Limits of nonlinear optical transmission systems induced by the non-ideal behaviours of the transmitter

A numerical analysis on the impact of the degrading effect that can be present in a real transmitter for high capacity optical transmission systems has been carried out. The author refers to the soliton propagation in the regime of fluctuating chromatic dispersion or Group Velocity Dispersion (GVD) regime, also known as dispersion management since this is the method that permits the highest capacity to be achieved. The result show that in the case of an external modulator, the transmitted signal can be considered as ideal if the chirp parameter is lower than 0.5 and the extinction ratio is higher than 16 dB. Conversely the presence of a directly modulated laser induces much stronger limitation but transmission at 10 Gbit/s on links 3000 km long can be achieved if the dispersion management method is used