The spatiotemporal self-focusing of chirped optical pulses propagating
in a nonlinear dispersive medium has been studied analytically and nu
merically. The analytic theory shows that the critical power for self-
focusing occurring in a dispersive media changes quadratically with th
e chirp parameter in both two and three dimensions. It is found that t
he critical wave action depends on the sign of the total chirp paramet
er. Analytic results show that the effect of chirp is similar to that
of beam ellipticity except that ellipticity always increases the criti
cal wave action. Numerical simulations are used to study the effect of
chirp and group-velocity dispersion on self-focusing. It is shown num
erically and analytically that the self-focusing process can be contro
lled by changing the chirp parameter.