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arXiv · 2507.06386

Subcycle phase matching effects in short attosecond pulse trains

N. Ouahioune·R. Martín-Hernández·D. Hoff·P. K. Maroju·C. Guo·R. Weissenbilder·S. Mikaelsson·A. L'Huillier·M Lucchini·C. L. Arnold·M. Gisselbrecht
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Abstract

Attosecond pulses produced by High-order Harmonic Generation (HHG) in gases driven by intense laser fields have become a cornerstone technique for probing ultrafast electronic motion in matter. These applications require a good knowledge of the temporal and spectral properties of the emitted radiation. In this work, we generate a train of two to three attosecond pulses that we characterize using two-color laser-assisted photoionization. \textcolor{black}{An unexpected spectral behavior, with more pulses at high energies than at low energies, is observed when the carrier-to-envelope phase of the laser field is changed by 90$^\circ$.} HHG simulations indicate that the time-dependent phase matching of the harmonics contributes in a non-trivial way to the structure of the pulse train. Two-color laser-assisted photoionization enables us to unravel the dynamical influence of subcycle phase matching on the spectral properties of the attosecond pulse train, going beyond the predictions of the response of a single atom to a strong laser field.

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N. Ouahioune, R. Martín-Hernández, D. Hoff, P. K. Maroju, C. Guo, R. Weissenbilder, S. Mikaelsson, A. L'Huillier, M Lucchini, C. L. Arnold, M. Gisselbrecht. 2026-02-27. Subcycle phase matching effects in short attosecond pulse trains. https://arxiv.org/abs/2507.06386

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