High harmonic generation in CO₂ using two-color femtosecond laser

High harmonic generation driven by two-color laser f ield in CO2 molecules were investigated experimentally. The optimized intensity of the 24th harmonic was obtained by changing filling gas pressure. In additional, harmonic output was improved by moving the laser focus with respect to the gas cell. There are two maximum values in two regions. The result is ascribed to different phase matching in the gas cell, favoring long and short electron trajectories during high harmonic generation respectively. The experiment results indicate that molecular high harmonic generated in two-color field may be a promising multi-wavelength tunable coherent XUV source.