Temperature-compensated ocean pressure sensor based on dual Fabry-Perot interferometers by wavelength demodulation

A dual Fabry-Perot interferometric fiber-optic pressure sensor with temperature compensation is proposed for high-precision measurement. By integrating two Fabry-Perot sensors within a specialized encapsulation structure to form a pressure measurement cavity and a temperature reference cavity, the system effectively decouples pressure and temperature effects on cavity length. The detection of pressure and temperature variations is achieved through cavity length demodulation of the acquired spectral data using a multi-extrema-tracing algorithm. The system exhibits a pressure sensitivity of -8.627 nm/MPa at 20 ℃ over the pressure range of 0 MPa - 10 MPa, with nonlinearity error and repeatability error equivalent to maximum pressure deviations of 5.085 Pa and 25.369 Pa, respectively. Additionally, the temperature sensitivities of the two sensors are 0.1848nm/°C and 0.2575 nm/°C, respectively. Based on the temperature responses of the sensors, temperature compensation and error correction are applied to enhance the precision of pressure measurement. With its outstanding linearity, stability, and precision, the system demonstrates great potential for dynamic pressure measurement in extreme ocean environments.