Self-guided propagation of ultrashort IR laser pulses in fused silica

Summary form only given. Intense ultrashort IR laser pulses propagating through atmosphere undergo important changes in their spatial and spectral characteristics. They self-organize in the form of narrow filaments with high peak intensity, which persist over exceptional long distances. This spectacular effect is explained in terms of a dynamic competition between self-focusing and multi-photon ionization. We report evidence of a similar filamentation process in fused silica. Using femtosecond (160 fs) IR laser pulses from a Ti:sapphire laser in a converging beam geometry, we observe the formation of a microsize filament with nearly constant diameter over several mm.