Large-deflection, high-speed, electrostatic actuators for optical switching applications

This dissertation demonstrates that electrostatic, comb-drive actuators may be used in applications requiring displacements of up to 150 μm in less than 1 msec. A nonlinear model of the actuator is developed to relate the three key performance measures: sensitivity, resonant frequency, and maximum deflection to the actuator dimensions. The model's predictions are matched by linear and nonlinear finite element analyses, and the dynamic behavior of the actuator is captured numerically using Simulink™. A suite of experiments are carried out on DRIE, single crystal silicon, electrostatic, comb-drive actuators to confirm the validity of the models.; A method is also developed to facilitate the synthesis of actuator designs when given a set of performance measures. This design method is used to describe the parameter space of acceptable designs and to choose a set of optimal actuator dimensions. Modifications to the design method are described for applications involving large forces and for applications customizing the force-deflection relationship.; Three novel actuator design improvements are implemented. First, a U-shaped shuttle allows the actuator area to be cut in half without degrading its performance. The folded-flexure suspension is placed external to the combs to provide electrical access to the electrodes via traces to bond pads on the perimeter of the die. Second, the comb teeth are designed with linearly increasing lengths to reduce side instability by a factor of two. Finally, the folded-flexure suspensions are fabricated in an initially bent configuration, improving the suspension stiffness ratio and reducing side instability by an additional factor of 30.; Two distinct actuation schemes are described. First, a static, push-pull scheme is used to cut the actuation distance in half. A second strategy, with a slightly more complicated drive waveform, uses the quality factor and a high-force, low-displacement, parallel-plate actuator to improve performance.; Finally, this dissertation shows that the electrostatic actuators may be configured to form an optical switch. Twelve independent actuators are used to satisfy the optical switching requirements of an existing optical data storage application. The optical switches are capable of maintaining 80% coupling efficiency while switching between any of twelve optical fibers in less than 1 msec.