Distributed sensing technology of high-spatial resolution based on dense ultra-short FBG array with large multiplexing capacity

We developed a large multiplexing capacity dense ultra-short (DUS)-FBG array for high spatial resolution distributed sensing applications. With identical central wavelength and low peak reflectivity (−40 dB), all the ultra-short FBGs share the short length (1 mm) and extremely small spacing (500 μm). The large multiplexing capacity and lower crosstalk of the DUS-FBG is investigated through both simulation and experiment. Use of DUS-FBG array interrogated by optical frequency domain reflectometry (OFDR) for distributed temperature and non-uniform strain sensing was conducted. We demonstrated high spatial resolution over 6680 FBGs along a 10 m-long fiber, and temperature and strain precision of 1.00 °Cand 20.02 μe. Distributed temperature and non-uniform strain sensing experiment results are consistent with the theoretical analysis, and verify the high spatial resolution and large multiplexing capacity.