Multifunctional Hybrid Metasurfaces for Dynamic Tuning of Terahertz Waves

摘要

Actively tuning optical transmission through hybrid metasurfacesrnincorporated with multifunctional active media holds great promise forrnthe next generation optical devices. In the terahertz (THz) range, theyrnremain rare due to the lack of dynamic and multifunctional designs andrnmaterials. Here, a vanadium dioxide (VO_2)-based hybrid metasurface isrnproposed to present multifunctional control of THz waves via electricallyrntriggering and ultrafast optical excitation. By minimizing the thermalrnmass of VO_2 and optimizing the VO_2 patterns within two side gaps of thernasymmetric split-ring resonators, a hybrid metasurface which can tunernthe THz wave with an absolute modulation depth up to 54% and a figurernof merit as high as 138% is hereby presented. The hybrid metasurfacernachieves a switching time of 2.2 s under the electrically triggering andrnoffers an ultrafast modulation within 30 ps under the femtosecondrnpulse excitation. More interestingly, owing to the intrinsic hysteresisrnbehavior of VO_2, the hybrid metasurface exhibits distinguishingrnmultistate transmission amplitudes with a single electrical input. Inrnshort, this study paves the way for robust multifunctionality inrnelectric-controlled terahertz switching, photonic memory, andrnultrafast terahertz optics.