  We study the possibility of efficient self-compression of femtosecond laser
pulses in nonlinear media with anomalous dispersion of group velocity during
the self-focusing of wave packets with a power several times greater than the
critical self-focusing power. The results of qualitative analysis of the
evolution of three-dimensional wave packets with the quasi-soliton field
distribution are confirmed by the computer simulation. The simulation proves
that the considered regime of compression of high-power laser pulses with
initial durations of about ten optical cycles is stable relative to
filamentation instability due to the influence of the nonlinear dispersion. We
demonstrate the possibility of self-compression of laser pulses at a
multi-millijoule energy level and up to one optical cycle with an energy
efficiency of more then 50%.
