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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 a wide range of applications. For a particular incident wavelength, the Brillouin frequency shift of self-propagating Brillouin scattering light becomes linear with temperature and strain, and distributed sensing of temperature or strain can be achieved by measuring the Brillouin frequency shift along the fiber. Brillouin power spectrum scanning is BOTDR common means of obtaining Brillouin frequency shift, there are two methods of optical frequency difference scanning and electric frequency scanning. Based on the wavelength dependence of Brillouin frequency shift, a wavelength-scan type BOTDR is proposed. The tunable laser is used as the light source, and the Brillouin power spectrum is obtained by scanning the wavelength of incident light. The method has the advantages of optical frequency difference scanning and electric frequency scanning. The experiment proves the feasibility of this method. The measurement of 23.4km optical fiber realizes the spatial resolution of 5m and the temperature measurement accuracy of 2.2 ℃.