中文摘要：

对纤芯为左手材料，内包层和外包层都为右手材料的双包层光纤进行了分析．在弱导情况下，且不考虑介质损耗，由亥姆霍兹方程出发，得到了HE、EH、TE和TM导模的色散方程，并在远离截止条件下，对其进行简化．所有的TE和TM模都是简并的．分别讨论了内包层折射率和厚度对该左手材料光纤最低阶导模的影响，画出了各自的色散曲线，并和右手材料光纤导模相应色散曲线进行了比较，发现左手材料光纤的低阶导模具有反常的色散特性．

英文摘要：

A doubly clad fiber with right-handed material inner and outer cladding, but left-handed material core is analyzed in weakly guiding approximation. Suppose a lossless fiber, the characteristic equations for four kinds HE,EH,TE and TM guided modes are derived and further simplified under far from cutoff condition. Dispersion curves for the lowest order mode of the every four kind modes are calculated for different inner cladding refractive index and thickness. Compared with corresponding curves for a common right-handed doubly clad fiber. It indicates that these curves show abnormal dispersions.