Statistical properties of polarisation dependent gain in fibre Raman amplifiers

The statistical effects of polarisation dependent gain in Raman amplifiers in co-pumped and counter-pumped configurations were analysed. The gain distribution obtained followed a normal distribution, with the standard deviation determined by the degree of polarisation (DOP) of the pump source and the added Raman gain. The polarisation dependent gain (PDG) is found to be substantial for a Raman amplifier if a highly polarised pump source is utilised. Using the Monte-Carlo technique to simulate the PDG with Mueller matrices of an array of random birefringent elements, the distribution approached a good normal distribution fit, similar to that obtained experimentally.