Abstract
We have fabricated a micrometer-sized nonlinear optical resonator consisting of a silica microsphere coated with J-aggregates of 1,1'-diethyl-2,2'-cyanine iodide in a thin silica film by a sol–gel process. The sphere diameter was 4.5 µm and the film thickness was estimated to be approximately 100 nm by scanning electron microscopy. The coating on the sphere was characterized by the fluorescence of the J-aggregates and the detection of whispering gallery modes (WGM) in the fluorescence spectrum. The optical evaluation of the sphere was performed in the attenuated-total-reflection configuration. We confirmed that the resonances in the scattering spectrum were due to WGMs, on the basis of a comparison of the experimentally obtained peak positions for coated and noncoated spheres, to those obtained using Mie's theory. The positions of the scattering peaks and the values of the full-width at half-maximum in the scattering spectrum for the coated sphere differ from those of the noncoated sphere.