title: A combination of concave/convex surfaces for field-enhancement optimization: the indented nanocone.
abstract: We introduce a design strategy to maximize the Near Field (NF) enhancement near plasmonic antennas. We start by identifying and studying the basic electromagnetic effects that contribute to the electric near field enhancement. Next, we show how the concatenation of a convex and a concave surface allows merging all the effects on a single, continuous nanoantenna. As an example of this NF maximization strategy, we engineer a nanostructure, the indented nanocone. This structure, combines all the studied NF maximization effects with a synergistic boost provided by a Fano-like interference effect activated by the presence of the concave surface. As a result, the antenna exhibits a NF amplitude enhancement of ~ 800, which transforms into ~1600 when coupled to a perfect metallic surface. This strong enhancement makes the proposed structure a robust candidate to be used in field enhancement based technologies. Further elaborations of the concept may produce even larger and more effective enhancements.
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA. aitzol@stanford.edu
authors.forename: Aitzol
authors.initials: A
authors.lastname: García-Etxarri
authors.forename: Peter
authors.initials: P
authors.lastname: Apell
authors.forename: Mikael
authors.initials: M
authors.lastname: Käll
authors.forename: Javier
authors.initials: J
authors.lastname: Aizpurua
mesh_terms: D001703:Biophysics / Q000379:methods; D015374:Biosensing Techniques; D004574:Electromagnetic Fields; D060733:Electromagnetic Radiation; D053768:Metal Nanoparticles / Q000737:chemistry; D015233:Models, Statistical; D008962:Models, Theoretical; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics / Q000379:methods; D012834:Silver / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods; D020349:Surface Plasmon Resonance; D013499:Surface Properties
chemical_list: D012834:Silver