Laser-field-related recombination interference in high-order harmonic generation from CO₂ molecules

We reinvestigate the modulation inversion of angular distribution of high-order harmonic generation (HHG) from impulsively aligned CO₂ molecules. The angular distribution is found to be sensitive to both the harmonic order and the intensity of the driving laser pulse for HHG. The roles of intramolecular quantum interference and the laser intensity are clarified. A laser-field-related recombination interference model is proposed to explain the modulation inversion of harmonic yield with respect to the molecular alignment. We conclude that the two-center interference in the recombination process can be manipulated by changing the laser intensity.