Simulations and realizations of active right-handed metamaterials with negative refractive index

The theory of determining the sign of the refractive index in active materials is discussed. Animations of numerical simulations are presented, supporting the claim that negative refractive index may occur in right-handed media. An example of such a medium, in the form of a lumped circuit model with active and passive resonances, is presented. (c) 2007 Optical Society of America.