Analytic approximation of amplified signal double Rayleigh scattering in pumped erbium doped fibres

The level of intensity noise caused by amplified signal double Rayleigh scattering in pumped erbium doped fibres, can be analytically approximated with a high accuracy, just by knowing the Rayleigh backscatter capture fraction, Rayleigh scatter loss and the gain and length of the EDF. Underlying assumptions are uniform inversion along the fibre and negligible incoherent effects