Abstract

A microdroplet acts as a lens to enhance the internal intensity of the input laser and as in. optical cavity to provide, feedback for the growth of nonlinear optical processes at specific wavelengths corresponding to the cavity modes, commonly referred to as morphology-dependent resonances (MDR’s) of the droplet. Stimulated Raman scattering (SRS) of various liquids has been observed in micrometer-sized droplet.¹The SRS gain is G_srs = g_R I_in, where I_in, is the input-laser intensity. The SRS intensity increases exponentially with I_in. until saturation. Lasing in water or ethanol microdroplets containing 10^-4 to 10^-5 M rhodamine 6G has also been observed. The lasing spectrum consists of one or more sets of evenly spaced peaks corresponding to the MDR’s of the droplet. Since the lasing gain is damped at threshold value, the lasing intensity-increases only linearly with I_in when saturation of the dye absorption can be neglected.

© 1993 Optical Society of America