Scattering reduction at near-infrared frequencies using plasmonic nanostructures

Novel fabrication, detection and analysis approaches were employed to experimentally demonstrate scattering reduction by a plasmonic nanostructure operating at 1550 nm. The nanostructure consisted of a silicon nanorod surrounded by a plasmonic metamaterial cover comprised of eight gold nanowires and was fabricated by a combination of electron beam lithography, focused ion beam milling and dry and wet etching. The optical standing wave pattern of the device in the near-field was obtained using heterodyne near-field scanning optical microscopy. It was found that the spatial curvature of the interference fringes of the optical standing wave pattern was directly related to the scattering reduction of the device. The experiments were in excellent agreement with the theoretical predictions and suggested that the device reduced the scattering by 9.5 dB when compared to a bare silicon nanorod of diameter 240 nm and by 6 dB when compared to a bare silicon nanorod of diameter 160 nm.