OBSERVATION OF INPUT AND OUTPUT STRUCTURAL RESONANCES IN THE RAMAN-SPECTRUM OF A SINGLE SPHEROIDAL DIELECTRIC MICROPARTICLE

The Raman spectrum measured on a slowly evaporating liquid droplet trapped by radiation pressure shows two sets of resonances: one set of strong but narrow resonances that can be interpreted as resonances in the transmitted field (input resonances) and a second set caused by resonances in the inelastically scattered field (output resonances). The second set is much weaker, but its peaks are spectrally broader by an order of magnitude. Comparison with calculated input resonances and comparison of the elastically scattered light with the calculated spectrum indicate that the optically levitated particle is spheroidal in shape. © 1990 Optical Society of America.