High Accuracy Optical Reflectometry and Its Applications in Measurement of Multiple-Path Interference in Optical Fiber Communication Systems

为了有效地解决光纤通信行业中的难题，如掺铒光纤放大器(EDFA)等光纤模块的诊断，光纤模块中多径干涉的测量等，本项目旨在通过将本课题组首创的光学相干函数合成(SOCF)技术与首席研究员开发的“波长扫描平均”方案相结合，提高光反射测量即光学反射分布测量的精度(反射分辨率)。特别是对光纤模块中瑞利散射和多次反射之间的干涉进行了深入的分析和数值模拟，证实了采用波长扫描平均法抑制…中的干涉起伏的有效性更多测量的反射分布。提出了一种新的双光调频方案，该方案同时采用高频正弦波作为分布式反射测量的相干峰，同时采用相对较慢的扫频进行波长扫描平均。利用这一新发明的方案，可以在短时间内获得高精度的光学分布的反射，而传统技术通常需要数千秒。在实验演示中，在50秒内获得了0.02-分贝精度的50m光纤反射分布。提出了一种新型的自适应载波零差检测方案，极大地提高了系统的动态范围，并在实验中成功地实现了对光纤模块内反射分布和多径干涉的测量。此外，还研究了该高性能功能光反射技术在多光路光纤接入网故障诊断中的应用。新提出和演示的技术也有助于分布式和多路复用光纤传感器的发展。较少

With the object of providing efficient solutions to the difficult problems in optical fiber communication industry, such as the diagnoses of optical fiber modules like erbium-doped optical amplifiers (EDFA), the measurement of multi-path interference in optical fiber modules, etc., this project is aiming at enhancing the accuracy (reflection resolution) of optical reflectometry, i.e., optical reflection distribution measurement, by merging the technique of "synthesis of optical coherence function" (SOCF), which is originally created by this research group, with the scheme of "wavelength sweeping averaging" developed by the head investigator before.Performance limiting factors, especially the interference among the Rayleigh scatterings and multiple reflections in optical fiber modules, are investigated thoroughly by analysis and numerical simulation, which confirm the effectiveness of employing wavelength sweeping averaging in SOCF in suppressing the interference-induced fluctuations in … More measured reflection distribution. A new scheme with dual optical frequency modulation is proposed, in which a high-fequency sinusoidal wave for synthesizing a coherence peak for distributed reflection measurement and a relatively slow sweeping for wavelength sweeping averaging are applied simultaneously. With this newly invented scheme, a reflection distributed with high accuracy can be obtained optically in short-time, which costs in general thousand of seconds with conventional techniques. In experiment demonstration, a reflection distribution with 0.02-dB accuracy for 50-m optical fiber is obtained within 50 seconds. Moreover, a novel homodyne detection scheme with adaptive carrier is also invented, which enhances the dynamic range of the system in great extent.With this high-accuracy high speed optical reflectometric system, the measurements for the reflection distribution and the multi-path interference in optical fiber modules are demonstrated successfully in experiment. In addition, the application of this high-performance functional optical reflectometry technology in the diagnosis of fiber access network with multiple optical paths is also investigated. The newly proposed and demonstrated techniques also contribute to the development of distributed and multiplexed fiber optic sensors. Less