Nonsoliton pulse evolution in normally dispersive fibers

For a typical nonreturn-to-zero pulse propagating in existing normally dispersive fibers, we provide a uniform description of the optical transmission. There are three distinct regimes of the governing nonlinear Schrödinger equation: the fully nonlinear dispersive regime, which covers a small region of the pulse, and two limiting asymptotic regimes, namely, nonlinear, weakly dispersive (for the bulk of the pulse) and linear dispersive (for the tails). For prediction of pulse degradation, the asymptotic regimes admit accurate, simplified models for both nonlinear-dispersive pulse spreading and the onset of optical shocks and oscillations at the fronts.