Backward waves and negative refraction in uniaxial dielectrics with negative dielectric permittivity along the anisotropy axis

Veselago medium (also called double negative material, backward medium, left‐handed medium) is a medium with both negative isotropic dielectric permittivity and permeability. It has the effect of backward waves with negative (anomalous) refraction, in contrast to the usual forward waves with normal refraction in normal isotropic dielectrics and/or magnetics. In this paper, examples of the existence of backward waves (with respect to the interface) without negative refraction, and negative refraction without backward waves in uniaxial dielectrics with negative permittivity along the anisotropy axis, are presented. Considering these examples increases the possibility of designing backward wave materials and negative refraction materials without using magnetic media.