title: High-field quantum calculation reveals time-dependent negative Kerr contribution.
abstract: The exact quantum time-dependent optical response of hydrogen under strong-field near-infrared excitation is investigated and compared to the perturbative model widely used for describing the effective atomic polarization induced by intense laser fields. By solving the full 3D time-dependent Schrödinger equation, we exhibit a supplementary, quasi-instantaneous defocusing contribution missing in the weak-field model of polarization. We show that this effect is far from being negligible, in particular when closures of ionization channels occur and stems from the interaction of electrons with their parent ions. It provides an interpretation of the higher-order Kerr effect recently observed in various gases.
authors.affiliation: Laboratoire Interdisciplinaire CARNOT de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon, France.
authors.forename: P
authors.initials: P
authors.lastname: Béjot
authors.affiliation: Centre Lasers Intenses et Applications, Université de Bordeaux-CNRS-CEA, UMR 5107, 351 Cours de la Libération, F-33405 Talence, France.
authors.forename: E
authors.initials: E
authors.lastname: Cormier
authors.affiliation: Laboratoire Interdisciplinaire CARNOT de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon, France.
authors.forename: E
authors.initials: E
authors.lastname: Hertz
authors.affiliation: Laboratoire Interdisciplinaire CARNOT de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon, France.
authors.forename: B
authors.initials: B
authors.lastname: Lavorel
authors.affiliation: Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, 1211 Geneva 4, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Kasparian
authors.affiliation: Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, 1211 Geneva 4, Switzerland.
authors.forename: J-P
authors.initials: JP
authors.lastname: Wolf
authors.affiliation: Laboratoire Interdisciplinaire CARNOT de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon, France.
authors.forename: O
authors.initials: O
authors.lastname: Faucher