Liquid-crystal-integrated metadevice: towards active multifunctional terahertz wave manipulations

Active terahertz elements with multifunction are highly expected in security screening, nondestructive evaluation, and wireless communications. Here, we propose an innovative terahertz metadevice that exhibits distinguishing functions for transmitted and reflected waves. The device is composed of a thin liquid crystal layer sandwiched by Au comb electrodes and a dual-ring resonator array. For transmission mode, the metadevice manifests the electromagnetically induced transparency analog. For reflection mode, it works as a perfect absorber. The comb electrodes actuate the in-plane switching of liquid crystals, making the metadevice actively tuned. 60 GHz frequency tuning of an electromagnetically induced transparency analog and 15% modulation depth of the absorption are demonstrated. Such modulations can be realized in the millisecond scale. The in-plane switching driving mode avoids the electrode connections among separate resonators, thus freeing the design of the metadevice. The proposed work may pave a bright road towards various active multifunctional terahertz apparatuses.