Liquid-level sensor based on SMS fiber structure

This paper describes the design and implementation of a liquid-level sensor based on a single-mode-multimode-single-mode (SMS) fiber structure. The transmission spectrum of the SMS fiber structure is affected by the fraction of the length of the etched multimode fiber that is surrounded by the liquid. The numerical simulation of spectral transmission of SMS fiber structure with different liquid-level is proposed. The experiment shows that for a liquid-level variation of 4mm, the resonance wavelength generates a blue-shift about 4 nm. Meanwhile the optical power in the wavelength range from 1523 nm to 1534 nm is decreasing as the liquid-level increasing. Also in the linear region, high sensitivity of 1.02 nm/mm and 1 dB/mm are achieves, respectively.