Iterative Normalized Cross-Correlation Method For Absolute Optical Path Difference Demodulation Of Dual Interferometers

It is still a challenge to realize the absolute optical path difference (OPD) demodulation of multi-interference systems with a narrow spectral interval and small OPD interval. In this paper, an iterative normalized cross-correlation algorithm is firstly proposed for demodulating the multiple absolute OPDs of a dual-interference system and applied to optical fiber sensing system. By constructing a template function in combined form, the optimal solutions of its components and OPDs are solved iteratively based on the reconstruction matrix method and cross-correlation algorithm, respectively. The simulation and experiment show that the demodulation accuracies near the OPDs of 560 mu m and 660 mu m are both up to 5 nm in different spectral intervals from 45 to 80 nm. The simulation results show that all demodulation precisions at the spectral interval of 55 nm do not exceed 4 nm when the OPD changes in the range of 650-670 mu m. Besides, the experimental verification shows the temperature accuracy (0.125 degrees C) with 95% confidence of T-distribution is very close to the control accuracy (0.1 degrees C). The proposed algorithm can improve the multiplexing capability of optical fiber sensor system and reduce its cost. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement