High-Q whispering gallery lasing from ZnO microcavities coated with a CsPbBr₃ perovskite film

Metal halide perovskites are exceptional gain media, yet practical perovskite lasers are hindered by the challenge of forming high-quality optical cavities without degrading the soft ionic lattice. Here, we demonstrate a hybrid lasing platform that circumvents this limitation by decoupling the cavity from the gain medium. We coated hydrothermal ZnO hexagonal microdisks possessing atomically smooth facets and a high refractive index with a thin 90 nm polycrystalline CsPbBr₃ film. Under femtosecond optical pumping, the hybrid structure exhibited robust whispering gallery mode lasing near 537 nm with a quality factor exceeding 10³ and a threshold of 140 µJ cm^-2. The emission was characterized by a clear threshold kink in the input-output curve and concomitant linewidth narrowing from 20 nm to below 1 nm. Numerical simulations confirmed that the lasing modes originated from the ZnO cavity and revealed that the cavity height critically governed vertical confinement, with a predicted optimal Q-factor of 1800. This technologically feasible, damage-free and scalable architecture separated photonic confinement from material gain, offering a route toward integrated perovskite coherent light sources.