Simultaneous measurement of refractive index and temperature based on a partial cone-shaped FBG

A refractive index and temperature simultaneous measurement sensor based on a partial cone-shaped fiber Bragg grating (FBG) was demonstrated. The bandwidth of the partial cone-shaped FBG is only affected by the surround refractive index (SRI), while the wavelength decided by the un-etched FBG is only sensitive to temperature. Utilizing the obvious difference of the bandwidth and the wavelength on the refractive index and temperature, two parameters can be distinguished and measured simultaneously using one partial cone-shaped FBG. Numerical simulation and experimental results are presented. Experimental results show that the proposed sensor has an average SRI sensitivity of −18.027 nm/RIU in the SRI range of 1.33–1.42 and a temperature sensitivity of 9.8 pm/°C in the range of 20–80 °C.