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Effects of Raman noise and double Rayleigh backscattering on bidirectionally Raman-pumped systems at constant fibre nonlinearity

The impact of Raman noise and double Rayleigh backscattering on the noise figure of a bidirectionally Raman-pumped transmission fibre is evaluated under the constraint of constant fibre nonlinearity. It is shown that there is an optimum Raman gain and percentage of forward pumping that maximises the effective noise figure improvement of a transmission fibre span.