100 kHz water window soft X-ray high-order harmonic generation through pulse self-compression in an antiresonant hollow-core fiber

Gebhardt M, Heuermann T, Klas R, Liu C, Kirsche A, Lenski M, Wang Z, Gaida C, Antonio-Lopez JE, Schuelzgen A, Amezcua-Correa R, Rothhardt J, Limpert J (2021)

Publication Type: Conference contribution

Publication year: 2021

Publisher: Institute of Electrical and Electronics Engineers Inc.

Conference Proceedings Title: 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021

Event location: Munich, DEU

ISBN: 9781665418768

DOI: 10.1109/CLEO/Europe-EQEC52157.2021.9542210

Abstract

Coherent soft X-ray (SXR) sources that provide a high photon flux in the water window are essential tools for advanced spectroscopy (e.g. of magnetic materials [1] and organic compounds [2] ) or for lens-less bio imaging with nm-scale resolution [3]. To date, such sources are mostly large-scale facilities like synchrotrons or free electron lasers. A promising alternative are laser-driven sources, based on high harmonic generation (HHG) in noble gases. Current state-of-the-art SXR HHG uses frequency converted Ti:Sa lasers (to ~2m wavelength to increase the phase matching cutoff) with multi-mJ pulse energies at 1 kHz repetition rate [1]. Most recently, there has been a strong push towards increasing the repetition rate of the driving lasers, and the SXR HHG, to enable faster data acquisition, space-charge-reduced SXR photoelectron spectroscopy or coincidence detection [4] , [5]. In this contribution, we present an approach to SXR HHG that is based on nonlinear pulse self-compression and HHG in the same helium gas-filled antiresonant hollow-core fiber (ARHCF). Because of the intensity enhancement resulting from temporal pulse self-compression, the experiments can be driven by moderate-energy, multi-cycle laser pulses, which facilitates repetition rate scaling. We coupled 100 fs-, 250J-pulses centered around 1.9m wavelength at a 98 kHz repetition rate to the ARHCF ( Fig. 1a ). When the fiber length (~1.2 m) and the gas pressure at its output (~3.8 bar) were chosen appropriately, the pulses close to its end ( Fig. 1b ) were self-compressed to <20 fs, leading to an on-axis peak intensity >4×10 14 W/cm 2. At this point, the gas is partially ionized, and the chosen pressure ensures phase matching between the driving laser and the generated SXR light ( Fig. 1b ). It is the first time that this approach is experimentally realized, and we have generated a photon flux >10 6 Ph/s/eV at the carbon K-edge ( Fig. 1c ). To the best of our knowledge, this is the highest photon flux at 300 eV reported to date at a laser repetition rate >1 kHz.

Involved external institutions

Friedrich-Schiller-Universität Jena DE Germany (DE) University of Central Florida (UCF) US United States (USA) (US)

How to cite

APA:

Gebhardt, M., Heuermann, T., Klas, R., Liu, C., Kirsche, A., Lenski, M.,... Limpert, J. (2021). 100 kHz water window soft X-ray high-order harmonic generation through pulse self-compression in an antiresonant hollow-core fiber. In 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021. Munich, DEU: Institute of Electrical and Electronics Engineers Inc..

MLA:

Gebhardt, M., et al. "100 kHz water window soft X-ray high-order harmonic generation through pulse self-compression in an antiresonant hollow-core fiber." Proceedings of the 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021, Munich, DEU Institute of Electrical and Electronics Engineers Inc., 2021.

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