Just above the soliton-fission threshold, where one or more solitons are liberated in a typical event, rare narrowband events are detected as deficiencies in redshifted energy [REF].
Extreme phenomena have been observed in single-shot studies of the temporal dynamics of optical beam filamentation in air[REF] and the two-dimensional transverse profiles of beams forming multiple filaments in a nonlinear Xenon cell [REF].