Algorithm of the Cavity Length Demodulation for Optical Fiber F-P Sensors Based on Nuttall Window Four-spectrum-line Interpolation FFT

When the fast Fourier transform (FFT) algorithm is used to analyze demodulate interference signal, nonsynchronous sampling of the interference optical spectrum would cause spectral leakage and fence effect, decreasing demodulation accuracy. Window functions and interpolation algorithms can effectively improve the demodulation accuracy of the FFT algorithm. Therefore, in this work, we propose an algorithm of cavity length demodulation for optical fiber F-P sensors based on Nuttall window four-spectrum-line interpolation FFT. The simulation results of numerical calculation show that the demodulation accuracy and speed of this algorithm are better than cubic spline interpolation and FFT algorithm.