Guiding Light in Monolayers of Sparse and Random Plasmonic Meta-atoms

Encouraged by the capacity of surface plasmons to confine and propagate electromagnetic fields, waveguiding concepts have been developed, including combinations of continuous metal films or ordered arrays of metal nanoparticles. So far, waveguiding in the latter systems has been based on near-field or diffractive coupling. Herein, we show that monolayers of sparse and disordered gold nanoparticles support a novel transverse-electric guided mode that, contrary to previous work, relies on the strong enhancement of the polarizability upon excitation of the nanoparticle LSPR, creating an effective refractive index sufficiently high to support light guidance over a large range of frequencies. Excitation of this guided mode offers interesting nanophotonics features and applications such as a tunable total absorption spectral band, attractive for light harvesting applications, or the generation of a large amplification of the sensitivity to changes of refractive index accompanied with striking enhancement of the limit of detection in real biosensing experiments. © 2011 American Chemical Society.This work was done with financial support from MULTIBIOPLAS of the Spanish Ministry of Science and Innovation (TEC2009-08729), the M. Botín Foundation, and EU MC2Access program. M. A. Otte acknowledges the “Programa de Formación de Profesorado Universitario (FPU)” of the Spanish Ministry of Education; B. Sepúlveda acknowledges the “Ramón and Cajal” program from Spanish Ministry of Science and Innovation for financial support; and David Regatos acknowledges financial support from “Programa de Formación de Investigadores del Departamento de Educación, Universidades e Investigación” of the Gobierno Vasco (Spain).Peer Reviewe