Effect of nonlinear dispersion on pulse self-compression in a defocusing noble gas

Media with a negative Kerr index (n2n2) offer an intriguing possibility to self-compress ultrashort laser pulses without the risk of spatial wave collapse. However, in the relevant frequency regions, the negative nonlinearity turns out to be highly dispersive as well. Here, we study the influence of nonlinear dispersion on the pulse self-compression in a defocusing xenon gas. Purely temporal (1+1)-dimensional investigations reveal and fully spatio-temporal simulations confirm that a temporal shift of high intensity zones of the compressed pulse due to the nonlinear dispersion is the main effect on the modulational instability (MI) mediated compression mechanism. In the special case of vanishing n2n2 for the center frequency, pulse compression leading to the ejection of a soliton is examined, which cannot be explained by MI.

Research highlights
► Negative Kerr index allows pulse self-compression without spatial wave collapse.
► Strong nonlinear dispersion does not prevent this solitary compression effect.
► Optimal compression parameters can be estimated from modulational instability theory.
► For vanishing Kerr index, nonlinear dispersion causes alternative compression scheme.