The hour-glass type nanostructures are fabricated by using the conventional Si processes. When beaming though these structures, we observed that light is collected by the micro scale pyramidal cavity, funneled through the nano-aperture by plasmonic resonance and collimated with enhanced transmission by the surrounding horn-like mirrors (optical horn-effect). Optical transmissions through pyramidal probes with various nano-aperture diameters were measured to be dependent upon the aperture area. For a diameter less than ~ 50 nm or less than area with ~10,000 nm2, the transmitted optical intensities are increasing due to the spp-mediated intra-band emission. For the aperture diameter greater than 100 nm, the strong spp-coupled emission is shown. In addition, for the Au (7×7) slit aperture array platform with the slit aperture for a ~ 10 nm width, the broad emission spectra ranging from 600 nm to 860 nm are observed possibly due to nearfield coupling with localized surface plasmon polariton (LSPP).
Recently there have been significant interests about fabrication of optical nanopore for single molecule analysis and manipulation. However, due to very small amount of the optical intensity through the tiny size of the nano-aperture, optical intensity enhancement via plasmonic effect by using pore array or periodic groove patterns have been tried. In addition, the double slits with nanoscale width is reported to provide the constructive interference of the surface plasmonic wave. In this report, the nanoscale double slits with Au aperture array has been fabricated and optically characterized.