Multiplexed polarization-OTDR system for multi-event detection

A novel scheme of polarization optical time domain reflectometry (POTDR) with a high degree of polarization was proposed for multi-event detection. Multiple 2×2 optical fiber couplers and fiber mirrors were employed for the multiplexed POTDR system. The system can be used for multi-event detection while the signal´s signal-to-noise ratio be improved significantly and the temporal depolarization effect can be almost completely suppressed. Without performing any data averaging, the intrusion event (action of removing fiber) can be detected and located precisely/instantaneously with good stability. Also the frequency components of vibration events can be obtained with a large dynamic range. In this paper intrusion behavior with low frequency and up to 950Hz vibration frequency has been detected simultaneously while the pulse repetition frequency is 2KHz. It shows a very good potential in intrusion detection, vibration frequency measurement, etc.