Monolithic silicon carbide metasurfaces for engineering arbitrary 3D perfect vector vortex beams.

Perfect vector vortex beams (PVVBs) can precisely control the light's polarization and phase along tailored intensity profiles, offering significant potential for advanced applications such as optical trapping and optical encryption. Extending PVVBs from 2D to 3D configurations would provide an additional spatial control dimension and enhance their information capacity. However, a compact and low-loss solution to generating 3D PVVBs remains unresolved. Here, we propose and demonstrate the use of monolithic silicon carbide metasurfaces with polarization-dependent phase-only modulation to engineer arbitrary PVVBs in 3D space. We reconstruct the 3D intensity and polarization distributions of PVVBs along customized trajectories, showing their independence from polarization orders and spherical coordinates on the Poincaré sphere. Additionally, we demonstrate a monolithic metasurface that encodes parallel-channel 3D PVVBs for information encryption. The 3D PVVBs generated from minimalist metasurfaces hold great promise for multidimensional micromanipulation and laser micromachining, high-security information processing and high-dimensional quantum entanglement.