Self-similar chain of metal nanospheres as an efficient nanolens

Kuiru Li*, Mark I. Stockman, David J. Bergman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


As an efficient nanolens, we propose a self-similar linear chain of several metal nanospheres with progressively decreasing sizes and separations. To describe such systems, we develop the multipole spectral expansion method. Optically excited, such a nanolens develops the nanofocus (“hottest spot”) in the gap between the smallest nanospheres, where the local fields are enhanced by orders of magnitude due to the multiplicative, cascade effect of its geometry and high [Formula presented] factor of the surface plasmon resonance. The spectral maximum of the enhancement is in the near-ultraviolet region, shifting toward the red region as the separation between the spheres decreases. The proposed system can be used for nanooptical detection, Raman characterization, nonlinear spectroscopy, nanomanipulation of single molecules or nanoparticles, and other applications.

Original languageEnglish
JournalPhysical Review Letters
Issue number22
StatePublished - 2003


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