Miniaturizing plasmonic arrays using extreme dispersion

Nanoplasmonics allows to enhance Purcell factor due to small mode volumes. Recently, use of diffractive modes, hybridized with plasmonic excitations, has enabled to increase the resonance Q-factors, promising to enhance occurring light-matter interactions. These hybrid modes, known as surface lattice resonances, require nanoparticle array sizes ranging from hundreds of micrometers to millimeters, making them unfeasible for several nanoscale photonic applications. Here, we propose to utilize extreme dispersion to dramatically miniaturize the required array sizes. The group index of the surrounding medium is shown to be directly linked to the array size, allowing up to two-orders-of-magnitude decrease in used dimensions. The increase in dispersion is achieved by utilizing Bragg-reflector waveguides. The work paves way for more efficient and smaller nanoplasmonic devices.