Nonlinear optical response in molecular nitrogen: from ab-initio calculations to optical pulse simulations

Area of Science:

• Atomic and Molecular Physics
• Nonlinear Optics
• Computational Chemistry

Background:

• Understanding light-matter interactions in gases is crucial for applications like high-harmonic generation.
• Simulating complex phenomena like nonlinear polarization and ionization requires advanced computational methods.
• Nitrogen molecules are fundamental systems for studying these interactions due to their prevalence and electronic properties.

Purpose of the Study:

• To develop a first-principle model for simulating nonlinear optical phenomena in nitrogen molecules.
• To accurately describe both nonlinear polarization and ionization processes.
• To enable space-and-time-resolved simulations of optical pulses with complex spectral dynamics.

Main Methods:

• Utilized first-principle multi-electron calculations.
• Employed the hybrid anti-symmetrized coupled channels method.
• Incorporated the metastable electronic state approach for simulations.

Main Results:

• Successfully created a model for nitrogen molecules that captures nonlinear polarization and ionization.
• The model is suitable for detailed simulations of optical pulse propagation.
• Demonstrated the model's utility by studying low-order harmonic generation in mid-infrared optical filaments.

Conclusions:

• The developed model provides a robust tool for investigating nonlinear optical processes in nitrogen.
• It facilitates accurate, space-and-time-resolved simulations essential for understanding light-matter interactions.
• The study highlights the model's capability in analyzing phenomena like harmonic generation in optical filaments.