Theoretical and experimental investigation of conversion of phase noise to intensity noise by Rayleigh scattering in optical fibers

The conversion of laser phase noise to intensity fluctuation noise in optical fibers due to mixing with Rayleigh scattered light is considered. A theory combining the laser quantum phase dynamics and the statistical scattering in the fiber leads to simple expressions for the spectral densities of the intensity fluctuations in a number of generic cases. These are compared with experiments involving distributed feedback semiconductor lasers and low-loss fibers with lengths up to 20 km.