Gap plasmon polariton structure for very efficient micro to nano scale   interfacing
  The seamless transition between micro-scale photonics and nano-scale plasmonics requires the mitigation between different waveguiding mechanisms as well as between few orders of magnitude in the field lateral size, down to a small fraction of a wavelength. By exploiting gap plasmon polariton waves both at the micro and nano scale, very high power transfer efficiency (>60%) can be achieved using an ultrashort (few microns) non adiabatic tapered gap plasmon waveguide. Same mechanism may be used to harvest impinging light waves and direct them into a nano hole or slit, to exhibit an anomalous transmission - without the conventional periodic structures. The special interplay of plasmonic and oscillating modes is analyzed. 
Pavel Ginzburg, David Arbel, and Meir Orenstein