Broadband optical transparency in plasmonic nanocomposite polymer films via exciton-plasmon energy transfer.

R Dhama,A R Rashed,G Strangi,A De Luca,M El Kabbash,V Caligiuri

doi:10.1364/oe.24.014632

Abstract

Inherent absorptive losses affect the performance of all plasmonic devices, limiting their fascinating applications in the visible range. Here, we report on the enhanced optical transparency obtained as a result of the broadband mitigation of optical losses in nanocomposite polymeric films, embedding core-shell quantum dots (CdSe@ZnS QDs) and gold nanoparticles (Au-NPs). Exciton-plasmon coupling enables non-radiative energy transfer processes from QDs to metal NPs, resulting in gain induced transparency of the hybrid flexible systems. Experimental evidences, such as fluorescence quenching and modifications of fluorescence lifetimes confirm the presence of this strong coupling between plexcitonic elements. Measures performed by means of an ultra-fast broadband pump-probe setup demonstrate loss compensation of gold NPs dispersed in plastic network in presence of gain. Furthermore, we compare two films containing different concentrations of gold NPs and same amount of QDs, to investigate the role of acceptor concentration (Au-NPs) in order to promote an effective and efficient energy transfer mechanism. Gain induced transparency in bulk systems represents a promising path towards the realization of loss compensated plasmonic devices.

Highlights

Nanoplasmonics enables attractive optical properties and various interdisciplinary applications based on localized surface plasmon resonances (LSPRs), defined as resonant collective free electrons oscillations of metallic nanostructures with incident electromagnetic waves
It is well known that negative real permittivity, an essential condition for realization of metamaterials is always accompanied with a large positive value of imaginary permittivity which diminishes figure of merit FOM = Re[ε(ω)]/Im[ε(ω)] and leads to strong absorptive losses in the plasmonic systems, making plasmonic devices inefficient in the optical range and impossible to harness most of their fascinating properties for real life applications [20, 21]
Hybrid nanocomposite polymer films are fabricated by starting from the synthesis of Oleylamine (OA-) coated Au-NPs and CdSe@ZnS QDs of 11 nm and 3 nm in diameter, respectively, following the methods reported in references [30, 31]

Summary

Introduction

Nanoplasmonics enables attractive optical properties and various interdisciplinary applications based on localized surface plasmon resonances (LSPRs), defined as resonant collective free electrons oscillations of metallic nanostructures with incident electromagnetic waves. It is well known that negative real permittivity, an essential condition for realization of metamaterials is always accompanied with a large positive value of imaginary permittivity which diminishes figure of merit FOM = Re[ε(ω)]/Im[ε(ω)] and leads to strong absorptive losses in the plasmonic systems, making plasmonic devices inefficient in the optical range and impossible to harness most of their fascinating properties for real life applications [20, 21]. Battling these absorptive losses will trace the future of nanophotonics and metamaterials. Gain-plasmon interaction must be investigated in a solid, chemically inert and optical transparent host in order to design low loss plasmonic devices and to envisage novel technological ideas

Methods

Results

Conclusion