High-precision FBG sensor demodulation based on a tunable Michelson interferometer with parallel FBGs

A high-precision signal demodulation scheme for fiber Bragg grating (FBG) is presented. The scheme utilizes a piezoelectric transducer (PZT) tuned co-located, multi-wavelength tunable FBGs (CMWT-FBGs) in one arm of the Michelson interferometer (MI), which adjusts its central-wavelength range to fully cover the wavelength shifts of the sensing FBG. The algorithm module utilizes a Savitzky-Golay (S-G) fitting algorithm to precisely locate the envelope peak of the interference signal, thereby accurately reconstructing the variations of the sensing FBG's central wavelength. Experimental results demonstrate that the modulation-demodulation scheme achieves a temperature accuracy of 1.33×10^-6°C and a strain accuracy of 1.04×10^-5<i>μ</i><i>ε</i>, respectively. These results show that the CMWT-FBGs-MI system offers a competitive advantage in high-speed and high-precision signal measurement, providing experimental and theoretical support for advancements in related fields.