手征媒质平板波导的传播特性

Propagation characteristics of the planar waveguide with chiral core

在求解Ｍａｘｗｅｌ方程的基础上，分析了芯区为手征介质对称平板波导的色散特性。给出了两种色散方程并研究了该波导各模式截止频率与芯区手征导纳的关系。由于手征导纳的引入，同阶模式的截止频率分离，其中右旋椭圆偏振（ＨＲ）分支的截止频率随手征导纳的增大而增大，左旋椭圆偏振（ＨＬ）分支的截止频率则减小。当手征导纳大于某一值时，ＨＲ分支的截止频率为无穷大即此分支不再存在，只有ＨＬ分支传导，模式色散曲线与普通平板波导相似。此时，偶模截止频率为零的模式只有一个，即存在单模工作区。

The characteristics of symmetric planar waveguide with chiral core are analyzed based on the Maxwell's equations. Two kinds of dispersion equations are given and the relation between the cutoff frequency and core chiral admittance is studied. Due to the introduction of the chirality, the cutoff frequency for the same order modes separates, cutoff frequency of HR branch (right elliptically polarized waves) increases with chiral admittance, but that of HL (left elliptically polarized waves) branchdecreases. When the chiral admittance exceeds a certain value, the cutoff frequency of HR branch is infinite, i.e., this branch becomes radiated mode, only HL branch can be guided, the dispersion curve is like that of the general waveguide. And there is only one even mode having zero cutoff frequency, i.e., there is a single mode area.