Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 78: Plasmonics and Nanooptics 3

O 78.7: Vortrag

Freitag, 9. September 2022, 12:00–12:15, H3

Polarization selective investigation of plasmonic Bloch modes with dark-field spectroscopy — •Maximilian Johannes Black and Nahid Talebi — Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany

Plasmonic and photonic crystals are widely used to mold the flow of light. Owing to its symmetry even the seemingly simple structure of a periodic square lattice of holes within a thin gold film shows a broad variety of plasmonic Bloch modes that are distinguished by the momenta and polarization. Therefore, the response of the system to the excitation is formed by a superposition of these modes. In this work we use polarization-selective optical dark-field microscopy to decompose these modes. Dark-field microspectroscopy is used to enhance the resolution and to suppress the background illumination, whereas linear polarizers both in the illumination and the detection path enable the selection of Bloch modes by polarization. We find that the dominating signal is formed by the selective excitation and detection of radiating magnetic moments. These and a variety of other modes are visualized by hyperspectral imaging. In the far-field reciprocal space interference fringes are resolved, indicating the propagation of the observed modes along the surface of the plasmonic crystal. Our results prove the possibility to thoroughly investigate plasmonic Bloch modes using dark-field microscopy, adding its versatility to the range of methods for measuring light-matter interactions.