Development of Distributed Vibration Sensing System Based on Polarization Optical Time Domain Reflectometry

摘要

A method using a polarization beam splitter (PBS) and a balanced photodetector (BPD) to differentially measure the changes of state of polarization (SOP) is proposed for polarization optical time domain reflectometry (POTDR). A laboratory system for long distance vibration fiber sensor based on this method is devised. The average algorithm and Fast Fourier Transform (FFT) method are used in data processing to realize fast measurement. Then an integrated system is realized. The improvements on the measuring sensitivity of SOP, response time, spatial resolution, frequency resolution and amplitude resolution, sensing distance of the system are all tested. A sensing system is achieved with sensing range of 14 km, response time of 2.26 s, spatial resolution of 10 m, amplitude resolution of 0.5 mm and frequency resolution of 1 Hz.