Noise resilient quasi-distributed sensing with an interferometric-noise-suppressing Golay coded optical source.

A noise-resilient demodulation technique is proposed and demonstrated with an interferometric-noise-suppressing (INS-) Golay coded optical pulse source for a quasi-distributed sensor array constructed by identical ultra-weak fiber Bragg gratings (UWFBGs).In combination with a medium coherence light source, coding-based time-efficient noise reduction is facilitated for closely-multiplexed UWFBG arrays, for which conventional Golay coding is inapplicable. With 32-bit INS-Golay coded pulse trains, 5.6-dB signal-to-noise ratio improvement is achieved as compared to the case where an uncoded pulse train is adopted. While the performance is almost as good as 32-time averaging, the time consumption for signal acquisition is only ∼1/8. The proposed INS-Golay coding method exhibits linearity up to 0.9986 in temperature sensing with a wavelength demodulation error of ∼±5 pm. The time efficiency of the method increases with increased code length, providing a solution that alleviates the trade-off between the demodulation accuracy and speed in the UWFBG-based sensing systems with closely-multiplexed sensors.