Investigated solution concentration sensor with the single mode-multimode-FBG

A new kind of solution concentration sensor is designed based on the SMF-EMMF-FBG structure. Sensing characteristics of FBG to solution concentration is researched, sensing detection of four kinds of solution is, experimentally realized with the wavelength differences between high modes and the fundamental mode, the higher order modes of the etched multimode fiber is more sensitive to the surrounding refractive index than the fundamental mode.