title: Enhancement of high-order harmonic generation at tuned wavelengths through adaptive control.
abstract: An adaptive learning loop enhances the efficiency and tuning of high-order harmonic generation. In comparison with simple chirp tuning, we observe a broader tuning range and a twofold to threefold enhancement in integrated photon flux in the cutoff region. The driving pulse temporal phase varies significantly for different tunings and is more complicated than a simple chirp. We compare our experimental results with a one-dimensional, time-dependent model that incorporates the intrinsic atomic response, the experimental pulse temporal phase, ionization effects, and transverse coherence of the spatial mode of the laser. The model agrees with our experimental results and indicates that a specific quantum path coupled with ionization effects determines the optimized harmonic spectrum.
authors.affiliation: Laboratoire d'Optique Appliquée, Ecole Nationale Supérieure des Techniques Avancées, Ecole Polytechnique, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR 7639), 91761 Palaiseau Cedex, France. reitze@phys.ufl.edu
authors.forename: David H
authors.initials: DH
authors.lastname: Reitze
authors.forename: Sophie
authors.initials: S
authors.lastname: Kazamias
authors.forename: Frederick
authors.initials: F
authors.lastname: Weihe
authors.forename: Geneviève
authors.initials: G
authors.lastname: Mullot
authors.forename: Denis
authors.initials: D
authors.lastname: Douillet
authors.forename: Frederika
authors.initials: F
authors.lastname: Augé
authors.forename: Olivier
authors.initials: O
authors.lastname: Albert
authors.forename: Vidya
authors.initials: V
authors.lastname: Ramanathan
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Chambaret
authors.forename: Danièle
authors.initials: D
authors.lastname: Hulin
authors.forename: Philippe
authors.initials: P
authors.lastname: Balcou