Optical femtosecond filaments in condensed media

The self-guiding of femtosecond light pulses in dense materials is investigated both theoretically and numerically for various laser wavelengths. Special attention is paid on chromatic dispersion, plasma gain, and multiphoton absorption in the nonlinear evolution of ultrashort filaments. First, by mapping the dispersion versus the ratio of beam power over the critical power for self-focusing we justify the existence of special propagation regimes, in which the beam self-channels with weak plasma response. Second, we prove that at low wavelengths multiphoton losses can quench the emission of free electrons, which justifies recent experimental observations of no apparent electron emission in water.