Full-Space Terahertz Airy Beam Shaping via Composite Bilayer Metasurface With Switchable Amplitude-Phase Encoding Channels

Terahertz (THz) Airy beams hold significant promise for directional wireless links in future 6G communications. Unlike conventional phased arrays with high power consumption and complexity, metasurfaces offer a platform for flexibly tailoring the Airy beam. However, existing THz metasurface-based Airy beam generators remain confined to one dimension, and experimental verification of their quasi-nondiffracting and self-healing characteristics is scarce. Here, we propose a composite bilayer metasurface for full-space THz Airy beam manipulation and experimentally demonstrate its transmission channel capabilities. By varying the structural rotation angles, the metasurface enables linearly polarized (LP) amplitude-phase and circularly polarized (CP) Pancharatnam-Berry (PB) phase, switching between distinct transmission channels at 0.99 THz and reflection channels at 0.538 and 0.553 THz. Ring Airy beams (RAB), phase-modulated ring Airy beams (PRAB), and elliptical Airy vortex beams (EAVB) are realized based on the proposed composite bilayer architecture. As proof-of-concept demonstrations, the prototypes of LP RAB and CP EAVB are fabricated and experimentally verified. The measured distributions show good agreement with simulations, confirming the ability of the metasurfaces to manipulate Airy beams across polarization states, frequencies, and transmission directions. This work provides a compact route toward multi-dimensional THz Airy beam manipulation with broad application prospects in areas such as free-space optical communications and 6G THz wireless communication.