关键词: 传感器, 光纤传感器, 分布式光纤传感, 分布式声波传感, 相干光时域反射计, 相位解调, 振动传感

Abstract: Distributed acoustic sensing (DAS) systems based on coherent optical time-domain reflectometry (COTDR) can obtain vibration information along the fiber length by demodulating the phase information from the backscattered Rayleigh signal in optical fibers. The phase demodulation algorithm is a key technology for phase extraction in DAS systems, and different algorithms exert varying effects on the demodulation results.This study investigates the impacts of two in-phase quadrature (IQ) demodulation algorithms, i.e.,differential cross-multiplying (DCM) and arctangent (Arctan), on the demodulation results. First, a theoretical analysis and numerical simulations based onDCM and Arctan are conducted. Subsequently, a COTDR-based DAS system is constructed to collect data, which are processed and analyzed using both algorithms. Experimental results indicate that the peak values of the demodulated signals obtained using the two algorithms differ by 0.04 rad, with an observed phase shift of 0.01 rad. In addition, based on the different characteristics of the two algorithms, recommendations for their application scenarios are provided.

Key words: Optical Fiber Sensor, Distributed Optical Fiber Sensing, Distributed Acoustic Sensing, COTDR, Phase Demodulation, Vibration Sensing