Temperature Cross-Sensitivity Optimization for Mach-Zehnder Interferometers Liquid Level Sensors

This paper presents an optimization for temperature cross-sensitivity compensation in a liquid level sensor based on an in-fiber Mach-Zehnder interferometer. A broadband source is used to illuminate the sensor id the transmitted spectrum is monitored with an optical spectrum analyzer. The spectra are analyzed for both temperature and liquid level variations, leading to 68 peaks with different temperature and level sensitivities. According to this difference among sensitivities, it is possible to measure simultaneously both parameters (temperature and level) by selecting two peaks. According to the highest correlation coefficient of liquid level estimation, the best couple of peaks is selected. The highest temperate and liquid level sensitivities achieved with individual peaks are 27.86 pm/CC and 6.34 pm/mm, respectively. After temperature compensation, the estimated liquid level presents a correlation coefficient higher than 0.97 with temperature estimation error +1.25 °C. The proposed sensor arrange is suitable for industrial applications where simultaneous measurements of temperature and level arc required.