Radiative frequency shift and linewidth of an atom dipole in the vicinity of a dielectric microsphere

The frequency shift and linewidth variation of an oscillator placed next to a dielectric microsphere are found within the framework of the classical approach. Both the frequency shift and the linewidth are shown to be substantially dependent on the location of the atom and the size of the microsphere and are capable of reaching very high values near the surface of the microsphere under resonance conditions. Near microsphere resonance, a blue frequency shift is predicted, leading to repulsive forces between the atom and the dielectric microsphere.