Wang Yuan, Chen Liang, Bao Xiaoyi
Opt Lett. 2021 Nov 15;46(22):5774-5777. doi: 10.1364/OL.441815.
Driven by the strong need for distributed high-frequency dynamic strain sensing, ultra-fast Brillouin optical time-domain analysis is rapidly becoming a vital technique. Thus, in this Letter, we propose and demonstrate a novel method by using a chirped pulse as a pump signal to extract the relative Brillouin frequency shift (BFS) changes through the real-time delays between adjacent Brillouin traces; this enables static and dynamic strain measurement without time-consuming frequency sweeping process. Benefiting from single-shot measurement based on Brillouin traces, the system has a high acquisition rate that is only limited by the sensor length without averaging, and is immune to the polarization fading problem, thanks to electrical delay time measurement. The pump source is a 1 MHz linewidth laser without a phase-locking loop; the laser frequency drifting noise could be compensated by the signal from the non-disturbed fiber section. In the experiments, BFS measurement resolution of 0.42 MHz with 4.5 m spatial resolution is demonstrated over a 5 km non-uniform fiber.
在分布式高频动态应变传感的强烈需求推动下，超快布里渊光时域分析正迅速成为一项关键技术。因此，在本信函中，我们提出并演示了一种新颖的方法，即使用啁啾脉冲作为泵浦信号，通过相邻布里渊迹线之间的实时延迟来提取相对布里渊频移（BFS）变化；这使得无需耗时的频率扫描过程即可进行静态和动态应变测量。受益于基于布里渊迹线的单次测量，该系统具有仅受传感器长度限制而无需平均的高采集速率，并且由于采用了电延迟时间测量，对偏振衰落问题具有免疫力。泵浦源是一个没有锁相环的1 MHz线宽激光器；激光频率漂移噪声可由未受干扰的光纤段的信号进行补偿。在实验中，在5 km的非均匀光纤上展示了具有4.5 m空间分辨率、BFS测量分辨率为0.42 MHz的结果。
