High-harmonic generation from hydrogen atoms driven by two-color mutually orthogonal laser fields

摘要

Calculations of high-harmonic spectra from hydrogen atoms driven by strong two-color orthogonal fields with wavelengths 800 and 400 nm are presented. The azimuthal symmetry of the electron dynamics is broken by the two-color orthogonal fields, and therefore the fully three-dimensional time-dependent Schr?dinger equation is solved by using the generalized pseudospectral method. The cycle-averaged collision angles as a function of phase delay between the orthogonal fields are evaluated from the harmonic spectra. The results are in qualitative agreement with a recent experiment with helium atoms. Furthermore, the timing and direction of recollisions during the high-harmonic generation are analyzed in the time-frequency domain to extract electron trajectory information on subcycle time scales. Comparison with recent model calculations is also made.