单模光纤中受激布里渊散射阈值研究

Analysis and Measurement of Stimulated Brillouin Scattering Threshold in Single Mode Fiber

分析和讨论了受激布里渊散射(SBS)阈值计算的Smith模型和Küng模型,研究了更为准确估算光纤中布里渊散射阈值的方法,通过布里渊增益系数与光纤长度的关系,发现对于较短长度光纤,其布里渊增益系数随着光纤长度变化范围较大,仅在长距离光纤时,布里渊增益系数才可以近似为常数。实验测量了25 km单模光纤的受激布里渊散射阈值,推导出用布里渊时域反射仪(BOTDR)测量受激布里渊散射阈值计算公式,最后用布里渊时域反射仪测量了不同长度光纤受激布里渊散射阈值,实验结果与理论分析吻合。

The Smith's model and Kung's model for calculating the threshold of stimulated Brillouin scattering (SBS) are analyzed and discussed. The more exact method is investigated. The relationship between critical gain coefficient and fiber length is obtained, which shows that the critical gain coefficient can be considered as constant only when fiber length is long enough. The SBS threshold of 25 km single mode fiber is measured by experiment. Finally, the experiment to measure SBS threshold using Brillouin optical-time-domain reflectometer (BOTDR) is done. The results are well agreed with the theoretical predication.