Liquid-level sensor based on chirped-fiber Bragg gratings

A novel liquid-level sensor based on a chirped-fiber Bragg grating (CFBG) is proposed，It is mainly constituted of a rectangular cantilever beam sensing mechanism and a fiber optic spectrometer. The expression of relationship between the liquid-level and the bandwidth of the reflection spectra of CFBG is derived. The liquid-level can be obtained by measuring the bandwidth of the reflection spectral of CFBG. The experimental results show that the reflection spectrum bandwidth of a CFBG is insensitive to temperature changes within the measuring range, and a good linear relationship of the bandwidth of the reflection spectrum with the measured liquid-level is obtained.