Multi-level effects in the high-order harmonic generation driven by intense frequency-comb laser fields*
Zhao Di†, Jiang Chen-Wei, Li Fu-Li
       
The P g → e as a function of Δ ϕ in ec-type three-level systems with dipole moment 〈 e | | c 〉 = 0.2 a.u., energy separation ħω gc = 0.23 a.u., and peak intensities (a) 1 × 1015 W/cm2 and (b) 2.5 × 1015 W/cm2. For comparison, P g → e in the two-level system is plotted with a red dashed line. Other parameters used are the same as those in Fig.  2 .