Extraordinary surface voltage effect in the invisibility cloak with an active device inside

TL;DR

This paper investigates the electromagnetic behavior of a spherical invisibility cloak with an active device inside, revealing extraordinary surface voltages that prevent wave escape and preserve wave properties upon reflection.

Contribution

It establishes the electromagnetic field solution for such cloaks and uncovers the physical nature of induced surface voltages at the inner boundary.

Findings

Induction of extraordinary electric and magnetic surface voltages at the inner boundary.

Surface voltages prevent electromagnetic waves from escaping the concealed region.

Surface voltages due to an internal electric dipole relate to auxiliary scalar potentials.

Abstract

The electromagnetic field solution for a spherical invisibility cloak with an active device inside is established. Extraordinary electric and magnetic surface voltages are induced at the inner boundary of a spherical cloak, which prevent electromagnetic waves from going out. The phase and handness of polarized waves obliquely incident on such boundaries is kept in the reflected waves. The surface voltages due to an electric dipole inside the concealed region are found equal to the auxiliary scalar potentials at the inner boundary, which consequently gain physical counterparts in this case.