On the Role of the Simplest Magnetoelectric Non-Reciprocity in Scattering and Absorption Manipulation

Scattering by a three-dimensional object (core) made of a linear medium and bounded by a conformal coating made of a Lorentz nonreciprocal medium is formulated as a set of coupled volume integral equations, which then is solved using the method of moments. The coating is characterized by the magnitude and the direction of a magnetoelectric-gyrotropy vector. In order to focus mainly on the role of the coating’s medium on scattering and absorption without bogging down with complicated shapes and sources, numerical results are shown for plane-wave incidence mostly for a spherical core made of an isotropic medium. The polarization state of the incident plane wave can have an appreciable impact on the differential scattering efficiency depending on the orientation of the propagation vector of the plane wave relative to the magnetoelectric-gyrotropy vector of the coating, as well as with the evolution of the electrical size of the core-coating structure. Moreover, a proper choice of the propagation direction and polarization state can result in raising/lowering the total scattering efficiency and absorption efficiency. Most remarkably, absorption reduction of a core made of a dissipative dielectric medium can be achieved regardless of the incident plane wave parameters and the electrical size of the core-coating structure when the incident plane wave is chosen to be anti parallel to the coating’s magnetoelectric-gyrotopy vector. This reduction can be achieved also for an anisotropic core, a dissipative coating, as well as an ellipsoidal core-coating structure.