High-Sensitivity Fabry–Perot Interferometer High-Temperature Fiber Sensor Based on Vernier Effect

A novel sensitivity-enhanced intrinsic fiber Fabry-Perot interferometer (IFFPI) high temperature sensor based on a hollow-core photonic crystal fiber (HC-PCF) and modified Vernier effect is proposed and experimentally demonstrated. The compact all fiber IFFPIs are easily constructed by splicing one end of the HC-PCF to a leading single mode fiber (SMF) and applying an arc at the other end of the HC-PCF to form a pure silica tip. The Vernier effect is formed by three beams of lights reflected from the SMF-PCF splicing joint, and the two air/glass interfaces on the ends of the collapsed HC-PCF tip, respectively. This Vernier effect based fiber sensor can stand with high temperature up to 1200°C, in this work, and experimental results exhibit good linearity, stability and repeatability. The temperature sensitivity can be further enhanced by reducing length of pure silica tip—that is, simply optimizing the discharge time and intensity. The fabrication of the sensitivity-enhanced IFFPI is straightforward, reproducible and low cost, which shows a potential for practical applications in various industrial processes.