We report experiments on self-focusing of femtosecond diffraction-resistant vortex beams in water. These beams are higher-order Bessel beams with weak azimuthal modulation of the transverse intensity patterns. The modulation overrides the self-focusing dynamics and results in the formation of regular bottlelike filament distributions. The peak-power thresholds for filamentation, at a particular distance, are relatively accurately estimated by the adaptation of the Marburger formula derived earlier for Gaussian beams. The nonlinear conversion of the incident conical waves into the localized spatial wave packets propagating near the beam axis is observed.
© 2011 Optical Society of America
Original Manuscript: August 8, 2011
Revised Manuscript: August 31, 2011
Manuscript Accepted: August 31, 2011
Published: September 23, 2011
Stacy Shiffler, Pavel Polynkin, and Jerome Moloney, "Self-focusing of femtosecond diffraction-resistant vortex beams in water," Opt. Lett. 36, 3834-3836 (2011)