Abstract

A propagating femtosecond laser pulse will result in a filament, when an ultrashort laser pulse with sufficient peak power undergoes self-focusing and consequently ionizes the molecules of air. A dynamic balance between diffraction, self-focusing, and plasma defocusing ensures that the laser pulse propagates over many Rayleigh lengths without significant diffraction. The laser filament is furthermore characterized by supercontinuum generation that can be attributed to self-phase modulation, X-wave formation and four-wave mixing [1]. Spatial and temporal focusing techniques have been numerically explored in [2] to control the supercontinuum generation that accompanies a laser filament. Temporal focusing, by adjusting the chirp of a broadband laser pulse, has been demonstrated in [3] to achieve optimal ionization at long distances.

© 2013 IEEE