Enhancing the nonlinear response of plasmonic nanowire antennas by engineering their terminations

Sub-wavelength light concentration by means of plasmonic nanoantennas is known to significantly enhance the nonlinear response. In nonlinear schemes involving multiple frequencies, however, it remains challenging to design nanoantennas that respond resonantly to more than one or eventually to all interacting frequencies. Considering plasmonic nanowire antennas, we hereby demonstrate the potential to engineer their resonances at more than one frequencies involved in the nonlinear process by carefully tailoring the antenna terminations. Although we consider here the degenerate nonlinear process of second harmonic generation, our approach can easily be extended to other nonlinear processes. PACS numbers: 73.20.Mf, 42.65.Ky, 42.65.Wi