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. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
High-gain harmonic generation with temporally overlapping seed pulses and application to ultrafast spectroscopy / Wituschek, Andreas; Bruder, Lukas; Allaria, Enrico; Bangert, Ulrich; Binz, Marcel; Callegari, Carlo; Cinquegrana, Paolo; Danailov, Miltcho; Demidovich, Alexander; Di Fraia, Michele; Feifel, Raimund; Laarmann, Tim; Michiels, Rupert; Mudrich, Marcel; Nikolov, Ivaylo; Piseri, Paolo; Plekan, Oksana; Charles Prince, Kevin; Przystawik, Andreas; Rebernic Ribič, Primož; Sigalotti, Paolo; Stranges, Stefano; Uhl, Daniel; Giannessi, Luca; Stienkemeier, Frank. - In: OPTICS EXPRESS. - ISSN 1094-4087. - 28:20(2020), pp. 29976-29990. [10.1364/OE.401249]
High-gain harmonic generation with temporally overlapping seed pulses and application to ultrafast spectroscopy
Stranges, Stefano;
2020
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. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing AgreementI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
