High-speed DPSK coherent systems in the presence of chromatic dispersion and Kerr effect

The error probability for a single-channel coherent optical differential phase-shift keying (DPSK) transmission system based on repeaterless links in the presence of fiber chromatic dispersion and Kerr effect is evaluated. An accurate model for both the optical signal propagation and the probability distribution of the receiver decision variable is obtained by using a numerical solution of the nonlinear Shrodinger equation and the characteristic function method. The results show that the selection of an optimized IF filter bandwidth is crucial to obtaining the best system performance. When chromatic dispersion dominates, the best performance is achieved in the normal dispersion region whereas when the Kerr effect has the most limiting effect on system performances, the lowest error probability is attained in the anomalous regime. The maximum link length is limited by the presence of Kerr effect, independently of the amount of transmitted optical power, to be shorter than a threshold length if an error probability of 10^-9 is to be achieved