Analysis of effects of macroscopic propagation and multiple molecular orbitals on the minimum in high-order harmonic generation of aligned CO$_{2}$

摘要

We report theoretical calculations on the effect of the multiple orbitalcontribution in high-order harmonic generation (HHG) from aligned CO$_2$ withinclusion of macroscopic propagation of harmonic fields in the medium. Ourresults show very good agreements with recent experiments for the dynamics ofthe minimum in HHG spectra as laser intensity or alignment angle changes.Calculations are carried out to check how the position of the minimum in HHGspectra depends on the degrees of molecular alignment, laser focusingconditions, and the effects of alignment-dependent ionization rates of thedifferent molecular orbitals. These analyses help to explain why the minimaobserved in different experiments may vary.