Negative refraction and planar focusing based on parity-time symmetric metasurfaces

Phys Rev Lett. 2014 Jul 11;113(2):023903. doi: 10.1103/PhysRevLett.113.023903. Epub 2014 Jul 10.

Abstract

We introduce a new mechanism to realize negative refraction and planar focusing using a pair of parity-time symmetric metasurfaces. In contrast to existing solutions that achieve these effects with negative-index metamaterials or phase conjugating surfaces, the proposed parity-time symmetric lens enables loss-free, all-angle negative refraction and planar focusing in free space, without relying on bulk metamaterials or nonlinear effects. This concept may represent a pivotal step towards loss-free negative refraction and highly efficient planar focusing by exploiting the largely uncharted scattering properties of parity-time symmetric systems.