Active metamaterials: Sign of refractive index and gain-assisted dispersion management
Active metamaterials: Sign of refractive index and gain-assisted dispersion management
We derive an approach to determine the causal direction of wavevectors of modes in optical metamaterials, which, in turn, determines signs of refractive index and impedance as a function of real and imaginary parts of dielectric permittivity and magnetic permeability. We use the developed technique to demonstrate that the interplay …