Modeling of Luminescence Spectra in Spherical Microresonators with an Emitting Shell

The luminescence spectra of a microresonator structure consisting of a spherical core of small diameter (3.5–6 μm) covered with a luminescent shell with a refractive index less than that of the core are modeled. Shell luminescence spectra, radial distribution of the whispering gallery mode (WGM) field, and mode parameters (wavelength, width, quality factor) are calculated using the expansion of the electromagnetic wave field in the basis of vector spherical harmonics and the method of spherical wave transfer matrices. The dependence of the luminescence spectra and WGM parameters on the geometric and optical parameters of the structure—the shell thickness, the refractive index of the shell, and the core diameter—is studied.