Dual-Dimensional EIT Manipulation for Angle-Multiplexed Ultrafast Terahertz Switching

Spatiotemporal multiplexing metasurfaces provide an effective approach to ultrafast multidimensional manipulation of terahertz (THz) waves, which is crucial for next-generation communication technology due to the high-capacity and high-speed characteristics. Here, a novel metadevice platform possessing active spatial resonance switching and ultrafast optical tuning abilities is designed and comprehensively investigated. Based on a double split ring resonator (DSRR) and a pair of split ring resonators (SRRs), the symmetry breaking caused by oblique incidence provides an extra degree of freedom to continuously alter the resonance behavior of the intrinsic structure. We experimentally demonstrate high-performance hybridization of electromagnetically induced transparency (EIT) and dual-band EIT resonance with a large modulation depth and great slow light effects. Meanwhile, owing to the outstanding compatibility and robustness of metamaterials, crystalline silicon (Si) bridges are embedded to achieve ultrafast photoactivated modulation. Due to the ultrashort relaxation time of photoinduced carriers in the Si crystals, the temporal dynamics of the switching process exhibit an ultrafast recovery within 1200 ps. The proposed strategy has excellent potential to overcome the bottlenecks of multifunctional active tuning systems.