Engineering a light–matter strong coupling regime in perovskite-based plasmonic metasurface: quasi-bound state in the continuum and exceptional points

Abstract

We present theoretically the formation of exciton-photon polaritons and exciton-surface plasmon polaritons in perovskite-based subwavelength lattice on metallic plane. It is showed that the later polaritons will be achieved as the perovskite layer is ultra thin (<50nm) while the co-existence of both polaritons will dominate as the thickness of the perovskite metasurface approaches wavelength-scale. In the two cases, the lower polaritonic branches consist of dark and bright modes corresponding to infinite and finite radiative quality factor, respectively. Another salient property in this work is that it allows one to obtain exceptional points (EPs) in momentum space with a four-fold enhancement of local density of states through engineering the perovskite metasurface. Our findings show that perovskite metasurface is an attractive and rich platform to make polaritonic devices, even with the presence of lossy metallic layer.