We investigate experimentally the nonlinear dynamics of a femtosecond pulse undergoing self-focusing in a normally dispersive medium. Above a certain threshold power, we observe that the pulse splits into two pulses, and measurements of the pulse spectra provide evidence that supercontinuum generation is closely connected with the temporal splitting. We also observe that the split pulses can undergo additional splittings. Our observations are in good agreement with the predictions of the theoretical model based on the nonlinear Schrödinger equation describing self-focusing in dispersive media.

• Received 21 June 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.3783