Phase control of multichannel molecular high-order harmonic generation by the asymmetric diatomic molecule HeH2+in two-color laser fields

Abstract

Multichannel molecular high-order harmonic generation (MHOHG) from the asymmetric diatomic molecule HeH${}^{2+}$ in two-color laser fields is investigated from numerical simulation of the corresponding time-dependent Schr\"odinger equation (TDSE). It is found that the laser-induced electron transfer (LIET) plays a crucial role in MHOHG, which leads to the multichannel harmonic generation from the ground and long-lifetime excited states. LIET is sensitive to the phase differences of the two-color laser pulses, which can be used to control the enhanced excitation (EE) and enhanced ionization (EI) of the system. Both EE and EI have a strong influence on the overall intensity of the MHOHG spectrum, and there may be four orders of magnitude difference in the MHOHG intensity between the enhanced and suppressed cases. In addition, owing to the asymmetry of the two-color laser fields and the recombination of electron with the neighboring ion, multiple cutoff energies are observed. The mechanism of these effects are confirmed by classical simulations.