Hannover 2013 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 5: Attosecond physics
A 5.5: Vortrag
Montag, 18. März 2013, 15:15–15:30, B 305
Prediction of attosecond light pulses in the VUV range in a high-harmonic generation regime — •Jost Henkel1,2, Tobias Witting2, Davide Fabris2, Manfred Lein1, Peter L. Knight2, John W. G. Tisch2, and Jonathan P. Marangos2 — 1Institut für Theoretische Physik and Centre for Quantum Engineering and Space-Time Research (QUEST), Leibniz Universität Hannover Appelstraße 2, 30167 Hannover, Germany — 2Blackett Laboratory, Imperial College London, Prince Consort Road, South Kensington, London SW7 2AZ, UK
Attosecond (as) pump-probe experiments are one of the ultimate goals for the investigation of electron and hole dynamics in atoms and molecules. For an efficient transient population of specific excited states, strong short light pulses with a narrow frequency spectrum are needed. To overcome limitations of current XUV sources, we propose to select high-harmonic frequencies in the VUV range with an indium filter. Its transmission window is centered at 15 eV and has a bandwidth of 3.7 eV, yielding a Fourier limit of 700 as. We confirm this by calculating high-order harmonic spectra from the solution of the time-dependent Schrödinger equation (TDSE). For a model neon atom we compare linearly polarised laser pulses to the polarisation gating method with elliptical pulses. Such below threshold harmonics have low sensitivity to the generating field’s ellipticity, leading to elliptically polarized attosecond pulses. The problematic lack of spontaneous decay in the TDSE, which causes strong below-threshold emission peaks, can be circumvented by accounting for macroscopic intensity averaging.