Coupling Emitters and Silver Nanowires to Achieve Long-Range Plasmon-Mediated Fluorescence Energy Transfer

Abstract

The development of quantum plasmonic circuitry requires efficient coupling between quantum emitters and plasmonic waveguides. A major experimental challenge is to simultaneously maximize the surface plasmon propagation length, the coupling efficiency into the plasmonic mode, and the Purcell factor. Addressing this challenge is also the key to enabling long-range energy transfer between quantum nanoemitters. Here, we use a dual-beam scanning confocal microscope to carefully investigate the interactions between fluorescent nanoparticles and surface plasmons on single-crystalline silver nanowires. By exciting the fluorescent nanoparticles via nanowire surface plasmons, we maximize the light-matter interactions and reach coupling efficiencies up to 44% together with 24× lifetime reduction and 4.1 μm propagation lengths. This improved optical performance enables the demonstration of long-range plasmon-mediated fluorescence energy transfer between two nanoparticles separated by micrometer distance. Our results provide guidelines toward practical realizations of efficient long-range fluorescence energy transfer for integrated plasmonics and quantum nano-optics.

Extending Single-Molecule Förster Resonance Energy Transfer (FRET) Range beyond 10 Nanometers in Zero-Mode Waveguides

“…This is a pure signature of FRET, highlighting the fundamental difference with far-field radiative energy transfer. [53][54][55][56][57] In a second set of experiments, we investigate dsDNA constructs with 10.2 nm D-A separation ( Fig. 3b,d).…”

Correlated blinking of fluorescent emitters mediated by single plasmons

“…In the meantime, experimental observations of plasmon-assisted energy transfer have so far involved ensembles of fluorescent emitters [12][13] [14].…”

A Self‐Assembled Plasmonic Substrate for Enhanced Fluorescence Resonance Energy Transfer

“…Previous single‐molecule imaging of EGFR dimerization has shown that there was only a 5% possibility to detect Cy3/Cy5 FRET for a single spot . Here we have observed brighter FRET signal and enhanced FRET efficiency on a plasmonic substrate, suggesting that a plasmonic substrate is especially advantageous when the FRET pair is separated by a relatively large distance, because the introduction of a plasmonic nanostructure near the FRET pair may increase the Förster distance . The self‐assembled plasmonic substrates, coupled with new fluorescence imaging technologies and introduction of emerging nanoscale fluorophores, opens the possibility for FRET imaging of live cells with improved temporal and spatial resolution …”

“…[14][15][16][17][18][19] Single-particle experiments have suggested that the FRET channel is turned on when the LSPR of plasmonic nanocrystal lies between the emission peak of the donor and absorption peak of the acceptor or right at the emission wavelength of the acceptor, and is turned off, while the LSPR is at the emission wavelength of the donor. [20] Both theoretical and experimental studies have found that the plasmonfluorophore interactions increase the Förster distance (the distance where the possibility of energy transfer is 50%), [21][22][23][24] modify FRET efficiency, [21,[25][26][27] and enable forbidden Förster dipole-dipole energy transfer by the strongly inhomogeneous local fields. [28] Despite these advantages incurred by plasmon modulation, there is still no planar plasmonic substrate available to serve as a universal platform for tailored on-surface FRET enhancement, which is highly desirable for biosensing, optical imaging, and solar energy conversion applications.…”

“…[52] Here we have observed brighter FRET signal and enhanced FRET efficiency on a plasmonic substrate, suggesting that a plasmonic substrate is especially advantageous when the FRET pair is separated by a relatively large distance, because the introduction of a plasmonic nanostructure near the FRET pair may increase the Förster distance. [21][22][23][24] The self-assembled plasmonic substrates, coupled with new fluorescence imaging technologies and introduction of emerging nanoscale fluorophores, opens the possibility for FRET imaging of live cells with improved temporal and spatial resolution. [2] In conclusion, we have developed a new approach to preparing high-performance plasmonic substrates for efficient fluorescence enhancement across a broad spectral range, in particular for FRET, based on interfacial self-assembly of PDAcoated plasmonic nanocrystals.…”