Electromagnetic modes in a three-layered structure made of single-negative materials
三层单负材料结构中电磁波模分析

The modes in a three-layered structure made of single-negative materials have been investigated. For the propagation mode, the tunneling mode can be formed in the structure. When tunneling mode appears the variations of electric field distribution and the transmission with incident angle are studied. We find that there appear two new localized modes when the thickness of the middle layer changes. The frequency interval of the two localized modes can be increased by decreasing the thickness of the middle layer. For the guided mode, the electromagnetic wave is evanescent in semi-infinite vacuum which is on the both sides of the structure. We have analyzed the existence condition of its electromagnetic mode,that is, the dispersion relation. The result shows that a strong local field appears in the interface of the material.