28 September 2007 Second-harmonic generation driven by asymmetric local fields in T-shaped gold nanodimers
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We demonstrate both experimentally and computationally that SHG from arrays of T-shaped gold nanodimers with differing nanogap sizes results from asymmetry in the local field distribution rather than strict dependence on the nanogap size. Normal-incidence SHG measurements reveal that the SHG responses depend non-trivially on the nanogap size. Calculations show that strong orthogonal polarization components, which are not present in the exciting field, are induced, and that these induced components yield the dominant SHG response. The calculations also reveal that field enhancement is roughly independent of nanogap size and persists even for large nanogap sizes. A simple phenomenological model wherein the local surface susceptibility of the nanodimer interacts with the local field distribution along the nanodimer perimeter qualitatively explains the experimental results with good agreement.
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Brian K. Canfield, Brian K. Canfield, Hannu Husu, Hannu Husu, Benfeng Bai, Benfeng Bai, Janne Laukkanen, Janne Laukkanen, Markku Kuittinen, Markku Kuittinen, Jari Turunen, Jari Turunen, Martti Kauranen, Martti Kauranen, } "Second-harmonic generation driven by asymmetric local fields in T-shaped gold nanodimers", Proc. SPIE 6641, Plasmonics: Metallic Nanostructures and Their Optical Properties V, 66410Q (28 September 2007); doi: 10.1117/12.733618; https://doi.org/10.1117/12.733618

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