Spectrally tunable ultrashort monochromatized extreme ultraviolet pulses at 100 kHz
preprintposted on 2023-06-08, 12:59 authored by Tamás Csizmadia, Zoltán Filus, Tímea Grósz, Peng Ye, Lénárd Gulyás Oldal, Massimo De Marco, Péter Jójárt, Imre Seres, Zsolt Bengery, Barnabás Gilicze, Matteo Lucchini, Mauro Nisoli, Fabio Frassetto, Fabio Samparisi, Luca Poletto, Katalin Varjú, Subhendu Kahaly, Balázs Major
We present the experimental realization of spectrally tunable, ultrashort, quasi-monochromatic extreme ultraviolet (XUV) pulses generated at 100 kHz repetition rate in a user-oriented gas high harmonic generation (GHHG) beamline of the Extreme Light Infrastructure - Attosecond Light Pulse Source (ELI ALPS) facility. Versatile spectral and temporal shaping of the XUV pulses are accomplished with a double-grating, time-delay compensated monochromator accommodating the two composing stages in a novel, asymmetrical geometry. This configuration supports the achievement of high monochromatic XUV flux (2.8+/-0.9*1e10 photons/s at 39.7 eV selected with 700 meV FWHM bandwidth) combined with ultrashort pulse duration (4.0+/-0.2 fs using 12.1+/-0.6 fs driving pulses) and small spot size (sub-100 um). Focusability, spectral bandwidth, and overall photon flux of the produced radiation were investigated covering a wide range of instrumental configurations. Moreover, complete temporal (intensity and phase) characterization of the few-femtosecond monochromatic XUV pulses - a goal that is difficult to achieve by conventional reconstruction techniques - has been realized using ptychographic algorithm on experimentally recorded XUV-IR pump-probe traces. The presented results contribute to in-situ, time-resolved experiments accessing direct information on the electronic structure dynamics of novel target materials.