Optical fiber interferometer could achieve various dynamic measurements by transforming phase change into intensity change. In this paper, a novel Michelson interferometer (MI) based on two polarization beam splitters (PBSs) is proposed. Two thirds of Rayleigh backscattering (RB) is separated from the signal light by using PBS and Faraday rotating mirror (FRM) due to the difference polarization properties between RB and signal light in optical fibers. And the signal-to-noise ratio (SNR) of system has been significantly improved. Within the detection range of 50 km, the localization experiments on this new interferometer show that the SNR is increased by 6.69 dB compared with traditional MI on the condition of 500 kHz sampling rate. And the positioning accuracy can achieve ±100 m in the first-order null-frequency. The sensing distance also increases from 36.17 km to 49.42 km with a SNR of 15 dB. This proposed sensing system exhibits high sensitivity in the low frequency region, which is of great importance for long-distance buried optical cable detection and location.

中文翻译：

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基于PBS的新型弱散射迈克尔逊干涉仪长距离干扰定位

光纤干涉仪可以通过将相位变化转化为强度变化来实现各种动态测量。在本文中，提出了一种基于两个偏振分束器 (PBS) 的新型迈克尔逊干涉仪 (MI)。由于 RB 和光纤中信号光的偏振特性不同，三分之二的瑞利背向散射 (RB) 通过使用 PBS 和法拉第旋转镜 (FRM) 从信号光中分离出来。并且系统的信噪比(SNR)得到了显着提高。在50 km的探测范围内，这种新型干涉仪的定位实验表明，在500 kHz采样率的条件下，信噪比比传统的MI提高了6.69 dB。并且在一阶零点频率下定位精度可以达到±100 m。感应距离也从 36.17 公里增加到 49.42 公里，SNR 为 15 dB。该传感系统在低频区域表现出高灵敏度，这对于长距离埋地光缆检测和定位非常重要。