Rising and falling time of amplified picosecond optical pulses by semiconductor optical amplifiers

After adopting the theoretical model that includes several physical mechanisms such as the position- and time-dependent carrier lifetime, the gain saturation caused by the depletion of carrier density owing to the stimulated emission, the gain compression induced by the intraband process of carrier heating and spectral hole burning, the gain asymmetry and shift, both the rising and falling time of amplified picosecond optical pulses by the semiconductor optical amplifiers (SOAs) have been investigated numerically. The results show that with the increase of the bias current of SOAs or the length of SOAs, the rising time will decrease and the falling time increase; the input pulse with a large peak power will accelerate the rising time shortening and the falling time lengthening; the gain compression has an obvious influence on the rising and falling time for several picosecond width input pulses and gives approximately no effect for the input pulses in the tens of picosecond range; the gain asymmetry and shift affects the rising and falling time.