Silver Nanoshell Plasmonically Controlled Emission of Semiconductor Quantum Dots in the Strong Coupling Regime

Abstract

Strong coupling between semiconductor excitons and localized surface plasmons (LSPs) giving rise to hybridized plexciton states in which energy is coherently and reversibly exchanged between the components is vital, especially in the area of quantum information processing from fundamental and practical points of view. Here, in photoluminescence spectra, rather than from common extinction or reflection measurements, we report on the direct observation of Rabi splitting of approximately 160 meV as an indication of strong coupling between excited states of CdSe/ZnS quantum dots (QDs) and LSP modes of silver nanoshells under nonresonant nanosecond pulsed laser excitation at room temperature. The strong coupling manifests itself as an anticrossing-like behavior of the two newly formed polaritons when tuning the silver nanoshell plasmon energies across the exciton line of the QDs. Further analysis substantiates the essentiality of high pump energy and collective strong coupling of many QDs with the radiative dipole mode of the metallic nanoparticles for the realization of strong coupling. Our finding opens up interesting directions for the investigation of strong coupling between LSPs and excitons from the perspective of radiative recombination under easily accessible experimental conditions.

Strong Plasmon-Wannier Mott Exciton Interaction with High Aspect Ratio Colloidal Quantum Wells

“…However, due to the relatively low exciton binding energy, imperfectly matched exciton dipole orientation with respect to electric field distribution, and fast non-radiative dissipative dynamics (i.e., Fö rster resonance energy transfer [FRET]) in a dense film, the Rabi splitting energy observed in a CQW-metal system is only 110 meV, even smaller than the value reported in colloidal quantum dots (up to 160 meV). 17,37 Generally, Rabi splitting energy ðZUÞ is in accordance with ZU = 2gf ffiffiffiffiffiffiffiffiffiffiffi ffi fN=V p , 12,13 where g is the coupling strength, f is the oscillation strength of the exciton, V is the optical mode volume, and N is the saturated concentration of excitons involved in strong coupling. Here, to achieve ultra-strong exciton-plasmon interaction, we utilize the high aspect ratio colloidal quantum wells (HARCQWs) with one lateral size tailored down to $6 nm (the exciton Bohr radius in CdSe, $ 5.7 nm) 38 as the exciton source.…”

Enhanced photoluminescence of silicon quantum dots in the presence of both energy transfer enhancement and emission enhancement mechanisms assisted by the double plasmon modes of gold nanorods

“…Noble metal nanoparticles have received extensive attention due to their unique surface plasmon effect. Surface plasmon resonance in metal nanoparticles is a collective oscillation of free electrons, resulting in the nanoscale confinement of electromagnetic fields near the metal surface 13-16. It has a series of novel optical properties, which have been widely employed to study the interactions between plasmons and illuminants, such as fluorescence enhancement, [17][18][19][20][21][22][23] realization of a nanolaser [24][25][26] and FRET regulation. [27][28][29][30] The energy transfer efficiency between silicon quantum dots is relatively low for its shortcomings mentioned above.…”

Numerical Study of Novel Ratiometric Sensors Based on Plasmon–Exciton Coupling

“…The strong interaction between LSPR and emitter leads to plasmon-exciton states behaving like vacuum Rabi splitting, i.e., splitting of energy levels and change of peak positions. 14,33,[35][36][37][40][41][42] There are three models to describe the strong coupling between plasmon and exciton, namely, classical, semi-classical, and quantum description. Mie's theory describes light as a classical field and uses the refractive index to account for the material properties based on Maxwell's theory.…”