Manipulation of High-Harmonic Generation Using an Engineered Two-Color Laser Field

High-harmonic generation (HHG) is a vital phenomenon in the field of attosecond science. Under the influence of a strong laser field, tunnel ionization, acceleration, and recombination of electrons can collectively produce extreme-ultraviolet and soft x-ray radiation. By tailoring the driving laser field, it is possible to manipulate the underlying electron dynamics and thereby the harmonic emission. In this work, we investigate how a temporally engineered two-color laser field can be used to modulate the yield of the high-order harmonics. Our two-color laser field consists of a femtosecond laser pulse (1030 nm) and its second harmonic (515 nm). By varying both the relative phase and the intensity of the two-color laser fields in a controlled way, we demonstrate that the harmonic generation shows strong sensitivity to these parameters. This modulation arises from the selective influence on tunnel ionization and the associated tunneled electron trajectories by the asymmetric laser field. Our semiclassical simulation captures these trajectory modifications and shows good qualitative agreement with our experimental observations.