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K-space imaging of the eigenmodes of sharp gold tapers for scanning near-field optical microscopy.

ABSTRACT: We investigate the radiation patterns of sharp conical gold tapers, which were designed as adiabatic nanofocusing probes for scanning near-field optical microscopy (SNOM). Field calculations show that only the lowest order eigenmode of such a taper can reach the very apex and thus induce the generation of strongly enhanced near-field signals. Higher-order modes are coupled into the far field at finite distances from the apex. Here, we demonstrate experimentally how to distinguish and separate between the lowest and higher-order eigenmodes of such a metallic taper by filtering in the spatial frequency domain. Our approach has the potential to considerably improve the signal-to-background ratio in spectroscopic experiments at the nanoscale.

SUBMITTER: Esmann M

PROVIDER: S-EPMC3817685 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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k-space imaging of the eigenmodes of sharp gold tapers for scanning near-field optical microscopy.

Esmann Martin M Becker Simon F SF da Cunha Bernard B BB Brauer Jens H JH Vogelgesang Ralf R Groß Petra P Lienau Christoph C

Beilstein journal of nanotechnology 20131002

We investigate the radiation patterns of sharp conical gold tapers, which were designed as adiabatic nanofocusing probes for scanning near-field optical microscopy (SNOM). Field calculations show that only the lowest order eigenmode of such a taper can reach the very apex and thus induce the generation of strongly enhanced near-field signals. Higher-order modes are coupled into the far field at finite distances from the apex. Here, we demonstrate experimentally how to distinguish and separate be ...[more]

PMID: 24205454

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