Bao Xiaoyi, Zhou Zichao, Wang Yuan
School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, Ontario K1N 6N5 Canada.
Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5 Canada.
Photonix. 2021;2(1):14. doi: 10.1186/s43074-021-00038-w. Epub 2021 Jul 30.
Distributed time-domain Brillouin scattering fiber sensors have been widely used to measure the changes of the temperature and strain. The linear dependence of the temperature and strain on the Brillouin frequency shift enabled the distributed temperature and strain sensing based on mapping of the Brillouin gain spectrum. In addition, an acoustic wave can be detected by the four wave mixing (FWM) associated SBS process, in which phase matching condition is satisfied via up-down conversion of SBS process through birefringence matching before and after the conversion process. Brillouin scattering can be considered as the scattering of a pump wave from a moving grating (acoustic phonon) which induces a Doppler frequency shift in the resulting Stokes wave. The frequency shift is dependent on many factors including the velocity of sound in the scattering medium as well as the index of refraction. Such a process can be used to monitor the gain of random fiber laser based on SBS, the distributed acoustic wave reflect the distributed SBS gain for random lasing radiation, as well as the relative intensity noise inside the laser gain medium. In this review paper, the distributed time-domain sensing system based on Brillouin scattering including Brillouin optical time-domain reflectometry (BOTDR), Brillouin optical time-domain analysis (BOTDA), and FWM enhanced SBS for acoustic wave detection are introduced for their working principles and recent progress. The distributed Brillouin sensors based on specialty fibers for simultaneous temperature and strain measurement are summarized. Applications for the Brillouin scattering time-domain sensors are briefly discussed.
分布式时域布里渊散射光纤传感器已被广泛用于测量温度和应变的变化。温度和应变与布里渊频移的线性关系使得基于布里渊增益谱映射的分布式温度和应变传感成为可能。此外，声波可以通过与受激布里渊散射（SBS）相关的四波混频（FWM）过程来检测，在该过程中，通过在转换过程前后通过双折射匹配对SBS过程进行上下转换来满足相位匹配条件。布里渊散射可以被视为泵浦波从移动光栅（声子）的散射，这会在产生的斯托克斯波中引起多普勒频移。频移取决于许多因素，包括散射介质中的声速以及折射率。这样的过程可用于监测基于SBS的随机光纤激光器的增益，分布式声波反映了随机激光辐射的分布式SBS增益以及激光增益介质内部的相对强度噪声。在这篇综述文章中，介绍了基于布里渊散射的分布式时域传感系统，包括布里渊光时域反射仪（BOTDR）、布里渊光时域分析（BOTDA）以及用于声波检测的FWM增强SBS，阐述了它们的工作原理和最新进展。总结了基于特种光纤的用于同时测量温度和应变的分布式布里渊传感器。简要讨论了布里渊散射时域传感器的应用。
