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Mayer N, Beaulieu S, Jiménez-Galán Á, Patchkovskii S, Kornilov O, Descamps D, Petit S, Smirnova O, Mairesse Y, Ivanov MY. Role of Spin-Orbit Coupling in High-Order Harmonic Generation Revealed by Supercycle Rydberg Trajectories. Phys Rev Lett 2022; 129:173202. [PMID: 36332250 DOI: 10.1103/physrevlett.129.173202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 07/26/2022] [Accepted: 09/08/2022] [Indexed: 06/16/2023]
Abstract
High-harmonic generation is typically thought of as a sub-laser-cycle process, with the electron's excursion in the continuum lasting a fraction of the optical cycle. However, it was recently suggested that long-lived Rydberg states can play a particularly important role in high harmonic generation by atoms driven by the combination of the counterrotating circularly polarized fundamental light field and its second harmonic. Here we report direct experimental evidence of very long and stable Rydberg trajectories contributing to high-harmonic generation in such fields. We track their dynamics inside the laser pulse using the spin-orbit evolution in the ionic core, utilizing the spin-orbit Larmor clock. We confirm their effect on harmonic emission both via microscopic simulations and by showing how this radiation can lead to a well-collimated macroscopic far-field signal. Our observations contrast sharply with the general view that long-lived Rydberg orbits should generate negligible contribution to the macroscopic far-field high harmonic response of the medium.
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Affiliation(s)
- N Mayer
- Max-Born-Institute, Max-Born Straße 2A, 12489 Berlin, Germany
| | - S Beaulieu
- Université de Bordeaux-CNRS-CEA, Centre Lasers Intenses et Applications (CELIA), UMR5107, F33405 Talence, France
| | - Á Jiménez-Galán
- Max-Born-Institute, Max-Born Straße 2A, 12489 Berlin, Germany
- Joint Attosecond Science Laboratory, National Research Council of Canada and University of Ottawa, Ottawa, Canada
| | - S Patchkovskii
- Max-Born-Institute, Max-Born Straße 2A, 12489 Berlin, Germany
| | - O Kornilov
- Max-Born-Institute, Max-Born Straße 2A, 12489 Berlin, Germany
| | - D Descamps
- Université de Bordeaux-CNRS-CEA, Centre Lasers Intenses et Applications (CELIA), UMR5107, F33405 Talence, France
| | - S Petit
- Université de Bordeaux-CNRS-CEA, Centre Lasers Intenses et Applications (CELIA), UMR5107, F33405 Talence, France
| | - O Smirnova
- Max-Born-Institute, Max-Born Straße 2A, 12489 Berlin, Germany
| | - Y Mairesse
- Université de Bordeaux-CNRS-CEA, Centre Lasers Intenses et Applications (CELIA), UMR5107, F33405 Talence, France
| | - M Y Ivanov
- Max-Born-Institute, Max-Born Straße 2A, 12489 Berlin, Germany
- Department of Physics, Humboldt University, Newtonstraße 15, D-12489 Berlin, Germany
- Blackett Laboratory, Imperial College London, SW7 2AZ London, United Kingdom
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