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对于布里渊分布式光纤传感器(DOFS),温度或应变的变化都会引起布里渊频移谱改变,因此存在交叉敏感问题。在以往对布里渊光时域反射(BOTDR)计的双参量传感研究中,采用单根光纤,通过同时检测布里渊频移和功率变化,实现双参量传感。但对于布里渊光时域分析(BOTDA),由于受激布里渊散射的偏振相关性,不能实现对受激散射光功率的准确检测,因此难以实现单光纤的双参量传感。针对这一问题采用温度和应变系数不同的双光纤进行双参量传感。先测量了几种常用光纤的温度和应变布里渊频移系数,然后选择G652和G652成缆两种光纤,通过构建系数矩阵,由两根光纤的布里渊频移计算得出温度和应力,从而实现了温度分辨率25℃左右,应变分辨率约为200με的双参量传感。
For the Brillouin distributed optical fiber sensor (DOFS), the change of temperature or strain will cause the change of Brillouin frequency spectrum, so there is cross-sensitivity problem. In the past, two-parameter sensing of Brillouin Optical Time Domain Reflectometry (BOTDR) was studied, and a single optical fiber was used to realize double-parameter sensing by detecting Brillouin frequency shift and power variation at the same time. However, for Brillouin Optical Time Domain Analysis (BOTDA), accurate detection of stimulated scattered light power can not be achieved due to the polarization dependence of stimulated Brillouin scattering, making it difficult to achieve single-fiber bi-parametric sensing. In response to this issue using dual temperature and strain coefficient of the double-fiber dual-sensor. Firstly, the temperature and strain Brillouin frequency shift coefficients of several commonly used optical fibers were measured, and then two types of optical fibers, G652 and G652, were selected. By constructing the coefficient matrix, the Brillouin frequency shift of two fibers was used to calculate the temperature and stress , So as to achieve the temperature resolution of about 25 ℃, the strain resolution of about 200με two-parameter sensing.