Transformation Optics And Its Applications In Electromagnetic Invisibility Cloak

we review the basic methodology of transformation optics and explain how to obtain the material parameters of transformation medium and electromagnetic fields propagating in it through using corresponding relations. As examples, cylindrical and spherical electromagnetic invisibility cloaks are introduced, we derive the permittivity and permeability of these two types of cloaks and get the fields inside the cloaks for the case of plane wave incidence.In addition, we investigate the effect of electrostatic shielding for a spherical in-visibility cloak with arbitrary charges inside the hidden region. The result reveals that the electric fields outside are purely determined by the total charges inside and equal to the fields of a point charge at the center of the cloak. As the total charges reduce to zero, the bodies can not be detected. If the total charges are nonzero, the electrostatic potential inside an ideal cloak tends to infinity. For unideal cloaks, this embarrassment is overcome, while they still have good behaviors of shielding. The potential across the inner surface of an ideal cloak is discontinuous due to the infinite polarization of the dielectric, however it can be alternatively interpreted as the dual Meissner effect of a dual superconductive layer with a surface magnetic current.Moreover, we introduce the electromagnetic shielding effect of invisibility cloak for radiative objects inside the cloaked region. Through calculating the radiation field of a radiative electric dipole inside cloak, we obtain the dyadic Green’s function with respect to the ideal spherical cloak and demonstrate the effect of electromagnetic shield-ing is valid for arbitrary radiative sources inside the cloaked region.