A single-crystalline silver plasmonic circuit for visible quantum emitters

Abstract: Plasmonic waveguides are key elements in nanophotonic devices serving as optical interconnects between nanoscale light sources and detectors. Multimode operation in plasmonic two-wire transmission lines promises important degrees of freedom for near-field manipulation and information encoding. However, highly confined plasmon propagation in gold nanostructures is typically limited to the near-infrared region due to ohmic losses, excluding all visible quantum emitters from plasmonic circuitry. Here, we report on top-down fabrication of complex plasmonic nanostructures in single-crystalline silver plates. We demonstrate controlled remote excitation of a small ensemble of fluorophores by a set of waveguide modes and emission of the visible luminescence into the waveguide with high efficiency. This approach opens up the study of nanoscale light-matter interaction between complex plasmonic waveguides and a large variety of quantum emitters available in the visible spectral range.