Electrical measurements of multipath interference in distributed Raman amplifiers

Measurements of multipath interference (MPI) using an electrical technique have shown that the use of distributed Raman amplification can significantl y increase the amount of MPI in a system. The MPI is primarily attributed t o double-Rayleigh scattering along the length of the transmission fiber. An alytical expressions for MPI have been developed that give good agreement w ith measurements and numerical simulations. These can be used to predict th e buildup of MPI in a lightwave transmission system. Poor connectors will c ause a further increase in MPI by causing back-reflections into the Raman g ain cavity.