Nonlinear optical polarization response and plasma generation in noble gases: Comparison of metastable-electronic-state-approach models to experiments

The nonlinear polarization response and plasma generation produced by intense optical pulses, modeled by the metastable-electronic-state approach, are verified against space-and-time resolved measurements with single-shot supercontinuum spectral interferometry. This first of a kind theory-experiment comparison is done in the intensity regime typical for optical filamentation, where self-focusing and plasma generation play competing roles. Excellent agreement between the theory and experiment shows that the self-focusing nonlinearity can be approximated by a single resonant state. Moreover, we demonstrate that inclusion of the post-adiabatic corrections, previously tested only in theoretic models, provides a viable description of the ionization rate in real gases.