Plasmonic Nanoantenna Optimization Using Characteristic Mode Analysis

Plasmonic nanoantennas are typically designed with RF-inspired rigorous parametric optimization processes that lack proper physical insights. In this article, we demonstrate a systematic optimization approach for nanoantennas based on characteristic mode analysis (CMA). A complex geometry, designated as split-ring two-wire antenna (SRA), is selected and optimized using the CMA technique. CMA identifies the dominant modes of the structure at the frequency of interest as well as explains the dependence of the modes on the structure's shape, size and material properties. These insights from CMA have been used in this study to efficiently optimize SRA shape, size, and material which yield more than 700% near-field intensity enhancement (NFIE) at the desired operating frequency. This proposed CMA-based optimization method can be adapted easily for many other nanoantenna applications, facilitating the development of improved nanostructures.