Double-sided polishing long period fiber grating sensors for measuring liquid refractive index

A new liquid refractive index sensor using double-sided polishing long-period fiber gratings (DSP-LPFG) is presented. The influence of residual cladding thickness on the sensitivity of measuring liquid refractive index is investigated. The proposed sensor response to external liquid refractive indices varying in the range of n=1.330 − 1.375 has been carried out by measuring the transmission wavelength changes. Experimental results show that well-controlled polishing parameters can significantly increase the sensitivity. The sensitivity of −143.396 nm/RIU can be obtained in this study.