Electrostatically Programmable Terahertz Metadevice for Parallel Opto‐Logic Functions

ABSTRACT In this study, we present an electrostatically tunable terahertz (THz) metamaterial (TTM) on a silicon (Si) substrate that combines two face‐to‐face fixed T‐shaped structures and two face‐to‐face released T‐shaped cantilevers. The released cantilevers can be bent upward after the fabrication process owing to the residual stress of the cantilevers. They can be bent downward to change the effective cantilever lengths from 22.5 to 37.5 µm by driving a DC bias voltage on the device. By calibrating the initial curvature from fabrication prestress and mapping displacement vs. DC bias voltage, the operating voltage range can be determined. Through driving two different bias voltages on the left and right cantilevers, four fixed bias states can be selected, and the resonances can be tuned. Using this fixed four‐state electrical encoding and a constant transmission threshold for logic readout, the MEMS‐based TTM realizes nine fundamental logic gates within the 0.655–0.785 THz band. Different gates are addressed by selecting the operating frequency, so multiple logic operations can be carried on separate spectral channels in parallel. This frequency‐selected scheme avoids gate‐specific remapping of the electrical states and provides a compact THz opto‐logic primitive that supports parallel spectral logic on a single chip.