Measurement of pulse amplitude and phase distortion in a semiconductor optical amplifier: from pulse compression to breakup

We have performed extensive measurements of the propagation of ultrashort p ulses in a semiconductor bulk amplifier using an ultrasensitive cross frequ ency-resolved optical gating technique, Pulses of 175-fs duration with ener gies from below 1 fJ to above 100 pJ are measured both in amplitude and pha se after propagation through the device. While only moderate reshaping effe cts occur at pulse energies of below I pJ, strong amplitude distortion toge ther with nonlinear chirp is found for input energies of 5-100 pJ, This lea ds to a pulse narrowing by more than a factor of two when the amplifier is biased for material transparency or absorption and to a pronounced pulse br eakup in the gain regime.