Nonlinear frequency shifting of optical NRZ pulses induced by electrostriction in fibers

The electrostrictive nonlinearity in optical fibers leads to cross-phase modulation between the pulses of a periodical train. First measurements of the resulting nonlinear frequency shift across the bit profiles agree well with the theoretical predictions. We present, we believe for the first time, an experimental and theoretical study of the role of electrostrictive nonlinearity in the propagation of optical nonreturn-to-zero (NRZ) pulse trains down optical fibers. Indeed, for certain resonant values of the pulse repetition rate, electrostriction may introduce a strong cross-phase modulation (XPM) among consecutive pulses.