Implementation of non-linearity management for Gaussian pulses in a fiber-optic link by means of second-harmonic-generating modules

We introduce a model for the non-linearity compensation ("management"), based on second-harmonic-generating [χ⁽²⁾] elements, integrated with amplifiers, which are periodically inserted into a fiber-optic link. The link features the Kerr [χ⁽³⁾] non-linearity, group-velocity dispersion (GVD), and loss. Simulations demonstrate that the system can directly provide for effective compensation of the fiber non-linearity for quasi-Gaussian pulses over the propagation distance z up to 10 fiber spans between the χ⁽²⁾ modules, and the interaction between adjacent pulses does not manifest itself over the same propagation distance, provided that the separation between them is ≃5 widths of the pulse or more. The results are sensitive to the correct choice of the mismatch parameter in the χ⁽²⁾ module, but not to variation of other parameters (for instance, peak power of the pulses). For larger values of z, distortion of the pulses commences under the action of GVD. This can be prevented by periodic dispersion compensation. Although the latter is not directly included into the model, it is demonstrated that the non-linearity and dispersion compensation can be implemented independently, as they take place at essentially different scales of z for typical NRZ pulses. Thus, the stable-transmission distance can be expanded much farther.