Berlin 2018 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 5: Whispering Gallery Mode Resonators II
KFM 5.6: Vortrag
Montag, 12. März 2018, 17:10–17:30, EMH 025
Whispering Gallery Modes in Self-Assembled Microspheres of Highly Fluorescent Polymers — Daniel Braam1, Guenther Prinz1, Kenichi Tabata2, Soh Kushida2, Daichi Okada2, Yohei Yamamoto2, and •Axel Lorke1 — 1Faculty of Physics and CENIDE, University Duisburg-Essen, Germany — 2Faculty of Pure and Applied Sciences, University of Tsukuba, Japan
We report on the realization of spherical microresonators by self-assembly of π-conjugated copolymers. These polymers combine the features of being a dye as well as a dielectric. They also enable facile, large-scale fabrication of microspheres with excellent optical and structural properties [1]. Single microspheres were investigated by photoluminescence in the visible regime. The spectra exhibit sharp whispering gallery modes (WGMs) with Q-factors up to 10 000 [2], superimposed upon a broad luminescence background. The high Q-factors, together with the properties of the polymer spheres, make it possible to study the evolution of WGMs, both inside a single sphere, as well as between optically coupled multi-sphere arrangements [3]. Strong optical excitation leads to a slight oblate deformation of the resonators. This results in a splitting of the WGMs, as the high degeneracy of perfectly spherical confinement is lifted [2]. Using suitable polymer blends with tunable fluorescence properties, efficient, long-range unidirectional photon energy transfer ("photon one-way street") can be demonstrated [3].
[1] K. Tabata et al., Sci. Rep. 4, 5902 (2014).
[2] D. Braam et al., Sci. Rep. 6, 19635 (2016).
[3] S. Kushida et al., ACS Nano 10, 5543 (2016).