Fig. 1. Physical structure diagram of fiber grating

Fig. 2. Diagram of fiber grating demodulation system based on tunable laser

Fig. 3. Gaussian fitting model and actual waveform of FBG reflection spectrum. (a) Gaussian fitting model; (b) actual waveform

Fig. 4. Error schematic of two algorithms. (a) Direct peak-finding algorithm; (b) power weighting algorithm

Fig. 5. Schematic diagram of Gaussian fitting algorithm

Fig. 6. Comparison of Gaussian fitting and Gaussian-LM algorithm fitting^[56]

Fig. 7. Calibration of true value central wavelength and comparison of Gaussian and Gaussian-LM algorithms^l56]

Fig. 8. Schematic diagram of three-point peak-finding algorithm^[58]

Fig. 9. Convolution results of Gaussian template and its first- and second-order differential forms with the original spectral signal^[53]

Fig. 10. FBG sensor network demodulation system diagram

Fig. 11. Results of Hilbert transform^[64]. (a) Smoothed spectrum signal; (b) Hilbert transformed spectrum signal

Fig. 12. Demodulation results of different types of distortion of FBG^[41]. (a) Light intensity attenuation; (b) spectral broadening; (c) spectral asymmetry