LAUSR

We proposed a multichannel optic fiber sensing system based on hybrid Sagnac structure to convert phase changes of light transmitting in optic fiber caused by vibrations to be detected into intensity changes of interference signals. By using the differential demodulation method, the originally applied vibration signal can be retrieved for further signal analysis. The auxiliary modulation method was introduced into this system so that even tiny vibration signals less than one period can also be detected precisely since all the original signals would be carried by the high frequency and large modulation signals. In the signal retrieve algorithm, we also added a response smoothing transform algorithm to improve the smoothness of the system's frequency response. Besides, in association with wavelength division multiplexer, this sensing system can realize multipoints' vibration detection. By designing the spatial arrangement of sensing fiber array according to application scenarios, this system can realize monitoring and positioning vibration sources with appropriate algorithms.