Modeling and measurement of longitudinal gain dynamics in saturated semiconductor optical amplifiers of different length

A new frequency-domain wave-propagation model that includes a position- and time-dependent carrier lifetime and the effect of amplified spontaneous emission is introduced and used to accurately simulate recovery time experiments in 0.5- and 1.0-mm long semiconductor optical amplifiers. It is compared to a constant lifetime model at different saturation levels, showing better performance and consistency. The role of the amplified spontaneous emission in saturated amplifiers is also discussed.