Filamentation of femtosecond Ti:Sapphire laser pulses at the first and second harmonics in liquid media.

The experimental results on transformation of the spectral and spatial characteristics of femtosecond Ti:Sapphire-laser pulses with wavelengths of 800 and 400 nm during filamentation in liquid media are presented. It is shown that spectral broadening of a laser pulse at both harmonics at the expense of phase self-modulation in a medium with cubic nonlinearity depends on pulse power and beam diameter. Emission with a maximum at 464 nm is observed during filamentation of the pulses with a wavelength of 400 nm in distilled water, which corresponds to stimulated Raman scattering of the water. Fluorescence of dissolved organic matter is observed in sea water. [ABSTRACT FROM AUTHOR]