Anti-Crosstalk Fiber-Optic Liquid Level Sensor Based on Hollow-Core Bragg Fiber

In this letter, we develop a novel fiber-optic sensor based on a hollow-core Bragg fiber (HCBF) for high-precision detection of liquid level. The intensity responses of anti-resonance reflecting optical waveguide are theoretically analyzed in terms of level and refractive index (RI) of liquid. Simultaneous measurements are conducted and the obvious intensity variations as the changed liquid level are exhibited, with near-zero RI crosstalk. The average liquid level sensitivity reaches −11.24 dB/cm in the range of $0 \sim 4$ cm, with high linearity. Additionally, high repeatability and low temperature intensity drift guarantee the measurement error can be constrained within 0.03 mm.