一种相干光时域反射计长度校准方法研究

Study on length calibration method of coherent optical time domain reflectometer

为满足相干光时域反射计(COTDR)在长距离通信状态监测中的长度校准需求,提出一种新型相干光时域反射计长度校准方法。该方法是利用光在光纤环中不断循环的原理,基于该原理研制COTDR长度校准装置,该装置是利用函数发生器发出的脉冲频率和脉冲宽度来控制光开关的开断时间,最终实现光在光纤环路中传播时间的控制。如果在光纤环路中加入光纤放大器,可以实现不同长度光纤链路的模拟,最终实现对相干光时域反射计长度的校准。实验结果表明:该装置中使用的光纤长度为150 km,光脉冲在光纤环路中最多能转7圈,因此该装置能够实现相干光时域反射计长度校准的最大范围为1050 km,其扩展不确定度为7.0 m,其中包含因子k为2。该方法不仅可以促进相干光时域反射计技术的发展,也为COTDR的长度校准提供思路。

In order to meet the length calibration requirements of coherent optical time domain reflectometer(COTDR)in state monitoring of long-distance communication,a new coherent optical time domain reflectometer length calibration method was proposed.The method utilized the principle that light circulated continuously in the fiber ring.And based on the principle,the COTDR length calibration device was developed.The device used the pulse frequency and pulse width emitted by the function generator to control the breaking time of the optical switch.Thereby it could realize the control of the propagation time of the light in the fiber loop.If a fiber amplifier was added to the fiber loop,simulation of fiber links of different lengths could be realized.Finally,the length calibration of the coherent optical time domain reflectometer was achieved.The experimental results showed that the length of the fiber used in the device is 150 km,and the optical pulse could be rotated up to 7 times in the fiber loop.Therefore,the maximum range of the coherent optical time domain reflectometer length calibration was 1050 km.Its extended uncertainty was 7.0 m,and the containing factor was 2.This method could not only promote the development of coherent optical time domain reflectometry technology,but also provided a good idea for COTDR length calibration.