Noble metal nanoparticles patterned in ordered arrays can interact and generate hybrid plasmonic−photonic resonances called surface lattice resonances (SLRs).
Decades ago theorists predicted that arrays of plasmonic nanostructures could interact collectively and generate hybrid plasmonic−photonic resonances far narrower than is possible with single nanoparticles. In these systems, the local surface plasmon resonances (LSPRs) of each particle couple with their neighbors via in-plane diffracted waves called Rayleigh anomalies (RAs). Over time, experimentalists developed nanofabrication and optical measurement tools to observe and study these plasmonic−photonic modes. This phenomenon is now commonly called a plasmonic surface lattice resonance (SLR) or a lattice plasmon. Later these lattice resonances were studied in a wide range of periodic nanostructures with different types of unit cells: single or paired (in a stack) nanodisks, the cylinders with the core-shell structure, dimers, and more complicated configurations. Such the structures have found wide applications in a number of areas, for example, in IR spectroscopy, narrowband light absorption, sensorics, lasers and enhanced fluorescence, just to name a few.
Notoriously that the conventional plasmonic materials are silver and gold, but in these latter days the alternative plasmonic materials such as transparent conductive oxides (AZO, GZO, ITO) and titanium nitride which allows to obtain high-Q modes in the telecommunication band are of great interest. Aluminum plasmonics emerged quite recently. Interest to this material is due to the fact that the plasma frequency of aluminum is higher than a one of silver or gold, allowing to observe the plasmon resonance in the ultraviolet (UV) region of the spectrum. This feature can be used, for example, in photocatalysis and for studying of organic and biological systems that exhibit strong UV absorption. The interest to aluminum in that respect is also due to its relative cheapness and feasibility that opens wide opportunities for manufacturing and mass production in such promising areas as color printing, photovoltaics, thermoplasmonics, holography. The plasmonic properties of Al structures were extensively studied in numerous articles: single nanoparticles with various shapes, dimers, heterodimers, and arrays. Surface lattice resonances (SLRs) with active tuning has been shown to cover wide range of frequencies in Al and used for nonlinear optics, lasers, temperature sensing, photoluminescence, light emission and confinement, quantum electrodynamics, sensor on Al metal film holes. It is evident that practical implementation and design of devices based on periodic arrays requires the understanding both of how the modes of individual particles in the array interact with the lattice modes and how to control the hybrid modes.
The concept of backscattering suppression of light by a single spherical particle has been proposed over three decades ago by Kerker. The Kerker effect can be observed in a variety of nanostructures from high-index constituents with strong electric and magnetic Mie resonances. Necessary requirement for the existence of a magnetic response limits the use of generally non-magnetic conventional plasmonic nanostructures for the Kerker effect. On a larger scale, i.e., in arrays of NPs, the Kerker effect can be implemented via collective lattice resonances (CLRs). Lattice Kerker effect arises due to interaction between lattice modes (i.e., CLRs) and resonances in a single NP, while conventional Kerker effect is based on resonances in a single NP.
We demonstrate for the first time the emergence of the lattice Kerker effect in regular plasmonic Al nanostructures. whereas for single lossy NPs it is in principle impossible to achieve within a framework of dipole approximation. The plasmonic lattice Kerker effect is based on the interference suppression of dominant ED (electric dipole) radiation (with negligible MQ - magnetic quadrupole - impact) by the cumulative contribution of the fields produced by MD (magnetic dipole) and EQ (electric quadrupole) that is introduced in classical electrodynamics.We show that a complete suppression of the backscattering can be tuned within the UV and visible spectral ranges by varying geometry of arrays, i.e. radius of NPs and the distance between them.High absorption and strong electric field localization are observed at the frequency which corresponds to the lattice Kerker effect.
