Features of the shape of the emission spectrum of a spherical microresonator with a high refractive index luminescent shell due to the polarization of the whispering gallery modes

The effect of the thickness and refractive index of the shell on the amplitudes of lines of the TE and TM polarized whispering gallery modes (WGMs) in the emission spectrum of a microcavity structure consisting of a spherical core covered with a luminescent shell with a refractive index greater than that of the core is studied. The luminescence spectra of the shell, the radial distribution of the WGM field, and the mode parameters (wavelength, quality factor, and effective volume) are calculated using the method of spherical wave transfer matrices. It is shown that at certain subwavelength shell thicknesses, the amplitude of the TE mode emission peak is many times greater than the amplitude of the TM mode peak with the same polar, azimuthal, and radial indices. This is explained by the fact that with these parameters of the shell, WGMs propagate inside the shell as waveguide modes.