Berlin 2014 – scientific programme

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P: Fachverband Plasmaphysik

P 27: Theory of nonideal Plasmas

P 27.2: Talk

Friday, March 21, 2014, 11:00–11:15, SPA HS201

Relativistic Frequency Synthesis of Light Fields — •Christian Rödel^1,2, Erich Eckner¹, Jana Bierbach^1,2, Mark Yeung^2,3, Brendan Dromey³, Thomas Hahn⁴, Silvio Fuchs^1,2, Arpa Galestian¹, Martin Wünsche¹, Stephan Kuschel^1,2, Dirk Hemmers⁴, Georg Pretzler⁴, Matthew Zepf^2,3, and Gerhard Paulus^1,2 — ¹Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, Jena — ²Helmholtz-Institut Jena — ³Centre for Plasma Physics, Queen's University Belfast, United Kingdom — ⁴Institut für Laser- und Plasmaphysik, Universität Düsseldorf

High harmonic generation from relativistically oscillating plasma surfaces typically exhibits a shallow, but generally decaying, spectral slope. We observed, however, an enhanced emission of particular harmonics for extremely steep plasma gradients approaching a step-like plasma density ramp. Numerical simulations reproduce the observations when matching the plasma conditions to those in the experiment and reveal a strong excitation of the surface plasma mode with the plasma frequency. A simple model of nonlinear frequency synthesis is able to explain the measured harmonic spectrum when relativistic nonlinear effects are taken into account. This novel type of relativistic nonlinearity may lead to a tunable, coherent XUV source of high efficiency.