Fig. 1. Schematic of two-color EEHG device

Fig. 2. Two-color seed laser system

Fig. 3. Seed laser THG system

Fig. 4. Experimental setup for two-color seed laser device

Fig. 5. Ultraviolet laser pulse generated by THG and conversion efficiency of THG.(a) Ultraviolet laser pulse generated by THG; (b) conversion efficiency of THG

Fig. 6. Spectrum and time delay of two-color seed laser. (a) Spectrum of two-color seed laser; (b) pulse time delay

Fig. 7. Bunching factor of 45th harmonic at entrance of undulator section

Fig. 8. Power and spectrum of soft X-ray two-color FEL. (a) Power P; (b) spectrum