Comparative study of mixed frequency-time-domain models of semiconductor laser optical amplifiers

A variety of mixed frequency-time-domain travelling wave models have been developed for the performance simulation of semiconductor laser optical amplifiers. One of the key differences among these models lies in their treatment of the phase of the interacting optical waves (signals and noises). Based on this criterion, the models are classified into the full-wave (phases of both signal and noise considered), the half-wave (only signal phase considered), and the full-power (all phases neglected) models. A systematic study on those models is carried out in the context of the signal-noise beating in optical amplifiers. It is found that only the full-wave model, which treats the beating between the signal and ASE noise in an incoherent manner, can provide the correct results, whereas the half-wave and the full-power models fail in cases where the interaction between the signal and ASE noise becomes significant.