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.
We propose a dualcontrolled switchable broadband metamaterial sandwichstructured absorber composed of black phosphorus (BP) and vanadium dioxide (VO 2 ), suitable for operation in the terahertz range. The proposed absorber consists of multilayered sinusoidally patterned BP, sandwiched between dielectric layers, and a VO 2 bottom layer. Numerical results reveal that the broadband absorption can be dynamically tuned over a wide range by adjusting the electron doping of BP and conductivity of VO 2 . Owing to the fully metallic state of VO 2 , the proposed absorber realizes a more than 98% absorptance with the bandwidth of 2.9 THz under TE polarization and more than 90% absorptance with the bandwidth of 3.25 THz under TM polarization when the armchair direction of BP is along the y axis and xaxis, respectively. Most importantly, by utilizing the dual independent controls in tandem, the state of proposed absorber can be switched from absorption (>98%) to reflection (>63.5%) while maintaining the broad bandwidth. Our research that utilizes the advantages of BP and VO 2 presents a new perspective on the design of tunable broadband THz absorbers promising for potential applications such as switching, modulation, and sensing.
A tunable bifunctional terahertz (THz) metamaterial device based on Dirac semimetal films (DSFs) and VO2 is presented. The insulator-to-metal phase transition of VO2 enables bifunctional asymmetric transmission and dual-directional absorption to be switched in the THz range. When VO2 serves as a dielectric, tunable broadband asymmetric transmission of linearly polarized THz waves can be achieved. When VO2 is in a metallic state, the proposed device acts as a tunable dual-directional absorber with perfect absorption in both illumination directions. In each case, the response can be tuned by varying the Fermi energy of the DSFs. This offers a new pathway for the development of tunable multifunctional THz metamaterial devices.
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