This paper presents a plasmonic bull's eye consisting of a micron-sized hole and a concentric nano-antenna metallic ring surrounded by periodic circular grooves on a thin gold film. The unique metallic nano-ring imbedded in the supra-wavelength-sized hole acts as an amplifying and filtering component to simultaneously provide a significantly lower spectral noise and a higher power transmission at the resonance wavelength, in comparison to prior sub-wavelength bull's eyes. Systematic numerical analyses based on finite-difference time-domain method were carried out to find the impacts of the structural parameters. Experimentally we integrated three proposed plasmonic structure on a cleaved facet of an optical fiber that can act as a spatially and spectrally multiplexed photon sorter. Transmission characteristics of the proposed devices were characterized in terms of the spectral response and signal to noise ratio. Potential applications of the fiber optic photon sorter were also discussed.

A novel compact optical engine for a micro projector display is experimentally demonstrated, which is composed of RGB light sources, a tapered 3 x 1 Fiber Optic Color Synthesizer (FOCS) along with a fiberized ball-lens, and a two dimensional micro electromechanical scanning mirror. In the proposed optical engine, we successfully employed an all-fiber beam shaping technique combining optical fiber taper and fiberized ball lens that can render a narrow beam and enhance the resolution of the screened image in the far field. Optical performances of the proposed device assembly are investigated in terms of power loss, collimating strength of the collimator assembly, and color gamut of the output.

We numerically investigated the enhanced optical transmission through sub-wavelength centered-polygonal hole arrays (CPHA) in a thin Ag film deposited on the silica substrate. In octagonal and decagonal-CPHAs, we observed new hybrid transmission characteristics that were inherited from both crystalline and quasi-crystalline hole arrays. This peculiar nature was attributed to the unique arrangement of CPHAs which can be covered with copies of a single unit cell as in crystalline arrays, and their rotational symmetry as observed in quasi-crystalline arrays. Hybrid natures in CPHAs were further investigated in the transmission spectra and Fourier space representations of the arrays. Contributions from the nearest neighbor hole-to-hole distance to enhanced transmission were analyzed in order to quantify the plasmonic contributions from the Air/Ag interface and Silica/Ag interface. We also investigated the impact of layer structure, Air/Ag/Air versus Air/Ag/Silica in the transmissions and found that in CPHAs in Air/Ag/Silica structures, contributions from the Air/Ag interface became dominant in contrast to crystalline hole arrays with lower fold symmetry.

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A subwavelength holey plasmonic structure was proposed by adiabatically tapering a photonic crystal fiber (PCF) and subsequently metalizing the cleaved end facet. By coupling a white light into the PCF side, we experimentally observed an enhanced optical transmission in the spectral domain through the plasmonic structure at the tapered end. We further showed numerically that the proposed device renders a focused directional beam, due to its Fresnel-zone-like configuration and the plasmonic lensing effects.