Photon-plasmon coupling in metal coated microtubular cavities

Noble metal nanostructures are known to be able to support plasmonic modes which are highly confined at the metal surfaces, exhibiting many novel phenomena. In particular, metal-coated optical cavities have been investigated... [ view full abstract ]

Noble metal nanostructures are known to be able to support plasmonic modes which are highly confined at the metal surfaces, exhibiting many novel phenomena. In particular, metal-coated optical cavities have been investigated to study surface plasmon polaritons (SPPs) in combination with optical whispering-gallery-mode (WGM) resonances, which result in SPP resonant and/or hybrid plasmon-photon modes localized at the metal surface. These kinds of plasmonic resonant cavities are capable to accommodate intense resonant EM fields on the metal layer surfaces suitable for various applications such as enhanced light-matter interactions or plasmonic microcavity lasers. In the recent study of thin-walled microtube cavity coated with a gold nano-cap, we reveal that the transverse magnetic (TM) polarized light predominantly excites the hybrid resonant modes in these opto-plasmonic microcavities. Remarkably, the exterior field of the hybrid mode is enhanced by more than an order of magnitude over previously reported designs and is caused by the light confinement in a narrow potential well. In addition, vertical gold nanogap is fabricated on microtube cavities to support localized surface plasmons (LSPs). By tuning the position of the gold nanogap on the tube surface, selective coupling between resonant light and LSPs are observed, and is explained by a modified quasi-potential model based on perturbation theory. These investigations interface surface plasmons and optical modes in hybrid opto-plasmonic microcavities towards promising applications such as enhanced light-matter interactions.