Theory on coherent perfect absorber and laser via a metamaterial slab with complex parameters

Abstract

We explicitly derive the general conditions of a metamaterial slab to achieve coherent perfect absorber (CPA) and laser under the excitation of two counter-propagating incident waves. Our results provide a unified theory that could be applied in designing homogenous metamaterial with complex parameters for realizing CPAs and lasers. Especially, the theory discusses two special cases, i.e., case 1) a metamaterial slab with complex permittivity and real permeability, or complex permeability and real permittivity, and case 2) a metamaterial slab with both complex permittivity and permeability, which encompass the entire range of metamaterials with complex parameters. For both cases, our theory accurately derives the required parameters of the metamaterial for CPA, laser and their coexistence, as validated by numerical simulations. Our work serves as a guide for designing CPAs and lasers via general metamaterial slabs of complex parameters.