Moving-focus versus self-waveguiding model for long-distance propagation of femtosecond pulses in air

Experiments on focused femtosecond pulse propagation in air in the infrared which can test whether a strict moving-focus model interpretation is applicable were recently analyzed by Lange et al. Using numerical simulations, we show that filament propagation can be given a consistent interpretation in terms of the dynamic spatial replenishment model. While the moving-focus model cannot explain the persistence of a filament past the linear focus, the self-waveguiding model also presents problems of interpretation.