Tunable vortex beam generation using an optical parametric oscillator with an antiresonant-ring interferometer

We report a high-average-power picosecond optical vortex source tunable in the near-infrared, using an antiresonant-ring (ARR) interferometer internal to an optical parametric oscillator (OPO) in combination with an external cylindrical lens for astigmatic mode conversion. The ARR OPO is tunable in the signal across 1457–1647 nm with a vortex intensity profile and up to 1 W of average power at 1602 nm. The corresponding idler is tunable over 3006–3945 nm in a Gaussian intensity profile with as much as 1.6 W at 3168 nm. The vortex signal and the Gaussian idler exhibit passive power stability better than 1.7% rms and 1.3% rms, respectively, over >1 h. The signal pulses have a Gaussian duration of <19 ps with a time–bandwidth product of 1τ1ν < 3.6 across the tuning range.