Bit-pattern-dependent non-degenerate four-wave-mixing crosstalk in dispersion-managed DWDM systems including walk-off

In this work, through a detailed derivation process, we obtain a semi-analytic model to deterministically calculate the variance of non-degenerate four-wave-mixing (FWM) noise for return-to-zero (RZ) dispersion and loss-managed system with lumped amplifiers including walk-off between channels. We show that, in general, when the value of duty cycle becomes smaller, the values of variance are more influenced by many factors, such as channel separation, dispersion management scheme and especially relative initial time delays of all interacting channels. For a 17-channel such system, the variance of non-degenerate FWM noise falling on the central channel is given.