Near-field and far-field electric dipole radiation in the vicinity of a planar dielectric half space

We have used the full Sommerfeld integral formalism as well as an asymptotic formalism to study the near- and far-field radiation patterns of an electric dipole in the vicinity of a planar dielectric half space. We present systematic results for the polarization dependence of the radiation patterns in both half spaces and the ratio of the integrated power radiated into the two half spaces as a function of the relative refractive index as well as the dipole position. We find that the radiation patterns are highly structured and directed. Furthermore, the ratio of the integrated power increases significantly on increasing the relative refractive index, which can be exploited to enhance the sensitivity of spectroscopic studies of surface-bound molecules; however this ratio drops quickly for a dipole more than 0.2 wavelength from the interface.