A U-shaped-wound fiber macro-bending loss crack sensor improved by an optical splitter

•The splitter is used to reduce temperature effects in a fiber link of optic sensors.•The measurement accuracy of two fiber macro-bending loss crack sensors are compared.•The sensing mechanism of the improved macro-bending loss crack sensor is analyzed. In traditional fiber macro-bending loss crack sensors, temperature can affect the light source and the fiber link between the light source and the optical splitter, thereby reducing the measurement accuracy of the sensor. In this study, by combining a U-shaped-wound fiber bending loss crack sensor and an optical splitter on the fiber link, we reduce the effect of temperature on the light source and the fiber link. Furthermore, the sensing mechanism of the improved fiber crack sensor is analyzed. Additionally, a comparison between the U-shaped-wound sensor and a butterfly-shaped sensor is carried out to compare both fiber crack sensors. The experimental results indicate that the optical splitter efficiently reduce the effect of temperature on the light source and the fiber link between the light source and the optical splitter and the U-shaped-wound fiber bending loss crack sensor has a better measurement accuracy.