Curved trajectories on transformed metal surfaces: Luneburg lens, beam-splitter, invisibility carpet and black hole for surface plasmon polaritons

Transformational optics are shown to markedly enhance the control of the electromagnetic wave trajectories within metamaterials with unconventional functionalities such as a beam splitter, a toroidal carpet, a Luneburg lens and a black hole, all of which are specially designed for surface plasmon polaritons propagating on a metal plate