Asymmetric temporal splitting of laser pulse and broad supercontinuum generation under femtosecond filamentation in YAG crystal

Abstract

We report an extensive theoretical research of the spectrum transformation and spatiotemporal nonlinear dynamics of the intense 200 fs laser pulses in normal (1.24 µm) and anomalous (1.9 µm) group velocity regions. We shed light on the influence of Raman nonlinearity on the laser pulse filamentation in YAG crystal and observed generation of broad supercontinuum induced by asymmetric Raman-initiated temporal splitting of the laser pulse. In the case of normal dispersive region, spectral broadening is related to the secondary temporal splitting of a trailing subpulse, whereas in the anomalous group velocity dispersion, generation of broadband supercontinuum is caused by temporal compression and emergence of numerous subpulses. It is shown that for the both group velocity dispersion regions the Raman nonlinearity does affect on the supercontinuum generation.