Efficient coupling between dielectric waveguide modes and exterior plasmon whispering gallery modes

摘要

Inefficient coupling between dielectric guided mode and plasmon mode has beenoverlooked in the past. The mechanism in it is essentially different from theconventional coupling between dielectric modes. Based on qualitativetheoretical analysis, we proposed two methods to strengthen the couplingbetween dielectric waveguide modes and exterior plasmon whispering gallerymodes. One is using a U-shaped bent waveguide to break the adiabatic modeconversion process, and the other is to render the dielectric mode ofhigher-order to reach phase matching with plasmon mode. Both the transmissionspectrum of waveguide and the energy spectrum of cavity demonstrate that thecoupling efficiencies can be greatly improved. These simple configurations arepotential for wide applications, for example, tunable integrated opticaldevices, nanolasers and sensors.