Propagation Dynamics of Intense Femtosecond Pulses: Multiple Splittings, Coalescence, and Continuum Generation

We present a scenario of $\left(3+1\right)$-dimensional spatiotemporal dynamics of femtosecond laser pulses in a nonlinear media with normal dispersion. The sequence of events at progressively higher powers can be characterized as single splitting, multiple splitting, and coalescence. Self-focusing and splitting events are in general spatially separated. Experimental data confirm the above scenario, with measurements at the highest powers corresponding to the regime of continuum generation.