A high-reliability dual Fabry–Perot cavity vibration sensor with an L-shaped optical path

We present a high-reliability fiber-optic Fabry-Perot vibration sensor with an L-shaped optical path and dual Fabry-Perot cavities. Two interferometric cavities were constructed using the nickel-based alloy Inconel 718 and sapphire materials to achieve temperature self-compensation. Additionally, an L-shaped optical path was adopted to enhance the sensor's deployment flexibility in confined environments. The sensor was also employed with a reliability packaging design, which further enhances its adaptability in harsh environments such as high temperatures and corrosive conditions. Experimental results show that the sensor exhibits a sensitivity of 41.235 nm/g, a resonance frequency of 2372.8 Hz, and a maximum measurement range of 110.85 g. It also showed stable operation during the temperature adaptability test within the range of 25-300°C. Furthermore, the sensor exhibits excellent consistency and stability during temperature cycling and long-term monitoring, with no noticeable drift observed throughout the testing period. This work proposes an effective solution for enhancing the reliability and environmental adaptability of fiber-optic Fabry-Perot vibration sensor under complex working conditions.