Investigation of interface states in single-negative metamaterial layered structures based on the phase properties

The physical mechanism of the interface states in layered structures consisting of single-negative metamaterials is investigated using a simple resonant cavity model. We found that the interface states and their corresponding tunneling transmission modes appeared when the resonant condition is satisfied. Such resonant condition depends on the phase changes inside the resonant cavity. Based on these results, we proposed an efficient method to precisely predict the frequencies of the tunneling interface states inside the single-negative metamaterial layers. Our method is effective for interface states corresponding to perfect or imperfect tunneling transmission. Composite right/left-handed transmission lines were used to realize the pair and sandwich metamaterial layered structures in the microwave region. Electromagnetic tunneling interface states were observed in the measurements, which agreed well with the theory. Our study offers a way for effectively designing metamaterial devices with novel electromagnetic tunneling properties.