Tunable vortex laser based on intra-cavity aspheric lens

Vortex light is used widely in quantum entanglement, optical communication, high-resolution imaging, optical detection, optical manipulation, and many other fields. In practical applications, stable and adjustable vortex light sources are needed for applying the orthogonal characteristics of vortex light with different orders. We demonstrate a tunable vortex laser based on an intra-cavity aspheric lens. By adjusting the position of the lens and the output coupler, several orders of vortex beams have been obtained at the same pump power. The spatial matching between the pump light and the modes in the cavity determines the preferentially oscillatory transverse mode. Furthermore, we compare the mode selection mechanisms in previous researches on vortex lasers, that is, the mode change caused by the thermal lens effect, and the dual feedback mechanism of the spherical lens with appreciable spherical aberration, and discuss the intrinsic similarity of these methods.