Spatiotemporal coupling of attosecond pulses

Cord L. Arnold, Lunds Universitet
Hampus Wikmark, Lunds Universitet
Chen Guo, Lunds Universitet
Jan Vogelsang, Lunds Universitet
Peter W. Smorenburg, ASML Netherlands BV
Hélène Coudert‐Alteirac, Lunds Universitet
Jan Lahl, Lunds Universitet
Jasper Peschel, Lunds Universitet
Piotr Rudawski, Lunds Universitet
Hugo Dacasa, Lunds Universitet
Stefanos Carlström, Max Born Institute
Sylvain Maclot, Lunds Universitet
Mette B. Gaarde, Louisiana State University
Per Johnsson, Lunds Universitet
Anne L'Huillier, Lunds Universitet


Attosecond pulses in the extreme ultraviolet (XUV) spectral range are today routinely generated via high-order harmonic generation (HHG), when intense ultrashort laser pulses are focused into a gaseous generation medium. The effect is most easily understood in a semi-classical picture [1]. An electron can tunnel ionize from the distorted atomic potential, pick up kinetic energy in the laser field, potentially return to its parent ion and recombine. The excess energy is emitted as XUV photon. The process repeats for every half-cycle of the driving field, resulting in a train of attosecond pulses and in the frequency domain in the well-known, odd-order comb of harmonics. Two main families of electron trajectories leading to the same photon energy can be distinguished into “short” and “long”, according to their time of travel in the continuum. Due to the complicated nature of the HHG process, attosecond pulses usually cannot be separated into their temporal and spatial profiles, but instead have strong chromatic aberration and are spatio-temporally coupled [2-4].