High-temperature-resistant strain sensor based on the asymmetric tapered Fabry–Pérot fiber

A high-temperature-resistant strain sensor based on an asymmetric tapered Fabry-Pérot fiber (FPI) structure is designed and validated experimentally. The strain sensor is constructed by fusing two standard single-mode optical fibers to form a microbubble and applying a taper on one side of the microbubble to form the asymmetric tapered structure. The strain characteristics of the sensor in the temperature range from room temperature to 425°C are determined. A good linear relationship is observed between the wavelength displacement and tensile strain in this temperature range. The strain sensitivity is 47.69 pm/µε at 25°C, and the linear response is reproducible in the range of 0-300 µε. In addition, the wavelength displacement due to the applied strain is stable with respect to each 100°C increase in the temperature, indicating that the FPI sensor has good temperature stability in the strain range between 0 and 300 µε. The average temperature sensitivity is 1.56 pm/°C in the temperature range between 25°C and 425°C, and the cross-sensitivity is very low. Our results show that the FPI sensor has strong resistance to high temperatures, boding well for applications such as aerospace components, metal processing, and gas boilers.