2021/07/06 by Rohit Chikkaraddy, Chikkaraddy, Rohit, Jeremy J Baumberg +1 · 1 citation
Physics and Astronomy · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Optics (physics.optics) #cond-mat.mes-hall #physics.app-ph #physics.optics
paper · pdf · doi:10.48550/arxiv.2107.02529
16 pages, 5 figures
arxiv created 2021/07/23 · arxiv updated 2021/07/26
Metal-insulator-metal (MIM) nanogaps in canonical nanoparticle-on-mirror geometry (NPoM) provide deep-subwavelength confinement of light with mode volumes smaller than V/V0 < 10-6. However, access to these hotspots is limited by the impendence mismatch between the high in-plane k// of trapped light and free-space plane-waves, making the in- and out-coupling of light difficult. Here, by constructing a nanoparticle-on-foil (NPoF) system with thin metal films, we show the mixing of insulator-metal-insulator (IMI) modes and MIM gap modes resulting in MIMI modes. This mixing provides multi-channel access to the plasmonic nanocavity through light incident from both sides of the metal film. The red-tuning and near-field strength of MIMI modes for thinner foils is measured experimentally with white-light scattering and surface-enhanced Raman scattering from individual NPoFs. We discuss further the utility of NPoF systems since the geometry allows tightly confined light to be accessed simply and through different ports.