During its propagation along a fiber, any noise is amplified by the modulated signal through the fiber’s nonlinearity-induced parametric gain. This nonlinear amplification of noise has been previously studied with the assumption that the signal can be approximated as continuous-wave. We present a novel method to analyze the parametric-gain-induced, nonlinear amplification of noise by an arbitrarily modulated signal based on perturbation theory. Because of the nonstationary nature of the output noise after its interaction with the modulated signal, the detailed correlation function is best computed in the frequency domain by assuming a given input bit sequence. The results are validated by split-step Fourier simulation and applied to obtain the probability distribution function of the detector statistics.
© 2004 Optical Society of America
Bo Xu and Maïté Brandt-Pearce, "Optical fiber parametric-gain-induced noise coloring and amplification by modulated signals," J. Opt. Soc. Am. B 21, 499-513 (2004)