Abstract
The onset and recurrence of multiple filamentary structures during the
propagation of high power 200 femtosecond laser pulse in air, is
reminiscent of the features observed in strong turbulence phenomena
in physics. This highly explosive behavior is modeled by a higher
dimensional Nonlinear Schroedinger
equation which displays a blow-up singularity in finite time. Usually
dissipation at short scales
is invoked as a means of regularization of this collapse singularity.
The NLS theory has been extremely
successful in explaining Langmuir turbulence in plasmas and similar
phenomena in fluids.
The present situation with high power ultrashort laser pulses shows some
added novel behavior. Collapse regularization through small scale
dissipation is not the key player. Instead, narrow plasma filaments
created in the nonlinear focal region, induce a strong defocusing lens
which evaluates most of the
light energy behind the light intensity hot-spot. Little energy is
therefore dissipated per collapse event
and this is important as the means of driving and sustaining the
nucleation of such structures persists for only 100-200 femtoseconds.
