Double-resonance stimulated Raman scattering in micrometer-sized droplets

Abstract

Programmed size ramping of an aerosol stream permits a Q-switched mode-locked 532-nm laser to satisfy periodically the input resonance condition of various low-order (l = 2 to l = 4) TE and TM morphology-dependent resonances in 23.0–23.7-μm-diameter ethanol droplets. The resulting size-versus-amplitude spectra of stimulated Raman scattered light revealed high-Q modes that are not normally observed in elastic scattering. Simultaneous elastic scattering measurements permit unambiguous identification of these input resonances. The relative output intensities of stimulated Raman scattering and time histories imply that the Q of the l = 2 modes is degraded to a value of 107 by the departure of the droplet from an ideal homogeneous sphere.