Superluminal group velocity in an anisotropic metamaterial

Based on boundary condition and hyperbolic dispersion relation, the superluminal group velocity in an anisotropic metamaterial (AMM) is investigated. The superluminal propagation is induced by the hyperbolic dispersion relation associated with the anisotropic AMM. It shown that a modulated Gaussian beam undergoes superluminal group velocity which depends on the choice of incident and optical axis angles. The superluminal prpagation does not violate the theory of special relativity because the group velocity is the velocity of the peak of the localized wave packet which does not carry information. It shown that an triglycine sulfate (TGS) crystal can be designed and the superluminal group velocity can be measured experimentally.