Leaky-wave optical radiation from subwavelength metamaterial or plasmonic arrays

We discuss in this paper the leaky-wave propagation properties for one- and two-dimensional arrays of metamaterial or plasmonic inclusions with subwavelength transverse cross section. Our analysis is based on the rigorous dynamic dipolar coupling among the array elements. We show that an isolated array of plasmonic nanoparticles supports leaky wave modes and may operate as a frequency-scanning leaky-wave nanoantenna. Extending these concepts to parallel linear arrays, we show that the modal spectrum splits into symmetric and anti-symmetric modes, with increased versatility in their radiation and guidance properties. Finally, we extend our analysis to two-dimensional arrays and connect the typical scattering resonances of planar arrangements of nanoparticles to their leaky-wave spectrum.