Zusammenfassung
Nanoparticle-on-mirror plasmonic nanocavities, capable
of extreme optical confinement and enhancement, have
triggered state-of-the-art progress in nanophotonics and development
of applications in enhanced spectroscopies. However, the
optical quality factor and thus performance of these nanoconstructs
are undermined by the granular polycrystalline metal films
(especially when they are optically thin) used as a mirror. Here,
we report an atomically smooth single-crystalline platform for lowloss
nanocavities using chemically synthesized gold microflakes as a
mirror. Nanocavities constructed using gold nanorods on such
microflakes exhibit a rich structure of plasmonic modes, which are
highly sensitive to the thickness of optically thin (down to ∼15 nm) microflakes. The microflakes endow nanocavities with
significantly improved quality factor (∼2 times) and scattering intensity (∼3 times) compared with their counterparts based on
deposited films. The developed low-loss nanocavities further allow for the integration with a mature platform of fiber optics, opening
opportunities for realizing nanocavity-based miniaturized photonic devices for practical applications.
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