Impact of multiple-path interference on the performance of coherent transmission systems employing distributed Raman amplification

Abstract

It is well known that distributed Raman amplification (DRA) may suffer from multiple-path interference, which is mainly due to double back-reflections (DBR) at discontinuities such as connectors/splices and double Rayleigh backscattering (DRB) within the fiber amplifier. In this work, the impact of DBR and DRB noise on the system performance is analytically assessed for standard single mode and large effective area low loss fiber links employing PDM-16QAM and DRA. Performance prediction errors due to negligence of DRB noise are estimated, and operation criteria are provided for mitigating back-reflection induced impairments.