Disentangling Long Trajectory Contributions in Two-Colour High Harmonic Generation

Abstract

This work investigates High Harmonic Generation (HHG) in gas targets, induced by intense two-colour driving fields. We compared classical trajectory Monte Carlo simulations based on a semiclassical model of strong field tunnel ionisation of helium to experimental HHG spectra, and investigated the relative contribution of long trajectories to low harmonic orders. This phenomenon can be found even when the experimental setup is chosen to suppress long trajectories and favour phase matching for short trajectories.

Keywords

• high harmonic spectroscopy
• classical trajectory Monte Carlo simulation
• strong-field ionisation
• two-colour high harmonic generation