Temporal and spectral effects of cross-phase modulation on copropagating ultrashort pulses in optical fibers.

Abstract

The effects of cross-phase modulation (XPM) on the evolution of copropagating ultrashort pulses in an optical fiber are discussed theoretically by solving the coupled-amplitude equations which include the contributions of self-phase modulation, XPM, pulse walk-off, and group-velocity dispersion. A pump-probe configuration is studied to isolate the XPM effects. In the case of nondispersive XPM, the probe shape remians nearly unchanged while the probe spectrum exhibits asymmetric spectral broadening and a shift toward the red or the blue side depending on the initial pump-probe delay. In the case of dispersive XPM, the combination of group-velocity dispersion and XPM lead to both temporal and spectral changes. The new XPM-induced phenomena, optical wave breaking, and pulse compression are discussed in detail.