Quasi-steady state self-trapping of first, second and third order subnanosecond soliton beams

Abstract

Self-trapping of pulsed laser beams exhibits a complex spatio-temporal behaviour, due to the temporal dependence of the intensity during the whole exciting laser pulse duration. Here we suppress the temporal dependence of self-induced convergence thanks to a well-suited excitation of the nonlinear medium: a temporal shaping device transforms gaussian laser pulses in ”flat topped“ subnanosecond pulses of high power (transient edges of these pulses are carrying negligible energies). Then the intensity dependence of the refractive index induces a quasi-steady state, stable beam self-trapping patterns agree satisfactorily with well known features of soliton propagation.