Coupled Optical Parity-Time Symmetric Non-Linear Dimers

We investigate the dynamics of coupled optical non-linear dimers with Parity-Time (PT) symmetry, induced by judiciously tailored gain/loss processes. We show that this system admits stationary solutions for non- linearity strength smaller than a critical value which depends on the gain/loss parameter. Then we examine the beam dynamics for such type of systems. We find that the interplay of non-linearity and PT-symmetry, results in a controlled unidirectional beam propagation. Applications of our results in optics as much as in the framework of atomic Bose-Einstein condensates are discussed.