Engineering of metal-clad optical nanocavity to optimize coupling with integrated waveguides

We propose a cladding engineering method that flexibly modifies the radiation patterns and rates of metal-clad nanoscale optical cavity. Optimally adjusting the cladding symmetry of the metal-clad nanoscale optical cavity modifies the modal symmetry and produces highly directional radiation that leads to 90% coupling efficiency into an integrated waveguide. In addition, the radiation rate of the cavity mode can be matched to its absorption rate by adjusting the thickness of the bottomcladding layer. This approach optimizes the energy-flow rate from the waveguide and maximizes the energy confined inside the nanoscale optical cavity.