Abstract

We present an ab initio investigation of below-threshold harmonic generation (BTHG) of Cs atom in intense mid-infrared laser fields by accurately solving the time-dependent Schrödinger equation. We find that the spectra yield in BTHG of Cs atom dependents on the light intensity in the multiphoton ionization regime, and the bound states play an important role in the channel selection process for BTHG. Combining with wavelet time-frequency transform, semiclassical trajectories simulation, and quantum channel analysis, the dynamical origin of the BTHG is uncovered.

© 2020 The Author(s)