Quantum path selection in high-harmonic generation by a phase-locked two-color field.

We report the results of our studies on the selection of the quantum path in high-harmonic generation (HHG) with a relative-phase-locked two-color laser field. It is shown that by tuning the relative phase between fundamental and second-harmonic fields, The timing of tunnel ionization and subsequent electron trajectories on the sub-cycle time scale can be controlled. We have clearly observed a phase-dependent two-step feature in the harmonic spectra that can be attributed to the selection of two major trajectories in the two-color field HHG.

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