Impact of double Rayleigh backscatter noise on digital and analog fiber systems

We have derived, and experimentally verified, an exact analytical expression for the noise power spectral density due to double Rayleigh backscattering in standard single mode fiber-optic transmission systems in terms of the autocorrelation function of the transmitted optical electric field. The analysis is used to examine the impact of double Rayleigh backscattering on chirped amplitude modulated-subcarrier multiplexed (AM-SCM), and optically amplified digital intensity modulated-direct detection (IM-DD) laser systems, with and without optical isolators in the link.