Control and characterization of multiple circularly polarized femtosecond filaments in argon

We provide what is believed to be the first experimental evidence of spatial control on multiple filamentation (MF) using circularly polarized femtosecond laser pulses. The exceptional shot-to-shot reproducibility of the MF pattern allowed complete characterization of the two copropagating high-energy filaments, revealing for the first time temporal (self-) compression of circularly polarized filamenting pulses to a fifth of the initial 57 fs laser pulse duration without any sophisticated chirp control. Compared with LP MF, an enhancement in spatial stability and an increase in energy throughput are reported for circular input polarization. (c) 2007 Optical Society of America.