Investigation of the characteristic properties of high-order harmonic spectrum in atoms using Bohmian trajectories

We study the electron quantum dynamics of high harmonic generation (HHG) processes of atomic hydrogen under intense near infrared (NIR) laser fields by means of the De Broglie-Bohm's framework of Bohmian mechanics. The proposed accurate 3D numerical scheme is utilized to discuss the mechanism of the multiple plateau generation and the cut-off extension, as the main characteristic features of HHG spectrum. One-color (1600 nm) and two-color (1600 nm + 800 nm) laser fields with different time delays are used to investigate the effect of pulse shape on electron dynamics and HHG process. The presented results on Bohmian trajectories and their energy content, along with the analysis of the emission time period of different groups of trajectories, provide a comprehensive and fresh electron dynamical picture and uncover novel mechanisms of the HHG processes and power spectra.