Abstract

Laser filamentation is a propagation regime reached with ultrashort laser pulses when their peak power exceeds a critical power of ∼10 GW in air at 800 nm. It results a beam maintaining a very high intensity in a thin channel of almost constant radius over several Rayleigh lengths [1]. Filamentation has been shown to deposit a significant part of the laser pulse energy in the medium through Raman rotational excitation, ionization and inverse Bremsstrahlung, which is eventually converted into neutral thermal energy [2]. The fast and localized heating of air leads to the formation of an outward propagating pressure wave and of a central low-density channel with the same cylindrical geometry as the filament [3]. This underdense channel then diffusively decays over a millisecond timescale. Such long-lived hydrodynamic structures have been used as virtual waveguides [4,5], but also open perspectives in the field of filamentation-guided discharges and their applications, and for aerodynamic control [6].

© 2015 IEEE