Temperature-insensitive liquid level sensor based on a U-shaped cascade core-offset structure

Abstract

A sensor based on a U-shaped cascade core-offset structure is proposed for liquid level measurement. The cladding modes are more easily excited by the core-offset structures. The U-shaped structure leads to more energy leakage into the cladding, making the sensor more sensitive to changes in the external environment. During the experiment, fiber optic liquid level sensors with different offsets are fabricated to study the liquid level sensitivities of these sensors. The experimental results show that the liquid level sensitivity is as high as 505.4 pm/mm in the range of 0–20 mm, while the sensor exhibits insensitive characteristics in the temperature range of 20–70°C. In addition, the sensor has the advantages of high sensitivity, low cost, and compactness, which make it ideal for use as a liquid level sensor in petrochemical and other applications.