Cross-domain switching on a phase-change metasurface: From OAM generation to polarization-addressed focusing

Reconfigurable metasurfaces offer a compact route for switching optical functions without mechanical motion, yet most implementations remain confined to tuning within a single functional domain. Here, we demonstrate a nonvolatile phase-change metasurface that integrates structured-light generation and spatial wavefront control within a single subwavelength-thick aperture at a fixed visible wavelength of 700 nm. In the amorphous state, circular-polarization addressing produces focused vortex beams with opposite topological charges (ℓ = +1 under LCP and ℓ = −1 under RCP), as confirmed by fork interferometry, with focal-spot widths of 0.82 μm (ℓ = +1) and 0.83 μm (ℓ = −1) at z = 35 μm. Upon crystallization, the device switches to linear-polarization addressing and enables polarization-selective wavefront shaping, including on-axis focusing and off-axis focusing with a lateral focal displacement of Δx = −3 μm at z = 50 μm. The metasurface supports repeatable switching over 10 amorphous–crystalline cycles with performance variation below 2.8%, confirming operational endurance. By unifying OAM manipulation and metalens-style focusing with focal-position switching in a single reprogrammable platform, this work establishes a cross-domain reconfigurable flat-optics architecture for compact imaging, adaptive photonics, and optical security.