title: Negative refraction and planar focusing based on parity-time symmetric metasurfaces.
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.
authors: Department of Electrical & Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: Romain
authors: R
authors: Fleury
authors: Department of Electrical & Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: Dimitrios L
authors: DL
authors: Sounas
authors: Department of Electrical & Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
authors: Andrea
authors: A
authors: Alù