Abstract-Dual-controlled switchable broadband terahertz absorber based on a graphene-vanadium dioxide metamaterial

Tongling Wang, Yuping Zhang, Huiyun Zhang, and Maoyong Cao

Schematic of graphene- and VO2-based metamaterial broadband absorber geometry. P = 15 µm, Lin = 3.8 µm, Lout = 6.8 µm, win = 0.5 µm, wout = 2 µm, d = 28 µm, and h = 0.7 µm.

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-10-2-369

We propose a dual-controlled switchable broadband terahertz (THz) metamaterial absorber based on a hybrid of vanadium dioxide (VO2) and graphene that demonstrates strong polarization-independent characteristics and works well at a wide range of incidence angles. The peak absorptance of the proposed absorber can be tuned from 26 to 99.2% by changing the Fermi energy of the graphene; the absorptance can be dynamically tuned from 9 to 99.2% by adjusting the conductivity of the vanadium dioxide because of its unique insulator-to-metal transition characteristic. Using these two independent controls in tandem, we found that the state of the proposed absorber can be switched from absorption (>96%) to reflection (>73.5%), and the transmittance can be tuned from 0% to 65% while maintaining broad bandwidth (1.05-1.6 THz), resulting in a better-performing switchable broadband terahertz absorber. Furthermore, we have provided a discussion of the interference theory in which the physical mechanism of the absorption is explained from an optical point of view. The absorber achieves dual-controlled absorptance switching via two independently controllable pathways, offering a new method for switching and modulation of broadband THz radiation.

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