A crossed focused vortex beam with application to cold molecules*

We report the generation of a crossed, focused, optical vortex beam by using a pair of hybrid holograms, which combine the vortex phase and lens phase onto a spatial light modulator. We study the intensity distributions of the vortex beam in free propagation space, and the relationship of its dark spot size with the incident Gaussian beam's waist, the lens's focal length, and its orbital angular momentum. Our results show that the crossed, focused, vortex beam's dark spot size can be as small as 16.3 mu m and adjustable by the quantum number of the orbital angular momentum, and can be used to increase the density of trapped molecules. Furthermore, we calculate the optical potential of the blue-detuned, crossed vortex beam for MgF molecules. It is applicable to cool and trap neutral molecules by intensity-gradient-induced Sisyphus cooling, as the intensity gradient of such vortex beam is extremely high near the focal point.

Automated summary

This study generated a crossed, focused optical vortex beam using hybrid holograms and analyzed its intensity distributions and the relationship of dark spot size with various parameters. The results show that the dark spot size of the vortex beam can be adjusted by the quantum number of orbital angular momentum and it can enhance the density of trapped molecules. Additionally, the optical potential of the blue-detuned, crossed vortex beam for MgF molecules was calculated, which could be used for cooling and trapping neutral molecules with high intensity gradient near the focal point.