Whispering Gallery Mode Lasing from Perovskite Polygonal Microcavities via Femtosecond Laser Direct Writing

Organic–inorganic halide perovskites have excellent intrinsic properties, such as long carrier lifetime, high photoluminescence quantum yield, and high gain, in whispering gallery mode (WGM) cavities by facile vapor self-assembly or solution process, which make them competitive for high-performance microlasers. However, the performance of perovskite-based microlasers is severely limited by the fabrication of microcavities, which results in poor reproducibility and uncontrolled morphology. Herein, we explore a reproducible method which combined thermal co-evaporation with femtosecond (fs) laser direct writing for formamidinium lead iodide (FAPbI3) perovskite polygon-shaped WGM microcavities. The microlasers pumped with the fs laser had a low threshold of 4.0–12.3 μJ/cm2 and narrow full width at half-maximum of 0.62–1.05 nm. Moreover, size- and shape-dependent WGM lasing performances are also investigated systematically. The results prove that FAPbI3 polygonal microcavities can serve as promising WGM lasers and have great potential for practical optoelectronic applications.