We investigate a unique type of zero-index medium with both gain and loss (ZIMGL), whose effective permittivity and permeability are both purely imaginary but of opposite signs. We analytically show that, by using a slab of ZIMGL with equal magnitude of loss and gain, simulation realization of a coherent perfect absorber (CPA) and laser, i.e., the so-called CPA laser, can be achieved. Previously the CPA laser was proposed in parity-time (PT) symmetric systems. However, the ZIMGL does not possess the PT symmetry and thus the underlying physics is distinctly different. By designing a photonic crystal (PC) composed of core-shell rods, with loss and gain distributed in either the core or the shell, we have realized such a ZIMGL. The CPA-laser functionality of such a PC is also confirmed in our numerical simulations. Our work provides a different approach for simultaneous realization of CPA and laser besides PT-symmetric systems.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by the State Key Program for Basic Research of China (Grants No. 2014CB360505 and No. 2012CB921501), National Natural Science Foundation of China (Grants No. 11374224 and No. 61671314), King Abdullah University of Science and Technology, a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), and the Hong Kong Research Grants Council (Grant No. AoE/P-02/12).