Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 34: Plasmonics and nanooptics: Light-matter interaction, spectroscopy III

O 34.4: Talk

Tuesday, March 13, 2018, 14:45–15:00, MA 041

Phase-resolved mapping of local optical near-fields around a single plasmonic nanoresonator — Martin Esmann, •Abbas Chimeh, Simon F. Becker, and Christoph Lienau — Institüt für Physik, Unversität Oldenburg

Plasmonic nanoantennas confine electromagnetic fields into nanoscale volumes. To fully understand and exploit this field localization, e.g., for nanoscale energy transport or for enhancing local nonlinear optical properties, a knowledge of their local optical response function, characterizing the electromagnetic fields emitted by the antenna in response to a point-like excitation in space and time, is highly desirable. Here, we show how to measure this local response function with ultrahigh, 5-nm spatial resolution by means of an isolated light spot, created by plasmonic nanofocusing [1]. Spectrally broadband surface plasmon polariton (SPP) waves are grating-coupled onto the shaft of conical gold taper and propagated towards the taper apex. The nanolocalized field at the apex locally excites a small gold rod acting as nanoantenna. The electric fields emitted by the rod are collected by the taper and emitted into the far field at a point scatterer at few microns distance from the apex. Its interference with a fraction of the incident light results in a spectral interferogram which carries full information on the local response of the antenna. By scanning the rod relative to the taper apex, we achieve fully spatially imaging of the local response function, directly mapping the dynamics of the locally emitted optical near field. [1] S. Schmidt et al., ACS Nano 6, 6040 (2012).