Generation of Enhanced Focused Airy Orbital Angular Momentum Beam With Metal-Only Huygens’ Metasurface

We present a novel phase modulation method for generating two-dimensional Airy vortex beams carrying orbital angular momentum (OAM) modes in microwave bands. This approach enhances the focal field intensity of the non-diffracting Airy OAM beam while simultaneously suppressing divergence at a longer distance without compromising its nondiffractive property. By leveraging Fourier optics theory, we theoretically analyze the propagation behavior of EM waves and outline a detailed design procedure. To achieve superior performance, a dual-polarized metal-only Huygens metasurface is designed at 5.8 GHz, synthesizing the full range of impedances required to attain 360-degree phase coverage and high transmission amplitude (-2 dB). To demonstrate the feasibility of our approach, we fabricate an experimental prototype using laser engraving, a cost-effective technique suitable for extreme environments. Full-wave simulations and experimental measurements are conducted to validate the design and its performance.