Gain dynamics in traveling-wave semiconductor optical amplifiers

A theoretical analysis of the optical properties of multiquantum well semiconductor optical amplifiers (MQW-SOA) have been performed in the time-dependent regime. We describe the interaction between pulse propagation and gain compression within a pump-probe excitation in polarization insensitive MQW-SOA. We use a phenomenological model based on rate equations (describing the carrier dynamics in the different heterolayers along the growth axis for both bulk and MQW structures), coupled with the description of picosecond optical pulse propagation within a semiconductor slab (along the active waveguide axis), to describe the way gain dynamics determine the optical response of the SOA. Our model agrees well with available experimental data and also reveals the conditions for the validity of previous simpler approaches.