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O: Fachverband Oberflächenphysik

O 44: Scanning probe techniques: Method development – Poster

O 44.6: Poster

Dienstag, 10. März 2026, 14:00–16:00, P2

Spectral interferometry scanning near-field optical microscopy; investigating resonant tip-sample near-field interactions — •Tom Jehle, Sam S. Nochowitz, Juanmei Duan, and Christoph Lienau — Institute of Physics, University of Oldenburg, 26129 Germany

Localized phonon polaritons and plasmon polaritons resonantly enhance near-field mediated light matter interactions and are key for strong coupling between single quantum emitters and nanocavities (1). Localized polariton resonances with high oscillator strength show tip-sample distance dependent frequency shifts in scanning probe experiments, requiring spectroscopic analysis at explicit tip-sample distances (2). Here, we introduce a broadband interferometric scattering-type SNOM technique (3) to reconstruct spectral amplitude and phase of visible light scattered from a gold taper. Harmonic sampling with a fast line camera allows reconstruction of spectra with high tip-sample distance resolution. Spectral amplitude, phase and the evaluation of the distance dependence of the near-field interaction allows the retrieval of the temporal near-field dynamics with sub-cycle precision. We demonstrate our technique by measuring the tip-sample distance dependent time dynamics of the near-field at the apex of a resonant gold taper coupled to its image. Our results pave the way towards hyperspectral imaging in the visible with nm spatial resolution and fs temporal resolution of the reconstructed time dynamics. (1) S. Hu et al., Nat. Commun. 15, 6835 (2024); (2) H. Wang et al., Nat Commun. 9, 2005 (2018); (3) J. Zhan et al., Nano Lett. 24 (49),15738 (2024)

Keywords: sSNOM; spectral interferometry; Ultrafast optical near fields; Ultrafast nanoscopy; Ultrafast oscilloscopy