Li Zonglei, Yan Lianshan, Shao Liyang, Pan Wei, Luo Bin, Liang Jiawei, He Haijun, Zhang Yunpeng
Opt Express. 2016 Mar 7;24(5):4824-4833. doi: 10.1364/OE.24.004824.
In order to cancel phase fluctuation induced Brillouin gain spectrum (BGS) and Brillouin phase spectrum (BPS) distortions, a new scheme with phase fluctuation cancellation (PFC) is proposed to realize precise BGS and BPS measurements in coherent BOTDA sensors. We present comprehensive and theoretical analysis about the effect of phase fluctuation on the shape of BGS and BPS, and further design a new experimental setup to fully cancel phase fluctuation induced measurement errors. In our new scheme, the two signals sent into the in-phase/quadrature (I/Q) demodulator are almost the same except for the additional amplitude amplification and phase shift induced by Brillouin gain, thus a strict phase synchronization between them has been realized (i.e., PFC). Experimental results show that the biggest BFS decoding error induced by phase fluctuation is reduced from 4.9MHz to 0.4MHz over a 40-km sensing fiber.
为了消除相位波动引起的布里渊增益谱（BGS）和布里渊相位谱（BPS）畸变，提出了一种具有相位波动消除（PFC）功能的新方案，以实现相干布里渊光时域分析（BOTDA）传感器中精确的BGS和BPS测量。我们对相位波动对BGS和BPS形状的影响进行了全面的理论分析，并进一步设计了一种新的实验装置，以完全消除相位波动引起的测量误差。在我们的新方案中，除了由布里渊增益引起的额外幅度放大和相位偏移外，发送到同相/正交（I/Q）解调器的两个信号几乎相同，因此实现了它们之间严格的相位同步（即PFC）。实验结果表明，在40 km的传感光纤上，由相位波动引起的最大布里渊频移（BFS）解码误差从4.9 MHz降低到了0.4 MHz。
