Loss-induced omnidirectional bending to the normal in ϵ-near-zero metamaterials.

Contrary to conventional wisdom that light bends away from the normal when it passes from high to low refractive index media, here we demonstrate an exotic phenomenon that the direction of electromagnetic power can bend toward the normal when light is incident from an arbitrary high refractive index medium (or air) to a ϵ-near-zero (ENZ) metamaterial. Moreover, the direction of the transmission is close to the normal for all angles of incidence. This anti-Snell's law refraction results from the interplay between ENZ and material loss. The loss can increase the transmission at the air-ENZ interface and collimate the beam inside the ENZ medium. Furthermore, in an ideal loss configuration, the propagation loss in anisotropic ENZ materials can approach zero when the material loss goes to infinity.