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搭建了一种新型的基于瑞利散射的布里渊光时域分析(Rayleigh Brillouin optical time domain analysis,RBOTDA)传感系统。该系统工作在单端,能克服传统BOTDA双端接入的缺点;采用两个EOM并联的结构产生含有连续基底光的脉冲光,探测光由基底连续光的瑞利散射提供,避免了多种受激布里渊散射(stimulated Brillouinscattering,SBS)作用带来的干扰,信噪比更高,传感距离更长;采用双边带探测方法,有效减少泵浦脉冲的损耗与非本地效应。建模解析了该系统中的SBS作用过程,并实验验证了系统的可行性。结果表明,布里渊增益谱完好地贴合洛伦兹曲线,非本地效应得到了有效的抑制;在2.4km光纤上,室温25℃下泵浦脉宽50ns时,布里渊频移为10.867GHz,布里渊线宽约为40.21MHz。
A new Rayleigh Brillouin optical time domain analysis (RBOTDA) sensing system is built. The system works in single-ended mode, which can overcome the disadvantage of traditional BOTDA double-ended access. The pulsed light with continuous base light is generated by using two EOM parallel structures. The detection light is provided by Rayleigh scattering of continuous light from the substrate, Stimulated Brillouinscattering (SBS), the signal-to-noise ratio is higher and the sensing distance is longer. The double-sideband detection method can effectively reduce the pump pulse loss and non-local effects. The SBS modeling process in the system was analyzed by modeling, and the feasibility of the system was verified experimentally. The results show that the Brillouin gain spectrum is well fitted to the Lorenz curve and the non-local effect is effectively suppressed. At 2.4 km fiber, the Brillouin frequency shift is 10.867 GHz, Brillouin line width of about 40.21MHz.