UC San Diego
Group velocity matching in high-order harmonic generation driven by mid-infrared lasers
- Author(s): Hernández-García, C
- Popmintchev, T
- Murnane, MM
- Kapteyn, HC
- Plaja, L
- Becker, A
- Jaron-Becker, A
- et al.
Published Web Locationhttps://doi.org/10.1088/1367-2630/18/7/073031
© 2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. We analyze the role of group-velocity matching (GVM) in the macroscopic build up of the high-harmonic signal generated in gas targets at high pressures. A definition of the walk-off length, associated with GVM, in the non-perturbative intensity regime of high-harmonic generation is given. Semiclassical predictions based on this definition are in excellent agreement with full quantum simulations. We demonstrate that group velocity matching is a relevant factor in high harmonic generation and the isolation of attosecond pulses driven by long wavelength lasers and preferentially selects contributions from the short quantum trajectories.