为简化系统结构、减小相干瑞利噪声对系统性能的影响, 提出了一种采用宽带光源的瑞利和布里渊散射自外差检测布里渊光时域反射温度传感系统.分析了瑞利和布里渊自外差检测原理, 研究了布里渊频移和自外差信号功率与光纤温度和应变的关系.设计并搭建采用宽带光源的自外差检测布里渊光时域反射温度传感系统, 获得了常温下沿光纤分布的自外差信号功率谱及不同温度时加温段光纤的功率谱, 验证了布里渊频移和自外差信号相对功率变化随温度的线性增加关系.通过实验数据获得的布里渊频移和相对功率变化的温度系数分别为1.07±0.01 MHz/℃和(0.37±0.09)%/℃.本文的研究结果为基于瑞利和布里渊自外差检测布里渊光时域反射传感系统的温度和应变同时测量提供了理论和实验依据.

To simplify the system structure and reduce the effect of coherent Rayleigh noise on system performance, a temperature sensing system based on Brillouin optical time domain reflectometry by employing broad-band laser and self-heterodyne detection of Rayleigh and Brillouin scattering was proposed. The principle of self-heterodyne detection of Rayleigh and Brillouin scattering was analyzed, and the relationships of Brillouin frequency shift and self-heterodyne detection signal power with temperature and strain were studied. A temperature sensing system based on Brillouin optical time domain reflectometry by employing broad-band laser and self-heterodyne detection was designed and constructed, the power spectrum of self-heterodyne detection signal along the sensing fiber at room temperature and the power spectra of the heated fiber at different temperature were obtained. The linear increase relationships of Brillouin frequency shift and change in relative self-heterodyne detection signal power with temperature were demonstrated. The temperature coefficients of Brillouin frequency shift and change in relative power were experimentally obtained to be 1.07±0.01 MHz/℃ and (0.37±0.09)% /℃. The results of this study can provide a theoretical and experimental basis for the simultaneous measurement of temperature and strain of Brillouin optical time domain reflectometer sensing system based on self-heterodyne detection of Rayleigh and Brillouin scattering.