Optical fiber sensor based on Mach–Zehnder interferometer combined with a fiber Bragg grating for simultaneous measurement of refractive index and temperature

An optical fiber sensor based on fiber Bragg grating (FBG) and Mach–Zehnder interferometer (MZI) is experimentally demonstrated for simultaneous measurement of refractive index (RI) and temperature. The MZI is formed by a single-mode–multimode–single-mode fiber structure and a spherical-shape structure. The temperature sensitivities of FBG and MZI are 0.0098 and 0.093 nm / ° C, respectively. Simultaneous measurement of RI and temperature can be realized using the sensitivity coefficient matrix. The sensor has the advantages of easy fabrication, good robustness, and high sensitivity.