Ultra-fast photoluminescence dynamics process based on CsPbBr₃ perovskite microspheres

Perovskite materials have demonstrated significant application potential in micro-/nano-scale light sources due to their excellent optoelectronic properties. Optical microcavities can enhance light-matter interaction, resulting in strong and ultrafast stimulated emission. However, temporal control of stimulated emission remains underexplored. In this work, we investigate the ultrafast photoluminescence dynamics of CsPbBr₃ perovskite microspheres and reveal a clear dependence of the strongest stimulated photoluminescence timing on the excitation intensity. Using a streak camera, we directly observe that increasing the pump fluence can either advance or delay the strongest stimulated photoluminescence emission by several picoseconds. A simplified rate equation model is employed to interpret this tunability in terms of the interplay between carrier density, optical gain, and microcavity mode shifts. These findings demonstrate a practical and precise method for modulating ultrafast light pulses through excitation intensity, offering possibilities for the design of compact optical modulators and high-speed photonic devices.