Active Controllable Coded Terahertz Narrow Bandpass Filter Based on Vanadium Dioxide

An active controllable terahertz filter with dual narrowband characteristics is proposed, which consists of two n-shaped waveguides and one vanadium dioxide defect. The simulation results show that at the resonance frequencies of 1.287 THz and 1.447 THz, the 3 dB bandwidth are 13 GHz and 3 GHz, the transmittance are 83% and 91%, and the Q value are 99.5 and 482, respectively. It has good frequency selection performance. In addition, by changing the temperature, vanadium dioxide can be converted between the metal state and the insulating state, and the two states are binary coded. At 1.287 THz and 1.447 THz, the switching function between passband and stopband can be realized. The presented filter can be used for temperature control switches in integrated photonic circuits.