Simulation Research of Ultrawideband Terahertz Absorber Based on VO ₂ With Polarization Insensitivity and Wide Incidence Angle Characteristics

In this article, a tunable broadband terahertz (THz) absorber is presented. The structure contains patterned vanadium dioxide (VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>), patterned Aurum (Au), polydimethylsiloxane (PDMS), and Au substrate. The proposed absorber utilizes the phase transition property of VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> to achieve dynamic absorption tuning. The numerical simulation results indicate that when the conductivity of VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> reaches <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 10^{5}$</tex-math> </inline-formula> S/m, the absorber can obtain more than 90% absorptivity in the range of 4.8–9.3 THz. When the conductivity becomes 200 S/m, the absorptivity drops to less than 5%, indicating that the THz absorption possesses significant dynamic tunability. By analyzing the electric field distribution at different conductivities and combining with the concept of relative impedance, the physical mechanism of broadband absorption is explored preliminarily. Meanwhile, the proposed absorber has polarization insensitivity and wide incidence angle characteristics simultaneously. As a result, the research in this article has good prospects in the application fields of THz detection, modulation, switching, and so on.