Suppression of soliton jitter by a copropagating support structure

A new way to suppress the soliton's jitter in long-haul optical communication systems is proposed that does not use in-line filters. Parallel to the information-carrier soliton stream, a periodic stiff array (consisting of bright or dark solitons) is launched in another mode, which may be either an orthogonal polarization or, more realistically, another wavelength. This support array induces, through the cross-phase modulation, an effective potential pinning of the signal solitons. Most promising is the scheme in which the support structure is an array of dark solitons (while the information is carried by the bright ones). In the analytical part of the work we derive a Langevin equation for the information soliton in the presence of the induced potential and of a random force representing the jitter, for both cases when the support channel has anomalous or normal dispersion. Next, we derive the corresponding Fokker-Planck equation. A solution to this equation explicitly demonstrates a strong suppression of the jitter in comparison with the Gordon-Haus limit. To check this mechanism directly we perform numerical simulations of the coupled nonlinear Schrodinger equations for the information and support channels, including the jitter-generating random perturbations acting in both of them. The simulations demonstrate that, while in the absence of the support structure the soliton's jitter is growing in accord with the Gordon-Haus law, the support structure strongly suppresses the jitter, as is predicted by the analysis. (C) 1997 Optical Society of America [S0140-3224(97)01412-4].