High quality factor, monodisperse micron-sized random lasers based on porous PLGA spheres

Miniature random lasers with high quality factor are crucial for applications in barcoding, bioimaging, and on-chip technologies. However, achieving monodisperse and size-tunable biocompatible random lasers has been a significant challenge. In this study, we employed poly(lactic-co-glycolic) acid (PLGA), a biocompatible material approved for medical use, as the base material for random lasers. By integrating a dye-doped PLGA solution with a microfluidic system, we successfully fabricated monodisperse and miniature dye-doped PLGA spheres with tunable sizes ranging from 25 to 52 µm. Upon optical pulse excitation, these spheres exhibited strong random lasing emission at 610-640 nm with a threshold of approximately 22 µJ·mm^-2. The lasing modes demonstrated a spectral linewidth of 0.2 nm, corresponding to a quality factor of 3100. Fourier transform analysis of the lasing emission revealed fundamental cavity lengths, providing insights into the properties of the random lasers.