Comparative study of hollow-core fiber Fabry–Perot interferometer high-temperature sensors

In this work, a comparative study of hollow-core fiber (HCF) Fabry–Perot interferometer (FPI) high-temperature sensors is carried out, where systematically investigations with both theory and experiments are performed. The sensing mechanisms of three types of HCF sensors (i.e., HCF silica-cavity FPI, sealed HCF air-cavity FPI, and opened HCF air-cavity FPI) are analyzed and compared in theory, and the temperature responses of these sensors are studied in experiments, which agree well with the theoretical analysis. This work may provide a valuable reference and guidance for the design, fabrication, and application of HCFs in high-temperature sensing fields.