Abstract
We report the investigation of the influence of periodic metallic arrays on the emission properties of organic emitters. Beforehand, the study of the coupling process between nanoparticles through the analysis of the extinction spectra related to Rayleigh anomalies indicate the crucial role of those latter in defining the nature of the excited grating modes. The obtained results emphasis that Rayleigh Anomalies can be considered as the intermediate between individual plasmonic and collective photonic responses. Thereafter, the experimental and numerical studies of the lattice modes and their associated effects on the lifetime and emission directivity of nearby emitters indicate that tuning the geometrical grating parameters offers a possibility to select a particular coupling process from a localized effect to a far field response. Depending on the coupling strength, the emission can be strongly altered by increasing the density of states or providing diffractive orders. Eventually, this study reports that the Rayleigh Anomalies play the role of an excitation source which drives the nanoparticles to act as a set of diffractive objects for shaping the emission to be highly directive.
Highlights
We report the investigation of the influence of periodic metallic arrays on the emission properties of organic emitters
The aim of our work is to study the role of Rayleigh Anomalies (RA) in the coupling process between Ag-NPs in periodic grating and their influence on the optical properties of nearby organic molecules
The typical device studied consists of a substrate of glass covered by a thin layer of an indium-tin oxide (ITO) of 140 nm thickness, on which a square array of silver nano-cylinders, with a diameter of 100 nm and a height of 35 nm, spatially extended on an area of 50 × 50 μm, is fabricated and uniformly covered by a passive thin organic layer of 100 nm 4,4′,4′′-Tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA)
Summary
We report the investigation of the influence of periodic metallic arrays on the emission properties of organic emitters. Nanoparticle arrays exhibit Rayleigh anomalies[11], which are associated to a diffractive phenomenon at a grazing angle in the plane of the structure They appear on the extinction spectra as sharp peaks, and depend on the angle of the incident wave, the index of the surrounding medium and the grating p eriod[11,12]. When the lattice constant is chosen comparable to λRA, the structures sustain the socalled surface lattice resonances (SLR), mixed modes sharing both plasmonic (LSPR) and photonic p roperties[13] These SLR are long living modes, delocalized on several grating cells. The presence of the Rayleigh Anomalies in the structure appears to be a necessary condition to excite the SLR modes At these specific wavelengths, NPs participate to collective diffraction phenomena where the energy is distributed in the plane of the array. These excited SLR modes have been described as mixed modes of localized plasmons vibrations combined with diffracted grazing w aves[15]
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