title: Absolute time-resolved x-ray laser gain measurement.
abstract: We present the first direct measurement of the time evolution of the gain of a soft x-ray laser amplifier. The measurement is based on the injection of a seed pulse, obtained by high-order harmonic generation, into an x-ray laser medium. Strong amplification occurs when the seed pulse is synchronized with the gain period. By precisely varying the delay between the x-ray laser plasma creation and the seed pulse injection, the actual temporal evolution of the soft x-ray amplifier gain is obtained with a subpicosecond resolution.
authors.affiliation: Laboratoire d'Optique Appliquée, ENSTA-Ecole Polytechnique, Chemin de la Hunière, 91761 Palaiseau, France.
authors.forename: T
authors.initials: T
authors.lastname: Mocek
authors.forename: S
authors.initials: S
authors.lastname: Sebban
authors.forename: G
authors.initials: G
authors.lastname: Maynard
authors.forename: Ph
authors.initials: P
authors.lastname: Zeitoun
authors.forename: G
authors.initials: G
authors.lastname: Faivre
authors.forename: A
authors.initials: A
authors.lastname: Hallou
authors.forename: M
authors.initials: M
authors.lastname: Fajardo
authors.forename: S
authors.initials: S
authors.lastname: Kazamias
authors.forename: B
authors.initials: B
authors.lastname: Cros
authors.forename: D
authors.initials: D
authors.lastname: Aubert
authors.forename: G
authors.initials: G
authors.lastname: de Lachèze-Murel
authors.forename: J P
authors.initials: JP
authors.lastname: Rousseau
authors.forename: J
authors.initials: J
authors.lastname: Dubau