Plasmon–Exciton Interactions: Spontaneous Emission and Strong Coupling

Abstract

The extraordinary optical properties of surface plasmons in metal nanostructures provide the possibilities to enhance and accelerate the spontaneous emission, and manipulate the decay and emission processes of quantum emitters. The extremely small mode volume of plasmonic nanocavities also benefits the realization of plasmon-exciton strong coupling. Here, the progress on the study of plasmon modified spontaneous emission and plasmon-exciton strong coupling are reviewed. The fundamentals of surface plasmons and quantum emitters, and the methods for assembling coupling systems of plasmonic nanostructures and quantum emitters are first introduced. Then the major aspects of plasmon modified spontaneous emission, including emission intensity, lifetime, spectral profile, direction, polarization, and energy transfer are reviewed. The coupling of quantum emitters and plasmonic waveguides is then discussed. Next, the developments of strong coupling between plasmonic structures and various quantum emitters are reviewed. Finally a few applications are highlighted followed by conclusions and outlook.

Plasmon-Enhanced Peroxidase-like Activity of Nitrogen-Doped Graphdiyne Oxide Quantum Dots/Gold–Silver Nanocage Heterostructures for Antimicrobial Applications

“…Heterojunction nanomaterials constructed using assembled single components demonstrate collective performance derived from the material combination, which exhibit great potential as multifunctional theranostic nanomedicines . In recent years, carbon-based quantum dots (CQDs), as a “zero-dimension” carbon nanomaterial, have drawn tremendous attention in the nanozyme-based therapeutics, especially for graphdiyne-based quantum dots (GDQDs), ,− which possess adaptable band gap (0.14–1.22 eV), high carrier mobility (10 4 –10 5 cm 2 V –1 s –1 ), well-distributed triangular pores, and high photostability, making it an ideal nanozyme with the property of strong coupling. − Localized surface plasmon resonance (LSPR) has been proposed as an effective strategy to improve reaction efficiency. − LSPR refers to the collective oscillation behavior of free electrons in plasmonic metals (Ag, Au, etc. ), as the frequency of incident photons matches the frequency of electron oscillation.…”

Strong Coupling in a Hybrid System of Silver Nanoparticles and J-Aggregates at Room Temperature

“…Thus, the results confirm that the observed splitting is in fact because of a strong coupling and agree with previous studies. 84−86 When the MB concentration exceeds 1.5 × 10 −6 mol/L, the magnitude no longer increases, but decreases, and the thickness of the MB also decreases, which is due to the new kind of dimer exciton that forms at a high MB concentration, 65,87,88 leading to the decreasing numbers of MB monomers that are involved in strong coupling. The maximum magnitude is achieved, and the corresponding concentration threshold is about 1.5 × 10 −6 mol/L.…”

Photoluminescence Properties of Gold Nanorod and J-Aggregate Hybrid Systems Studied by Scanning Near-Field Optical Microscopy

“…Collective oscillations of free electrons in metal nanostructures, known as plasmons, have attracted much attention due to their unique optical properties. , Plasmons interact with molecules in the vicinity of the structure. , Strength of the interaction is correlated to the energy exchange rate between the plasmon and excited state of the molecule. − As the exchange rate is faster than the energy dissipation rate, strong coupling occurs, and optical properties of the interacting system are substantially modulated. In this case, the electronic states of the plasmon and the molecule are strongly coupled and split into high- and low-energy coupled states compared to the original states.…”