On‐Chip Direction‐Multiplexed Meta‐Optics for High‐Capacity 3D Holography

Abstract Metasurfaces are recently incorporated with waveguides for in‐plane wave manipulation and extraction, enhancing the capability and design flexibility of integrated photonic devices. However, the unique guided‐wave‐driven scheme poses challenges in achieving multiplexed functionality for on‐chip integrated metasurfaces. Here, an on‐chip direction‐multiplexing strategy is proposed and demonstrated for high‐capacity 3D multiplane projection in free space. By exploring and utilizing the direction‐dependence of the guided‐wave‐driven detour phase manipulation, a 16‐channel on‐chip holography is realized with different images independently encoded at distinct z planes for all four illumination directions. Moreover, the on‐chip full‐space 3D holography is demonstrated by exploiting the conjugated relation of the optical responses driven by the opposite on‐chip illuminations, enabling observation of a total of 16 holographic images in full‐space. The demonstrated on‐chip direction‐multiplexed holography exhibits low background noise or crosstalk and offers high information density and quality, which shows promise for practical applications in data storage, 3D display, and virtual/augmented reality.