SBS threshold dependence on line coding in phase-modulated coherent optical systems

Two main applications are foreseen in the future communication environment for optical coherent transmission systems: long-haul high-capacity links and multichannel FDM systems. The technological developments in high-power, narrow-linewidth, single-mode semiconductor lasers and wide-band high-sensitivity coherent receivers lead to systems in which the main limitation to the maximum link length is constituted by nonlinear effects. In particular in single-channel systems the most important nonlinear effect is stimulated Brillouin scattering (SBS). The dependence of the stimulated Brillouin threshold on the adopted line code in phase-modulated coherent optical systems is studied considering some of the most common line codes.