https://doi.org/10.1140/epjd/s10053-021-00153-0
Regular Article - Optical Phenomena and Photonics
Extreme ultraviolet photon effect on ionization and recombination of high-order harmonic generation
1
Laboratory of Modern Physics, Liaoning University of Technology, 121000, Jinzhou, China
2
Department of Pathophysiology, Basic Medical College of Zhengzhou University, 450001, Zhengzhou, China
Received:
23
November
2020
Accepted:
13
April
2021
Published online:
29
April
2021
The extreme ultraviolet (XUV) pulse effect on the ionization and recombination of the high-order harmonic generation has been theoretically studied. It is shown that (i) with the introduction of a shorter duration XUV pulse to a fundamental infrared (IR) pulse, the XUV photon can only be absorbed during the electron ionization process. Thus, the harmonic signal can be enhanced due to the XUV resonance transition and ionization. (ii) With the introduction of a longer-duration XUV pulse to a fundamental IR pulse, the XUV photon can be absorbed not only in the electron ionization process, but also in the electron recombination process. As a result, not only the harmonic signal can be improved, but also the harmonic cutoff can be extended with an additional XUV photon energy region (
. Moreover, as the XUV intensity increases, much more XUV photons can be absorbed in the electron recombination process, thus leading to the harmonic cutoff extension with the extra photon energy region of 
.
© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2021
