On the Impact of Non-Linear Phase-Noise on the Assessment of Long-Haul   Uncompensated Coherent Systems Performance
  We accurately characterize nonlinear phase noise in uncompensated coherent optical systems. We find that, though present, its impact on system performance is typically negligible in a wide range of practical system scenarios. 
Y. Jiang, A. Carena, P. Poggiolini, F. Forghieri
physics.optics