Accurate retrieval of pulse-splitting dynamics of a femtosecond filament in water by time-resolved shadowgraphy

By means of a time-resolved, shadowgraphic method we observed directly the development of the pulsesplitting dynamics of a femtosecond laser pulse propagating in the filamentary regime in water. For the first time to our knowledge, the relative splitting velocity was measured. We compare the experimental data with numerical simulations. A possible scenario for the splitting event and evolution of the fragments is discussed.