Pulse compression and X wave generation by cross-phase-modulation induced spatiotemporal reshaping

Filamentation dynamics in the normal group-velocity-dispersion regime (in condensed media) is interpretable in terms of the spontaneous formation of X waves that is, stationary (non-dispersive and non-diffractive) wave packets characterized by a central high-intensity spike surrounded by slowly decaying tails that continuously sustain the central peak through a refuelling mechanism. Here we investigate numerically and experimentally the role of Cross-Phase-Modulation (XPM) from an intense pump to a weaker seed signal in the presence of pump filamentation.