Parity-time (PT) symmetric periodic structures, near the spontaneous PT-symmetry breaking point, can act as unidirectional invisible media. In this regime, the reflection from one end is diminished while it is enhanced from the other. Furthermore, the transmission coefficient and phase are indistinguishable from those expected in the absence of a grating.… (More)
We analyze the impact of loss in lattices of coupled optical waveguides and find that, in such a case, the hopping between adjacent waveguides is necessarily complex. This results not only in a transition of the light spreading from ballistic to diffusive, but also in a new kind of diffraction that is caused by loss dispersion. We prove our theoretical… (More)
A comparison between light dynamics in Pℐ -symmetric and passive optical coupler is presented. We show that, apart from an overall damping factor, the dymanics in the passive coupler fully reproduce thePℐ -symmetric ones.
We show that two-dimensional continuous time coherent random walks are possible in free space by properly tailoring the associated initial wave functions. Theoretical predictions along with classical experiments demonstrate the feasibility of our scheme.
We report on optical non-paraxial beams that exhibit a self-accelerating behavior in radial direction. Hence, the intensity profile evolves on a spiraling trajectory. The beam parameters have been optimized for high contrast and rotation rate.