Stepwise Electrostatic Actuator System for THz Reflect Arrays

We present the concept, design, fabrication, and characterization of a stepwise electrostatic actuator system intended for THz beam steering reflect arrays. The system is based on multiple electrostatic actuators forming a serial arrangement and connected by springs. A stepwise displacement is generated by successively activating the single actuators. Based on a derived transfer function, the system is analysed, and the design of the actuators and springs is optimised. During the fabrication process, the handle layer is locally released to prevent a parasitic pull-in of the electrodes. The characterization of different uni- and bi-directional 3-step systems allows the derivation of design rules for systems with more steps and shows a linear total throw of 35.8±0.2 micrometer at 50 V.