Management of Wavefront Reformation and Intense Focusing in Photonic Lattices with Local PT-Symmetry

PT-symmetric optics is an emerging field, with numerous applications in photonics. Here, we theoretically propose and study PT-symmetric architectures supporting novel beam-propagation controlled by appropriate manipulation of the system’s amplifying and dissipative elements. The base-platforms to observe these dynamics are binary photonic waveguide lattices consisting of dimmers, with amplification in one site and equivalent dissipation in the other. We show that these structures support caustic-wave bending in addition to aberration-free high-intensity wave focusing. Furthermore we show that subjected to a transverse index of refraction gradient, these lattices support Bloch-Zener oscillations. The existence, periodicity and stability of these Bloch-Zener oscillations are dictated by the amplification/dissipation parameter. Finally–utilizing isomorphic relations–we propose a simple experimental framework, of a single PT dimer with a periodically driven coupling, wherein these phenomena can be observed.