Erlangen 2022 – scientific programme

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K: Fachverband Kurzzeit- und angewandte Laserphysik

K 2: Poster

K 2.1: Poster

Tuesday, March 15, 2022, 16:30–18:30, P

Extreme self-regulation in high-harmonic generation — •Evaldas Svirplys¹, Katalin Kovács², Muhammad Anus¹, Omair Ghafur¹, Katalin Varjú^3,4, Marc J. J. Vrakking¹, Valer Tosa², Balázs Major^3,4, and Bernd Schütte¹ — ¹Max-Born-Institut, Berlin, Germany — ²National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania — ³ELI-ALPS, Szeged, Hungary — ⁴Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary

We present a novel High-harmonic generation (HHG) scheme that shows extreme self-regulation of the driving laser intensity. Near-infrared (NIR) laser pulses are focused into a high-pressure atomic jet, leading to intensities of about 10¹⁶ W/cm², which is much higher than the optimal intensity for HHG. Substantial Spectral reshaping of the NIR 50-fs laser pulse was observed in each atomic species investigated (Xe, Kr, Ar, Ne, He), resulting in the observation of a ten-fold increase of the initial NIR bandwidth. Our experimental and numerical study shows that ionization-induced self-phase modulation is responsible for the spectral broadening, while plasma-induced defocusing results in a substantial decrease and self-regulation of the NIR intensity. This allows for the build-up of phase-matched HHG and results in the generation of continuous spectra ranging from 18-140 eV albeit using long driving laser pulses. This flexible and compact HHG scheme is ideally suited for absorption spectroscopy, allowing to access different spectral ranges without the need for tedious optimization procedures.