Lasing emission from an evaporating layered microdroplet

We report the first observations, to our knowledge, of lasing emission from a single, evaporating, layered, micrometer-sized droplet. The droplet consists of an ~7.9-microm-radius glass core covered by a liquid shell of an initial 3 x 10(-4) M Rhodamine 6G dye-doped glycerin/water solution. After pumping by a doubled (532 nm) Nd:YAG pulsed laser, droplet lasing occurs over a range of shell thicknesses from ~14.5 to ~0.4 microm. At the smallest shell thickness, a dramatic increase in both the number and intensity of the lasing peaks occurs, in addition to a large (>40-nm) blue shift in the spectral bandwidth of lasing emission. A discussion of possible enhancement mechanisms responsible for these novel findings is given.