Distributed Fiber Optic Vibration Sensing (DVS) is an advanced optical sensing technology that uses single-mode optical fiber (SMF, G652 recommended) as both the sensing medium and signal transmission carrier. Unlike traditional point-type vibration sensors, DVS realizes continuous, real-time. Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. However, their practical deployment remains hindered by two major challenges: (1) degradation of recognition accuracy in dynamic conditions, and. The sensors presented in this chapter are fiber optic intensity modulated vibrations sensors which are non-contact (extrinsic sensor) to the vibrating object. Three sensors presented make use of non-contact vibration measurement method with plastic fiber using distinct designs, improvement of the. Because of the problem of low recognition accuracy in the recognition of intrusion vibration events by the distributed Sagnac type optical fiber sensing system, this paper combines the traditional optical fiber vibration signal recognition idea and the characteristics of automatic feature. Abstract – Vibration causes mechanical distortions in fiber-optic transmission lines that induce time (phase) fluctuations.