  For the purpose of using plasmonics in an integrated scheme where single
emitters can be probed efficiently, we experimentally and theoretically study
the scattering properties of single nano-rod gold antennas as well as antenna
arrays placed on one-dimensional dielectric silicon nitride waveguides. Using
real space and Fourier microscopy correlated with waveguide transmission
measurements, we quantify the spectral properties, absolute strength and
directivity of scattering. The scattering processes can be well understood in
the framework of the physics of dipolar objects placed on a planar layered
environment with a waveguiding layer. We use the single plasmonic structures on
top of the waveguide as dipolar building blocks for new types of antennas where
the waveguide enhances the coupling between antenna elements. We report on
waveguide hybridized Yagi-Uda antennas which show directionality in
out-coupling of guided modes as well as directionality for in-coupling into the
waveguide of localized excitations positioned at the feed element. These
measurements together with simulations demonstrate that this system is ideal as
a platform for plasmon quantum optics schemes as well as for fluorescence
lab-on-chip applications.
