Plasmonics: The promise of highly integrated optical devices

This paper reviews the fundamentals of surface plasmon polariton (SPP) excitations, sustained by interfaces between metallic and insulating media, with a focus on applications in waveguiding of electromagnetic waves at visible and near-infrared frequencies. The large wavevectors accessible via SPP oscillations allow for significantly reduced wavelengths and thus increased confinement of the propagating modes, promising a subwavelength photonic infrastructure suitable for integration on Si-based photonic chips. Various geometries such as single interfaces, multilayer structures, and nanoparticle ensembles are discussed and their properties assessed in terms of light confinement and energy attenuation of the guided modes. Metal/insulator/metal (MIM) and certain forms of nanoparticle waveguides promise novel avenues for light confinement, guiding, and coupling, which could provide the basis for subwavelength photonic devices.