Refractive index and temperature sensor based on Mach-Zehnder interferometer with thin fibers

Abstract An all-fiber Mach-Zehnder interferometric sensor for refractive index (RI) and temperature measurement is proposed and experimentally demonstrated. The proposed sensor is fabricated with three segments of two type of thin fibers sandwiched between two standard single-mode fibers (SMFs). The variation of ambient RI and temperature causes the change of phase difference between the cladding modes and the core mode, which leads to the shift of interference spectrum. The two resonance dips shift in the wavelength spectrum is used to investigate the RI and temperature characteristics of the sensor. Experimental results show that the two dips have different responses of RI and temperature, which indicates that the sensor can realize simultaneous RI and temperature measurement. The maximum sensing sensitivities are −169.0879 nm/RIU and 0.0464 nm/°C, respectively. The proposed sensor exhibits potential applications in physical, biological and chemical sensing fields due to its high sensitivity, good linearity, simple fabrication and low cost.