Experimental cross-polarization detection of coupling far-field light to   highly confined plasmonic gap modes via nanoantennas
  We experimentally demonstrate the coupling of far-field light to highly confined plasmonic gap modes via connected nanoantennas. The excitation of plasmonic gap modes is shown to depend on the polarization, position and wavelength of the incident beam. Far-field measurements performed in crossed polarization allow for the detection of extremely weak signals re-emitted from gap waveguides and can increase the signal-to-noise ratio dramatically. 
Jing Wen, Peter Banzer, Arian Kriesch, Daniel Ploss, Bernhard   Schmauss, Ulf Peschel
physics.optics