Li Zonglei, Zhou Yin, Jiang Biqiang, Gan Xuetao, Yan Lianshan, Zhao Jianlin
Opt Lett. 2021 Feb 15;46(4):757-760. doi: 10.1364/OL.415419.
The employment of coherent detection in a Brillouin optical time domain analysis (BOTDA) fiber sensor brings benefits, including signal-to-noise ratio enhancement, non-local effect reduction, and sensing speed improvement. Recently, it was found that the performance of a coherent-detection BOTDA fiber sensor suffers from phase fluctuations introduced by the fiber group delay jitter. Here, we propose a phase fluctuation cancellation approach based on optical subcarrier multiplexing. In a proof-of-concept experiment, the phase stability for in-phase/quadrature demodulation reaches a standard deviation value of as small as 0.4 mrad. The variations in the Brillouin gain and phase spectra caused by the phase fluctuation are then effectively alleviated, resulting in an enhancement of the Brillouin frequency shift measurement certainty along the whole sensing fiber.
在布里渊光时域分析（BOTDA）光纤传感器中采用相干检测具有诸多益处，包括提高信噪比、降低非局部效应以及提升传感速度。最近，人们发现相干检测BOTDA光纤传感器的性能会受到光纤群时延抖动引入的相位波动的影响。在此，我们提出一种基于光载波复用的相位波动消除方法。在概念验证实验中，同相/正交解调的相位稳定性达到了低至0.4毫弧度的标准差值。由相位波动引起的布里渊增益和相位谱的变化随后得到有效缓解，从而提高了沿整个传感光纤的布里渊频移测量精度。
