Abstract

Recently self-channelled propagation of intense femtosecond pulses has been observed in air over distances reaching several tens of meters [1,2]. We have further investigated this effect using pulses of various durations between 60 and 150 fs delivered by a Ti:sapphire oscillator-amplifier chain. The spectral, spatial and energy characteristics of the propagating pulse, as well as the associated forward conical emission have been recorded [2]. Combining experimental results with numerical modelling we obtain a consistent physical picture of the self-channelling process. Self guiding is interpreted as resulting from the competition between non-linear self-focusing, and the defocusing effects due to the formation of a low density plasma.

© 1996 Optical Society of America