  Using a high-quality GaAs planar microcavity, we optically generate polariton
pairs, and verify their correlations by means of time-resolved single-photon
detection. We find that correlations between the different modes are
consistently lower than identical mode correlations, which is attributed to the
presence of uncorrelated background. We discuss a model to quantify the effects
of such a background on the observed correlations. Using spectral and temporal
filtering, the background can be suppressed and a change in photon statistics
towards non-classical correlations is observed. These results improve our
understanding of the statistics of polariton-polariton scattering and
background mechanisms, and pave the way to the generation of entangled
polariton pairs.
