Mie Exciton-Polariton in a Perovskite Metasurface

Exciton-polariton arising from strong light-matter interaction between exciton and optical cavity has attracted considerable attention due to its potential applications in Bose-Einstein condensation, lowthreshold lasing, and slow light. In recent years, two-dimensional lead halide perovskite has emerged as an ideal candidate for realizing exciton polariton at room temperature because it has large exciton binding energy and quantum yield. Here, we demonstrate that strong coupling could be enabled with a perovskite metasurface that supports multipolar Mie resonance, including magnetic quadrupole dominant, anapole, and toroidal resonances. For an array of perovskite nanodisks, the strong coupling behavior between these resonances and exciton is confirmed by the anticrossing features in absorption spectra mapping, while the Rabi splitting is increased from 230.7 meV in magnetic quadrupole-exciton strong coupling to 253 meV in both anapole-exciton and toroidal-exciton strong coupling. The enhanced Rabi splitting is attributed to the stronger field localization within the perovskite instead of within the air gap. In addition, we find that the Rabi splitting depends on the oscillatory strength of the exciton mode and can then be boosted to 362 meV in anapole-exciton strong coupling. Our results provide promising ways to improve the performance of optoelectronic devices such as low-threshold lasers and slow-light devices.