Low-cost high-performance temperature sensor based on unsymmetrical U-shaped microfiber

Abstract

A novel temperature sensor based on microfiber (MF) interferometer with low-cost, long-term reliability and high repeatability was developed. The experimental results indicate that the unsymmetrical U-shaped MF has particularly advantages of a thinner waist diameter and better sensing stability compared with symmetrical U-shaped MF in terms of structure and spectrum. The air temperature sensitivity of 10 pm/°C was observed by the sensor with a diameter of 4.26 μm. In order to study the relationship between the structure parameters of transition region and the performance of temperature sensor, we fabricated another MF with a larger taper angle of transition region. The new sensor fabricated with this MF obtained a higher temperature sensitivity of 16.7 pm/°C. Considering the impact force from the temperature measurement environment (such as air and liquid environment), the MF interferometer was packaged in a special glass tube to enhance its impact resistance. After that this proposed sensing structure was applied to the measurement of liquid temperature. Results show that its temperature sensitivity is about 349.5 pm/°C when the liquid temperature changes from 18 °C to 30 °C. The sensor designed in this paper has the advantages of good resistance to liquid impact and high sensitivity. It is of great significance to the application of optical fiber sensor in the detection of liquid and atmospheric environment.