title: Complete temporal characterization of asymmetric pulse compression in a laser wakefield.
abstract: We present complete experimental characterization of the temporal shape of an intense ultrashort 200-TW laser pulse driving a laser wakefield. The phase of the pulse was uniquely measured by using (second-order) frequency-resolved optical gating. The pulses are asymmetrically compressed and exhibit a positive chirp consistent with the expected asymmetric self-phase-modulation due to photon acceleration or deceleration in a relativistic plasma wave. The measured pulse duration decreases linearly with increasing length and density of the plasma, in quantitative agreement with the intensity-dependent group velocity variation in the plasma wave.
authors.affiliation: Blackett Laboratory, Imperial College, London SW7 2AZ, United Kingdom. j.schreiber@imperial.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Schreiber
authors.forename: C
authors.initials: C
authors.lastname: Bellei
authors.forename: S P D
authors.initials: SP
authors.lastname: Mangles
authors.forename: C
authors.initials: C
authors.lastname: Kamperidis
authors.forename: S
authors.initials: S
authors.lastname: Kneip
authors.forename: S R
authors.initials: SR
authors.lastname: Nagel
authors.forename: C A J
authors.initials: CA
authors.lastname: Palmer
authors.forename: P P
authors.initials: PP
authors.lastname: Rajeev
authors.forename: M J V
authors.initials: MJ
authors.lastname: Streeter
authors.forename: Z
authors.initials: Z
authors.lastname: Najmudin