title: Postionization regimes of femtosecond laser pulses self-channeling in air.
abstract: An optical self-guiding of femtosecond filaments in air is identified in a regime where plasma generation ceases to support the self-channeling process. Group-velocity dispersion is shown to keep the beam temporally and spatially localized upon a few meters by taking over the ionization of air molecules, once the pulse peak power becomes close to the self-focusing threshold. In this regime, the pulse undergoes slow splitting events that maintain a residual self-guiding with light intensities as high as 10 TW/cm2, as soon as the electron plasma density has fallen down below 10(15) cm(-3).
authors.affiliation: Département de Physique Théorique et Appliquée, CEA/DAM Ile de France, B.P. 12, F-91680 Bruyères-le-Châtel, France. stephanie.champeaux@cea.fr
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Champeaux
authors.forename: Luc
authors.initials: L
authors.lastname: Bergé