Two-photon pumped lasing from methanol micro-droplets doped by a weakly fluorescent dye

We report lasing induced by two-photon absorption (TPA) from micro-droplets of a weakly fluorescent dye (DASPI) doped in methanol. Dye-doped methanol droplets, of uniform diameter of 20 μm, are generated using a piezo-driven capillary. The droplet size is determined by a direct imaging technique as well as from peak separations of lasing (morphology dependent resonances – MDRs) spectra. The threshold for TPA-induced lasing of droplets with 0.01 M concentration of the dye is determined to be about 0.4 GW cm−2. The lasing spectral emission from the micro-droplets exhibits well-resolved structure that is related to the MDR.