对称单负介质包层平面波导的模式特征

系统研究了负μ材料(MNG)作为包层的对称三层平板波导的传输特性. 研究发现，这种波导既支持快波的传播，又支持TE₀，TE₁模式的慢波传输. 其模式特性不同于左手介质波导和传统介质波导，导模存在的模折射率范围要比它们的大. MNG波导的TE₀快波模缺失，且TE_m模(m>1)的传播常数大于TM_m模的传播常数. TE_m模具有双模特征，且与波导的结构参数密切相关，导致波导中的净能流出现负值. 关键词： 单负介质 平板波导 快波与慢波 传播常数

The mode characteristics of a symmetrical slab waveguide with single-negative-material cladding

The propagating characteristics of a symmetrical three-layer slab waveguide with mu-negative (MNG) media are studied in detail. It is found the MNG waveguide can propagate not only quick waves but also slow waves of TE₀ and TE₁ modes. The properties of this guided mode are different from those of the left-handed waveguide and the conventional waveguide. In MNG slab waveguide, the region of effective refractive index of the guided mode is wider than those of the other two. In addition, the TE₀ fundamental guided mode does not exist at all, while the higher-order TE guided modes and all TM guided modes do exist. However the surface wave of TE₀ and TE₁ modes can emerge under a certain condition. The propagation constant of higher-order TE mode is greater than that of the TM mode of the same order. Two TE modes of the same order can coexist in the MNG, which is closely related to the structural parameters. The energy fluxes of two TE modes are oppositely directed inside and outside the inner layer, therefore the total energy flux can be negative.