Parity breaking effects in nonlinear dielectric media

In this work, we study the interplay between nonlinear and parity odd phenomena, in the context of light-matter systems. Nonlinear phenomena alone have been investigated in 1D dielectric systems such as Quadratic and Kerr media. For the Quadratic case, the presence of half-cycle-pulses is an example of these nonlinear effects, given that they can be described by solitons.

On the other hand, for the Kerr case, nonlinearities lead to Modulation Instability, where the envelope dynamics becomes unbounded as the wave train propagates throughout the medium.

We introduce, in these previous models, dispersive terms that break parity and time-reversal symmetries, but preserve their combination (PT).

For the Quadratic case, the solitons are modified in a way that left-moving solitons behave as bright solitons, whereas the right-moving solitons become dark solitons. And, for the Kerr case, this nonreciprocity suppresses modulation-instability giving rise to islands of stability in the lower-polariton branch.