A High-Sensitivity Pressure Sensor Based on Optical Fabry–Pérot Cavities for Extreme Deep-Sea Applications

This article presents a novel optical Fabry–Pérot (F–P) interferometric pressure sensor with an extensive measurement range, specifically designed for the high-pressure and high-salinity conditions of the ocean. Utilizing ultrahigh-precision demodulation techniques, the sensor adeptly captures minute structural deformations, significantly reducing material fatigue and enhancing overall sensitivity. It demonstrates exceptional performance features, including superior repeatability, excellent linearity over a wide measurement spectrum, and significant scalability—attributes crucial for diverse pressure measurement applications. Optimized for fatigue resistance and stability over extended operational periods, the sensor is positioned as an ideal tool for deep-sea exploration and as a critical tool for multiparameter optical sensing integration. Additionally, an improved simulation model was developed to include processing and analysis errors, enhancing the system’s predictive accuracy under varied environmental conditions. We describe the working principles of the sensor and present both theoretical analyses and standard experimental comparisons. The experimental results highlight the sensor’s accuracy, long-term stability, expansive measurement capacity, and strong environmental adaptability. Key performance indicators include a dual-range sensitivity of 0.125 pm/bar in the 0–400 bar range and 0.066 pm/bar from 400 to 1200 bar, a pressure resolution of 0.75 bar (0.063% F.S.), and an Allan variance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1}.{12} \times {10}^{-{11}}$ </tex-math></inline-formula> nm under a 1000-bar load. Based on the experimental results, an online calibration method for optical measurement chamber length based on the free spectral range (FSR) is proposed, addressing the identified measurement challenges and offering constructive insights to improve the adaptability of marine optical sensors to environmental conditions.