We obtain a convergent power series expansion for the first branch of the dispersion relation for sub-wavelength plasmonic crystals consisting of plasmonic rods with frequency-dependent dielectric permittivity embedded in a host medium with unit permittivity. The expansion parameter is η=kd =2φdλ, where k is the norm of a fixed wavevector, d is the period of the crystal and λ is the wavelength, and the plasma frequency scales inversely to d, making the dielectric permittivity in the rods large and negative. The expressions for the series coefficients (also called dynamic correctors) and the radius of convergence in η are explicitly related to the solutions of higher order cell problems and the geometry of the rods. Within the radius of convergence, we are able to compute the dispersion relation and the fields and define dynamic effective properties in a mathematically rigorous manner. Explicit error estimates show that a good approximation to the true dispersion relation is obtained using only a few terms of the expansion. The convergence proof requires the use of properties of the Catalan numbers to show that the series coefficients are exponentially bounded in the H1 Sobolev norm. This journal is © 2010 The Royal Society.
Publication Source (Journal or Book title)
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Fortes, S., Lipton, R., & Shipman, S. (2010). Sub-wavelength plasmonic crystals: Dispersion relations and effective properties. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 466 (2119), 1993-2020. https://doi.org/10.1098/rspa.2009.0542