Tunable ultra-broadband terahertz perfect absorber based on vanadium oxide metamaterial

A dynamically tunable ultra-broadband terahertz perfect metamaterial absorber based on vanadium oxide (VO2) is proposed and numerically demonstrated. The excellent absorption bandwidth of greater than 90% absorptance is as wide as 5.10 THz from 3.03 to 8.13 THz under normal incidence. By changing the conductivity of VO2 from 200 S/m to 2x10(5) S/m, the absorption intensity can be dynamically tuned from 1.47% to 100%. The ultrabroad bandwidth and flexibility are dramatically improved compared with previously reported VO2 based absorbers. The physical mechanism of the ultra-wideband absorption is discussed based on the interference cancellation, impedance matching theory, and field distributions. The influences of structure parameters on perfect absorption are also discussed. In addition, the absorber has the advantages of insensitivity to polarization and incident angle. Such a tunable ultra-broadband absorber may have promising potential in the applications of modulating, cloaking, switching, and imaging technology. (C) 2021 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement