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Highly nondegenerate four-wave mixing among subpicosecond optical pulses in a semiconductor optical amplifier

We have demonstrated, for the first time, the highly nondegenerate four-wave mixing (FWM) among subpicosecond optical pulses in a 1.3-/spl mu/m multiple-quantum-well (MQW) semiconductor optical amplifier (SOA). We could directly measure the FWM signal in the output spectrum by current pulse pumping of the device. We achieved a high conversion efficiency of over 10% at a frequency conversion range of less than 1 THz. The limitation of conversion efficiency due to the gain saturation of the SOA was effectively overcome by using the short optical pulses.