Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Plasmonics and Nanooptics V: Light-Matter Interaction

O 37.8: Talk

Tuesday, March 21, 2017, 15:45–16:00, TRE Ma

Coherent phase-resolved near-field spectroscopy of single gold nanorods enabled by self-interference in an ultrasharp gold taper — Martin Esmann, Simon F. Becker, •Abbas Chimeh, Ralf Vogelgesang, and Christoph Lienau — University of Oldenburg

Plasmonic nanofocusing of light on an ultrasharp gold taper enables spectroscopic analysis of optical near-fields around individual metallic nanoparticles [1]. In order to characterize the ultrafast time-dynamics of these near-fields, the scheme should be extended to include the measurement of phase-resolved spectra. To this end, a stable inline interferometer is implemented in such a taper and plasmonic-nanofocusing spectroscopy is combined with spectral interferometry. In this method, surface plasmon polaritons are launched by a coupler on a pyramidal metallic taper and propagate towards the taper apex where they form a confined nanometer-scale light source [1]. After optical interaction with a sample, a part of the incident field is reflected backwards to the taper and interferes with the incident field on it. The interference signal is then collected from a scatterer on the shaft and spectrally resolved. Here, we implemented this method for the first time and use it to record local broadband optical spectra of single gold nanorod with 10x40 nm dimensions. We demonstrate phase-coherent mapping of optical near-field with sub-10 nanometer spatial resolution and provide a detailed analysis how near-field spectra are generated in this novel and highly sensitive interferometric measurement scheme.

[1] S. Schmidt et al., ACS Nano 6, 6040 (2012).