Parametric polariton solitons in coherently pumped semiconductor microcavities

We demonstrate the existence of parametric solitons due to four-wave mixing in a coherently pumped semiconductor microcavity operating in the strong-coupling regime. These spatial solitons are localized in the direction perpendicular to the pump momentum and form periodic trains of pulses in the direction parallel to it. The parametric solitons constitute a family continuously parameterized by the energies and momenta of the signal and idler components. They also play a profound role in the formation of two-dimensional polariton solitons.