Theory of tailorable optical response of two-dimensional arrays of plasmonic nanoparticles at dielectric interfaces

Abstract

Two-dimensional arrays of plasmonic nanoparticles at interfaces are promising candidates for novel optical metamaterials. Such systems materialise from ‘top–down’ patterning or ‘bottom–up’ self-assembly of nanoparticles at liquid/liquid or liquid/solid interfaces. Here, we present a comprehensive analysis of an extended effective quasi-static four-layer-stack model for the description of plasmon-resonance-enhanced optical responses of such systems. We investigate in detail the effects of the size of nanoparticles, average interparticle separation, dielectric constants of the media constituting the interface, and the nanoparticle position relative to the interface. Interesting interplays of these different factors are explored first for normally incident light. For off-normal incidence, the strong effects of the polarisation of light are found at large incident angles, which allows to dynamically tune the reflectance spectra. All the predictions of the theory are tested against full-wave simulations, proving this simplistic model to be adequate within the quasi-static limit. The model takes seconds to calculate the system’s optical response and makes it easy to unravel the effect of each system parameter. This helps rapid rationalization of experimental data and understanding of the optical signals from these novel ‘metamaterials’, optimised for light reflection or harvesting.

An electro-tunable Fabry–Perot interferometer based on dual mirror-on-mirror nanoplasmonic metamaterials

“…The frames shown in the middle of the insulating cavity side walls act as the negatively polarized electrodes. reflection scheme [32,41]. The relative permittivities of layers 1 and 9, representing the media through which light enters and exits the FPI device, are denoted by ε 1 and ε 9 , respectively.…”

Electrochemical plasmonic metamaterials: towards fast electro-tuneable reflecting nanoshutters

“…This shows how closely DL model can reproduce the experimentally measured values of permittivity of both gold and ITO over the range of optical wavelengths (λ) of interest. For the system under study, we estimate the optical response from a layer of subwavelength NPs using our quasi-static effective medium theory 10,11 . First we describe the quasi-static polarizability of a cuboid of dimensions L x x L y x L z (for incident light polarized along one of its three axes) as 16…”

“…This term refers to plasmonic metasystems based on electrode/electrolyte interfaces, solid-liquid or liquid-liquid 1 , which involve adsorption-desorption of plasmonic nanoparticles from the solution to the interface, tuned by variation of electrode potential and controlled by electrolyte concentration and pH of the solution. It has been predicted theoretically and shown experimentally, that rearrangements of such nanoparticles -from dispersion in the bulk to formation of arrays at the interface, may dramatically change optical properties of the interface 10 , be it mirror-window switching 2 , tuneable colour mirrors 11 , or SERS sensors 12 . One can read more about the progress in this area in recent review articles 1 .…”

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“…To the day, there is a number of well-established numerical procedures and theoretical models which allow to calculate electromagnetic properties of NPs embedded in half-space [15,16] or stratified media [17][18][19][20].…”