Propagation of ultrashort optical pulses in a semiconductor optical amplifier: simulation and experiments

We apply a new rate-equation model to study the propagation of sub-picosecond optical pulses in a semiconductor optical amplifier (SOA). This model accounts for the dynamics of important ultrafast intraband processes in SOAs, such as two-photon absorption, free-carrier absorption, self- and cross phase modulation, self- and cross polarisation modulation, carrier heating, spectral and spatial hole burning. Using our model, we have obtained numerical results for the carrier/gain dynamics, the amplitude/phase changes of 200fs optical pulses as well as the nonlinear polarization rotation induced by the optical pulse in pump-probe experiments in a SOA. These results are in good agreement with our preliminary experimental measurements, which confirms that SOAs are good candidates for all-optical ultrafast switching devices in optical communication systems.