Cavity Length Sequence Matching Algorithm Based on Combined Valley Peak Positioning for Fiber-Optic Fabry-Perot Sensors

Abstract

To solve the problem of low demodulation accuracy of conventional peak-to-peak algorithm for fiber-optic Fabry-Perot (FP) sensors due to failure of determining the interference order, a novel cavity length sequence matching demodulation algorithm based on a combined valley peak positioning is proposed. Firstly, a pair of a peak and its neighboring valley in the reflection spectrum is selected and positioned, and two groups of interference orders are supposed to generate two groups of cavity length sequences. Finally, these cavity lengths are compared to find the real interference order of the peak and valley for the extraction of the accurate cavity length. In order to verify the feasibility and performance of the proposed algorithm, simulations and experiments were carried out for fiber-optic FP sensors with cavity lengths in the range of 15–115 μm. A demodulation accuracy better than 8.8 nm was found. The proposed algorithm can achieve highly accurate cavity length demodulation of fiber-optic FP sensors.