Nonlinear phase-locking of parametric optical processes:: the sliding resonance effect

We describe a new basic type of nonlinear interaction between optical pulses which considers parametric processes occurring in the presence of cross-phase modulation. The resulting sliding resonance effect strongly influences the phase-matching conditions, giving rise to a nonlinear phase-locking mechanism. The explicit example of the resulting modified parametric amplification is considered in detail using both analytical and numerical approaches. Preliminary experimental results which evidence the extension of this effect to four-wave mixing processes will also be presented.