Sensitivity-enhanced Sagnac interferometer temperature sensor based on Vernier effect with the help of Fabry-Perot interferometer

A sensitivity-enhanced temperature sensor based on Vernier-effect was demonstrated. Vernier-effect is achieved by a cascaded configuration with a fiber Sagnac interferometer (FSI) and a Fabry-Perot interferometer (FPI). FSI, which consists of a certain length of polarization maintaining fiber, is for temperature sensing, while. FPI acts as a filter due the temperature insensitivity. Experimental results show that the temperature sens or has a high sensitivity of -29 nm/°C and the enhancement factor is about 10.3.