Ionization-induced high-order nonlinear susceptibility

Saturation of the All-Optical Kerr Effect

“…Our analysis also qualitatively agrees with solutions of the time-dependent Schrödinger Equation for atomic hydrogen [25] Agreement with corresponding calculations for argon performed in Ref. [26] are shown by the dashed-dotted curve in Fig. (3), indicating a favorable agreement of the inversion intensity within reasonable error margins.…”

High-order nonlinear refractive indices for He, Ne, Kr, and Xe atoms

“…Our results strongly suggest that the defocusing during filament propagation does not stem from a negative value of quartic nonlinear refractive index. This further confirms that filament stabilization is most likely to be induced by the generation of free electrons [16,21,48,50,51].…”

High-Field Quantum Calculation Reveals Time-Dependent Negative Kerr Contribution

“…This stems from the fact that the atomic states are not eigenstates of the dressed atomic system, and consequently are not quantum observables of the system during the interaction. This result sheds a new light on the higher order Kerr effect controversy which had crystalized the debate around this question [14][15][16][17][18].…”

“…This time-dependent effect becomes even more pronounced for longer pulses (>50 fs) where the system remains resonant over long time. It may therefore seem natural to investigate which transitions (e.g., bound-bound, bound-continuum, and continuum-continuum transitions as defined in [14]) mostly contribute to the Kerr saturation and inversion in order to exhibit a simple physical interpretation about the sign inversion of the Kerr effect at high intensity. However, like the amount of ionized electrons in the presence of the external field, the bound-bound, boundcontinuum, and continuum-continuum contributions to the total polarizability (i.e.…”