Real-Time, High-Resolution, and Wide-Dynamic-Range Demodulation Algorithm for Fiber Fabry–Pérot Sensors

Fabry–Pérot interferometer (FPI) sensors have been widely employed in precision measurement applications. The trade-off among resolution, dynamic range, and real-time capability in conventional spectral demodulation algorithms, however, constrains their achievable performance in practice. In this paper, a real-time, high-resolution and wide-dynamic-range demodulation algorithm for FPI sensors is proposed within a discrete Fourier transform (DFT)-based spectral demodulation framework. A modified frequency estimation method is introduced to extend the effective dynamic range, and a refined phase reconstruction strategy is employed to suppress the phase jumps under different signal-to-noise ratio (SNR) conditions. The proposed algorithm realizes a cavity-length resolution of 0.086 nm at a spectral SNR of 29.4 dB, and maintains stable and continuous demodulation over a cavity-length variation exceeding 195 μm. In the experimental system, the demodulation rate is limited to 33 kHz by the sampling rate of the spectrometer, whereas demodulation speed analysis indicates that the proposed algorithm is capable of supporting rates exceeding 100 kHz. In addition, the pressure sensing experiment further confirms its applicability in practical sensing scenarios. The proposed algorithm is expected to provide an effective demodulation solution for high-resolution and real-time FPI sensing applications.