Focusing Properties of High-Order Harmonics
Open Access
- 1 January 2021
- journal article
- Published by American Association for the Advancement of Science (AAAS) in Ultrafast Science
Abstract
Many applications of the extreme ultraviolet (XUV) radiation obtained by high-order harmonic generation (HHG) in gases require a small focus area in order to enable attosecond pulses to reach a high intensity. Here, high-order harmonics generated in Ar with a multiterawatt laser system in a loose focusing geometry are focused to a few micrometers using two toroidal mirrors in a Wolter configuration with a high demagnification factor. Using a knife-edge measurement technique, we determine the position and size of the XUV foci as a function of harmonic order. We show that the focus properties vary with harmonic order and the generation conditions. Simulations, based on a classical description of the harmonic dipole phase and assuming that the individual harmonics can be described as Gaussian beams, reproduce the experimental behavior. We discuss how the generation geometry affects the intensity and duration of the focused attosecond pulses.Keywords
Funding Information
- European Cooperation in Science and Technology
- Horizon 2020 Framework Programme (654148)
- Laserlab-Europe
- Crafoord Foundation
- Knut and Alice Wallenberg Foundation
- H2020 European Research Council
- Vetenskapsrådet
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