All-dielectric reflective metasurface for orbital angular momentum beam generation

Orbital angular momentum (OAM) beams have recently attracted attention due to their intrinsic properties and their many novelty applications. The use of dielectric metasurfaces as highly efficient and ultra-thin functional optical platforms for OAM beam generation has been discussed in detail in earlier research. However, reflective all-dielectric metasurfaces for high quality OAM beam generation have been rarely investigated. In this work, a high-quality OAM beam generator applying an all-dielectric reflective metasurface is proposed, with an operation waveband from 1500 to 1600 nm. Simulation results show that good quality OAM beams (mode purity ~99%) can be generated with high efficiency (conversion rate > 97%) and high reflectance (> 0.8). With such superior performance, the proposed reflective all-dielectric metasurface can provide new possibilities in free-space optical communication systems.