Semi-integer harmonic generation from an argon atom by bichromatic counter-rotating circularly polarized laser field
Qi Tong, Huo Xiao-Xin, Zhang Jun †, Liu Xue-Shen ‡
       

(a) HHG spectrum by the BCCP laser field with ω1 = 0.056 a.u. and ω2 = 1.5ω1, (b) quantum transition diagram of harmonic emission. The pink line represents the right-handed photon; the orange line represents the left-handed photon.