Optimization and performance of high-resolution micro-optomechanical thermal sensors

The ability to detect optically the deflections of microfabricated bi-material cantilever beams with 3 pm resolution has allowed the measurement of temperature, optical power, and energy with 2 mu K, 76 pW, and 15 fJ resolution, respectively. The thickness ratio of the two beam materials is optimized to produce 40% improvement over previous designs. The governing equations for the sensor performance have been developed and form the basis for designing better cantilever shape for further performance improvements. Efforts are underway to detect cantilever deflections with 100 fm resolution, so that the thermal performance can be improved by an order of magnitude. Such unprecedentedly high resolutions are opening up promising prospects for their use in infrared detection and in studying molecular-level adsorption and surface chemical reactions.