Tuning Performance and Mechanism of Gate-tuned Graphene Grating for Dynamically Controlling Terahertz Wavefront

Recently, dynamically controlling of the terahertz wavefront has attract tremendous attention due to both scientific curiosity and potential applications in many fields. However, the available tunable components in the terahertz band are low efficiency and difficult to integrated with other terahertz components, due to the low light-matter interaction in this frequency range. Here, we design a tunable grating fabricated of graphene combined with metasurfaces. Coupled-mode-theory (CMT) analyses reveal the underlying physics, that is through the control of the applied voltage, graphene as tunable absorption loss, can realize dynamically controlling on the amplitude and phase of THz wavefront.