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Collective strong light-matter coupling in hierarchical microcavity-plasmon-exciton systems
摘要： Polaritons are compositional light-matter quasiparticles that arise as a result of strong coupling between the vacuum field of a resonant optical cavity and electronic excitations in quantum emitters. Reaching such a regime is often hard, as it requires materials possessing high oscillator strengths to interact with the relevant optical mode. Two-dimensional transition metal dichalcogenides (TMDCs) have recently emerged as promising candidates for realization of strong coupling regime at room temperature. However, these materials typically provide coupling strengths in the range of 10-40 meV, which may be insufficient for reaching strong coupling with low quality factor resonators. Here, we demonstrate a universal scheme that allows a straightforward realization of strong coupling with 2D materials and beyond. By intermixing plasmonic excitations in nanoparticle arrays with excitons in a WS2 monolayer inside a resonant metallic microcavity, we fabricate a hierarchical system with the collective microcavity-plasmon-exciton Rabi splitting exceeding ~500 meV at room temperature. Photoluminescence measurements of the coupled systems show dominant emission from the lower polariton branch, indicating the participation of excitons in the coupling process. Strong coupling has been recently suggested to affect numerous optical- and material-related properties including chemical reactivity, exciton transport and optical nonlinearities. With the universal scheme presented here, strong coupling across a wide spectral range is within easy reach and therefore exploring these exciting phenomena can be further pursued in a much broader class of materials.
关键词： TMDC,Strong plasmon-exciton coupling,collective Rabi splitting,monolayer WS2
更新于2025-09-23 15:21:21
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Monitoring strong coupling in nonlocal plasmonics with electron spectroscopies
摘要： Plasmon-exciton polaritons provide exciting possibilities to control light-matter interactions at the nanoscale by enabling closer investigation of quantum optical effects and facilitating novel technologies based, for instance, on Bose-Einstein condensation and polaritonic lasing. Nevertheless, observing and visualizing polaritons is challenging, and traditional optical microscopy techniques often lead to ambiguities regarding the emergence and strength of the plasmon-exciton coupling. Electron microscopy offers a more robust means to study and verify the nature of plexcitons, but it is still hindered by instrument limitations and resolution. A simple theoretical description of electron beam-excited plexcitons is therefore vital to complement ongoing experimental efforts. Here we apply analytic solutions for the electron-loss and photon-emission probabilities to evaluate plasmon-exciton coupling studied either with the recently adopted technique of electron energy-loss spectroscopy, or with the so-far unexplored in this context cathodoluminescence spectroscopy. Foreseeing the necessity to account for quantum corrections in the plasmonic response, we extend these solutions within the framework of general nonlocal hydrodynamic descriptions. As a specific example, we study core-shell spherical plasmon-molecule hybrids, going beyond the standard local-response approximation through the hydrodynamic Drude model for screening and the generalized nonlocal optical response theory for nonlocal damping. We show that electron microscopies are extremely powerful in describing the interaction of emitters with the otherwise weakly excited by optical means higher-order plasmonic multipoles, a response that survives when quantum-informed models are considered. Our work provides, therefore, both a robust theoretical background and supporting argumentation to the open quest for improving and further utilizing electron microscopies in strong-coupling nanophotonics.
关键词： electron energy-loss spectroscopy,nonlocal hydrodynamic descriptions,cathodoluminescence spectroscopy,quantum plasmonics,Plasmon-exciton polaritons
更新于2025-09-23 15:19:57
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Effects of near-field electromagnetic coupling in dimers of nanoparticles with a silver core and a J-aggregate dye shell
摘要： We report a theoretical study of the plasmon – exciton coupling effect on the absorption spectra of pairs of closely spaced double-layer hybrid nanoparticles consisting of a metallic core and a J-aggregate dye shell. The effect of frequency conversion of plasmonic lines due to the near-field interaction between plasmons and Frenkel excitons of the organic shell is demonstrated. The effect leads to the appearance of additional spectral lines in the long-wavelength part of the spectrum of the system of hybrid particles. The shapes and the relative intensities of the additional lines exactly reproduce the specific features of the original spectrum of plasmonic absorption bands in uncoated metallic nanoparticles. The discovered phenomenon can be used to design new types of high-sensitivity nanosensors, based on plasmon – exciton effects and principles of near-field optics.
关键词： near-field electromagnetic coupling,nanophotonics,Frenkel excitons,dimers of metalorganic nanoparticles,plasmon – exciton interaction,molecular J-aggregates,localised plasmons,absorption spectra
更新于2025-09-19 17:15:36
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Colloidal Assembly of Aua??Quantum Dota??Au Sandwiched Nanostructures with Strong Plasmona??Exciton Coupling
摘要： Strong plasmon-exciton coupling could occur in hybrid metal-dye/semiconductor nanostructures, where the fast energy exchange between plasmons and excitons leads to two new eigenmodes of the system, known as Rabi splitting. In experiment, strongly coupled nanosystems are difficult to obtain because they require some strict conditions, such as low plasmonic damping, small plasmon mode volume, and good spectral overlap. This work demonstrates strongly coupled metal-semiconductor nanostructures can be constructed using colloidal assembly. Specifically, sandwiched Au-QD-Au nanostructures were created through the assembly of Au nanoparticles and colloidal quantum dots (QDs). The sizes of the QDs and the assembly conditions were varied to control the mode volume of the plasmonic cavity formed between the two Au nanoparticles. With decreased gap size, Rabi splitting was observed in both dark-field scattering and fluorescence spectra of single Au-QD-Au nanostructures. Theoretical simulations revealed that the strong coupling occurred between the excitons and the octupolar plasmon modes.
