Ultrahigh-Sensitivity High-Temperature Strain Sensor Based on Miniature Fabry–Pérot Interferometer

Abstract

The strain sensors capable of high sensitivity and a wide measurement range in high-temperature environments are in urgent demand across numerous industrial fields. Herein, we propose an ultrahigh-sensitivity high-temperature strain sensor, which can simultaneously obtain temperature and strain signals. The Fabry–Pérot interferometer (FPI), composed of a hollow-core fiber and the end faces of single-mode and multimode optical fibers, is attached to a sensitive substrate that is fabricated through wet etching and picosecond laser cutting processes. Strain is measured by the change in the length of the FPI caused by its bending deformation. Meanwhile, a fiber Bragg grating (FBG) integrated into the FPI structure is used for temperature sensing and compensation in real time. The self-designed sensor has a high sensitivity of 21.46 nm/<inline-formula> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> in the whole strain range of 0–<inline-formula> <tex-math notation="LaTeX">$3121~\mu \varepsilon $ </tex-math></inline-formula>, and can operate stably at temperatures up to <inline-formula> <tex-math notation="LaTeX">$1000~^{\circ }$ </tex-math></inline-formula>C. Moreover, the sensor exhibits good linear response, consistent repeatability, minor long-term drift, low hysteresis, and low cross sensitivity. It provides a reliable solution for highly sensitive simultaneous detection of strain and temperature in harsh conditions, such as high temperatures and strong impacts over a wide range.