Resonances of the nonlinear refractive index of optical fibers

Summary form only given. In this paper we report the frequency behavior of the nonlinear refractive index of optical fibers for telecommunications, accurately measured through a polarization-insensitive cross-phase modulation technique. The experimental setup is shown. The sinusoidally intensity modulated pump and the probe copropagate in the fiber under test and the phase shift induced by the pump on the probe is measured by an interferometric technique.