High average power ultraviolet picosecond optical vortex generation

We reported on high average power ultraviolet (UV) picosecond optical vortex generation without any spatial separation of the phase singularity due to the walk-off effect by employing a pair of β-BaB₂O₄ and reversed β-BaB₂O₄ crystals. The UV vortex output power was measured to be 1.76 W, corresponding to the optical-optical conversion efficiency of 17 %.