A Virtual Pivot Point MEMS Actuator with Externally Mounted Mirror: Design, Fabrication and Characterization

In this paper, the design, fabrication, and characterization of a virtual pivot point micro electromechanical systems (MEMS) electrostatic actuator with externally mounted mirror is presented. The point of rotation of the movable arm of the actuator is distant from the physical actuator. This is a requirement for certain applications, such as an external cavity laser in Littman configuration. A maximum rotational radius of 5 mm from the virtual pivot point was achieved. A detailed analytical analysis for the displacement of the structure is presented. The dynamic characterization of the device with a finite element analysis simulation shows that the resonance frequency of the in-plane rotational mode is well separated from that of the out-of-plane bending mode, confirming high in-plane stability. The devices were fabricated on a silicon-on-insulator wafer with device layer thickness of 100 µm. Thin mirrors were fabricated by dicing a 100 µm thick silicon wafer. A resonance frequency of about 5.9 ´ 102 Hz for the maximum sized mounted mirror (1.7 mm ´ 100 µm ´ 1.0 mm) was determined by optical characterization