Abstract
Both nearly degenerate four-wave mixing (FWM) and cavity-enhanced highly nondegenerate four-wave mixing have been studied in a GaAs/AlGaAs semiconductor laser operated above threshold. It is observed that the cavity-enhanced highly nondegenerate FWM signal is of the same order as the nearly degenerate FWM signal. A four-wave mixing signal enhancement of about 90 dB as compared to the background signal is observed at the pump-probe detuning corresponding to the round-trip frequency of the pump laser. The probe amplification is measured in the same frequency range and a large enhancement is also observed.