A Wideband Polarization-Independent Metasurface Absorber Using Vanadium Dioxide (VO₂)

In the paper, a tunable wideband terahertz (THz) absorber incorporating a metasurface (MS) structure has been proposed and analyzed. The MS consists of Vanadium dioxide rings as the upper layer, gold (Au) as the bottom layer and silicon dioxide as the dielectric layer in between. The structure exhibits an outstanding absorption bandwidth achieving over 90% absorbance within the range of frequency from 5.52 to 10.88 THz when subjected to normal incidence. Moreover, when the conductivity of Vanadium dioxide changes from 200 to 2e5 S/m, the intensity of the absorption peak can be varied from 3.3 to 99.9%. The structure is also polarization insensitive in nature owing to the fourfold symmetry. It is indicated by the result that the MS absorber maintains of over 90% for incident angles up to 50 degrees under transverse electric (TE) as well as transverse magnetic (TM) polarization. The power loss analysis shows that the top layer consisting of Vanadium dioxide is primarily responsible for absorption. The designed absorber holds great potential in the fields of modulation, imaging, sensing, and switching technology.