Bi-directional extraordinary absorption, transmission multifunctional metamaterial based on circular metal-VO2 composites

Abstract

Multifunctional metamaterials play a crucial role in advancing terahertz technology. In this paper, a multifunctional metamaterial composed solely of circular metal-vanadium dioxide (VO2) is designed and numerically demonstrated. The device comprises a top layer of circular VO2 ring, two polyimide dielectric layers, with two metal layers etched and filled with VO2, and a bottom embedded silver (Ag) circular ring dielectric layer. The metamaterial serves as a broadband and narrowband absorptive or transmissive substrate, utilizing the phase transition of VO2 between its metal and dielectric states. When VO2 is in its metal phase, the top circular VO2 ring periodic array functions as a broadband absorber, exhibiting a relative absorption bandwidth of approximately 93%. Meanwhile, the bottom circular Ag ring periodic array functions as a narrowband absorber and exhibits high sensitivity. In contrast, when VO2 is in the insulating phase, the metamaterial acts as a broadband transmittance substrate, exhibiting a maximum transmittance greater than 85%. This proposed metamaterial holds tremendous potential for utilization across various applications within the terahertz band, spanning from terahertz stealth radar to tunable biosensors and photodetectors.