Spatiotemporal instability of an intense subpicosecond laser pulse in gases

A spatiotemporal instability of a high-intensity (10¹⁵ — 10¹⁶ W cm^–2) laser pulse in a defocusing medium (plasma) is demonstrated and investigated. The plasma is assumed to form in the course of passage of the pulse through an atmospheric-density gas. The reason for the appearance of this instability is the time dependence of the nonlinear response of the medium (nonlinear dispersion).