Investigating plasmonic gap modes coupled to nanoantennas

Plasmonic gap waveguides allow for light confinement below the diffraction limit. In combination with an impedance matched nanoantenna they can be excited from the far field. In this contribution the authors investigated nanoantennas coupled to gap plasmonic waveguides with a near-field scanning optical microscope (NSOM), but also experimentally demonstrate the coupling of far-field optical beams to highly confined plasmonic gap modes.