Spontaneous-Emission Coupling from an Excited Atom into a Symmetrical Metal-Cladding Optical Waveguide

We consider the coupling behavior which transfers the energy of the spontaneous emission from an atom embedded in free space into a symmetrical metal-cladding optical waveguide. The ratio for spontaneous emission into the waveguide modes is derived by using a compact form of Green's function for a multilayer. Up to 90% of the spontaneous emission energy fed into the waveguide is demonstrated when the atom is positioned above the waveguide in a limited space range.