Longitudinally engineered metasurfaces for 3D vectorial holography.

The ability to precisely generate and manipulate three-dimensional (3D) vectorial optical fields is crucial for advancing applications in volumetric displays, secure data encoding, and optical information processing. However, conventional holographic techniques generally lack the capability to simultaneously control both light intensity and polarization within a volumetric region, thereby limiting the full realization of complex 3D vectorial light fields. Here, we present a metasurface-based platform for 3D vectorial holography that enables independent and programmable control over axial intensity and polarization profiles within structured beam arrays. By decomposing complex volumetric holographic targets into a dense array of non-diffracting beams-each governed by a tailored longitudinal response function-we achieve broadband, high-fidelity reconstruction of vectorial light fields encoded in both spatial intensity and polarization domains. Moreover, we demonstrate a vectorial encryption scheme that exploits the combined axial intensity and polarization degrees of freedom to realize secure, key-based optical information encoding. This approach provides a compact, integrable, and scalable solution for 3D vectorial holographic projection and volumetric vector beam shaping, offering a versatile platform for high-capacity optical storage, secure communication, and emerging quantum photonic technologies.