Investigation of Coupling between Higher-Order Kerr Effect Coefficient Variations and Pressure on Intense Laser Propagation in Air

This paper numerically investigates the coupling effects of Higher-Order Kerr Effect (HOKE) coefficient variations and pressure on intense laser propagation in air, via five designed HOKE coefficient combination cases. Results show that HOKE modulation modes dictate filamentation deviations from the baseline: same-direction modulation (synchronous focusing/defocusing adjustment) causes slight filamentation changes, while reverse-direction modulation induces extreme nonlinear imbalance with significant differences. Air pressure exerts a selective regulatory effect: at high pressure, laser-gas nonlinear interaction dominates filamentation, making small-range HOKE coefficient fluctuations negligible for same-direction modulation. However, the extreme nonlinear balance from reverse-direction modulation is insensitive to pressure, with its filamentation differences from the baseline persisting across all pressure ranges. This study clarifies the intrinsic coupling mechanism and pressure?s selective suppression effect, suggesting same-direction HOKE coefficients are preferable for engineering applications, with their small fluctuations ignorable under high-pressure conditions.