Spatial Resolution Enhancement in OFDR Using Margenau Hill Spectrogram

Abstract

We presented an optical frequency domain reflectometry (OFDR) demodulation method utilizing Margenau Hill Spectrogram (MHS) algorithm for spatial resolution enhancement while maintaining sensing accuracy at same level. The trade-off between spatial resolution and sensing accuracy is reduced due to the enhanced time-frequency concentration of MHS compared to conventional short-time Fourier transform (STFT). The capability and advantage of MHS in OFDR demodulation with improved spatial resolution is analyzed in theory, simulation and experiment. The OFDR system with the proposed MHS algorithm is capable of sensing strain up to 1500 μϵ. Compared to conventional OFDR using STFT with 50-point window length, the spatial resolution has improved from 5.0 mm to 0.1 mm, while the average sensing quality factor value at strained section maintained 0.515, which means the sensing accuracy stays at the same level.