Tunable terahertz band-pass filter based on MEMS reconfigurable metamaterials

We present a tunable terahertz (THz) band-pass filter based on electrostatically actuated microelectromechanical systems (MEMS) reconfigurable metamaterials. The unit cell of the filter consists of a U-shaped structure and a fat-T shaped structure. The fat-T shaped structure connects with a movable frame which is actuated by two columns of electrostatic comb actuators. Initially, the filter has two passbands whose central resonance frequencies locate at 0.66 THz and 1.31 THz, respectively. When the actuators are biased with direct currents (DC) voltages, the fat-T shaped structures will move to the U-shaped structures. And thus, the transmition of the peak at 0.66 THz will decrease, and the modulation depth can reach 84.4%. Meanwhile, the resonance frequency of the high-frequency passband shows distinct blueshift, and the largest frequency shift arrives to 0.195 THz. The simulation results obtained from the finite-intergration-technology (FIT) show that these two resonance peaks are produced by two LC resonators on the two arms and one resonator on the bottom of the U-shaped structure. A flinite element analysis (FEA) method is introduced to study the electromechanical performance of the actuator, and a displacement of 4 µm is achieved at DC 120 V. The tunable THz band-pass filter can be applied in THz communication, THz frequency selection and THz sensing.