Inhibition of multi-filamentation of high-power laser beams.

We experimentally demonstrate the control and complete elimination of multi-filamentation in condensed matter by varying the focusing geometry. In particular, increasing the input beam power enables the extension of the filament length without generating multi-filaments up to 1400 times the critical power in fused silica at an 800 nm wavelength. Furthermore, the generated single filament exhibits spatial solitary wave behavior.

Higher-order nonlinearities revisited and their effect on harmonic generation.

We report on harmonic generation experiments and calculations in air to investigate the theoretical prediction of Kolesik et al. [Opt. Lett.