少模光纤中折射率微扰对模式消光比的影响  

Influence of Refractive Index Perturbation on Mode Extinction Ratio in Few-Mode Fibers

作　　者：谢艳秋 武保剑[1] 文峰[1] Xie Yanqiu;Wu Baojian;Wen Feng(Key Laboratorn of Optical Fiber Sensing and Communicatious,Ministry of Education,University of Electronic Science and Technology of China,Chengdu,Sichuan,611731,China)

机构地区：[1]电子科技大学光纤传感与通信教育部重点实验室,四川成都611731

出　　处：《光学学报》2020年第23期48-53,共6页Acta Optica Sinica

基　　金：国家重点研发计划(2018YFB1801003)。

摘　　要：根据时域微扰波动方程,推导了少模光纤中存在折射率微扰时的模式耦合方程,分析了少模光纤连接时模式的耦合特性及其对信号模式消光比的影响。以两模光纤为例,研究了最大模式耦合效率与微扰/非微扰光纤间连接损耗系数之间的关系,当模间耦合很小时前者约为后者的4倍。给出了存在折射率微扰时少模光纤的模式消光比公式,计算表明,当两个模式之间的有效相位失配因子与模式耦合系数之比大于10,或者模式耦合系数与模式耦合长度之积小于0.2时,信号模式消光比可达20 dB以上。According to the time-domain perturbation wave equation, we derived the mode-coupled equation with the refractive index perturbation in the few-mode fibers. Then, the equation was used to analyze the mode coupling characteristics and their influence on the mode extinction ratio of signals in the case of few-mode fiber connection. Taking a two-mode fiber as an example, we investigated the relationship between the maximum mode coupling efficiency and the connection loss coefficient of perturbative/non-perturbative fibers. It is found that the maximum mode coupling efficiency is about 4 times the connection loss coefficient when the inter-mode coupling is very small. Furthermore, we put forward a formula of mode extinction ratio in the presence of refractive index perturbation in few-mode fibers. The calculation results show that the mode extinction ratio of the signals can be higher than 20 dB when the ratio of the effective phase mismatch factor to the mode coupling coefficient is greater than 10 or the product of mode coupling coefficient and length is less than 0.2.

关 键 词：光纤光学 模式耦合 折射率微扰 模式消光比 

分 类 号：O436[机械工程—光学工程]