Phase-dependent ionization of hydrogen by intense sub-cycle pulses

Area of Science:

• Atomic Physics
• Quantum Mechanics
• Laser-Matter Interactions

Background:

• Understanding electron behavior in intense laser fields is crucial for fields like attosecond science.
• The carrier-envelope phase (CEP) of laser pulses influences electron dynamics.
• Previous models often assume tunneling ionization, dependent on peak field amplitude.

Purpose of the Study:

• To investigate the carrier-envelope phase (CEP) dependence of hydrogen atom ionization.
• To explore ionization dynamics with intense, sub-femtosecond laser pulses.
• To compare simulation and analytical results with existing ionization models.

Main Methods:

• Performed computational simulations of atomic ionization.
• Conducted analytical calculations to model the process.
• Utilized intense, sub-cycle, sub-femtosecond laser pulses in the models.

Main Results:

• Demonstrated strong carrier-envelope phase dependence in hydrogen ionization.
• Observed that sine-like pulses ionize more than cosine-like pulses for the same pulse energy.
• Found this behavior contradicts predictions from standard tunneling ionization models.

Conclusions:

• The ionization of hydrogen atoms by ultrashort laser pulses is highly sensitive to the carrier-envelope phase.
• Classical orbit time effects become significant for sub-femtosecond pulses, altering ionization pathways.
• Results necessitate a re-evaluation of ionization models for extreme ultraviolet laser-matter interactions.