Role of the dressed and bound states on below-threshold harmonic generation of He atom
Zhou Jian-Wei, Jiao Zhi-Hong †, Li Peng-Cheng ‡, Zhou Xiao-Xin §
       

The population of the excited states 2p, 3p, and 4p of He near the end of laser pulse for (a) I = 2.0×1014 W/cm2, λ = 335 nm; (b) I = 1.4×1014 W/cm2, λ = 470 nm; and (c) I = 1.4×1014 W/cm2, λ = 425 nm.