Optical fiber refractive index sensor with temperature calibration ability

We proposed a type of optical fiber refractive index(RI) sensor with the temperature calibration ability. The sensing head consisted of two very short lengths of multimode fiber (MMF) and a length of refractivity-insensitive fiber Bragg grating (FBG) fused between them, which had a total length of 14 mm. Here the FBG was used as the temperature calibration component for refractivity measurement. The experimental results show that the RI sensitivity of this sensor is about 126 nm, the temperature sensitivity of the resonance wavelength is 35.09 pm/℃, and the temperature sensitivity of the FBG is 11.14 pm/℃. Compared with the general refractive index sensors, this sensor with a good temperature calibration ability has better application prospect.