Resonance Engineering via Harnessing Anti-Parallel Dipole Image Coupling

Abstract: Precise control of plasmonic resonances across a broad spectral range is central to the development of tunable optical devices. Yet, achieving both redshifts and blueshifts within a single nanostructure has remained elusive. Here we introduce a metal-dielectric-metal (MDM) nanodisk array that enables bidirectional tuning of resonance wavelengths throughout the near-infrared (NIR) region. The observed spectral evolution follows the plasmon ruler relationship, with unprecedented tuning properties. In particular, we report a record blueshift response of 457.82 nm for a small nanodisk thickness variation of only 5-10 nm, the highest blueshift response demonstrated in plasmonic architectures to date. This platform offers finely tunable resonances spanning an exceptionally wide NIR range, providing new insights into electromagnetic (EM) coupling mechanisms and establishing a foundation for next-generation tunable devices in sensing, optical communications, and dynamic displays.