Supercontinuum generation of femtosecond filaments at different laser wavelengths in air

This study analyzes numerically supercontinuum generation for the three laser wavelengths of 248 nm, 800 nm and 1550 nm, on the basis of different nonlinear Schrodinger-like equations for the electric field envelope involving or not space-time focusing and self-steepening operators. A numerical analysis of the unidirectional propagation equation is also performed, avoiding any Taylor expansion of the dispersion relation. Several photo-ionization models, fixing the level of the filament intensity in the range of 10 to 100 TW/cm², are investigated. Finally, emphasis is given on long-range propagation over several meters in air.