对于普通单模光纤的自发布里渊散射光,其频移和光功率都是温度和应变的函数,因此检测散射光信号的布里渊频移和光功率,即可同时得到沿光纤一维分布的温度和应变。采用光相干检测的布里渊光时域反射计适合于长距离分布式传感,但存在检测信号的偏振相关性和幅度解调问题。采用偏振分集接收和小波分析对传感信号进行处理,同时得到了布里渊散射光的频移和功率,从而实现了25 km普通单模光纤的分布式双参量传感。

For the normal single-mode optical-fiber,the frequency shift and optical power of Brillouin scattering light are the functions of the temperature and strain. So,the temperature and strain of the optical-fiber can be obtained together,when Brillouin frequency shift and the optical power are able to be detected simultaneously. Brillouin optical time domain reflectometer with coherent detecting is suitable for long-distance distributed sensing,but there exist two critical problems. One is the polarization relative detecting signal;the other is how to demodulate the wideband photoelectric signal. The orthogonal polarization diversity reception and real-time wavelet transform are adopted to deal with these problems,in order to get the frequency and power of the scattering light at the same time. The experimental procedures and results are presented in the text. A laboratorial system of 25 km distributed Brillouin optical time domain reflectometer is achieved for two-parameter sensing.