“Reporting on the latest advancements in optoelectronics, researchers have synthesized formamidinium lead bromide (FAPbBr3) nanocrystals (NCs) with varying sizes using ligand-assisted precipitation (LARP) technology at room temperature. These NCs exhibit pure green emission, excellent stability, and superior carrier transport characteristics. Through photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectroscopy, they characterized the amplified spontaneous emission (ASE) properties. Nonlinear optical properties were studied using the Z-scan technique and two-photon excited fluorescence method. The FAPbBr3 NCs demonstrated one- and two-photon pumped ASE with low thresholds, showcasing potential as a green-emitting frequency-upconversion material for high-performance two-photon pump lasers.”