Electrostatically actuated micromirror for resonant cavity enhanced detectors

This paper presents the design, fabrication and measurement results of a vertically moving, electrostatically actuated micromirror. The single crystalline silicon substrate allows the design of a symmetrical and mechanically stable mirror suspension while keeping a geometry with high fill factors and maintaining elasticity and thus keeping the actuation voltage below 25 V. The device is being developed for the use in a tunable resonant cavity enhanced detector (RCED) for the mid-infrared (Arnold, 2005). RCED´s make use of a standing wave formed in an optical cavity and are only sensitive at the resonances. The wavelengths of the resonances are hereby depending on the distance of the two cavity mirrors (Unlu, 1995). Such narrowband detector systems are sought- after in multispectral infrared (IR) thermography or infrared spectroscopy (Musca, 2005).