Coherent Dynamics of Excitonic Nonlinear Optical Response in the Nonperturbative Regime

We report experimental and theoretical studies of the transient nonlinear response from semiconductor microcavities. We show that, in the nonperturbative regime, oscillations in time-integrated transient four-wave mixing do not correspond to normal mode oscillations of either the exciton or photon population in the cavity. Coherent nonlinear responses arising from band filling, excitation-induced dephasing, and renormalized electric fields feature highly distinctive dynamical behaviors. Coherent dynamics in transient four-wave mixing reflects interference between these nonlinear processes. {copyright} {ital 1998} {ital The American Physical Society }