Design, fabrication, and characterization of nanometer-scale ridged aperture optical antennae

摘要

We investigate light concentration and field enhancement in nanometer-scale ridged aperture antennae. Resent numerical simulations have shown that nanoscale ridged apertures can concentrate light into nanometer domain. Most importantly, these ridge apertures also provide an optical transmission enhancement several orders of magnitude higher compared to regularly shaped nanoscale apertures. We employ the finite-difference time-domain (FDTD) method to design these apertures and fabricate them in thin metal films. A home-built near field scanning optical microscope (NSOM) is used to map the near-field intensity distribution of the light transmitted through these apertures. It is shown that the ridged apertures can produce a concentrated light spot far beyond the diffraction limit, with transmission enhancement orders of magnitude higher than regularly shaped apertures. Nanolithography applications of these nanoscale ridged aperture antennae are demonstrated.