Research on Photonic Crystal Fiber Sensor Network Based on Fast Fourier Transform Bandpass Filtering

In this paper, we have solved the problem that the cascaded photonic crystal fiber interferometers (PCFIs) built by fusion splicing are difficult to demodulate. In order to reduce the demodulation difficulty of the sensor network, we find that controlling the lengths of the collapsed regions can make the output spectra of partial interferometers more sinusoidal. We perform Fast Fourier Transform (FFT) processing on individual interferometer and select interferometers that can be used in cascade through frequency division multiplexing (FDM). In order to simplify and increase the accuracy of demodulation, this paper adopts the method of combining FFT and FFT band-pass filtering technology, and finally realizes the separate demodulation of strain for five cascaded interferometers. This method can be applied in the demodulation of any composed spectrum with arbitrary waveform formed by the cascaded sensors. Finally, it is experimentally verified that the interferometer is not subject to temperature crosstalk.