在布里渊光时域分析(BOTDA)光纤传感器中,由于受激布里渊散射的偏振相关性的影响,激励光和探测光的偏振态随机变化引起的信号起伏严重影响布里渊散射光信号的稳定测量。通过建立与偏振态有关的激励光和探测光的耦合方程,推导出接收探测光光强关于激励光和探测光偏振态的理论公式,并由此提出偏振扩展接收技术。理论分析表明,偏振扩展接收技术可以有效地抑制偏振相关信号衰落。通过对耦合方程进行模拟,验证了理论分析的正确性和偏振扩展接收技术的可行性。最后给出了采用偏振扩展接收的布里渊光时域分析实验结果,与理论分析和模拟具有较好的一致性。

Because stimulated Brillouin scattering is polarization related, in Brillouin optical time-domain analysis (BOTDA) sensing system, the steady measurement of sensing signals is seriously affected by the random change of polarization state of pump light and probe light, which causes the measured signal fluctuant. Through constructing coupling equations about the polarization states of pump light and probe light, we deduce the function about probe light intensity referred to the polarization state of pump light and probe light. And a novel method, called polarization expanding receiving method, is proposed to eliminate the polarization related signal fading. Numerically simulated results of coupling equations prove that the polarization expanding receiving technique is feasible for Brillouin optical time-domain analysis (BOTDA), and the theoretical analysis is correct. Finally, a primary experimental result with the proposed method is present, which is coincident with the theoretical and simulating results.