slightly lossy materials. Indicative papers on this topic: GrapheneAbsorber, AbsorbingGrating.

• Simple Meshes: The beneficial characteristics of uniaxial hyperbolic media can be imitated by employing simple metallic meshes. The negligible reflections from such a grid by two supplementary incidence angles are shown below. Structures with similar grid features can be used to control the incoming waves in a more complicated way, since the shape, the density and the length of the formed single-mode waveguides offer additional degrees of freedom to the designer. Indicative papers on this topic: HyperbolicMedia, AttenuationComparison.