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We report on a straightforward way to increase the photoluminescence enhancement of nanoemitters induced by optical nanotantennas. The nanoantennas are placed above a gold film-silica bilayer, which produces a drastic increase of the scattered radiation power and near field enhancement. We demonstrate this increase via photoluminescence enhancement using an organic emitter of low quantum efficiency, Tetraphenylporphyrin (TPP). An increase of the photoluminescence enhancement by a factor larger than three is observed compared to antennas without the reflecting-layer. In addition, we study the possibility of influencing the polarization of the light emitted by utilizing asymmetry of dimer antennas.

Surface Plasmon Polaritons (SPPs) are excited at the interface between a thin gold film and air via the illumination of nanoslits etched into the film. The coupling efficiency to the two propagation directions away from the slits is determined by leakage radiation microscopy, when the angle of incidence of the pump beam is changed from 0° to 20°. We find that preferential coupling of SPPs into one direction can be achieved for non-normal incidence in the case of single slits and slit pairs. The proportion of SPP excited into one direction can be in excess of 90%. We further provide a simple model of the process, and directly compare the performances of the two approaches.

We introduce a point-like scanning single-photon source that operates at room temperature and offers an exceptional photostability (no blinking, no bleaching). This is obtained by grafting in a controlled way a diamond nanocrystal (size around 20 nm) with single nitrogen-vacancy color-center occupancy at the apex of an optical probe. As an application, we image metallic nanostructures in the near-field, thereby achieving a near-field scanning single-photon microscopy working at room temperature on the long term. Our work may be of importance to various emerging fields of nanoscience where an accurate positioning of a quantum emitter is required such as for example quantum plasmonics.