Parametric polariton amplification in semiconductor microcavities - art. no. 127403

We present novel experimental results demonstrating the coherence propertie s of the nonlinear emission from semiconductor microcavities in the strong coupling regime, recently interpreted. by parametric polariton four-wave mi xing. We use a geometry corresponding to degenerate four-wave mixing. In ad dition to the predicted threshold dependence of the emission on the pump po wer and spectral blueshift, we observe a phase dependence of the amplificat ion which is a signature of a coherent polariton wave mixing process.