Orbital angular momentum generation via a spiral phase microsphere.

Vortex beam carrying orbital angular momentum (OAM) attracts much attention in many research fields for its special phase and intensity distributions. In this Letter, a novel design called the spiral phase microsphere (SPMS) is proposed for the first time, to the best of our knowledge, which can convert incident plane wave light into the focused vortex beam that carries OAM with different topological charges l=±1 and ±2. The vortex beam generation is verified by a self-interfered modification of the SPMS. The generation of the vortex beams by the SPMS irradiated by a single-wavelength incident light is studied using the CST MICROWAVE STUDIO simulation. The SPMS provides a new approach to achieve high-efficiency and high-integrated photonic applications related with OAM.