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arXiv · 2007.12423

High-Gain Harmonic Generation with temporally overlapping seed pulses and application to ultrafast spectroscopy

Andreas Wituschek·Lukas Bruder·Enrico Allaria·Ulrich Bangert·Marcel Binz·Carlo Callegari·Paolo Cinquegrana·Miltcho Danailov·Alexander Demidovich·Michele Di Fraia·Raimund Feifel·Tim Laarmann·Rupert Michiels·Marcel Mudrich·Ivaylo Nikolov·Paolo Piseri·Oksana Plekan·Kevin Charles Prince·Andreas Przystawik·Primož Rebernic Ribič·Paolo Sigalotti·Stefano Stranges·Daniel Uhl·Luca Giannessi·Frank Stienkemeier
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Abstract

Collinear double-pulse seeding of the High-Gain Harmonic Generation (HGHG) process in a free-electron laser (FEL) is a promising approach to facilitate various coherent nonlinear spectroscopy schemes in the extreme ultraviolet (XUV) spectral range. However, in collinear arrangements using a single nonlinear medium, temporally overlapping seed pulses may introduce nonlinear mixing signals that compromise the experiment at short time delays. Here, we investigate these effects in detail by extending the analysis described in a recent publication (Wituschek et al., Nat. Commun., 11, 883, 2020). High-order fringe-resolved autocorrelation and wave-packet interferometry experiments at photon energies > $23\,$eV are performed, accompanied by numerical simulations. It turns out that both the autocorrelation and the wave-packet interferometry data are very sensitive to saturation effects and can thus be used to characterize saturation in the HGHG process. Our results further imply that time-resolved spectroscopy experiments are feasible even for time delays smaller than the seed pulse duration.

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Andreas Wituschek, Lukas Bruder, Enrico Allaria, Ulrich Bangert, Marcel Binz, Carlo Callegari, Paolo Cinquegrana, Miltcho Danailov, Alexander Demidovich, Michele Di Fraia, Raimund Feifel, Tim Laarmann, Rupert Michiels, Marcel Mudrich, Ivaylo Nikolov, Paolo Piseri, Oksana Plekan, Kevin Charles Prince, Andreas Przystawik, Primož Rebernic Ribič, Paolo Sigalotti, Stefano Stranges, Daniel Uhl, Luca Giannessi, Frank Stienkemeier. 2020-07-24. High-Gain Harmonic Generation with temporally overlapping seed pulses and application to ultrafast spectroscopy. https://doi.org/10.1364/oe.401249

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