High-Q Terahertz Filters of Vo2-Based Metamaterials with Large Modulation Depths by Optical Tunneling

Recently, reconfigurable terahertz band-pass filters based on the design of metamaterials with vanadium dioxide (VO2) have been investigated extensively. VO2-based THz devices with high-quality tunable narrowband transmission and good stop-band rejection have yet to be reported, which are essential for THz wave filtering components or systems. Here, we present a reconfigurable filter in combination with a dielectric metamaterial structure and a VO2 thin film. Utilizing the cavity optical tunneling effects of THz wave, the device demonstrates a high band-pass transmission up to 99.7% at 0.246 THz with a narrow bandwidth of 0.00077 THz, an ultra-high Q-factor of 319 and wide nearly-suppressed sidebands. The narrowband transmitted wave can be modulated considerably by using the phase transition of VO2. By efficiently tuning the cavity layer thickness in the metamaterial, the designed filter can be optimized for different transmission wavelengths, and further accomplish the switch between the narrow band-pass filter and wideband reflector. Additionally, the change of the incident conditions is adopted to achieve a similar switching function. The proposed device has a promising potential for various THz applications, where a tunable high-Q transmission band with high-suppression sidebands is required.