Exploration of laser-driven electron-multirescattering dynamics in high-order harmonic generation

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Dynamics
• Nonlinear Optics

Background:

• High-order harmonic generation (HHG) is crucial for producing ultrashort laser pulses.
• Multiple rescattering dynamics in HHG are complex and not fully understood.
• Understanding these dynamics is key to controlling HHG for advanced applications.

Purpose of the Study:

• Investigate the dynamical origin of multiple rescattering processes in HHG.
• Differentiate contributions from odd and even electron returning times.
• Elucidate the roles of tunneling and multiphoton ionization in these processes.

Main Methods:

• Performed fully ab initio quantum calculations.
• Extended empirical mode decomposition to analyze rescattering contributions.
• Analyzed electron trajectories associated with different ionization regimes.

Main Results:

• Tunneling ionization is linked to odd rescatterings and short electron trajectories.
• Multiphoton ionization is linked to even rescatterings and long electron trajectories.
• Alternating occurrence of multiphoton and tunneling ionization regimes in multiple rescattering was observed.

Conclusions:

• Uncovered the dynamical origin of multiple rescattering processes in HHG.
• Provided new insights into controlling HHG for ultrabroadband supercontinuum generation.
• Offered pathways for optimizing the production of single ultrashort attosecond laser pulses.