Coherent perfect absorption and laser modes in a cylindrical structure of conjugate metamaterials

In this work, we theoretically find that coherent perfect absorption (CPA) and lasermodes can be realized in a two-dimensional cylindrical structure composed of conjugatemetamaterials (CMs). The required phase factors of CMs for achieving CPA and lasermodes are determined by the geometric size of theCMcylinder, which is a unique feature comparedwith other non-Hermitian optical systems. Based on this property, we also demonstrate that CPA and lasermodes can exist simultaneously in aCMcylinder with an extremely large size, where the excitations of CPA and laser modes depend on the angularmomentumof coherent incident light. Therefore, comparedwith the well knownparity time symmetry, ourwork opens up a brand-new path to obtainingCPA and laser modes, and is a significant advance in non-Hermitian optical systems.