Impacts of dispersion maps on nonlinear distortion in distributed Raman amplified multi-span systems

The influences of dispersion maps on three major nonlinear effects (SPM, XPM and SRS) in distributed Raman amplified fiber transmission systems with periodic dispersion compensation are numerically investigated at identical nonlinear phase shift. The results show that compared with lumped amplification, distributed amplification tends to enhance the SPM/XPM induced penalties provided per span complete DC is used. However, these performance differences can be canceled out by means of optimal dispersion managements. Moreover, distributed Raman amplification can change the optimal dispersion maps for XPM effects. On the other hand, the impacts of SRS crosstalk are mainly determined by wavelength spacing and walk-off parameter, and the effects of dispersion management are quite limited. For a system with properly designed fiber dispersion characteristics, SRS induced waveform distortion can be well suppressed.