Room-Temperature Exceptional-Point-Driven Polariton Lasing from Perovskite Metasurface

摘要

Excitons in lead bromide perovskites exhibit high binding energy and highoscillator strength, allowing for a strong light-matter coupling regime inthe perovskite-based cavities localizing photons at the nanoscale. Thisopens up the way for the realization of exciton-polariton Bose–Einsteincondensation and polariton lasing at room temperature – the inversionfreelow-threshold stimulated emission. However, polariton lasing inperovskite planar photon cavities without Bragg mirrors has not yet beenobserved and proved experimentally. In this study, perovskite metasurfaceis employed, fabricated with nanoimprint lithography, supporting so-calledexceptional points to demonstrate the room-temperature polariton lasing.The exceptional points in exciton-polariton dispersion of the metasurfaceappear upon optically pumping in the nonlinear regime in the spectralvicinity of a symmetry-protected bound state in the continuum providinghigh mode confinement with the enhanced local density of states beneficialfor polariton condensation. The observed lasing emission possesseshigh directivity with a divergence angle of 1° over one axis. The employednanoimprinting approach for solution-processable large-scale polaritonlasers is compatible with various planar photonic platforms suitable foron-chip integration.