Fluorescence seeding of weaker-gain Raman modes in microdroplets: enhancement of stimulated Raman scattering.

Fluorescence seeding by dissolving a fluorescent dye in a liquid droplet enhances the stimulated Raman scattering of a weaker-gain Raman mode. With the dye fluorescence at the Stokes wavelength of the weaker-gain Raman mode, the weaker-gain Raman mode can now build up from the much stronger fluorescence instead of from the weaker spontaneous Raman scattering. With fluorescence seeding, the weaker-gain C-C-O Raman mode of ethanol can be observed at a much lower input-laser intensity and can be more intense than the stronger-gain C-H Raman mode.