Active Terahertz Nonlocal Metasurfaces With Liquid Crystal Elastomers

Achieving active tunability in metasurfaces remains a critical challenge, with conventional local metasurfaces limited by dispersive wavefront deflection and broad resonances that lack spectral selectivity. In contrast, nonlocal metasurfaces exhibit high selectivity, offering a promising platform for dynamic functionality. Here, an active nonlocal metasurface with exceptional spectral and spatial selectivity is experimentally demonstrated, leveraging the physics of bound states in the continuum and coupling phase. The metasurface achieves a deflected beam with a quality factor of 22 and a narrow beamwidth of 5 degrees, focusing energy more precisely than local metasurfaces across both spectral and spatial domains. By integrating a liquid crystal elastomer substrate, tunable azimuthal deflection of 3 degrees with 4.5% in-plane deformation is realized. Furthermore, the coupling phase introduces polarization-dependent in-plane wavevectors, enabling the spatial separation of orthogonal polarization components while maintaining high selectivity and tunability. This active nonlocal metasurface architecture shows strong potential for polarization-division multiplexing and demultiplexing with low cost and high environmental adaptation, paving the way for advanced terahertz devices, such as signal relays, processors, modulators, and transmitters, for next-generation wireless communications.