Temperature monitoring with a fully integrable on chip interferometric silicon micro-sensor based on the thermo-optic effect

An array of silicon interferometric temperature micro-sensors is presented based on the thermo-optic effect. These sensors, consisting of planar Fabry-Perot cavities of various length, realised on the same chip, have been fabricated adopting standard microelectronic technologies. This permits the full integration of the sensors with other active silicon opto- and electronic devices. Moreover, the possibility of realising on the same chip sensors with lengths ranging from microns to millimetres allows the use of the noise-immune fringe counting technique. By monitoring the output of all the interferometers at the same time, in fact, the direction of changing and a rough estimation of the temperature is given by the shorter cavities, while a more and more accurate measurement is furnished by the longer cavities.