A Liquid Level Sensor Based on Long-Period Fiber Grating With Superimposed Dual-Peak

This letter presents a high-sensitivity wavelength-modulated liquid level sensor based on the long-period fiber grating with superimposed dual-peak. The liquid level sensor has a novel sensing mechanism and a simple structure. In theory, the sensing mechanism of the liquid level sensor is analyzed in detail. Experimentally, we fabricated a long-period fiber grating according to the simulated parameters. The experimental results show a linear range of 57% of the length of the overall long-period fiber grating and yields sensitivity of 10.7-nm change in wavelength per millimeter, and the sensitivity is 17 times higher than the traditional long-period fiber grating-based liquid level sensors.