Anomalous long-range propagation of femtosecond laser pulses through air: moving focus or pulse self-guiding?

Abstract : Self-guided propagation of femtosecond laser pulses is studied for a converging-beam configuration. Channeling of the pulse energy through various gases is observed over distances well beyond the lens focal point, a fact that cannot be explained by the moving-focus model. The results are in good agreement with three-dimensional numerical simulations.