This letter is the first demonstration of material modification using tightlyfocused femtosecond laser vortex beams. Double-charge femtosecond vortices weresynthesized with the polarization-singularity beam converter described in Ref[1] 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 controllingthe pulse energy we consistently machine high-quality micron-size ring-shapedstructures with less than 100 nm uniform groove thickness.
展开▼
