Passive Vibration-Sensing System Using Hybrid Alignment Nematic Liquid-Crystal Gratings

Unlike the commonly used electrically controlled birefringence mode liquid crystals, hybrid alignment nematic (HAN) liquid crystals eliminate the threshold voltage. Therefore, they have excellent application prospects in low-voltage photonic components. This article discloses a power-free vibration detection system based on optical fiber, HAN, and a passive vibration transducer. Using the photo alignment techniques, we fabricated HAN grating cells and deployed them into the vibration sensing system, achieving a sensitivity of 13.1 rad/m/s. Meanwhile, we measured the frequency response and resolution and analyzed its performance in actual conditions. The system has excellent cost-efficiency and optimization spaces, which can be applied in large-scale vibration monitoring in the field.