Multilayer gap plasmons

Gap plasmons offer promising applications in photonics, yet research has primarily focused on single gap plasmon modes. This work introduces and computationally examines multilayer gap plasmons (GPs) in structures composed of alternating perfectly conducting slabs with periodic subwavelength slits and dielectric layers. Our analysis of systems ranging from 3 to 51 layers, as well as an infinite layer configuration, reveals that these structures support GP modes throughout the multilayers with wavenumber spectra extending both below and above the vacuum wavenumber. Adjacent layers exhibit either complete in-phase or out-of-phase behavior, with coherence increasing as the wavenumber approaches its maximum allowable value. These findings suggest potential applications for multilayer gap plasmon structures in photonic devices.