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K: Fachverband Kurzzeitphysik
K 5: Laserstrahlwechselwirkung und Laseranwendungen
K 5.5: Vortrag
Dienstag, 26. Februar 2013, 15:00–15:15, HS 4
High Harmonic Generation from Relativistic Plasma Surfaces in Steep Plasma Density Gradients — •Erich Eckner1, Christian Rödel1,2, Daniel an der Brügge3, Jana Bierbach1,2, Mark Yeung4, Thomas Hahn5, Brendan Dromey4, Dirk Hemmers5, Georg Pretzler5, Oswald Willi5, Alexander Pukhov3, Matthew Zepf2,3, and Gerhard Paulus1,2 — 1Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena — 2Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany — 3Institut für Theoretische Physik, Heinrich-Heine Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf — 4Centre for Plasma Physics, Queen’s University Belfast, BT7 1NN, United Kingdom — 5Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
High harmonic generation by the interaction of intense laser pulses from relativistically oscillating surface plasmas is studied experimentally. Our observations reveal that efficient generation (10−4 … 10−6 at 20-40 eV) requires steep plasma density scale lengths (Lp/λ < 1). However, the harmonic efficiency declines for the steepest plasma density scale lengths Lp → 0. We have further observed a strong influence of the plasma scale length on the spectral fine structure of the high harmonics. While sharp harmonic lines are obtained for short plasma scale lengths, an extended plasma profile leads to strongly modulated harmonic spectra. Our experimental findings are reproduced by numerical simulations and simple analytical models.