Metasurface-Based Orbital Angular Momentum Multi-Dimensional Demultiplexer and Decoder

Light beams possess various dimensions, such as wavelength, spin angular momentum (SAM), and orbital angular momentum (OAM), which are indispensable in numerous optical applications. However, traditional techniques entail multiple attempts to disclose desired optical information, utilizing unwieldy multi-pass systems or mechanically moving parts that are cumbersome to integrate into compact and integrated optical systems. Here, a single-layer dielectric metasurface platform is proposed that enables multi-dimensional demultiplexing and decoding, circumventing the need for conventional bulk optical elements. The platform can demultiplex 3D light parameters (wavelength, SAM, and OAM) and focus them at distinct spatial positions on a designated focal plane, providing a superior alternative to far-field beams for integration with optical fiber and communication chips. The study verifies 132-bit independent channels for a multi-dimensional demultiplexer and demonstrates the metasurface-based component's ability to function as an elliptic polarization decoder through a 4-bit elliptic polarization coding transmission experiment. This work provides a compact and efficient platform for demultiplexing multi-dimensional SAM and OAM states over a broad wavelength range, with potential implications for optical communications, optical data storage, optical information encryption, and quantum information sciences.