Switchable narrowband THz metasurface filter based on vanadium dioxide

A switchable narrowband THz metasurface filter based on vanadium dioxide (VO₂) is demonstrated which can be switched between the “ON” and “OFF” state by applying a bias current to VO2. In the initial “ON” state without applying the bias current, the transmittance of the filter is greater than 80% from 0.72 to 0.78 THz and reaches a maximum of 92% at the center frequency of 0.75 THz. After applying 300 mA current to VO2, the filter is in the “OFF” state and the transmittance is almost zero over the entire frequency range from 0.4 to 1.1 THz. Furthermore, considering the influence of the substrate thickness of the filter on the actual application of the device, the response of the filter with different thicknesses of the substrate is numerically simulated, and the results show that the filter performance is still good when the thickness of the substrate increases to 500 μm.