Negative refraction in multilayered metal-dielectric metamaterials with ellipse-like isofrequence surfaces

Abstract

Negative refraction in multilayered metal-dielectric metamaterials is usually based on negative refractive indices or hyperbolic-like isofrequency surfaces. In this study, we reveal that ellipse-like isofrequency surfaces can also lead to negative refraction. This phenomenon is theoretically demonstrated by analyzing the group velocities of refracted beams based on the exact transfer-matrix method and verified by numerical simulation based on the finite-element method. The corresponding physics mechanism is investigated through the energy flow of the ellipse-like modes in the metallic and dielectric layers. The results are also compared with the case of energy flow of hyperbolic-like modes. Moreover, negative double refraction is realized because negatively refracted beams can be enabled by ellipse-like and hyperbolic-like isofrequency surfaces simultaneously.