On the transition to pseudo-linear regime in dispersion managed systems with NRZ, RZ and duobinary signal formats

The transition to the pseudo- or quasi-linear regime in single channel transmission for non-return-to-zero, return-to-zero and duobinary signal formats is investigated. An expression for the transition bit rate to such regime, valid for the three different formats, is proposed. Several duty cycles and pulse shapes are assessed in the case of the return-to-zero format. Dependencies of the transition bit rate on fibre parameters are presented in an explicit form and confirmed using extensive simulation for standard singlemode fibre and nonzero dispersion shifted fibre. Using the obtained expression, the origin of the main transmission impairments in single channel transmission can be assessed and conclusions about the optimum post-compensating dispersion managed scheme can be drawn.