Raman lasing near 630 nm from stationary glycerol-water microdroplets on a superhydrophobic surface

Abstract

We demonstrate, for the first time to our knowledge, Raman lasing from stationary microdroplets on a superhydrophobic surface. In the experiments, glycerol-water microdroplets with radii in the 11-15 mu m range were pumped at 532 nm with a pulsed, frequency-doubled Nd:YAG laser. Two distinct operation regimes of the microdroplets were observed: cavity-enhanced Raman scattering and Raman lasing. In the latter case, the Raman lasing signal was higher than the background by more than 30 dB. Investigation of the Raman spectra of various glycerol-water mixtures indicates that lasing occurs within the glycerol Raman band. Raman lasing was not sustained; rather, oscillation would occur in temporally separated bursts. Increasing the rate of convective cooling by nitrogen purging improved the lasing performance and reduced the average interburst separation from 2.3 to 0.4 s.