C+L波段低弯曲损耗非耦合三模组渐变折射率光纤设计  

Design of Uncoupled Three-Mode-Group Graded-Index Fiber with Low Bending Loss in C+L Band

作　　者：王卓 崔明杰 余长源[1,2,3] WANG Zhuo;CUI Ming-jie;YU Chang-yuan(Department of Electrical and Electronic Engineering,The Hong Kong Polytechnic University,Hong Kong 999077,China;Photonics Research Institute,The Hong Kong Polytechnic University,Hong Kong 999077,China;The Hong Kong Polytechnic University Shenzhen Research Institute,Shenzhen,Guangdong 518057,China)

机构地区：[1]香港理工大学电机及电子工程学系,中国香港999077 [2]香港理工大学光子研究院,中国香港999077 [3]香港理工大学深圳研究院,广东深圳518057

出　　处：《电子学报》2024年第8期2659-2667,共9页Acta Electronica Sinica

基　　金：国家重点研发计划(No.2018YFB1800902)。

摘　　要：光纤是现代通信网络中最为稳定的信号传输媒介,提升光纤模式的数量是满足通信容量日益增加的有效方法.本文设计了低弯曲损耗的非耦合三模组(LP_(01),LP_(11),LP_(21))渐变折射率光纤,运用分层分析法给出了渐变折射率光纤中模组的严格截止条件.此外,利用有限元仿真软件求解光纤模式的有效模场面积和弯曲损耗,得到低弯曲损耗条件下在C+L波段(1530~1625 nm)传输三模组的设计区间.揭示了纤芯中心折射率凹陷和沟槽层共同作用可促进光纤径向高阶模式的截止.模拟结果表明,所设计光纤的模组间有效折射率差大于等于3×10^(-3),弯曲半径为30 mm时的最大弯曲损耗为1.3 d B/km,符合ITU-T推荐的低弯曲损耗条件.而且,在1550 nm波长下,模组内简并模有较小的差分模式群时延(≈176 ps/km),可通过4×4多输入多输出技术补偿简并模之间的串扰.该光纤可适用于C+L波段上实现模组间非耦合的空分复用信号传输.Optical fiber is the most stable medium for signal transmission in modern communication networks.In⁃creasing the number of fiber modes is an effective way to meet the increasing demand for communication capacity.In this paper,a kind of uncoupled three-mode-group(LP_(01),LP_(11),LP_(21))graded-index fiber with low bending loss is designed.The strict cut-off conditions of the mode groups in the graded-index optical fiber are obtained by using the stratified method.In addition,the effective mode area and bending losses are calculated by a finite element simulation software,and the design region of three-mode-group transmission in the C+L(1530~1625 nm)band with low bending loss is obtained.It is re⁃vealed that the combined effects of the concave refractive index at the core center and the trench layer can promote the cut⁃off of radial higher-order modes in the fiber.The simulation results show that the designed fiber has a large effective index difference between mode groups that is≥3×10^(-3),and the maximum bending loss is 1.3 dB/km when the bending radius is 30 mm,which meets the low bending loss condition recommended by ITU-T.In addition,at the wavelength of 1550 nm,the degenerate modes in the same mode group have a relatively small differential mode group delay(≈176 ps/km),and the crosstalk between degenerate modes can be compensated by 4×4 multi-input multi-output technique.This fiber can be used in the C+L band to realize uncoupled space-division multiplexing signal transmission.

关 键 词：少模光纤 渐变折射率 低弯曲损耗 空分复用 光纤通信 

分 类 号：TN253[电子电信—物理电子学]