Impact evaluation of the SOA spontaneous emission in ultrafast all-optical processing schemes

In ultrafast all-optical signal processing schemes based on nonlinear effects in SOAs, the impact of the device spontaneous emission noise is not negligible. Therefore a numerical extended model is developed in order to predict SOA noise behaviour. The proposed tool takes into account all the gain recovery dynamics, the current-induced gain saturation, and the gain spectrum dependence on the injected current. The noise spectrum at the output of the device is investigated as a function of the injected current and of the input power, and the numerical results are experimentally validated. The importance of the ASE introduction in the numerical analysis of the SOA-based schemes for ultrafast all-optical processing is demonstrated studying two particular applications. In particular, the effects of high detuning FWM and of XGM are analysed in the presence and absence of ASE noise.