A compact LPFG refractive index sensor with high sensitivity based on thin core -no core-thin core fiber structure

A novel refractive index (RI) sensor based on the thin core -no core-thin core (TNT) fiber structure is proposed. We investigated the RI and temperature sensitivity of this sensor, which has a higher RI sensitivity due to the stronger evanescent field generated by RI modulation. The software simulation and experiment validation show that the maximal RI and the temperature sensitivity of the TNT fiber structure are 880 nm/RIU and −0.066 nm/°C.