为提高测温精度和空间分辨率,搭建了基于电光调制器调制探测光脉冲的布里渊光时域反射分布式温度传感系统。分析并验证了电光调制器输出探测光脉冲信号的特性、电信号解调系统中窄带滤波器中心频率以及检波器响应速率对反射测温精度和空间分辨率的影响。结果显示,中心频率为700 MHz的窄带滤波器进行布里渊增益谱扫描时,布里渊光时域反射测温系统可获得高的测温精度；采用响应速率较快的检波器获得的系统空间分辨率较高。在此基础上,采用电光调制器调制脉宽约10 ns的探测光脉冲进行测温实验,在约3 km的传感距离上获得了±1.24 ℃的测温精度和1.217 m的空间分辨率,实现了较高空间分辨率和温度精度的分布式光纤传感测量。该实验可为BOTDR温度传感解调系统中器件参数的选择提供参考。

In order to improve the temperature measurement accuracy and the spatial resolution, the experimental setup of Brillouin optical time domain reflectometry (BOTDR)which uses the electro-optical modulator(EOM) as the optical pulse modulator to produce the probe pulse is proposed and demonstrated. Firstly, the characteristic of the probe pulse generated by the EOM is analyzed. Moreover, the influences of the central frequency of the bandpass filter (BPF) and the response time of the radiodetector (RD) in the electrical signal demodulation system on the temperature measurement accuracy and spatial resolution are respectively investigated. The results show that the higher temperature accuracy can be obtained when the BPF with the central frequency of 700 MHz is utilized to scan Brillouin gain spectrum. And the RD with faster response time can be expected to enhance the spatial resolution in the BOTDR system. On this basis,the probe optical pulse with width of 10 ns modulated by the EOM is employed to measure the temperature along the test fiber. Finally, the temperature measurement accuracy of ±1.24 ℃ and the spatial resolution of 1.217 m are achieved over a 3 km sensing fiber. The higher temperature accuracy and higher spatial resolution are obtained by using the EOM in a BOTDR. The experimental results are helpful in designing the demodulation system of the BOTDR temperature sensor.