Phys. Rev. Lett. 111, 213901 (2013)

Credit: © 2013 APS

Invisibility cloaks that guide light around three-dimensional objects have captured the attention of scientists, but their practical realizations have been hard to come by. The reason for this is because of the various limitations and complexities in the material properties required to implement them in devices. Now, Yang Hao and colleagues propose an appealing strategy for realizing cloaks for surface waves, which in practice means that waves propagating on a curved, bumpy surface appear to be travelling on a flat surface instead. Their key idea is to cover the surface with a thin coating characterized by a refractive index that varies according to the position of the wave on the curved surface. In this way, the cloaks can be shown to be omnidirectional and able to conceal large objects without resorting to complex material properties. All of which may have interesting implications for devices relying on electromagnetic surface waves.