Switchable bifunctional metamaterial for terahertz anomalous reflection and broadband absorption
Zekai Zhou, Zhengyong Song
Abstract
Abstract A terahertz switchable metamaterial is proposed with bifunctional properties based on a mixed structure of graphene and vanadium dioxide (VO 2 ). When VO 2 is metal, this metamaterial can be used to perform the function of anomalous reflection. It is composed of VO 2 blocks, topas spacer, and VO 2 film. By adjusting the size of VO 2 blocks, the gradient transformation is formed, so the normally incident beam is reflected to the left side at the angle of 38.4° at 3.0 THz. When VO 2 is insulator, this design can be used to realize a broadband absorber. It has a broadband absorption with more than 90% absorptance in the range of 1.29–3.08 THz, and there are two absorption peaks with 99% absorptance at 1.545 THz and 2.55 THz. By adjusting Fermi energy level of graphene, intensity and bandwidth of broadband absorption can be dynamically changed. In addition, the designed metamaterial is insensitive to incident angle. Our design could be applied in many promising fields as intelligent absorption and terahertz switch.