All-Fiber Mach–Zehnder Interferometer for Liquid Level Measurement

A new liquid level sensor based on in fiber Mach-Zehnder interferometer (MZI) is proposed and demonstrated. The MZI is formed by cascading two peanut-shaped fiber structures in single-mode fiber. In the water level experiment, the sensitivities of sensors with lengths of 53.5 and 75.4 mm are -0.1025 and -0.0279 nm/mm, respectively. The absolute value of sensitivity increases with the refractive index of liquid. The MZI presented in this paper has advantages of low cost and ease of fabrication, which can be a potential advantage in the liquid level measurement.