Strong Coupling of Exciton and High‐Q Mode in All‐Perovskite Metasurfaces

Abstract

Recently developed halide perovskite semiconductors are viewed as an excellent platform to realize exciton‐polariton at room temperature due to their large oscillation strength. Here, the optimized strong coupling between the exciton of perovskite and quasi‐bound state in the continuum (QBIC) with high‐quality factor (Q‐factor), supported by all‐perovskite metagrating, including magnetic dipole (MD)‐QBIC and toroidal dipole (TD)‐QBIC is demonstrated. By taking advantage of extreme electric field confinement enabled by a high‐Q mode, it is found that the maximum Rabi splitting can be enhanced up to a record high value of 400 meV, almost twice the Rabi splitting reported in the same perovskite‐based subwavelength metasurface. The simulation results reveal that both the Q‐factor of QBIC mode and the thickness of the perovskite metasurface play dominant roles in the enhanced strong coupling. It is also demonstrated that adding a protection layer of poly(methyl methacrylate) on the top of the perovskite metagrating has a negligible effect on the maximized Rabi‐splitting. These results suggest a new approach for studying exciton‐polaritons and may pave the way toward flexible, large‐scale, and low‐cost integrated polaritonic devices and the realization of polariton lasing at room temperature.

Topological Control of 2D Perovskite Emission in the Strong Coupling Regime

“…85 Theoretical studies on polaritonic BICs in the perovskite platform were also reported recently. 86,87 In conclusion, we demonstrated topological polarization singularities in polariton emission. The polarization vortices (in circular patterns) and CP eigenstates (in symmetry-broken patterns) were measured by the Stokes parameter measurements of PL in momentum space.…”

“…The Bose–Einstein condensation was demonstrated at low temperature using polariton BICs, and a polarization vortex in the perovskite metasurface was observed at room temperature . Theoretical studies on polaritonic BICs in the perovskite platform were also reported recently. , …”

Realization of Polaritonic Topological Charge at Room Temperature Using Polariton Bound States in the Continuum from Perovskite Metasurface

“…While most of the milestones of polaritonic physics have been achieved with excitonic materials operating at cryogenic temperatures (≈10 K), recent progress in materials science has promoted many polaritonic demonstrations at room temperature with a wide variety of high bandgap semiconductors, ranging from GaN, [24,25] ZnO, [26] to organic semiconductors, [27,28] and transition metal dichalcogenide monolayers, [29,30] as well as perovskite materials. [31][32][33][34][35][36][37][38][39][40][41] Very recently, the strong coupling regime between photonic BICs and excitonic resonances has been theoretically suggested, [42][43][44][45] with two experimental demonstrations. [46,47] The result of such a coupling is the formation of polariton-BICs (pol-BICs): hybrid excitations that are completely decoupled from the radiative continuum.…”

“…[38] Most recently, it has been theoretically suggested that perovskite metasurfaces can be harnessed to engineer the imaginary part (i.e., losses) of the polaritonic energy-momentum dispersion at room temperature via BIC and exceptional point concepts. [43,45] On the other hand, purely photonic BICs in perovskite-based resonant metasurface have been reported to make ultra-fast switches [7] and tunable microlasers. [49] In this work, we experimentally demonstrate the formation of pol-BICs in an excitonic metasurface made from hybrid 2D perovskites.…”

Strong coupling of excitons in patterned few-layer WS2 with guided mode and bound state in the continuum

“…1,21 Later on, multilayer microcavity schemes with some large binding energy materials were used to obtain hybrid exciton-polariton, [22][23][24][25][26][27] but these were limited by the difficulty of fabrication. Very recently, thanks to the incorporation of lead halide perovskites [28][29][30][31][32] and two-dimensional materials, [33][34][35][36][37][38][39] the disadvantages faced previously have been swept away, which paves the way for the realization of exciton-polariton through strong coupling with specially designed photonic structures at room temperature.…”