Spatial structure and stability of the macroscopically occupied polariton state in the microcavity optical parametric oscillator

Transverse spatial images of the signal generated in semiconductor microcavities under conditions of resonant parametric scattering are obtained. When the system is pumped significantly above the threshold, the signal image is found to be highly structured, consisting of a set of localized bright spots. By comparison with a numerical model, it is shown that the structure arises from the blueshift generated by the nonlinear polariton-polariton interaction which drives the microcavity optical parametric oscillator, in combination with partially ordered spatial fluctuations in the cavity mode energy. An important outcome is that the form and stability of the signal is strongly influenced by the local cavity disorder.