Excitation of confined modes on particle arrays

We describe both theoretically and experimentally the existence
and excitation of confined modes in planar arrays of gold nanodisks.
Ordered 2D lattices of monodispersive nanoparticles are manufactured,
embedded in a silica matrix, and exposed to evanescent prism-coupling
illumination, leading to dark features in the reflectivity, which signal the
presence of confined modes guided along the arrays. We find remarkable
agreement between theory and experiment in the frequency-momentum
dispersion of the resonances. Direct excitation of these modes reveals
long propagation distances and deep extinction features. This combined
experimental and theoretical characterization of guidedmodes shows a good
understanding of the optical response of metallic particles arrays, which
can be beneficial in future designs of optical-signal and distant-sensing
applications.