Interferometric fiber sensors (IFSs) are widely investigated due to the remarkable superiorities of high sensitivity and precision, small size and immune to EMI, etc. Signal demodulation is a key technology for fiber interferometric sensor. Wavelength tracking demodulation technique is the most commonly used method for IFSs. But the results are easily affected by factors such as noise or sampling rate due to the severe information redundancy.
Professor Ping Lu of theWuhan National Laboratory for Optoelectronics(WNLO)proposed a phase demodulation method based on fast Fourier analysis. Broadband light source is employed to acquire the interferential spectrum of the sensor structure. Fast Fourier analysis of the sensing spectrum indicates the intrinsic spatial frequencies. In many micro parameters sensing applications the OPD variation is small enough compared to the initial OPD value, so the spatial frequencies can be regarded as constants. The interferential phase variation introduced by the measurands can be reflected in the Fourier phase item at the corresponding spatial frequencies. This proposed algorithm computes the phase variation from all the sampling points, so there is no redundant information and the demodulation results demonstrate a much higher stability. This method can be applied to quasi-distributed sensing system using frequency-division multiplexed IFS,etc.
This work has been published in Opt. Express Vol.25, No.18,21094-21106(2017) in4,September, titled“Phase demodulation of interferometric fiber sensor based on fast Fourier analysis”.This work was supported by the National Natural Science Foundation of China under Grant 61290315, 61290311 and 61275083.
