Electrically Triggered Tunable Terahertz Band-Pass Filter Based on VO2 Hybrid Metamaterial

We demonstrate an electrically triggered tunable terahertz (THz) band-pass filter based on vanadium dioxide (VO2) embedded hybrid metamaterials. The unit cell of the filter consists of two cross resonators 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 applied currents. The mechanism of tunability is that the conductivity of the VO2 film changes with the applied currents. The relation between the upper cut-off frequency and the geometries is investigated using finite integration time domain method. The sample is fabricated by a thin film process, and characterized using a THz time domain spectroscopy system. The results show that, when the bias current rises from 0 to 0.27 A, the transmission decreases from 0.85 to 0.01. The maximum modulation depth reaches 96%, and the full width at half maximum is about 0.44 THz. This tunable THz band-pass filter has potential applications in THz communication, imaging, and spectroscopy systems.