Theory of Photonic Crystals and Microcavities :: The Microcavity OPO
When the lower polariton branch of a semiconductor microcavity is pumped resonantly at an angle of 10-20 degrees, the excitonic non-linearity can cause an Optical Parametric Oscillator (OPO) state to switch on, with a signal at close to zero degrees, and the corresponding idler on the other side of the pump. We have developed a theory of this phenomenon, which shows that the behaviour can only be understood in a model where the the self-interaction ('blue-shift') effects in the pump, signal and idler are taken into account.
The states of the microcavity OPO, in a model including the self-interaction of all the modes. The dotted curve is the dependence of pump-polariton population on pump power, when only the pump state is occupied, while the solid and dashed lines indicate the populations when the OPO is turned on at different signal angles.