Electrodynamics of transformation-based invisibility cloaking

Abstract

The existing knowledge on the electrodynamics of invisibility cloaking based on transformation optics is reviewed from an integrated science and engineering perspective. Several significant electromagnetic problems that have resulted in intense discussions in the past few years are summarized in terms of propagation, scattering, radiation and fabrication. Finally, the road ahead toward invisibility cloaking and transformation optics is discussed from the viewpoint of the author. After the invention of transformation optics in 2006, scientists began developing ways to direct electromagnetic radiation around objects. Baile Zhang from Nanyang Technological University in Singapore reviews the progress made towards such ‘invisibility cloaks’ and surveys the challenges lying ahead. He describes the transition from artificial structures known as metamaterials, which are traditionally the basis of invisibility cloaks, to natural materials, which have been used very recently to implement such devices. By considering both science and engineering perspectives, Zhang discusses approaches for optimizing, in an iterative manner, the properties of cloak materials and device performance targets. He identifies two key challenges toward future applications: overcoming bandwidth limitations and the implementation of three-dimensional cloaking structures.