Few-cycle laser-pulse collapse in Kerr media: The role of group-velocity dispersion andX-wave formation

Abstract

We study ultrashort laser-pulse propagation and filamentation dynamics in dispersive Kerr media. We identify the regime for which the filamentation threshold $({P}_{\mathrm{th}})$ is considerably higher than the critical power $({P}_{\mathrm{cr}})$ for monochromatic beam collapse in pure Kerr media. In particular, we compare the threshold for the formation of filaments with that for the formation of $\mathsf{X}$-waves. At powers ${P}_{\mathrm{cr}}<P<{P}_{\mathrm{th}}$, self-focusing is arrested by group-velocity dispersion, and no filaments or $\mathsf{X}$-waves are formed. At $P\ensuremath{\geqslant}{P}_{\mathrm{th}}$, we observe $\mathsf{X}$-wave formation and a weak filamentation regime. At $P⪢{P}_{\mathrm{th}}$, we observe both $\mathsf{X}$-waves and fully formed filaments.