Plasmon Resonant Cavities in Vertical Nanowire Arrays
ABSTRACT We investigate tunable plasmon resonant cavity arrays in paired parallel nanowire waveguides. Resonances are observed when the waveguide length is an odd multiple of quarter plasmon wavelengths, consistent with boundary conditions of node and antinode at the ends. Two nanowire waveguides satisfy the dispersion relation of a planar metal-dielectric-metal waveguide of equivalent width equal to the square field average weighted gap. Confinement factors over 10(3) are possible due to plasmon focusing in the interwire space.
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ABSTRACT: We report improved light transparency over a broad bandwidth in a metal-layered structure with two film-coupled subwavelength non-close-packed plasmonic arrays. Through the introduction of dual ultrathin dielectric spacing layers between the metal layer and the double plasmonic disk arrays, coupling of the input and output effects of light is efficiently enhanced through strong near-field localized plasmon resonances between adjacent plasmonic disks and the near-field plasmon cavity mode in the gap between the double plasmonic arrays and the metal layer. A broad bandwidth of 300 nm with near-unity light transmittance (above 90%) in the optical regime is achieved through the localized plasmon resonances and the symmetrical structure used here. The transparency of this structure is polarization independent and incident angle insensitive, and can be tuned by varying the structure parameters and the dielectric environment. In addition, the period of the plasmonic arrays and the thickness of the nanometer-separated plasmonic structure are less than λ /20 and λ/8, respectively. These values suggest that the proposed structure may have potential applications in deep subwavelength optoelectronic devices, including broadband optically transparent electrodes, highly integrated light input and output components, and plasmonic filters.IEEE Photonics Journal 12/2013; 5(6):4809011-4809011. DOI:10.1109/JPHOT.2013.2292369 · 2.33 Impact Factor
Conference Paper: Femtomolar molecular detection with CNT based SERS substrate[Show abstract] [Hide abstract]
ABSTRACT: We report a highly sensitive substrate for surface enhanced Raman spectroscopy (SERS) enabled by arrays of metal (gold and silver) nanowires on the template of vertically aligned (VA-) carbon nanotubes (CNTs) coated with a high-k dielectric hafnia (HfO2) layer as a potential barrier. Femtomolar detection of 1,2 bis-(4-pyridyl)-ethylene (BPE) is demonstrated with this non-resonant substrate. Comparison of SERS performance with and without the hafnia potential barrier establishes the critical contribution of this dielectric nano spacer to the large sensitivity. This behavior is attributed to the relief of electric charge leakage from metal to the CNT template in the presence of the virtual energy potential barrier. The VA-CNT substrate, when covered by dielectric barriers, can be a great template for a practical and reproducible SERS substrate.SPIE NanoScience + Engineering; 09/2014
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ABSTRACT: We theoretically investigate the optical properties of a late-model plasmonic nanostructure consisting of double mutually staggered silver (Ag) nanoparticle arrays sandwiched by two continuous Ag films. Double robust plasmonic resonances with transmission both more than 86% are achieved via the cooperative effects of plasmon gap modes and optical cavity modes. The transparency response can be efficiently modified by varying the diameter of nanoparticles, the distance between the plasmonic arrays and the metal films, the dielectric environment, the thickness of the double film and the gap distance between the double mutually staggered plasmonic Ag nanoparticle arrays. The structure proposed here may provide potential applications in highly integrated optoelectronic devices, such as transparent conductors, plasmonic filters and sensors.Optics Communications 06/2014; 321:219–225. DOI:10.1016/j.optcom.2014.02.020 · 1.54 Impact Factor