Harmonic generation by atoms in circularly polarized two-color laser fields with coplanar polarizations and commensurate frequencies - art. no. 053402

摘要

The generation of harmonics by atoms or ions in a two-color, coplanar field configuration with commensurate frequencies is investigated through both an analytical calculation based on the Lewenstein model and the numerical ab initio solution of the time-dependent Schrodinger equation of a two-dimensional model ion. Through the analytical model, selection rules for the harmonic orders in this field configuration, a generalized cutoff for the harmonic spectra, and an integral expression for the harmonic dipole strength are provided. The numerical results are employed to test the predictions of the analytical model. The scaling of the cutoff as a function of both one of the laser intensities and frequency ratio eta as well as entire spectra for different eta and laser intensities are presented and analyzed. The theoretical cutoff is found to be an upper limit for the numerical results. Other discrepancies between analytical model and numerical results are clarified by taking into account the probabilities of the absorption processes involved. [References: 18]