Gate-tuned graphene meta-devices for dynamically controlling terahertz wavefronts

Abstract Dynamical controls on terahertz (THz) wavefronts are crucial for many applications, but available mechanism requests tunable elements with sub-micrometer sizes that difficult to find in the THz regime. Here, different from local-tuning mechanism, we propose an alternative approach construct wavefront-control meta-devices combining specifically designed metasurfaces and globally tuned graphene layers. Coupled-mode-theory (CMT) analyses reveal serves as a loss drive whole meta-device transit one functional phase another passing through intermediate regime, exhibiting distinct far-field (FF) reflection wavefronts. As proof of concept, design/fabricate experimentally demonstrate it can reflect normally incident wave pre-designed directions polarizations under appropriate gating voltages. We finally design numerically generate vectorial beams continuously varying polarization distributions upon gating. These findings pave road realizing wide range such sensing, imaging, wireless communications.