Waveguide‐Based Four‐Channel Crosstalk‐Free Metahologram Multiplexed by Diffraction Orders

ABSTRACT Metaholograms have attracted significant attention for their ability to project high‐quality images within a compact form factor. Although various multiplexing strategies have been explored for multi‐channel metaholograms, current approaches still face limitations in display channel extension and inter‐channel crosstalk elimination. Here, we introduce a waveguide‐based metahologram that enables four independent, crosstalk‐free display channels via diffraction‐order multiplexing. The metaholograms are integrated onto the top surface of a flat glass waveguide and modulate guided light through detour phase. With carefully designed device parameters, light diffracted into four distinct orders is selectively out‐coupled to form crosstalk‐free holographic images. To decouple the detour phase modulations between different orders, we develop an adaptive‐weight phase‐retrieval algorithm that simultaneously optimizes phase profiles across multiple diffraction orders to realize independent image encoding. Extending this strategy, we also demonstrate a six‐channel metahologram for two full‐color image projection, highlighting the versatility and scalability of the design. This work offers a new pathway toward compact, high‐capacity holographic devices, with promising applications in AR/VR displays, information storage, and image encryption.