An Ultrathin, Fast‐Response, Large‐Scale Liquid‐Crystal‐Facilitated Multi‐Functional Reconfigurable Metasurface for Comprehensive Wavefront Modulation

The rapid advancement of prevailing communication/sensing technologies necessitates cost‐effective millimeter‐wave arrays equipped with a massive number of phase‐shifting cells to perform complicated beamforming tasks. Conventional approaches employing semiconductor switch/varactor components or tunable materials encounter obstacles such as quantization loss, high cost, high complexity, and limited adaptability for realizing large‐scale arrays. Here, a low‐cost, ultrathin, fast‐response, and large‐scale solution relying on metasurface concepts combined together with liquid crystal (LC) materials requiring a layer thickness of only 5 µm is reported. Rather than immersing resonant structures in LCs, a joint material‐circuit‐based strategy is devised, via integrating deep‐subwavelength‐thick LCs into slow‐wave structures, to achieve constitutive metacells with continuous phase shifting and stable reflectivity. An LC‐facilitated reconfigurable metasurface sub‐system containing more than 2300 metacells is realized with its unprecedented comprehensive wavefront manipulation capacity validated through various beamforming functions, including beam focusing/steering, reconfigurable vortex beams, and tunable holograms, demonstrating a milli‐second‐level function‐switching speed. The proposed methodology offers a paradigm shift for modulating electromagnetic waves in a non‐resonating broadband fashion with fast‐response and low‐cost properties by exploiting functionalized LC‐enabled metasurfaces. Moreover, this extremely agile metasurface‐enabled antenna technology will facilitate a transformative impact on communication/sensing systems and empower new possibilities for wavefront engineering and diffractive wave calculation/inference. A low‐cost, ultrathin, fast‐response, and large‐scale millimeter‐wave beamforming array is reported relying on metasurface concepts combined together with ultrathin liquid crystals. The demonstrated device, characterized by its remarkable beamforming flexibility, real‐time tunability, and extensive degrees of freedom, stands to pave the way for sophisticated wavefront modulation and revolutionize the way liquid crystals can be exploited for tailoring electromagnetic waves.