环形中空光子晶体光纤用于多阶涡旋光传输  

Annular and Hollow-Core Photonic Crystal Fiber for Propagation of Multi-Order V orticity

作　　者：靳晓玲 王有为 孙兵 张祖兴 陈明阳[2] Jin Xiaoling;Wang Youweil;Sun Bingl;Zhang Zuxing;Chen Mingyang(Institute of Advanced Photonic Technology,College of Electromic and Optical Engineering&College of Microelectronics,Nanjing University of Posts and Telecommunications,Nanjing,Jiangsu 210023,China;School of Mechanical Engineering,Jiangsu University,Zhenjiang,Jiangsu 212013,China)

机构地区：[1]南京邮电大学电子与光学工程学院、微电子学院先进光子技术研究所,江苏南京210023 [2]江苏大学机械工程学院,江苏镇江212013

出　　处：《中国激光》2021年第11期123-130,共8页Chinese Journal of Lasers

基　　金：国家重点研发计划(2017YFC0306100);中国博士后创新人才支持计划(BX201600077,2017M611877);南京邮电大学1311人才计划。

摘　　要：根据光子晶体光纤多孔等特性,提出--种涡旋光传输的环形中空光子晶体光纤设计方案。利用有限元法对环形光纤结构参数进行优化设计,并分析光纤中多阶涡旋光的传输特性。具体分析结果表明,当光纤中心孔直径取5.6μm,第一层空气孔直径取2.67μm,最外层空气孔的直径取2.87μm,孔间距取3.09μm,在1.3~2μm波段内,同一矢量模式组对应的HE模和EH模之间的有效折射率差最小超过3.04×10^(-3),最大达到了1.55×10^(-2),并且能应用于光纤较小弯曲情形(弯曲半径可以低至18mm)。该光子晶体光纤能实现涡旋光模式稳定传输,为今后进一步研究并应用涡旋光奠定了良好的基础。Objective Orbital angular momentum (OAM)beams have recently spurred great interest because they are widely applicable to optical manipulation,quantum information,imaging,and communications.The four states of the OAMl,mmode family have been already demonstrated in multiple-input multiple-output(MIMO)-free transmission.When using the four states of a LPl,m mode (l≥1)in an optical fiber with circular symmetry,4×4 MIMO processing is necessary.As N×N MIMO complexity scales with N2,OAM modes are preferred in communication systems for mobile device management.However,the effective refractive index differenceΔneffbetween the HE(l+1)m and EH(l-1)m modes should be below 10-4 to minimize coupling between the OAM modes.Ring-core geometry,usually with a high-index contrast,is well adaptable to the guidance of OAM modes because it can eliminate the undesirable modes (m=2)and reaches a sufficiently large intra-mode-group OAMΔneff value.Moreover,avoiding the higher-order OAM modes (m≥2)simplifies the multiplexing-demultiplexing of the modes because all OAM modes present an annular-shaped intensity.Methods Photonic crystal fibers (PCFs)can be flexibly designed to provide unique fiber properties such as endlessly single mode,controllable nonlinearity and confinement loss,and tailorable chromatic dispersion.The PCF structure that realizes OAM-mode transmission is potentially applicable to fiber communications.Although air-silica PCFs achieving high index contrast,OAM-dedicated PCFs are not yet realized,and an OAM with l=1guidance in a PCF has been reported only in twisted PCFs.This study evaluates the potential of a new ring-core PCF designed for guiding OAM modes with low mode coupling.Such a geometry appears to be easily manufactured by the stack-and-draw method.Results and Discussions In the proposed structure[Fig.1(a)],the solid ring core is installed in a central hole surrounded by a circular ring of air holes in the cladding structure.This structure is prolongated by several rings of air holes with hexagonal symmetry.

关 键 词：光纤光学 光子晶体光纤 涡旋光 矢量模式 弯曲损耗 

分 类 号：TN253[电子电信—物理电子学]