Signatures of the excitonic memory effects in four-wave mixing processes in cavity polaritons

We report the signatures of the exciton correlation effects with finite mem ory time in frequency domain degenerate four-wave mixing (DFWM) in semicond uctor microcavity. By utilizing the polarization selection rules. we discri minate instantaneous, mean-held interactions between excitons with the same spins, long-living correlation due to the formation of biexciton state by excitons with opposite spins, and short-memory correlation effects in the c ontinuum of unbound two-exciton states. The DFWM spectra give us the relati ve contributions of these effects and the upper limit for the time of the e xciton-exciton correlation in the unbound hva-exciton continuum. The obtain ed results reveal the basis of the cavity polariton scattering model for th e DFWM processes in high-Q GaAs microcavity.