Performance Tradeoffs in MEMS Sensors with High-Finesse Fabry-Perot Interferometry Detection

A detailed analysis with experimental verification of optical sensors based on Fabry-Perot interferometers is presented. This type of sensor consists of two partially transparent parallel plates with reflective inner surfaces, forming a cavity with an optical resonance that depends on the distance between the plates. At resonant wavelengths, the incident light energy is transmitted through the device and intensity peaks occur. The distance between the plates can be obtained by detecting the wavelength of the transmitted light. Various optical sensors can be based on this concept, e.g. accelerometers, pressure sensors, and microphones. This paper considers factors affecting the performance of such sensors, including mechanical-thermal noise, contribution of noise in the detection system, and effects of reflectivity, surface roughness and parallelism of the mirrors.