53. High-Speed and High-Precision Wavelength Demodulation of Fiber Bragg Grating Sensor Network

Through the technologies of wavelength division multiplex and time division multiplex, fiber Bragg grating (FBG) sensor network was built. Based on System on Programmable Chip technology and fiber comb filter, a high-speed and high-precision wavelength demodulation scheme of FBG sensor network was proposed. The optical system and hardware circuit for demodulation system were designed specifically. To improve the accuracy of demodulation system of FBG, a constant temperature channel of the demodulation system connected with a fiber comb filter, which offered reference points to calibrate the Bragg grating center wavelength. Based on 32-bit soft-core processor NoisII, the embedded system collected and processed the photoelectric signal voltage transformed to rectangular voltage pulse. The upper computer displayed dynamically the FBG wavelength demodulation process and calibrated the Bragg grating center wavelength. The experiment results of wavelength demodulation and calibration show that, the wavelength demodulation system has many advantages, such as flexibility, stabilization, easy maintenance, high-speed, high-precision, and so on. The wavelength demodulation precision is ±2 pm.