A new ultrathin metasurface enables true 3D vectorial holography by engineering the longitudinal evolution of hundreds of structured beams to control axial intensity and polarization within a volumetric region.

The platform enables an all-optical encryption scheme where information is encoded by depth and polarization signatures; without the correct polarization key and axial position, the output appears scrambled, providing hardware-level security resistant to digital analysis.

The technology is scalable: increasing the number of Bessel components or decreasing pixel size could boost axial resolution and enable richer volumetric scenes, with potential applications in high-density optical data storage, secure communications, volumetric displays, optical steganography, and quantum light engineering.

Experimentally, the device reconstructs sequences of high-contrast axial-depth images across a broad visible range, with full Stokes polarimetry confirming accurate polarization trajectories and the ability to traverse complex paths on the Poincare sphere.

The method decomposes a target 3D light field into a dense array of quasi non-diffracting beams, each with a tailored longitudinal response function that describes how its intensity and polarization evolve along the propagation axis, synthesized by combining multiple Bessel beam components.

The metasurface is built from rectangular amorphous silicon nanopillars on a fused silica substrate, acting as anisotropic scatterers to precisely control amplitude, phase, and polarization, implemented via a dual matrix holography framework to map the desired vectorial field to nanopillar geometries and orientations.