Sending femtosecond pulses in circles: highly nonparaxial accelerating beams

We use caustic beam shaping on 100 fs pulses to experimentally generate nonparaxial accelerating beams along a 60 degrees circular arc, moving laterally by 14 mu m over a 28 mu m propagation length. This is the highest degree of transverse acceleration reported to our knowledge. Using diffraction integral theory and numerical beam propagation simulations, we show that circular acceleration trajectories represent a unique class of nonparaxial diffraction-free beam profile which also preserves the femtosecond temporal structure in the vicinity of the caustic. (C) 2012 Optical Society of America