Ultra-Broadband Tunable Terahertz Metamaterial Absorber Based on Double-Layer Vanadium Dioxide Square Ring Arrays

Abstract

Based on the phase transition of vanadium dioxide(VO2), an ultra-broadband tunable terahertz metamaterial absorber is proposed. The absorber consists of bilayer VO2 square ring arrays with different sizes, which are completely wrapped in Topas and placed on gold substrate. The simulation results show that the absorption greater than 90% has frequencies ranging from 1.63 THz to 12.39 THz, which provides an absorption frequency bandwidth of 10.76 THz, and a relative bandwidth of 153.5%. By changing the electrical conductivity of VO2, the absorption intensity can be dynamically adjusted between 4.4% and 99.9%. The physical mechanism of complete absorption is elucidated by the impedance matching theory and field distribution. The proposed absorber has demonstrated its properties of polarization insensitivity and wide-angle absorption, and therefore has a variety of application prospects in the terahertz range, such as stealth, modulation, and sensing.

Tunable polarization-independent and angle-insensitive ultra-broadband terahertz absorber with vanadium dioxide

“…From the figure, it can be observed that when the conductivity of VO 2 reaches 2 × 10 5 S m −1 , the real part of the relative impedance of the absorber is close to 1 and the imaginary part is almost 0 in the frequency range from 1.99 THz to 6.19 THz. This result clearly shows that the impedance of the absorber has reached a state of almost perfect matching with the impedance of the free space in this frequency range [43], which minimizes the reflection and significantly improves the absorber's performance in absorbing electromagnetic waves [44].…”

Structures, principles, and properties of metamaterial perfect absorbers

“…1 In thermal optoelectronics, thermal imaging and thermal emission, the need for broadband and omnidirectional absorbers with thin and compact structures is urgent. 2 Therefore, the emergence of MPAs perfectly meets this need.…”

Carbon-based ultrabroadband tunable terahertz metasurface absorber

“…34,35 In recent years, absorber structures based on graphite resonators have been reported to achieve broadband THz absorption, but they cannot be dynamically tuned. [36][37][38] So far, some multilayer graphene-based structures, 39 multilayer VO 2 -based structures, 40 or multilayer metal/dielectric structures 41 have been designed to achieve tunable ultra-wideband absorption bandwidth. However, these structures greatly increase the difficulty of manufacturing, and the performance of devices is not reliable due to the characteristics of metals in certain environments.…”