Subdiffraction Light Concentration by J-Aggregate Nanostructures

We show, by accurate scattering calculations, that nanostructures obtained from thin films of J-aggregate dyes,despite their insulating behavior, are able to concentrate the electromagnetic field at optical frequencies like metallicnanoparticles. These results promise to widely enlarge the range of plasmonic materials, thus opening new perspectives innanophotonics. Specifically we investigate ultrathin nanodisks and nanodisk dimers that can be obtained by standardnanolithography and nanopatterning techniques. These molecular aggregates display highly attractive nonlinear opticalproperties, which can be exploited for the realization of ultracompact devices for switching by light on the nanoscale without the need of additional nonlinear materials.