基于空芯反谐振光纤的三芯结构宽带耦合器设计  

Design of Three-Core Structure Broadband Coupler Based onHollow-Core Anti-Resonant Optical Fiber

作　　者：陈乐 陈明阳[1] Chen Le;Chen Mingyang(School of Mechanical Engineering,Jiangsu University,Zhenjiang 212000,Jiangsu,China)

机构地区：[1]江苏大学机械工程学院,江苏镇江212000

出　　处：《光学学报》2024年第7期188-195,共8页Acta Optica Sinica

摘　　要：提出一种基于三芯结构空芯反谐振光纤的太赫兹耦合器。采用有限元分析法对太赫兹光纤的模式特性进行分析,并基于耦合理论得到其耦合特性曲线。仿真结果表明,三芯结构模式具有比单芯结构更低的传输损耗,其耦合长度可通过改变纤芯间隔和隔离包层管的间隙进行调节。采用长度为223.2 mm的三芯结构空芯光纤可以实现插入损耗小于3.5 dB、带宽达到0.52 THz的宽带、均匀分束。Objective The special wavelength position of terahertz waves makes them the link between microphotonics and macroscopic electronics.However,the terahertz wave transmission in free space is easily affected by the water vapor absorption in the air.The optical fiber structure is proposed to transmit terahertz waves and realize effective transmission control.Among them,the hollow-core THz fiber based on the anti-resonant principle can limit the wave transmission in the air fiber core,which greatly reduces the influence of material absorption.The optical fiber coupler is the key device for beam splitting and transmission tailoring.Due to the existence of absorption loss in THz fiber,the insertion losses of THz fiber couplers are usually large and affect their utilization.Although the transmission loss of THz fibers with hollow-core structures is low,the design of THz couplers with broadband beam splitting is generally difficult.Methods We propose a hollow-core anti-resonant fiber coupler based on the three-core symmetry structure.By employing its structure symmetry,broadband beam splitting can be realized,and the transmission loss of the coupler can be reduced via the hollow-core structure.The mode and coupling characteristics of the coupler are analyzed by the finite element method,and the relationship between the coupling length and the fiber structure parameters is verified.The mode loss characteristics of the coupler are analyzed,and then the beam splitting structure with low loss and wide bandwidth is obtained.Results and Discussions We design a hollow-core three-core anti-resonant fiber.At the frequency of 1 THz,the coupling length increases with the rising core distance(Fig.4).As can be seen from the relation curve between D1 and binding loss,since the even mode field expands more to the intermediate core,the increase in D1 leads to the growing mode field,and the improvement in the binding ability of the core reduces the binding loss,while the odd mode is less affected by D1[Fig.5(a)].With the increasing D1,the

关 键 词：光学器件 空芯太赫兹光纤 反谐振 模式耦合 损耗特性 带宽分析 

分 类 号：TN253[电子电信—物理电子学]