Generation of High-Order Resonance Modes in Visible and Near-Infrared Range from Square Ring-Disk System

A novel square ring-disk (SRD) nanostructure is designed by combining a square ring with a square disk, and its high-order plasmonic resonance is investigated numerically by using COMSOL Multiphysics. The symmetry break of the system is obtained by adjusting the relative position of the square disk and the square ring. The quadrupolar, octupolar, and hexadecapolar plasmonic resonance modes on the square ring and the dipolar plasmonic resonance on the square disk are successfully generated, and their resonance peaks are presented. Meanwhile, the hexadecapolar mode of the square ring appears only when the square disk moves vertically to the polarization direction of the incident light. This research may have potential application in designing high-performance biochemical sensor or SERS and SEF devices in the visible and near-infrared wavelength range.