Electromagnetic waves and the realization of negative refraction in gyrotropic chiral medium

The behavior of wave propagation, the possibility of backward eigenwaves, the realization of negative refractive index, and the impedance of the eigenmodes of gyrotropic chiral media axe examined in detail. Since the gyrotropic parameters in the permittivity and permeability tensors favor the realization of the negative refraction in gyrotropic chiral medium, the negative-index media (NIM) can be achieved far off the resonances of the permittivity and permeability. From those wavenumbers obtained, we find that two of them are backward propagating waves at certain frequency bands. The helicity and polaxization states are shown. We further study the impedance of the backward eigenmodes with potential applications in impedance matching for perfect lenses and high-directivity antennas. Due to the off-diagonal gyrotropic parameters, the negative refractive index can be achieved when the material parameters and frequency are properly chosen.