High photon flux table-top coherent extreme-ultraviolet source

By S. Hädrich, A. Klenke, J. Rothhardt, M. Krebs, A. Hoffmann, O. Pronin, V. Pervak, Jens Limpert, A. Tünnermann. Nature Photonics, 2014

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High photon flux with up to 1012 photons in the 25–40 eV range has been achieved in a new table-top coherent extreme ultraviolet (EUV) source based on phase-matched high-harmonic generation using a fibre laser. Intense and compact EUV sources are needed for certain types of spectroscopic and imaging applications. High harmonic generation (HHG) enables extreme-ultraviolet radiation with table-top set-ups1. Its exceptional properties, such as coherence and (sub)-femtosecond pulse durations, have led to a diversity of applications1. Some of these require a high photon flux and megahertz repetition rates, for example, to avoid space charge effects in photoelectron spectroscopy2,3,4. To date, this has only been achieved with enhancement cavities5. Here, we establish a novel route towards powerful HHG sources. By achieving phase-matched HHG of a megahertz fibre laser we generate a broad plateau (25 eV–40 eV) of strong harmonics, each containing more than 1 × 1012 photons s–1, which constitutes an increase by more than one order of magnitude in that wavelength range6,7,8. The strongest harmonic (H25, 30 eV) has an average power of 143 μW (3 × 1013 photons s–1). This concept will greatly advance and facilitate applications in photoelectron or coincidence spectroscopy9, coherent diffractive imaging10 or (multidimensional) surface science2.

Subfields: Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/b98d05240c5966af522afad9edda00337144c5a2