Coherent fiber-optic sensor for vibration localization

A novel distributed fiber-optic vibration sensor is proposed and experimentally demonstrated. The sensor relies on a dual Mach-Zehnder ring interferometric architecture associated to a new coherent detection scheme, borrowed from high bit rate coherent optical communications, which performs a completely passive management of polarization and phase variables of the received optical signal. The proposed solution thus makes feasible the actual in-field applicability of the cost-effectiveness and high sensitivity featured by interferometric sensors. Sensor performance in terms of vibration localization accuracy has been experimentally verified.