Rotational Vortex Metasurface Arrays Enabling Tunable Perfect Petal‐Shaped Beam Emissions

Abstract

AbstractActively tunable petal‐shaped pattern emissions have been successfully demonstrated by the cascade of two innovative rotational vortex metasurface arrays (RVMAs). To ensure accurate cascade, each RVMA comprises a central unit with the capability to converge light, surrounded by six units designed for emitting converging vortex beams (VBs) and converging perfect vortex beams (PVBs) with topological numbers (TCs) of 3, 6, and 9, respectively. Notably, although the number of spiral branches and the diameters of the VB and PVB are determined in accordance with specific design TCs, the diameters and the number of petals for the petal‐shaped beam emissions are actively adjusted through the rotation of the RVMAs. Interestingly, the superimposition of these VBs, PVBs, or both, consistently generates petal‐shaped beams with various petal numbers and diameters, highlighting the remarkable versatility of the approach. To demonstrate the proposed concept across wavelengths, indicating its broadband operation capability, RVMA performance in the visible spectrum is thoroughly investigated, ranging from 450 to 600 nm. The tunability of the cascade of RVMAs for petal‐shaped emissions featuring diverse diameters and petal numbers has been validated at visible wavelengths, affirming the broad capabilities of the concept presented in this study.