PT optical lattices and universality in beam dynamics

Beam dynamics in synthetic optical media with PT symmetries imposed by a balanced arrangement of gain or loss is investigated. We find that the beam power evolution is insensitive to microscopic details of the system and that it follows three distinct universal laws which depend only on the magnitude of the gain or loss parameter. Our theoretical calculations are confirmed numerically for the experimentally realizable case of a lattice consisting of coupled PT-symmetric dimers