Parametric Scattering of Cavity Polaritons

We report frequency-domain degenerate four-wave mixing results on excitons in a semiconductor microcavity in the strong coupling regime. The excitation is kept to the χ⁽³⁾ limit. The spectral response shows strong polarization dependence. We analyze the data with a new model where the degenerate four-wave mixing process is described as an elastic scattering of two cavity polaritons mediated by the state filling effect and the two-body attractive and repulsive interaction between excitons. From the polarization and detuning dependence, the ratio of the coupling constants of these three terms is uniquely determined. We find that the attractive interaction term and the state filling are the dominant contributions to the nonlinearity.