调制器消光比对光纤分布式扰动传感器的影响  

Influence of extinction ratio of the modulator on fiber-optic distributed disturbance sensor

作　　者：李勤[1] 张春熹[1] 李立京[1] 梁生[2] 钟翔[1] 李传生 

机构地区：[1]北京航空航天大学仪器科学与光电工程学院,北京100191 [2]北京交通大学理学院,北京100044 [3]国家电网智能电网研究院,北京100192

出　　处：《光电子．激光》2014年第4期631-636,共6页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(61205074)资助项目

摘　　要：基于多波干涉原理,建立了调制器消光比(ER)不理想条件下基于相位敏感光时域反射(OTDR)的光纤分布式扰动传感器(FDDS)光路系统输出信号模型,研究了调制器ER对FDDS定位精度的影响机理。仿真结果表明:调制器的ER不理想引起泄漏光产生的后向散射相干曲线是噪声源,它会导致传感器的信噪比(SNR)恶化。因此,调制器的ER是引起定位误差甚至传感器无法定位的一个关键因素;当调制器的ER分别低于10.2dB和7.8dB时,依据有扰动减无扰动定位方法以及移动平均和移动差分算法得到的传感器SNR低于2dB,定位算法失效。通过调节声光调制器的驱动电压来改变衍射效率从而改变调制器的ER,实验结果与数值仿真基本一致。The signal models of the fiber-optic distributed disturbance sensor （FDDS） based on the optical time-domain reflectometry （OTDR） under the unsatisfactory modulator conditions are established in accordance with coherent lightwave theory. According to the mathematical models, the effects of the extinction ratio （ER） of the modulator on the sensor are simulated and investigated by experiment. The simulation results demonstrate that the Rayleigh backscattered coherent trace generated by the leaked light waves from the unsatisfactory modulator is an important source of noise. Thus the ER of the modulator is a critical factor that results in the location errors and the reduction of the signal-to-noise ratio （SNR）. The SNR is less than 2 dB by subtraction of the traces with disturbances from the traces without disturbances and by moving averaging and moving differential methods, when the extinction ratios of the laser are less than 10.2 dB and 7.8 dB,respectively. It means that the two location methods fail to locate the disturbance. The voltage of the driver for the acousto-optic modulator （AOM） is adjusted to change the ER of the modulator thanks to the variation of the diffractive efficiency. Numerical results are proved by the experiment and the investigation results are helpful to select the modulator and improve the location precision of the sensor.

关 键 词：光纤分布式扰动传感器(FDDS) 相位敏感光时域反射(OTDR) 消光比(ER) 相干瑞利散射 入侵检测 

分 类 号：TP212.1[自动化与计算机技术—检测技术与自动化装置]