Reflective Liquid Level Sensor Based on Parallel Connection of Cascaded FBG and SNCS Structure

We describe and demonstrate a liquid level sensor by parallel connection of two liquid level sensors that consists of single-mode-no-core-single-mode fiber structure followed by a fiber Bragg grating. The parallel connection can extend measurement range of liquid level. The structure parameters are optimized and the performance of the sensor is experimentally demonstrated. Results show that the sensor can achieve a linear sensitivity of 0.196 dB/mm within the liquid level range of 0-59 mm and 0.233 dB/mm within 59-117 mm. It has great potential in industrial applications due to its simple structure and extended measurement range, also it can be applied in multi-point measurement.