Twelve-channel detection of spin and orbital angular momenta via dielectric metasurface

Spin angular momentum (SAM) and orbital angular momentum (OAM) have opened up new avenues in optical communication and imaging processing. However, detection of these states concurrently requires complicated optical setups. Here, we propose a 12-channel detection for SAM and OAM modes with a dielectric ultracompact metasurface. The phase profile is constructed with both propagation phase and geometric phase. Adopting spin photonic Hall effect and off-axis focusing scheme, light beams carrying different vortices are demultiplexed into several vortex beams with distinct topological charges, and each can be recognized with different focused spots on a transverse plane with unique azimuthal coordinate. The proposed design efficiently demultiplexes the incident with different SAM and OAM modes through a single layer metasurface. We envision this work will pave the way for high-capacity optical communication applications and integrated optical systems.