We investigate the conditions yielding plasmon-exciton strong coupling at the single emitter level in the gap between two metal nanoparticles. A quasi-analytical transformation optics approach is developed that makes possible a thorough exploration of this hybrid system incorporating the full richness of its plasmonic spectrum. This allows us to reveal that by placing the emitter away from the cavity center, its coupling to multipolar dark modes of both even and odd parity increases remarkably. This way, reversible dynamics in the population of the quantum emitter takes place in feasible implementations of this archetypal nanocavity.
Single-walled carbon nanotubes (SWCNTs) are promising absorbers and emitters to enable novel photonic and optoelectronic applications but are also known to severely suffer from low optical quantum yields. Here we demonstrate SWCNTs excitons coupled to plasmonic nanocavities reaching deeply into the Purcell regime with FP=234 (average FP=76), near unity quantum yields of 70% (average 41%), and a photon emission rate of 1.7 MHz into the first lens. The measured ultra-narrow exciton linewidth (18 micro eV) implies furthermore generation of indistinguishable single photons from a SWCNT. To demonst…
We discuss coupling of site-selectively induced quantum emitters in exfoliated monolayers of WSe$_2$ to plasmonic nanostructures. Squared and rectangular gold nanopillars, which are arranged in pitches of \SI{4}{\micro\meter} on the surface, have sizes of tens of nanometers, and act as seeds for the formation of quantum emitters in the atomically thin materials. We observe chraracteristic narrow-band emission signals from the monolayers, which correspond well with the positions of the metallic nanopillars with and without thin dielectric coating. Single photon emission from the emitters is con…
Atomically thin semiconductors can be readily integrated into a wide range of nanophotonic architectures for applications in quantum photonics and novel optoelectronic devices. We report the observation of nonlocal interactions of \textit{free} trions in pristine hBN/MoS$_2$/hBN heterostructures coupled to single mode (Q $>10^4$) quasi 0D nanocavities. The high excitonic and photonic quality of the interaction system stems from our integrated nanofabrication approach simultaneously with the hBN encapsulation and the maximized local cavity field amplitude within the MoS$_2$ monolayer. We observ…
Strong interactions between surface plasmons in ultra-compact nanocavities and excitons in two dimensional materials have attracted wide interests for its prospective realization of polariton devices at room temperature. Here, we propose a continuous transition from weak coupling to strong coupling between excitons in MoS2 monolayer and highly localized plasmons in ultra-compact nanoantenna. The nanoantenna is assembled by a silver nanocube positioned over a gold film and separated by a dielectric spacer layer. We observed a 1570-fold enhancement in the photoluminescence at weak coupling regim…
Controlling light-matter interactions in solid-state systems has motivated intense research to produce bosonic quasi-particles known as exciton-polaritons, which requires strong coupling between excitons and cavity photons. Ultra-low threshold coherent light emitters can be achieved through lasing from exciton-polariton condensates, but this generally requires sophisticated device structures and cryogenic temperatures. Polaritonic nanolasers operating at room temperature lie on the crucial path of related research, not only for the exploration of polariton physics at the nanoscale but also for…
Large coupling strengths in exciton-photon interactions are important for quantum photonic network, while strong cavity-quantum-dot interactions have been focused on s-shell excitons with small coupling strengths. Here we demonstrate strong interactions between cavities and p-shell excitons with a great enhancement by the \textit{in situ} wave-function control. The p-shell excitons are demonstrated with much larger wave-function extents and nonlocal interactions beyond the dipole approximation. Then the interaction is tuned from the nonlocal to local regime by the wave-function shrinking, duri…
Quadrupole topological insulator is a symmetry-protected higher-order topological phase with intriguing topology of Wannier bands, which, however, has not yet been realized in plasmonic metamaterials. Here, we propose a lattice of plasmon-polaritonic nanocavities which can realize quadrupole topological insulators by exploiting the geometry-dependent sign-reversal of the couplings between the daisy-like nanocavities. The designed system exhibits various topological and trivial phases as characterized by the nested Wannier bands and the topological quadrupole moment which can be controlled by t…
Solid-state single-quantum emitters are a crucial resource for on-chip photonic quantum technologies and require efficient cavity-emitter coupling to realize quantum networks beyond the single-node level. Previous approaches to enhance light-matter interactions rely on forming nanocavities around randomly located quantum dots or color centers but lack spatial control of the quantum emitter itself that is required for scaling. Here we demonstrate a deterministic approach to achieve Purcell-enhancement at lithographically defined locations using the sharp corner of a metal nanocube for both elec…
Lasers are ubiquitous for information storage, processing, communications, sensing, biological research, and medical applications [1]. To decrease their energy and materials usage, a key quest is to miniaturize lasers down to nanocavities [2]. Obtaining the smallest mode volumes demands plasmonic nanocavities, but for these, gain comes from only single or few emitters. Until now, lasing in such devices was unobtainable due to low gain and high cavity losses [3]. Here, we demonstrate a plasmonic nanolaser approaching the single-molecule emitter regime. The lasing transition significantly broade…
We develop a non-local dielectric response theory to describe the temperature dependence of exciton lifetime in metal-semiconductor heterostructures. Coupling between excitons and surface plasmons results in a strongly nonmonotonous behaviour of exciton radiative decay rate versus temperature. Tuning the plasmon frequency one can control the efficiency of exciton emission of light.
