Distributed amplification: how Raman gain impacts other fiber nonlinearities

The gain and noise figure of distributed amplifiers can be integrated and lumped at the end of each fiber span. This paper investigates whether this convenient simplification is valid in the presence of fiber nonlinearities. Distributed Raman amplification affects other fiber nonlinearities by changing the evolution of signal power along the fiber. Depending on system parameters can impact on self phase modulation and four wave mixing when gain is greater than -15 dB and increases the signal-to-signal Raman power transfer for all system at much lower gain values.