Fig. 1. The harmonics generated from He driven by two-color driving pulse with different ξ for fundamental pulse

Fig. 2. The waveforms of electric fields for driving laser field and 23rd harmonic （o.c. is the optical cycle of fundamental pulse）

Fig. 3. The emission characters of harmonics generated by driving laser field with ξ=0.7 for fundamental pulse

Fig. 4. The impact of intensity ratio between two incident laser beams on harmonic emission （I_ω/I_3ω=1∶1， 1∶3， 1∶7 and 1∶9）

Fig. 5. The influence of laser phase φω on ellipticity of harmonics