Simultaneous measurement of refractive index and temperature using a Mach-Zehnder interferometer with forward core-cladding-core recoupling

Abstract A Mach-Zehnder interferometer based on single-mode-multimode-thin-core-single-mode fiber structure is proposed and experimentally demonstrated for measuring refractive index and temperature simultaneously. The transmission dips of the sensor will shift when the ambient refractive index and temperature change, so it is possible to measure the refractive index and temperature by monitoring the wavelength shifts of the two transmission dips due to different interference orders. The experimental results show that the sensing sensitivities of refractive index and temperature are −18.1764 nm/RIU and 0.0733 nm/°C within the refractive index range from1.3105 to 1.3517 and the temperature range from 25 °C to 50 °C, respectively. Its cost effectiveness, robustness and easy fabrication will have attractive potential applications in chemical and biological sensing.