Percolating plasmonic networks for light emission control

Abstract

Optical nanoantennas have revolutionised the way we manipulate single photons emitted by individual light sources in a nanostructured photonic environment. Complex plasmonic architectures allow for multiscale light control by shortening or stretching the light wavelength for a fixed operating frequency, meeting the size of the emitter and that of propagating modes. Here, we study self-assembled semi-continuous gold films and lithographic gold networks characterised by large local density of optical state (LDOS) fluctuations around the electrical percolation threshold, a regime where the surface is characterised by large metal clusters with fractal topology. We study the formation of plasmonic networks and their effect on light emission from embedded fluorescent probes in these systems. Through fluorescence dynamics experiments we discuss the role of global long-range interactions linked to the degree of percolation and to the network fractality, as well as the local near-field contributions coming from the local electro-magnetic fields and the topology. Our experiments indicate that local properties dominate the fluorescence modification.

Random matrix approach to plasmon resonances in the random impedance network model of disordered nanocomposites

“…Predictions of the considered model are in qualitative agreement with the results of recent experiments with lithographic networks [55] and disordered nanocomposite films [56]. In particular, experimentally measured Purcell enhancement and absorption spectra demonstrate the presence of a broad maximum whose width depends on the metal filling p, as well as the presence of an optimal filling which maximizes the absorption band.…”

Enhancement of two-photon photoluminescence and SERS for low-coverage gold films

“…After all, the main requirements for SERS substrates are not only high reproducibility and robust fabrication procedure, but also large-area homogeneity, low cost, and possibility for mass production. One route for the fabrication of large-area structures with "hot spots" could be realized with the semi-continuous metallic films [27][28][29]. These films can be obtained by evaporation of noble metals like gold or silver onto a dielectric or semiconductor substrate.…”

Probing Extended Modes on Disordered Plasmonic Networks by Wavefront Shaping

“…[16][17][18] Disordered semicontinuous metal films, in particular, exhibit intrinsic optical properties that strongly differ from those of bulk metals or ensembles of single nanoparticles, such as broadband absorption [19][20][21] and giant field fluctuations. [22][23][24] Previous experimental work has tried to quantify the spatial extent of these modes in the near-field, [25][26][27][28][29][30][31] where non radiative components (dark modes) dominate over radiative ones (bright modes).…”