Quasi-bound states in the continuum for electromagnetic induced transparency and strong excitonic coupling
Hodjat Hajian, Xia Zhang, O. McCormack, Yongliang Zhang, Jack Dobie, Ivan D. Rukhlenko, Ekmel Özbay, A. Louise Bradley
Abstract
Advancing on previous reports, we utilize quasi-bound states in the continuum (q-BICs) supported by a metasurface of TiO 2 meta-atoms with broken inversion symmetry on an SiO 2 substrate, for two possible applications. Firstly, we demonstrate that by tuning the metasurface's asymmetric parameter, a spectral overlap between a broad q-BIC and a narrow magnetic dipole resonance is achieved, yielding an electromagnetic induced transparency analogue with a 50 μs group delay. Secondly, we have found that, due to the strong coupling between the q-BIC and WS 2 exciton at room temperature and normal incidence, by integrating a single layer of WS 2 to the metasurface, a 37.9 meV Rabi splitting in the absorptance spectrum with 50% absorption efficiency is obtained. These findings promise feasible two-port devices for visible range slow-light characteristics or nanoscale excitonic coupling.