Abstract

A chain of metallic particles, of sufficiently small diameter and spacing, allows linearly polarized plasmonic waves to propagate along the chain. In this paper, we consider how these waves are altered when the host is a nematic or cholesteric liquid crystal (NLC or CLC). In an NLC host, with the principal axis (director) oriented either parallel or perpendicular to the chain, we find that the dispersion relations of both the longitudinal ($L$) and transverse ($T$) modes are significantly altered relative to those of an isotropic host. Furthermore, when the director is perpendicular to the chain, the doubly degenerate $T$ branch is split into two nondegenerate linearly polarized branches by the anisotropy of the host material. In a CLC liquid crystal with a twist axis parallel to the chain, the two $T$ branches are again found to be split, but are no longer linearly polarized; the dispersion relations depend on the cholesteric pitch angle. To illustrate these results, we calculate the $L$ and $T$ dispersion relations for both types of liquid crystals, assuming that the metal is described by a Drude dielectric function. The formalism can, in principle, include single-particle damping and could be generalized to include radiation damping. The present work suggests that the dispersion relations of plasmonic waves on a chain of nanoparticles can be controlled by immersing the chain in an NLC or a CLC and varying the director axis or pitch angle by applying suitable external fields.

© 2013 Optical Society of America

Dispersion relations in metal nanoparticle chains: necessity of the multipole approach

Brice Rolly, Nicolas Bonod, and Brian Stout
J. Opt. Soc. Am. B 29(5) 1012-1019 (2012)

Waveguiding properties of short linear chains of nonspherical metal nanoparticles

Ilia L. Rasskazov, Sergei V. Karpov, and Vadim A. Markel
J. Opt. Soc. Am. B 31(12) 2981-2989 (2014)

Complex dispersion relation of a double chain of lossy metal nanoparticles

Massimiliano Guasoni and Matteo Conforti
J. Opt. Soc. Am. B 28(5) 1019-1025 (2011)

Experimental measurement of the dispersion relations of the surface plasmon modes of metal nanoparticle chains

K. B. Crozier, E. Togan, E. Simsek, and T. Yang
Opt. Express 15(26) 17482-17493 (2007)

Localized optical modes in a defect-containing liquid-crystal structure adjacent to the metal

Maxim V. Pyatnov, Stepan Ya. Vetrov, and Ivan V. Timofeev
J. Opt. Soc. Am. B 34(9) 2011-2017 (2017)