High Sensitive Refractive Index Sensor Based on Dispersion Turning Point Long-Period Fiber Gratings in Tapered Fiber

We proposed a highly sensitive refractive index sensor based on the long-period fiber gratings (LPFGs) inscribed in the tapered fiber at dispersion turning point (DTP). The sensitivity of the refractive index sensor can reach 19473.3 nm/RIU. By reducing the fiber diameter, the evanescent field of the tapered fiber is enhanced, and the LPFG is inscribed at the DTP to improve the refractive index sensitivity of the grating. The proposed sensor has excellent refractive index sensitivity and has potential applications in water quality analysis, concentration measurement, food safety and industrial production.