Terahertz Pancharatnam-Berry-phase metasurface for vectorial focusing and vortex beams

In recent years, with the maturation of micro-nanotechnology, metasurface has become a vibrant research topic. Nevertheless, metasurface that exploits Pancharatnam-Berry (PB) phase to create multiple focusing or orbital angular momentum (OAM) with distinct polarizations remain rarely reported. Here we design two terahertz metasurfaces for versatile wavefront control. Utilizing PB phase, the first metasurface generates three independent focal spots, and each is exclusively accessed by x-polarized, y-polarized, or left-handed circularly polarized (LCP) waves. The second metasurface under linearly polarized (LP) incidence generates a vortex beam (VB) with topological charge (TC=1) and 0 ∘ polarization as well as a second vortex with TC = − 1 and 90 ∘ polarization. Illuminated by LCP wave, metasurface produces a vortex with TC = 1 that preserves incident LCP state. Both functionalities are confirmed through simulations, demonstrating polarization-multiplexed wavefront engineering. These compact and multichannel metasurfaces offer new routes toward information processing.