Effects of the magnetodipole corrections on the spectra of spheroidal whispering gallery mode resonators interacting with a dielectric nanoparticle.

Interaction between whispering gallery mode (WGM) resonators and nanoparticles is an area of active interest in fundamental understanding of nanoparticle-induced spectral modifications of the WGM resonances in sensing applications. Existing theories of this phenomenon assume that nanoparticles can be described taking into account only the electrodipole contribution to the field of the nanoparticle. In this paper, we explore theoretically the effects of the magnetodipole contribution to the nanoparticle's field and show that this contribution might become significant even in situations when electrodipole approximation is expected to remain valid.