Observation of fano resonances in all-dielectric nanoparticle oligomers

Katie E. Chong, Ben Hopkins, Isabelle Staude*, Andrey E. Miroshnichenko, Jason Dominguez, Manuel Decker, Dragomir N. Neshev, Igal Brener, Yuri S. Kivshar

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    168 Citations (Scopus)

    Abstract

    It is well-known that oligomers made of metallic nanoparticles are able to support sharp Fano resonances originating from the interference of two plasmonic resonant modes with different spectral width. While such plasmonic oligomers suffer from high dissipative losses, a new route for achieving Fano resonances in nanoparticle oligomers has opened up after the recent experimental observations of electric and magnetic resonances in low-loss dielectric nanoparticles. Here, light scattering by all-dielectric oligomers composed of silicon nanoparticles is studied experimentally for the first time. Pronounced Fano resonances are observed for a variety of lithographically-fabricated heptamer nanostructures consisting of a central particle of varying size, encircled by six nanoparticles of constant size. Based on a full collective mode analysis, the origin of the observed Fano resonances is revealed as a result of interference of the optically-induced magnetic dipole mode of the central particle with the collective mode of the nanoparticle structure. This allows for effective tuning of the Fano resonance to a desired spectral position by a controlled size variation of the central particle. Such optically-induced magnetic Fano resonances in all-dielectric oligomers offer new opportunities for sensing and nonlinear applications. Optically induced magnetic Fano resonances in all-dielectric nanoparticle oligomers are experimentally observed in arrays of heptamer structures composed of silicon nanodisks. Their measured linear-optical extinction spectra reveal pronounced Fano resonances associated with the strong magnetic response of high-refractive index all-dielectric nanoparticles. The resonance can be tuned by varying the diameter of the central nanodisk.

    Original languageEnglish
    Pages (from-to)1985-1990
    Number of pages6
    JournalSmall
    Volume10
    Issue number10
    DOIs
    Publication statusPublished - 28 May 2014

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