Measurement of the nonlinear coefficient of optical fibers by femtosecond pulses and spectral interferometry

Accurate measurements of the nonlinear coefficient (gamma) of optical-communication fibers are performed by using 110-fs pulses. The nonlinear phase shift induced by self-phase modulation over a propagation length shorter than 1 m is detected by the spectral-interferometry technique. The value of (gamma) is obtained by comparing the measured frequency-dependent nonlinear phase with the numerical solution of the nonlinear propagation equation.