BEAM FILAMENTATION AND THE WHITE-LIGHT CONTINUUM DIVERGENCE

We investigate the spatial characteristics of the white light continuu m generated in water by femtosecond Ti:sapphire laser pulses with peak power well above the self-focusing threshold. The wavelength dependen ce of the divergence of the white light generated in small-scale filam ents was measured. The observed dependence was interpreted, using self -phase modulation theory, as resulting from the radial intensity distr ibution in the small-scale filaments. Based on this interpretation the intensity profile in the filament was reconstructed.