Mode Selection of High-Quality Microlasers in Thermally Evaporated Perovskite Films by Femtosecond Laser Direct Writing

Halide perovskites have garnered significant attention in the laser field for their exceptional optical gain properties. However, the fabrication of high-quality perovskite micronano lasers with excellent reproducibility and controllability remains a critical challenge, impeding the practical application of perovskite-based lasers. Here, we demonstrate high-performance whispering gallery mode (WGM) lasers by combining femtosecond laser direct writing (FLDW) with thermally evaporated CsPbBr 3 perovskite films. The films exhibited a high net optical gain (1609 cm –1 ) and a long gain lifetime of 239 ps, which facilitated the population inversion; thus, a low-threshold random laser is achieved. The excellent radiative emission and suppressed Auger loss further prompted the lasing behaviors of the perovskite WGM microcavities. A single-mode perovskite WGM laser with a low threshold (6.82 μJ/cm 2 ) and narrow linewidth (0.22 nm) is repeatedly prepared using FLDW. Especially, the degree of polarization of the WGM lasing is as high as 96.12%, among the highest values. Furthermore, benefiting from the high controllability, precise size control can facilitate the regulation of the laser threshold and mode characteristics. This study demonstrates that the application between FLDW and a commercially compatible thermal evaporation process in perovskite micronano lasers will significantly accelerate the integration and reproducibility process of perovskite optoelectronic devices.