波长扫描型布里渊光时域反射仪

A Wavelength-Scanning Brillouin Optical Time Domain Reflectometer

布里渊光时域反射仪(BOTDR)是一种具有广泛应用前景的分布式光纤传感器。对于特定的入射波长,自发布里渊散射光的布里渊频移与温度和应变成线性关系,通过测量光纤沿线布里渊频移分布可实现温度或应变的分布式传感。布里渊功率谱扫描是BOTDR获取布里渊频移的常用手段,已有光频差扫描与电频扫描两种方式。基于布里渊频移对波长的依赖性,提出一种波长扫描型BOTDR。采用可调谐激光器作为光源,通过扫描入射光波长,来获取布里渊功率谱,该方法兼具光频差扫描与电频扫描的优点。实验证明了该方法的可行性,对23.4km光纤进行测量,实现了5m的空间分辨率与2.2℃的温度测量精度。

Brillouin optical time domain reflectometer （BOTDR） is a distributed optical fiber sensor with broad application prospects. For a given input light wavelength, the Brillouin frequency shift of spontaneous Brillouin scattering light has a linear relationship with both temperature and strain. The distributed temperature or strain can be obtained by measuring the Brillouin frequency shift （BFS） along the fiber. In a BOTDR, Brillouin power spectrum scanning is a commonly used means to obtain the BFS, and there has been two types： the optical frequency-difference scanning method and the electrical frequency scanning method, A wavelength scanning BOTDR is proposed based on the wavelength dependence of the BFS. With a tunable laser as the light source, the Brillouin power spectrum is obtained by scanning the input light wavelength. This method combines the advantages of the optical frequency- difference scanning method and the electrical frequency scanning method. The feasibility of this proposed method is demonstrated experimentally. By use of this method, a temperature accuracy of 2.2 ℃ along a 23.4 km sensing fiber with a 5 m spatial resolution is achieved.