Optical frequency domain reflectometry vibration sensing based on fiber Bragg grating

Vibration detection and analysis can provide raw data for early detection, diagnosis, and prevention of mechanical faults. Meanwhile, fiber Bragg grating(FBG) sensors offer advantages such as strong anti-interference capability, high precision, and high signal-to-noise ratio compared to traditional electro-mechanical sensors. Addressing the limitation of traditional fiber optic grating-based vibration sensing systems, which is constrained by the Nyquist theorem, an FBG-based OFDR vibration sensing system is proposed. Leveraging the Doppler effect, this system achieves the capability of measuring high vibration frequencies at low repetition rates. Additionally, an adaptive orthogonal demodulation algorithm is introduced to mitigate the spectral broadening issue caused by the non-negligible grating length. Experimental results demonstrate that this system can measure vibration frequencies as high as 30 kHz with a repetition rate of 10 Hz. Comparative analyses between experimental and simulated data validate the performance advantages of the proposed demodulation algorithm.