Electrically Triggered Tunable Terahertz Modulator Based on VO2 Hybrid Metasurface

We demonstrate an electrically triggered tunable terahertz (THz) modulator based on vanadium dioxide (VO2) embedded hybrid metasurface. The unit cell of the filter consists of two plates butted together with a split gap and a central bar. The phase transition of VO2 is induced by the ohmic heating of the central bar. The transmission can be modulated by the temperature caused by the ohmic heating. The mechanism of tunability is that the conductivity of the VO2 film changes with the applied currents. The relation between the modulation frequency and the geometries is investigated using finite element method (FEM). The simulation results show that, when the temperature of the VO2 film increases from 65 to $70^{\circ}\mathrm{C}$, a redshift from 0.65 THz with a 99% modulation depth to 0.3 THz with a 94% modulation depth is obtained. This tunable THz modulator has potential applications in THz communication, imaging, and spectroscopy systems.