Dispersion-managed Soliton Propagation Research Articles

Higher-order Gabitov–Turitsyn equation for solitons in optical fibers

The higher-order multiple-scale asymptotic analysis is carried out for the Gabitov–Turitsyn equation that governs the propagation of dispersion-managed solitons through optical fibers. The averaged equation, with the consideration of higher-order terms, provides an in-depth understanding of the soliton propagation through an optical fiber. The polarization preserving fibers as well as birefringent fibers are considered in this paper. Finally, the study is extended to the case of multiple channels, namely dispersion-flattened fibers.

Effects of periodically inhomogeneous birefringence on dispersion-managed soliton propagation and interaction

Effects of the periodically inhomogeneous birefringence on the dispersion-managed soliton propagation are investigated by the numerical simulation. It is found that the birefringence leads to the disintegration of the soliton, enhances the interaction between solitons, and there is the worst period length corresponding to the largest effect. The theoretical analyses prove the existence of the worst period length by the variational approach, and the worst period length relates to the dispersion map and the pulse amplitude. Finally the nonlinear gain combining the filter is introduced to suppress effectively the effects.

Parametric Resonance and Radiative Decay of Dispersion-Managed Solitons

We study propagation of dispersion-managed solitons in optical fibers which are modeled by the nonlinear Schrodinger equation with a periodic dispersion coefficient. When the dispersion variations are weak compared to the average dispersion, we develop perturbation series expansions and construct asymptotic solutions at the first and second orders of approximation. Due to a parametric resonance between the dispersion map and the dispersion-managed soliton, the soliton generates continuous-wave radiation leading to its radiative decay. The nonlinear Fermi golden rule for radiative decay of dispersion-managed solitons is derived from the solvability condition for the perturbation series expansions. Analytical results are compared to direct numerical simulations, and good agreement is obtained.

Dispersion-managed soliton propagation in optic fibers with random dispersion

Propagation of dispersion-managed solitons in optic fibers with randomly distributed dispersion is studied. It is shown that the effect of the dispersion fluctuations can be described within the framework of a modified nonlinear Schrodinger equation with a frequency-dependent damping term (∼ω4). The presence of randomly modulated dispersion leads to the damping of optical pulses. The condition for stable pulse propagation is determined based on the corresponding variational equations.

Stability analysis of dispersion-managed soliton propagation with reamplification, reshaping, and retiming all-optical regeneration

We analyze the propagation stability of dispersion-managed solitons in long-distance fiber optic links, as it is influenced by in-line control elements such as synchronous intensity modulators and filters. The soliton stability analysis permits us to optimize dispersion map design as well as the input optical pulse’s energy and prechirp in the presence of periodic all-optical regeneration. Substantial agreement is obtained between the predictions of linear stability analysis and beam propagation simulations. Dispersion mapping and control are optimized for amplification, reshaping, and retiming regeneration of long-haul transmissions at a 40-Gbit/s channel rate.

Stabilization of dispersion-managed solitons in random optical fibers by strong dispersion management

The propagation of dispersion-managed solitons in optical fibers with randomly perturbed dispersion maps is considered. The interplay between the periodic dispersion management and the random dispersive fluctuations is precisely analyzed. Analytic expressions are derived for the moments of the pulse widths as well as for the probability density functions. It is shown that a strong dispersion management stabilizes the soliton, while a small anomalous residual dispersion is necessary for preventing from a stochastic resonance phenomenon. Analytical results are confirmed by direct numerical simulations.

Dispersion-managed soliton propagation in short-period dispersion maps

We show through detailed numerical simulations that stable dispersion-managed solitons exist in short-period dispersion maps characterized by a dispersion-management period that is less than the amplifier spacing. These pulses show regular dynamics within the amplifier span and have greater energy enhancement than the conventional dispersion-managed soliton. We also show that greater interaction is obtained in this regime as a result of this increased enhancement.

Disintegration of a soliton in a dispersion-managed optical communication line with random parameters

The propagation of dispersion-managed solitons in optical fiber links with a random dispersion map has been studied. Two types of randomness are considered:random dispersion magnitudes and random lengths of the spans. By numerical simulations, disintegration of a soliton propagating in such an optical communication line is shown to occur. It is observed that the stability of the soliton propagation is affected more by modulations of the dispersion magnitudes of the spans than by modulations of the span lengths. Results of numerical simulations of the soliton breakup distance confirm theoretical predictions in the averaged dynamics limit.

Experimental demonstration of long-distance dispersion-managed soliton propagation at zero average dispersion

We observed for the first time stable propagation of dispersion-managed solitons with zero or slightly below normal average dispersion over 28000 km in a recirculating fiber loop. Comparison between theory and experiment provides a highly sensitive estimate of the average dispersion.

Collisions in dispersion-managed soliton propagation

We study collisions in dispersion-managed soliton propagation for wavelength-division multiplexing application at zero net dispersion when the Gordon-Haus timing jitter is removed. We show that the collisions can lead to group-velocity changes and spectral collapse. Large channel separation ameliorates the effects. Filters prevent spectral collapse but do not affect the velocity changes.

Energy enhancement of dispersion-managed solitons in optical fiber transmission systems with lumped amplifiers

We simulated dispersion-managed soliton propagation in optical fiber transmission systems with lumped amplifiers and loss. The energy enhancement of dispersion-managed solitons can be more or less than in the lossless case, depending delicately on the amplifiers arrangement. In all cases, there is a maximum enhancement factor beyond which the dispersion-managed soliton no longer exists and which also depends delicately on the arrangement.

Dispersion-managed solitons in the normal dispersion regime: a physical interpretation

We present an analytic description of dispersion-managed soliton propagation based on split-step and variational models. Using these models, we derive the threshold map strength for the existence of dispersion-managed solitons in the normal dispersion regime and obtain a bound on the maximum normal average dispersion.

Dispersion-managed solitons with net positive dispersion

Propagation of dispersion-managed solitons in the net positive-dispersion regime is studied. A new form of sideband generation that is due to perturbations is identified. Some collision anomalies are pointed out.

Soliton interaction in dispersion-managed links

Terrestrial systems based on dispersion-managed solitons are limited by the signal-to-noise-ratio degradation that is due to amplifier noise and soliton interaction. The propagation of dispersion-managed solitons is modeled with two parameters. Rules for determining easily the steady propagation conditions are given. For the study of the soliton interaction, two more parameters per soliton are required (time and frequency). An accurate modeling of the time and frequency shifts induced by the interaction is derived with a Lagrangian formalism. Both single and alternate polarizations are considered. The interaction is shown to be increased with dispersion-managed solitons as compared to path-averaged solitons; however, system performance is shown to be better with dispersion-managed solitons thanks to increased soliton energy.

Dispersion-managed soliton interactions in optical fibers

We simulated dispersion-managed soliton propagation and interaction in optical fibers. The energy-enhancement factor, together with the time-bandwidth product and the stretching factor, were calculated as a function of the difference in absolute values of accumulated dispersion in the fiber spans. The interaction strength of the dispersion-managed solitons was found to depend on the stretching factor. When this factor is less than 1.5, the interaction is weaker than for ideal solitons. When it is more than 1.5, there is a strong interaction between the pulses, which constrains the energy enhancement for practical applications.