A High-Gain Vibration Detection System Based on Phase Coding and Weakly Reflective Grating Arrays

In this paper, we propose a vibration detection system utilizing a weakly reflective grating array and phase coding technique. By using differential phase shift keying (DPSK) modulation technique, the sequence encoding information is replaced by the phase and the demodulation of broadband optical DPSK signals are realized by using Mach-Zehnder interferometer (MZI). We utilize coding techniques to achieve correlation localization for event localization in the grating array. Vibration events are detected through the use of grating arrays equipped with adjustable filters (TF). The resultant fluctuations in light intensity, caused by these vibrations, are subsequently quantified as correlation values. These values can then be utilized to reconstruct the waveform of the vibration signal. Simultaneously, we employed Fast Fourier Transform (FFT) and power spectral density (PSD) analysis techniques to analyze the signal. Experimental results demonstrate that the proposed system achieves a frequency response range of 1 kHz, with a signal-to-noise ratio exceeding 42 dB.