Controlling Nonsequential Double Ionization in Two-Color Circularly Polarized Femtosecond Laser Fields.

Area of Science:

• Strong-field physics
• Quantum optics
• Atomic, molecular, and optical (AMO) physics

Background:

• Strong-field laser interactions with atoms can lead to complex phenomena like double ionization.
• Circularly polarized light in laser fields creates unique electron trajectories and enables specific light emissions.

Purpose of the Study:

• To experimentally observe nonsequential double ionization (NDI) in two-color circularly polarized femtosecond laser fields.
• To investigate the control of NDI by manipulating laser field parameters.
• To optimize the generation of circularly polarized high harmonic beams.

Main Methods:

• Utilizing two-color circularly polarized femtosecond laser fields.
• Performing experimental measurements of photoelectron trajectories and ionization yields.
• Conducting classical simulations to explain experimental observations and guide optimization.

Main Results:

• First experimental observation of nonsequential double ionization in tailored laser fields.
• Demonstrated enhancement and suppression of NDI by varying laser intensity ratio and helicity.
• Identified electron-ion rescattering as a key mechanism controllable by laser parameters.

Conclusions:

• Nonsequential double ionization is controllable in two-color circularly polarized laser fields.
• Laser parameter tuning offers a pathway to optimize high-energy electron-ion rescattering.
• This work provides insights for maximizing the generation of circularly polarized high harmonic beams.