High sensitivity temperature sensor using microfiber based Mach-Zehnder interferometer

A high sensitive temperature sensor based on Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. Temperature measurement is achieved by immerging a section of microfiber into the refractive index (RI) liquid with a high thermo-optic coefficient. A slight change of ambient temperature will lead to the enhanced variation of the liquid index. Due to the evanescent field of microfiber, microfiber effective refractive index will be changed, and subsequently the optical length. Thus, by measuring the free spectral range (FSR) of the MZI, the temperature sensor can achieve a high sensitivity of 6.44nm/°C at the temperature of 20.6°C.