High-resolution distributed analysis on Brillouin dynamic grating by differential measurement and matched filtering

Improvement of spatial resolution in the distributed analysis on Brillouin dynamic grating (BDG) in a polarization-maintaining fiber (PMF) is demonstrated using a differential measurement (DM) scheme and a matched RF low-pass filter. The DM is applied to remove the reflection signals from uncorrelated positions, and a RF low pass filter optimized for a target spatial resolution is used to suppress the high-frequency common noise remaining in the BDG spectrum. In experimental confirmation distribution of the BDG spectra in a 1 km PMF is measured with a 5 cm spatial resolution, which is equal to the nominal spatial resolution determined by the synthesis of optical coherence function in the correlation-domain analysis system.