Simultaneously spatially and temporally focused femtosecond vortex beams for laser micromachining

We combine conventional beam shaping with simultaneous spatial and temporal focusing (SSTF) to generate femtosecond SSTF vortex beams. We demonstrate the utility of these beam structures by producing single-shot encryption of doughnut-shaped ablation marks on the back surfaces of glass plates. The SSTF enables this type of machining by significantly reducing the nonlinear beam distortions on propagation through the glass. (c) 2018 Optical Society of America