Terahertz frequency selective surface with reconfigurable polarization characteristics using vanadium dioxide

In this paper, we present a design technique to realize reconfigurable terahertz (THz) frequency selective surface (FSS) polarizer. Our approach relies on combining vanadium dioxide (VO₂) patches with metallic resonators. Vanadium dioxide behaves as an insulator at room temperatures and as a metal at high temperatures with a characteristic insulator-metal transition temperature of ̃68 °C. We used this attribute to realize a reconfigurable single- to dual-polarized bandpass FSS structure at 0.5 THz. Along with the simulation results, FSS structures fabricated on sapphire substrates were measured using THz time-domain spectroscopy. Measured extinction ratio of ̃25 dB was achieved for the THz polarizer with just a single FSS layer. Good agreement between simulation and experiments were obtained.