Xiao Yihong, Liu Huanhuan, Li Jialong, Shen Xingliang, Zhao Ziyan, Dang Hong, Zou Defeng, Zhang Aoyan, Wang Pinhuang, Zhao Zhiyong, Chen Gina Jinna, Shum Perry Ping
Opt Express. 2024 Jul 15;32(15):26793-26807. doi: 10.1364/OE.528514.
Multi-core fiber (MCF) has attracted increasing attention for application in distributed fiber sensing owing to its unique properties of independent light transmission in multiple spatial channels. Here, we report a distributed acoustic sensing (DAS) system integrated MCF to suppress coherent fading, which overcomes an inevitable challenge in DAS systems. Because the parallel spatial cores in MCF allow the use of space-division multiplexed (SDM) technology, we propose that fading can be effectively suppressed by merging different signals with the spatial rotated-vector-average (SRVA) method. We theoretically analyze the principle of SRVA in fading suppression, and identify that it can effectively reduce phase noise with preventing phase unwrapping failures. In our experiment, a DAS system with 2.58-km length MCF have been investigated, the fading rate of Rayleigh backscattered signals is effectively reduced by three orders of magnitude and the amplitude fluctuation range is decreased by 21.9 dB. Compared with the conventional spectrum extraction and remix method (SERM), SRVA reduces the noise level by 9.5 dB, which also shows excellent low-frequency signal recovery ability. Benefiting from its fading suppression, the false alarm of localization is mitigated and the phase recovery can be distortionless. The proposed and verified method is helpful for the application of SDM-based MCF in long-distance distributed fiber sensors and accelerates the progress of integrated sensing and communication.
多芯光纤（MCF）因其在多个空间通道中独立光传输的独特特性，在分布式光纤传感应用中受到越来越多的关注。在此，我们报道了一种集成MCF的分布式声学传感（DAS）系统，以抑制相干衰落，这克服了DAS系统中不可避免的挑战。由于MCF中的并行空间纤芯允许使用空分复用（SDM）技术，我们提出通过空间旋转矢量平均（SRVA）方法合并不同信号可以有效抑制衰落。我们从理论上分析了SRVA在衰落抑制中的原理，并确定它可以有效降低相位噪声并防止相位解缠失败。在我们的实验中，研究了一个长度为2.58公里的MCF的DAS系统，瑞利背向散射信号的衰落率有效降低了三个数量级，幅度波动范围减小了21.9 dB。与传统的频谱提取和重新混合方法（SERM）相比，SRVA将噪声水平降低了9.5 dB，这也显示出优异的低频信号恢复能力。受益于其衰落抑制，定位的误报得到缓解，相位恢复可以无失真。所提出并经过验证的方法有助于基于SDM的MCF在长距离分布式光纤传感器中的应用，并加速集成传感与通信技术的发展。
