Phase noise insensitive measurements of the nonlinear refractive index in fiber links

摘要

A method for measuring the nonlinear refractive index, n_2, along optically amplified fiber transmission lines of high-bit-rate transmission systems is presented in this paper. Measurements of the Kerr-induced nonlinear phase-shift as a function of the optical power are performed through a cross-phase-modulation scheme by using a coherent delayed-self-homodyne technique that we demonstrate to be a solution particularly insensitive to the phase noise in high-frequency operation. Experiments performed at 2.5 Gbit/s are in agreement with theoretical predictions.