Аннотации:
The powerful tools of transformation optics (TO) allow an effective distortion of a region of
space by carefully engineering the material inhomogeneity and anisotropy, and have been
successfully applied in recent years to control electromagnetic fields in many different scenarios,
e.g., to realize invisibility cloaks and planar lenses. For various field transformations, it is not
necessary to use volumetric inhomogeneous materials, and suitably designed ultrathin
metasurfaces with tailored spatial or spectral responses may be able to realize similar
functionalities within smaller footprints and more robust mechanisms. Here, inspired by the
concept of metamaterial TO lenses, we discuss field transformations enabled by parity-time (PT)
symmetric metasurfaces, which can emulate negative refraction. We first analyze a simple
realization based on homogeneous and local metasurfaces to achieve negative refraction and
imaging, and we then extend our results to arbitrary PT-symmetric two-port networks to realize
aberration-free planar imaging