Active controllable bandwidth of THz metamaterial bandpass filter based on vanadium dioxide

A terahertz metamaterial bandpass filter with actively control bandwidth based on vanadium dioxide is proposed. This filter has an initial bandwidth with 0.32 THz without a bias voltage. By applying different bias voltages on different parts of the metal patterns, not only the bandwidth can be continuously adjusted, but also the passband frequency can be shifted. Simulation results show that the ranges of the bandwidth increasing and decreasing are 0.13 THz and 0.12 THz, respectively. And the range of the passband frequency shifting is 0.12 THz. Meanwhile, excellent broadband response and bandpass performance can still be maintained during the phase transition process. The physical mechanism of the bandwidth tunability is elucidated by comparing the surface current and electric field distributions of the insulator and metal phase. In addition, it can keep stable working performance when the incident angle varies up to 40 degrees. This bandwidth tunable terahertz passband filter can eliminate undesired information to obtain useful information more flexibly and has a great potential in terahertz communication, bioimaging and safety detection.