Controlled high-harmonic generation using two-color laser fields for isolated attosecond pulse generation in argon

Isolated attosecond pulses with broad spectral range provide a powerful tool for probing ultra-fast studies in atoms and molecules. In this study, we report two-color laser field control on high-harmonic generation (HHG) in argon for attosecond pulse generation. Two-color laser fields are synthesized by keeping the wavelength of the first laser fixed while varying the second laser. In HHG, the harmonic cut-off and synthesis of an isolated attosecond pulse are strongly dependent on the electric field waveform, laser pulse duration, the time delays between the two lasers, the carrier–envelope phase (CEP) of the laser, and laser intensities. The use of two-color driving fields enables extending the harmonic cut-off to the water window region, which offers better control over the microscopic electron dynamics and flexibility of tuning compared to single-laser HHG. Our study demonstrates an isolated attosecond pulse with 345 eV energy and 449 attosecond full width at half-maximum (FWHM) pulse width for −1.2fs time delay between the two lasers of 5 fs FWHM each. For ΔCEP=3 π /2, an isolated attosecond pulse with a pulse width of 340 attosecond FWHM is obtained with a cut-off photon energy of 367 eV. These ultra-short pulses will be highly beneficial for investigating the electron dynamics study inside atoms, molecules, solids, and other systems, where fundamental processes occur on the attosecond timescale.