Accurate noise characterization of wavelength converters based on XGM in SOAs

Wavelength conversion (WCR) has recently emerged as an important technique that can be used to manage the spectacular increase in traffic in dense wavelength division multiplexing (DWDM) networks. WCR is extremely useful to solve contention, reduce wavelength blocking and a wide range of WCR methods have been reported. The optimum placement of these devices within a network remains an unexplored area and accurate models to measure the performance of the system are becoming vital. Therefore, this paper presents an original noise characterization of a class of WCRs based on cross-gain modulation (XGM) in semiconductor optical amplifiers (SOAs) when the components from spontaneous emission of the SOAs at the receiver are dominant over thermal and shot noise terms. A new and simple expression for the error probability (P_e) is presented offering considerable additional accuracy in sensitivity assessment compared with the Gaussian approach when ASE noise is dominant. Simulation comparisons are presented in different scenarios for a standard system working at 2.5 Gb/s in a metropolitan area network taking into account the key parameters when such systems are designed.