Mariñelarena Jon, Iribas Haritz, Urricelqui Javier, Loayssa Alayn
Opt Express. 2019 Mar 4;27(5):6310-6319. doi: 10.1364/OE.27.006310.
We demonstrate a technique to compensate the nonlocal effects that appear in Brillouin optical time-domain analysis sensors when pump pulses with limited extinction ratio are deployed. These recently discovered nonlocal effects are originated in the interaction between the probe wave and the pulse pedestal. Hence, their compensation method is based on deploying a modulation (dithering) of the optical frequency of the probe and pulse pedestal waves that provides a reduction of the effective interaction length between them. This is implemented by taking advantage of the chirp associated to the direct current modulation of a semiconductor laser used as common source for both waves. The net effect of this procedure is that the probe and pulse pedestal waves display efficient Brillouin interaction just at correlation peaks along the fiber where the frequency difference between both waves remains constant. Proof-of-concept experiments in a 25-km sensing link demonstrate the performance of the technique, where large errors of more than 10 MHz in the measurement of the Brillouin frequency shift are completely compensated by introducing a sinusoidal dithering to the laser source.
我们展示了一种技术，用于补偿在布里渊光时域分析传感器中，当部署具有有限消光比的泵浦脉冲时出现的非局部效应。这些最近发现的非局部效应源于探测波与脉冲基座之间的相互作用。因此，它们的补偿方法基于对探测波和脉冲基座波的光频率进行调制（抖动），这会减少它们之间的有效相互作用长度。这是通过利用与用作这两个波的共同源的半导体激光器的直流调制相关的啁啾来实现的。该过程的净效果是，探测波和脉冲基座波仅在光纤上相关峰处显示有效的布里渊相互作用，此时两个波之间的频率差保持恒定。在25公里传感链路中的概念验证实验证明了该技术的性能，其中通过对激光源引入正弦抖动，完全补偿了布里渊频移测量中超过10 MHz的大误差。
