Reshaping plasmon modes by film interference

Abstract

Localized surface plasmon resonances (LSPRs) in metal nanostructures have been a central subject of nano-photonics due to their ability to manipulate light beyond the optical diffraction limit. Nevertheless, the large intrinsic dissipations of LSPRs have severely hindered their applications, so the on-demand control of the LSPR modes is highly desired and remains open yet. Here, we experimentally and theoretically demonstrate that the plasmon mode can be effectively engineered by interacting with constructive or destructive modes supported by film interference. When a metal nanoparticle interacts with a constructive mode, the dissipation linewidth of its LSPR mode shows a significant reduction of 58%. Simultaneously, the scattering intensity is remarkably enhanced, in vast favor of measuring weak signals from small nanoparticles. Furthermore, the film-destructive-interference splitting in the scattering spectrum by weak coupling, rather than strong coupling, is revealed if the plasmon particles interact with the destructive mode, resulting in two new hybrid plasmon modes with narrow linewidths. The effective polarizability model of reshaping the LSPR modes by the film interference is present to well understand the experimental observations. Our work may pave the way toward low-loss plasmonic photonics and its practical applications.