Hnatovsky, CyrilShvedov, Vladlen G.Krolikowski, WieslawRode, Andrei V.2016-02-222016-02-220146-9592http://hdl.handle.net/1885/98299This letter is the first demonstration of material modification using tightly focused femtosecond laser vortex beams. Double-charge femtosecond vortices were synthesized with the polarization-singularity beam converter described in Ref and then focused using moderate and high numerical aperture optics (viz., NA = 0.45 and 0.9) to ablate fused silica and soda-lime glasses. By controlling the pulse energy we consistently machine high-quality micron-size ring-shaped structures with less than 100 nm uniform groove thickness.We acknowledge financial support from the National Health and Medical Research Council of Australia and the Australian Research Council.3 pages© 2010 Optical Society of Americamaterialfemtosecondlaservortexbeams2010-10-1510.1364/OL.35.0034172016-02-24