Detuning dependence of four-wave mixing between picosecond pulses in a multi-quantum well semiconductor optical amplifier

Four-wave mixing is investigated experimentally using frequency resolved optical gating in a multi-quantum well semiconductor optical amplifier. Demultiplexing is carried out from 80 GHz to 10 GHz using two picosecond pulses. The pump-probe detuning is varied and it is found that the probe phase is preserved in the four- wave mixing signal across the central portion of the pulse. Also, the pedestals present in the four-wave mixing waveform are measured and it is found that the impact of these pedestals increases as a function of the detuning due to the carrier dynamics in the device.