Novel Lasing Modes Observed in a Levitated Single Dye-Doped Microdroplet

Novel modes of laser emission from levitated microdroplets have been observed. A single dye-doped glycerol droplet of micrometer size was confined in an ion trap and irradiated by a pulsed or a cw green laser. Photographic images of the emitting droplet and emission spectra were simultaneously recorded and compared each other for various intensities of the exciting laser. Both the images and the spectra obtained from the strongly excited droplet have no resemblance to those from the weakly excited one. With stronger excitation, lasing action was found to occur in the droplet in specific surface azimuthal modes. Relations between lasing modes and spectra are discussed.