Coherent perfect absorber and laser in purely imaginary conjugate metamaterials (1708.02004v1)

Abstract: Conjugate metamaterials, in which the permittivity and the permeability are complex conjugates of each other, possess the elements of loss and gain simultaneously. By employing a conjugate metamaterial with a purely imaginary form, we propose a mechanism for realizing both coherent perfect absorber (CPA) and laser modes, which have been widely investigated in parity-time symmetric systems. Moreover, the general conditions for obtaining CPA and laser modes, including obtaining them simultaneously, are revealed by analyzing the wave scattering properties of a slab made of purely imaginary conjugate metamaterials. Specifically, in a purely imaginary conjugate metamaterial slab with a sub-unity effective refractive index, perfect absorption can be realized for the incident wave from air.