High-harmonic generation with combined infrared and extreme ultraviolet fields

High-order harmonic generation (HHG) is a nonlinear optical process usually interpreted as a sequence of ionization of an atom or molecule by a strong laser field and the following recombination under emission of an extreme ultraviolet photon. We investigate HHG for combined infrared and extreme ultraviolet fields acting on a system possessing two essential states, with the excited state being either a bound state or a resonance. We report shifts of the HHG peak positions compared to the HHG spectrum from an infrared field only and a peak splitting depending on the presence of Rabi oscillations.