Electron-Hole Plasma Lasing Dynamics in CsPbCl_mBr_3-mMicroplate Lasers

Despite many successful realizations of laser operations in various micro/nanostructured lead halide perovskites (LHPs), the electron-hole plasma (EHP) lasing dynamics has only rarely been reported, especially for wide-gap Cl-rich perovskites. In this work, the temporal lasing dynamics of whispering gallery mode (WGM) CsPbClmBr3-m microplate lasers are systematically investigated, for the first time, with a streak camera system. As the pump fluence increases, the gain profile exhibits a monotonous redshift, indicating the EHP lasing in the microplate cavity, while an opposite shift of the gain region is observed with time decay due to the gradual depletion of carriers. This directly reflects the change of the bandgap renormalization effect at varying pump fluences. Additionally, the individual lasing modes present identifiable blueshifts with elevated pump levels and redshifts with time delay, which can be unraveled by the carrier-induced refractive index change in the LHP cavity. Moreover, the wavelength-dependent lasing duration demonstrates that lasing in the EHP regime depends not only on the carrier density, but also on the bandgap variation with carrier density. By directly modulating the pump fluence, the onset delay of the microlaser can be efficiently tuned. Our results provide a comprehensive understanding of the EHP lasing mechanism and carrier dynamics in the WGM LHP micro/nanolasers and will push their technological relevance in integrated photonics.