Buffering surface plasmons in nanoparticle waveguides at the virtual localized transition

BUSTOS MARUN, RAUL A; CORONADO, EDUARDO A; PASTAWSKI, HORACIO M

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

merican Physical Society

Año: 2010 vol. 82 p. 354341 - 354346

0163-1829

We study the plasmonic energy transfer from a locally excited nanoparticle LE-NP to a linear array of small NPs and we obtain the parametric dependence of the response function. An analytical expression allows us to distinguish the extended resonant states and the localized ones, as well as an elusive regime of virtual states. This last appears when the resonance width collapses and before it becomes a localized state. Contrary to common wisdom, the highest excitation transfer does not occur when the system has a well defined extended resonant state but just at the virtual-localized transition, where the main plasmonic modes have eigenfrequencies at the passband edge. The slow group velocity at this critical frequency enables the excitation buffering and hence favors a strong signal inside the chain. A similar situation should appear in many other physicalsystems. The extreme sensitivity of this transition to the waveguide and LE-NP parameters provides new tools for plasmonics.