High Sensitive Refractive Index Sensor Based on Cladding Mode Recoupled Chirped FBG

A simple but highly sensitive refractometer based on chirped fiber Bragg grating (CFBG) is proposed and investigated experimentally. Intensive reflected cladding modes can be excited within a large wavelength range through a multimode fiber CFBG structure. Experimental results show that the intensity of reflected cladding modes in CFBG is modulated by surrounding refractive index (RI) changes, which provide a high sensitive and cost-effective solution for RI measurement.