Second-Harmonic Generation of High-Intensity Light Waves under the Influence of Cubic Nonlinearity

This study examines the implications of cubic nonlinearity on second-harmonic generation (SHG) within high-intensity optical fields, elucidating how cubic nonlinearity inherent to the medium perturbs the ideal phase interrelation among the interacting waves, culminating in diminished energy conversion efficiency and inducing spectrum modulation. A methodology is advanced for identifying the optimal wave vector mismatch that maximizes SHG efficiency while circumventing second-harmonic (SH) pulse modulation. Through simulations of the SHG mechanism, conducted under varying intensities (1-5 TW/cm²) and contrasting durations (10 ns and 50 fs), the research underscores the efficacy of this approach. Notably, an optimal wave vector mismatch scenario facilitated the attainment of an 86% energy conversion efficiency, utilizing a 0.5 mm thick KDP crystal, with the procedure peaking at an intensity of 5 TW/cm² and a pulse duration of 48 fs.