Generation of Coherent XUV Radiation at High Repetition Rates

High Harmonic Generation — HHG

Focusing an ultrashort pulse laser onto a target, typically a noble gas, allows to generate harmonics of the fundamental laser frequency. Due to the outstanding properties of the generated radiation, such as short wavelength and pulse duration and laser-like coherence, it found numerous applications in physics, chemistry and biology.

High repetition rate XUV sources are needed in various fields in order to reduce measurement times and improve the signal to noise ratio (for example in time-resolved photoelectron spectroscopy on surfaces). Other applications such as seeding of free electron lasers put enormous demands to the XUV laser source.

By optimizing and improving the driving laser system and the generation process we achieve unprecedented repetition rates and average power in the XUV.

Attosecond sources and dynamics

High harmonic generation is inherently linked to the attosecond pulses (1 as = 10^-18s), which are a unique tool for looking into electronic processes in atoms and molecules.

Our work involves the generation itself, employing compact high power few-cycle laser sources, as well as complete spectral and temporal characterization of the generated radiation. Careful analysis of the emitted attosecond pulses allows gaining information about the electronic, atomic or molecular structure and dynamics of the generating medium. Such studies enable in-depth understanding of the underlying physical processes and optimizing attosecond pulse generation.

Recently, we managed to reliably generate XUV continua at very high laser repetition rates.

The research leading to these results is partly funded by the German Federal Ministry of Education and Research (BMBF) under contract 13N12082 , the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. [240460] “PECS,” and the Thuringian Ministry for Economy, Labour, and Technology (TMWAT, Project no. 2011 FGR 0103).