Two-photon coherent propagation and third-harmonic generation.

Area of Science:

• Nonlinear Optics
• Atomic Physics
• Quantum Electronics

Background:

• Third-harmonic generation (THG) is a key nonlinear optical process.
• Coherent two-photon propagation influences harmonic generation efficiency.
• Lithium vapor offers unique atomic properties for nonlinear interactions.

Purpose of the Study:

• To theoretically investigate THG in lithium vapor under specific propagation conditions.
• To determine the optimal fundamental pulse parameters for maximizing THG efficiency.
• To predict the spectral and intensity characteristics of the generated third harmonic.

Main Methods:

• Numerical calculations of nonlinear wave propagation.
• Modeling of coherent two-photon excitation and ionization dynamics.
• Parametric studies of pulse shape, frequency, and intensity.

Main Results:

• Predicted an optimal third-harmonic energy conversion efficiency of 8%.
• Identified specific fundamental pulse shapes, frequencies, and intensities for optimal conversion.
• Detailed the interplay between pulse propagation and harmonic generation in lithium vapor.

Conclusions:

• Achieving high THG efficiency in lithium vapor is feasible with optimized pulse parameters.
• The findings provide a theoretical basis for experimental realization of efficient THG.
• This work contributes to the development of advanced light sources based on nonlinear processes.