Tunable Terahertz Filter and Modulator Based on Electrostatic MEMS Reconfigurable SRR Array

This paper demonstrates a tunable terahertz (THz) filter and a modulator based on an electrostatic micro electro mechanical systems (MEMS) reconfigurable split ring resonator (SRR) array. The device uses tunable metamaterial concept, in which an RF-MEMS (radio frequency-MEMS) capacitor is embedded in each SRR unit cell to tune the electromagnetic resonant frequency. By utilizing THz time domain spectroscopy (THz-TDS) measurement and through the voltage actuation, we have controlled the THz transmission of the metamaterial device, and thus demonstrated a tunable filter. Since the low loss material of fused quartz is used as the substrate, the device shows a high contrast ratio THz switch at a given frequency by controlling the capacitance of the RF-MEMS capacitor. The dynamic performance of the switch, i.e., the modulation ability, is also characterized by THz-TDS. The measurement results show up to 2 kHz of the modulation speed with the TDS operated. The device is developed by the surface micromachining process with three photolithography steps.