Erlangen 2018 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 3: Ultrashort Laser Pulses

Q 3.2: Vortrag

Montag, 5. März 2018, 10:45–11:00, K 0.023

Quasi-phase matched high harmonic generation in spatially structured Al plasmas — •Michael Wöstmann and Helmut Zacharias — Westfälische-Wilhelms Universität Münster, Physikalisches Institut, Wilhelm-Klemm-Straße 10, 48149 Münster

A route is presented in order to realize quasi-phase-matching of high-order harmonic generation in laser produced plasmas. This requires the spatial modulation of the plasma. A simple stack of thin target material (ca. 0.5 mm) and spacers is used in order to induce the modulation. The exact dimensions are derived by measuring the coherence lengths in unmodulated plasmas and the beam profile with respect to the focal position of the harmonic generating beam. The geometric phase advance of the fundamental radiation through its focus is found to be the governing parameter for resetting the phase of the emitted harmonic radiation between two slices of plasma. Applying four separated plasma plumes, an enhancement factor of 170 is observed for the 25th harmonic in relation to the maximal harmonic intensity generated in an unmodulated plasma of the same composition. The principle is expected to work even better at higher harmonic orders.