关键词： Au-QD-Au nanostructures,Rabi splitting,octupolar plasmon modes,plasmon-exciton coupling,colloidal assembly
更新于2025-09-19 17:13:59
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Plasmon-Enhanced Fluorescence in Gold Nanorod-Quantum Dot Coupled Systems
摘要： Plasmon-exciton coupling is of great importance to many optical devices and applications. One of the coupling manifestations is plasmon-enhanced fluorescence. Although this effect is demonstrated in numerous experimental and theoretical works, there are different particle shapes for which this effect is not fully investigated. In this work electrostatic complexes of gold nanorods and CdSe/CdZnS quantum dots were studied. Double-resonant gold nanorods have an advantage of the simultaneous enhancement of the absorption and emission when the plasmon bands match the excitation and fluorescence wavelengths of an emitter. A relationship between the concentration of quantum dots in the complexes and the enhancement factor was established. It was demonstrated that the enhancement factor is inversely proportional to the concentration of quantum dots. The maximal fluorescence enhancement by 10.8 times was observed in the complex with the smallest relative concentration of 2.5 quantum dots per rod and approximately 5 nm distance between them. Moreover, the influence of quantum dot location on the gold nanorod surface plays an important role. Theoretical study and experimental data indicate that only the position near the nanorod ends provides the enhancement. At the same time, the localization of quantum dots on the sides of the nanorods leads to the fluorescence quenching.
关键词： quantum dot fluorescence,gold nanorod-quantum dot complexes,plasmon-enhanced fluorescence,plasmon-exciton coupling,gold nanorods
更新于2025-09-11 14:15:04
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Prospects and applications of plasmon-exciton interactions in the near-field regime
摘要： Plasmonics is a rapidly developing field at the boundary of fundamental sciences and device engineering, which exploits the ability of metal nanostructures to concentrate electromagnetic radiation. The principal challenge lies in achieving an efficient conversion of the plasmon-concentrated field into some form of useful energy. To date, a substantial progress has been made within the scientific community in identifying the major pathways of the plasmon energy conversion. Strategies based on the hot electron injection and the near-field energy transfer have already shown promise in a number of proof-of-principle plasmonic architectures. Nevertheless, there are several fundamental questions that need to be addressed in the future to facilitate the transition of plasmonics to a variety of applications in both light amplification and optical detection. Of particular interest is a plasmon-induced resonance energy transfer (PIRET) process that couples the plasmon evanescent field to a semiconductor absorber via dipole-dipole interaction. This relatively unexplored mechanism has emerged as a promising light conversion strategy in the areas of photovoltaics and photocatalysis and represents the main focus of the present minireview. Along these lines, we highlight the key advances in this area and review some of the challenges associated with applications of the PIRET mechanism in nanostructured systems.
关键词： plasmon-exciton,PIRET,plasmonics,plasmon
更新于2025-09-09 09:28:46
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Fluorescent Metal-Semiconductor Hybrid Structures by Ultrasound-Assisted In-Situ Growth of Gold Nanoparticles on Silica-Coated CdSe-Dot/CdS-Rod Nanocrystals
摘要： Gold nanocrystals (AuNCs) were grown on the surface of silica coated CdSe-dot/CdS-rod core/shell nanocrystals by reduction of Au3+ ions in polyethylene glycol under ultrasonic irradiation. The polyethylene glycol not only prevents the penetration of gold ions or precursor molecules into the silica shell, but it also acts as the reducing agent for Au3+ ions. The silica shell’s surface promotes the heterogeneous nucleation of gold nanocrystals, while the ultrasonic irradiation accelerates and enhances the gold nucleation on the silica surface, and ensures the formation of AuNCs with a relatively narrow size distribution. The plasmon-exciton interaction in these metal-semiconductor hybrid systems leads to decreased fluorescence lifetimes and strongly reduced fluorescence blinking of individual hybrid structures.
关键词： ultrasonic irradiation,Gold nanocrystals,CdSe-dot/CdS-rod nanocrystals,plasmon-exciton interaction,polyethylene glycol
更新于2025-09-09 09:28:46
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Control of electromagnetically induced grating by surface plasmon and tunneling in a hybrid QD-MNP system
摘要： We investigate the electromagnetically induced grating (EIG) in a quantum dot-metal nanoparticle (QD-MNP) hybrid system. The EIG can be controlled and improved by the surface plasmon effect and the interdot tunneling effect between quantum dots. By manipulating the tunneling effect and the QD-MNP distance, not only the first-order diffraction intensity of the grating can be efficiently enhanced, but also the EIG can be switched from the absorption grating to the gain grating. Almost two times of the first-order diffraction efficiencies can be achieved in the gain gratings compared with the absorption gratings.
关键词： electromagnetically induced grating,dot-metal nanoparticle,electromagnetically induced transparency,plasmon-exciton effect,tunneling
更新于2025-09-04 15:30:14