“…Various techniques such as infrared [1], radar [2], microwave [3], electric fence [4], accelerometer [5], and fiber optic have been adopted to implement the PIDS. Among them, PIDSs using fiber optic interferometric sensors are of interest since they have plenty advantages, such as lightweight, immunity to electromagnetic interference and multiplexing, high-temperature performance, low energy requirement, high corrosion resistance, high environmental resistance, high sensitivity, water proof, and so on.…”