Optical vortex generation from an anti-resonant-ring picosecond optical parametric oscillator

Optical vortices are beams with screw like (helical) phase variation along the propagation direction. This phase variation is given by exp(imθ) in the azimuthal plane, where m is the charge of optical vortices. Due to the doughnut shape intensity distribution and orbital angular momentum (OAM) content, optical vortices have found applications in various fields of science and technology. Commercially available mode converters transforming Gaussian beam into vortices suffer from the common drawback of low power handling capabilities and/or narrow wavelength coverage. To avoid such limitations, here we present a new technique of generating high power optical vortices over a wide wavelength range by using a Gaussian beam pumped anti-resonant-ring (ARR) optical parametric oscillator (OPO) [1]. By controlling the superposition of the Gaussian beams of an intracavity ARR, we have generated first-order HG modes [2] and further transformed into optical vortices using cylindrical lens [3], providing tunability across1457 nm to 1647 nm with an output power as high as 539 mW.