From exciton resonance to frequency mixing in the femtosecond nondegenerate four-wave mixing

We demonstrate a transition from exciton resonance to frequency mixing for the first time, in the nondegenerate femtosecond four wave mixing (FWM) of a GaAs-AlGaAs multiple quantum well. The frequency mixing which is dominant at high intensity and high detuning survives only within the pulse-width.