We study theoretically the interactions of excitonic states with surface electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled carbon nanotubes. We show that these interactions can result in strong exciton-surface-plasmon coupling. The exciton absorption lineshapes exhibit the line (Rabi) splitting $~0.1-0.3$ eV as the exciton energy is tuned to the nearest interband surface plasmon resonance of the nanotube. We expect this effect to open a path to new optoelectronic device applications of semiconducting carbon nanotubes.
We study theoretically the interactions of excitonic states with surface electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled carbon nanotubes. We show that these interactions can result in strong exciton-surface-plasmon coupling. The exciton absorption line shape exhibits Rabi splitting ~0.1 eV as the exciton energy is tuned to the nearest interband surface plasmon resonance of the nanotube. We also show that the quantum confined Stark effect may be used as a tool to control the exciton binding energy and the nanotube band gap in carbon nanotubes in order, e.g., to bri…
Coherent energy exchange between plasmons and excitons is a phenomenon that arises in the strong coupling regime resulting in distinct hybrid states. The DNA-origami technique provides an ideal framework to custom-tune plasmon-exciton nanostructures. By employing this well controlled self-assembly process, we realized hybrid states by precisely positioning metallic nanoparticles in a defined spatial arrangement with fixed nanometer-sized interparticle spacing. Varying the nanoparticle diameter between 30 nm and 60 nm while keeping their separation distance constant allowed us to precisely adju…
We consider the effect of electromagnetic coupling between localized surface plasmons in a metallic nanoparticle (NP) and excitons or weakly interacting electron-hole pairs in a semiconductor matrix where the NP is embedded. An expression is derived for the NP polarizability renormalized by this coupling and two possible situations are analyzed, both compatable with the conditions for Fano-type resonances: (i) a narrow bound exciton transition overlapping with the NP surface plasmon resonance (SPR), and (ii) SPR overlapping with a parabolic absorption band due to electron-hole transitions in t…
Using the ultrafast pump-probe transient absorption spectroscopy, the femtosecond-resolved plasmon-exciton interaction of graphene-Ag nanowire hybrids is experimentally investigated, in the VIS-NIR region. The plasmonic lifetime of Ag nanowire is about 150 femtosecond (fs). For a single layer of graphene, the fast dynamic process at 275 fs is due to the excitation of graphene excitons, and the slow process at 1.4 picosecond (ps) is due to the plasmonic hot electron interaction with phonons of graphene. For the graphene-Ag nanowire hybrids, the time scale of the plasmon-induced hot electron tra…
We use the macroscopic quantum electrodynamics approach suitable for absorbing and dispersing media to study the properties and role of collective surface excitations --- excitons and plasmons --- in single-wall and double-wall carbon nanotubes. We show that the interactions of excitonic states with surface electromagnetic modes in individual small-diameter (<~1 nm) single-walled carbon nanotubes can result in strong exciton-surface-plasmon coupling. Optical response of individual nanotubes exhibits Rabi splitting ~0.1 eV, both in the linear excitation regime and in the non-linear excitation r…
We study the collective, superradiant behavior in the system of emitter-dressed Ag nanorods. Starting from the Drude model for the plasmon oscillations, we arrive at a semi-empirical Hamiltonian describing the coupling between quantized surface plasmon modes and the quantum emitters that can be controlled by manipulating their geometry, spacing, and orientation. