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arXiv · 1603.07905

Role of Excited States In High-order Harmonic Generation

Samuel Beaulieu·Seth Camp·Dominique Descamps·Antoine Comby·Vincent Wanie·Stéphane Petit·François Légaré·Kenneth J. Schafer·Mette B. Gaarde·Fabrice Catoire·Yann Mairesse
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Abstract

We investigate the role of excited states in High-order Harmonic Generation by studying the spectral, spatial and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. We show that the population of excited states can lead either to direct XUV emission through Free Induction Decay or to the generation of high-order harmonics through ionization from these states and recombination to the ground state. By using the attosecond lighthouse technique, we demonstrate that the high-harmonic emission from excited states is temporally delayed by a few femtoseconds compared to the usual harmonics, leading to a strong nonadiabatic spectral redshift.

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Samuel Beaulieu, Seth Camp, Dominique Descamps, Antoine Comby, Vincent Wanie, Stéphane Petit, François Légaré, Kenneth J. Schafer, Mette B. Gaarde, Fabrice Catoire, Yann Mairesse. 2016-10-18. Role of Excited States In High-order Harmonic Generation. https://doi.org/10.1103/physrevlett.117.203001

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