title: Raman enhancement on a broadband meta-surface.
abstract: Plasmonic metamaterials allow confinement of light to deep subwavelength dimensions, while allowing for the tailoring of dispersion and electromagnetic mode density to enhance specific photonic properties. Optical resonances of plasmonic molecules have been extensively investigated; however, benefits of strong coupling of dimers have been overlooked. Here, we construct a plasmonic meta-surface through coupling of diatomic plasmonic molecules which contain a heavy and light meta-atom. Presence and coupling of two distinct types of localized modes in the plasmonic molecule allow formation and engineering of a rich band structure in a seemingly simple and common geometry, resulting in a broadband and quasi-omni-directional meta-surface. Surface-enhanced Raman scattering benefits from the simultaneous presence of plasmonic resonances at the excitation and scattering frequencies, and by proper design of the band structure to satisfy this condition, highly repeatable and spatially uniform Raman enhancement is demonstrated. On the basis of calculations of the field enhancement distribution within a unit cell, spatial uniformity of the enhancement at the nanoscale is discussed. Raman scattering constitutes an example of nonlinear optical processes, where the wavelength conversion during scattering may be viewed as a photonic transition between the bands of the meta-material.
authors: UNAM Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey. ayas@bilkent.edu.tr
authors: Sencer
authors: S
authors: Ayas
authors: Hasan
authors: H
authors: Güner
authors: Burak
authors: B
authors: Türker
authors: Okan Öner
authors: OÖ
authors: Ekiz
authors: Faruk
authors: F
authors: Dirisaglik
authors: Ali Kemal
authors: AK
authors: Okyay
authors: Aykutlu
authors: A
authors: Dâna
mesh_terms: D003198:Computer Simulation; D008027:Light; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008956:Models, Chemical; D008958:Models, Molecular; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000379:methods*