Simultaneous Measurement of Refractive Index and Temperature Based on Modal Interference

A simple optical fiber sensor configuration for simultaneous measurement of refractive index (RI) and temperature based on modal interference is proposed and experimentally demonstrated. The sensing configuration is formed by splicing two multimode fibers among three single mode fibers. Due to the different sensitivity responses of the two wavelength transmission dips formed by the cladding modes interfering with the core mode, it is possible to measure the RI and temperature by monitoring the wavelength shifts of the two transmission dips. The experimental results indicate that the sensing sensitivities of RI and temperature are -37.9322 nm/RIU and 0.0522 nm/°C within the RI range from 1.3105 to 1.3517 and the temperature range from 25°C to 85°C, respectively. The proposed sensor configuration features the advantages of easy to fabricate, robust, cost effective, and high sensitivity, making it exhibit potential applications in physical, biological, and chemical sensing.