Abstract

The observation of long-distance apparently self-guided pulses in air at GW peak powers^1-4 has attracted much recent interest, with applications in communications and lightning channeling envisioned.² The basic phenomenon characterized by long filaments and propagation over tens of meters is not in dispute, but the physical mechanism underlying it has still to be uncovered in detail. Early discussions centered on the idea that the nonlinear self-focusing (SF) in air would be partially countered by the defocusing effect of the electron plasma generated by multiphoton absorption (MPA) and result in a stable self-guided beam. Recently, Brodeur et al.⁴ have used the moving focus model to explain the features of the filaments observed in their experiments.

© 1998 Optical Society of America