Large Displacement Actuators With Multi-Point Stability for a MEMS-Driven THz Beam Steering Concept

We present a micro-electromechanical reflectarray driven by large displacement actuators with multi-point stability that is intended for THz beam steering. The reflectarray consists of a stack of multiple SOI-chips each featuring a movable reflector. The position of each reflector is individually varied by in-plane mechanical digital-to-analog converters (DAC) that address 27 discrete and equidistant positions driven by only three pairs of cascaded tri-stable electrostatic actuators. Generally, the mechanical DAC addresses
$3^{n}$
equidistant positions at a minimum number of
$2n$
actuators. The reflector displacement is enlarged by combining the DAC output with a mechanical leverage. We demonstrate an SOI-fabrication method allowing to stack multiple chips for a one-dimensional array featuring large displacement DACs and large reflector surfaces. The full-wave electromagnetic simulations of the reflectarray verify its feasibility for terahertz beam steering applications. The electro-mechanical characterization shows the high-resolution displacement of single actuation systems as well as the functionality of a stacked
$3\times1$
reflectarray. [2022-0149]