Propagation of an optical pulse in a fiber link with random dispersion management

Abstract

A model of a long optical communication line consisting of alternating segments with anomalous and normal dispersion, whose lengths are picked up randomly from a certain interval, is considered. At the first stage of the analysis, we calculate small changes of parameters of a quasi-Gaussian pulse passing a two-segment cell by means of the variational approach (VA), and approximate the evolution of the pulse passing many cells by smoothed ODEs with random coefficients, which are then solved numerically. Next, we perform systematic direct simulations of the model. Results are presented as dependences of the pulse's mean width, and standard deviation of the width from its mean value, on the propagation distance. The results produced by VA and direct simulations are similar. Averaging over 200 different realizations of the random-length set reveals slow long-scale dynamics of the pulse, frequently in the form of long-period oscillations of its width. It is thus found that the soliton is most stable in the case of the zero path-average dispersion (PAD), less stable in the case of anomalous PAD, and least stable in the case of normal PAD. The soliton's stability also strongly depends on its energy, the soliton with small energy being much more robust than its large-energy counterpart.