Effect of carrier dynamics on mode shift in the ultrafast timescale of perovskite microlasers

In semiconductor-based microlasers, the lasing performance and device properties are closely related to the behavior of the excited carriers. Comprehending their laser mechanisms and controlling laser behavior on ultrafast timescales is crucial. This paper employs a microscopic optical Kerr-gate method to investigate the lasing dynamic in a composite perovskite micro/nanostructure. The results show that the laser dynamics are influenced by bandgap renormalization and band-filling (BF) effects. At lower levels of pump fluence, the energy transfer process has the potential to impact the refractive index, resulting in a negligible transient mode shift. At higher levels of pump fluence, the observed extension of the stimulated radiation lifetime indicates the involvement of the hot carrier cooling process in laser emission. This mechanism facilitates the modulation of energy level occupancy states, resulting in a stable resonance wavelength during the initial few picoseconds. As the hot carriers cool, the BF effect can induce a notable change in the refractive index, leading to a redshift in the resonant modes. This study can offer insights into the lasing behavior driven by carrier dynamics and provide a promising strategy to regulate lasing performance in microcavity at ultrafast timescale.