Strongly anisotropic media: the THz perspectives of left-handed   materials
  We demonstrate that non-magnetic ($\mu \equiv 1$) left-handed materials can be effectively used for waveguide imaging systems. We also propose a specific THz realization of the non-magnetic left-handed material based on homogeneous, naturally-occurring media. 
Viktor A. Podolskiy, Leo Alekseev, Evgenii E. Narimanov