Switchable Metasurface with High-Efficiency Absorption and Broadband Polarization Conversion for Terahertz Detection

In this article, taking advantage of the phase transition characteristics of vanadium dioxide (VO
2
), an alternate absorption and polarization conversion mode switchable metasurface is proposed. The metallic condition of VO
2
leads to the formation of a broadband absorber, which provides more than 90% absorption over a wide spectral range of 3.32 THz to 5.30 THz. Due to the regularity of the meta-atom, the absorber is insensitive to polarization and maintains a high retention rate in the range of angle of incidence from 0° to 45°. When VO
2
is insulated, the calculation results show that when the x-polarization waves or y-polarization waves are incident vertically, the cross-polarization conversion rate (PCR) can reach more than 90% in the range of 2.29 THz to 7.85 THz. The proposed metasurface may be used in imaging systems and terahertz detection.