title: Dispersion-tunable designer-plasmonic resonator with enhanced high-order resonances.
abstract: We propose and experimentally demonstrate an approach to efficiently tune the dispersion of a designer-plasmonic resonator, or a plasmonic 'meta-atom', by incorporating an extra ground plane underneath. We demonstrate that this ground plane is able to enhance resonances, and the enhancing effect can render those higher-order azimuthal modes, being absent in previously reported designer-plasmonic resonators, experimentally observable. After incorporating the ground plane, all resonance modes are red shifted with their Q factors enhanced. By increasing the separation from the planar resonator to the underneath ground plane, all enhanced modes are blue shifted with Q factors decreased slightly, whose trend is opposite to increasing the thickness of a dielectric substrate of a common meta-atom without a ground. These results may find potential applications in tunable designer-plasmonic sensors and plasmonic metamaterial designs.
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Zhen
authors.initials: Z
authors.lastname: Gao
authors.forename: Xihang
authors.initials: X
authors.lastname: Shi
authors.forename: Zhaoju
authors.initials: Z
authors.lastname: Yang
authors.forename: Xiao
authors.initials: X
authors.lastname: Lin
authors.forename: Baile
authors.initials: B
authors.lastname: Zhang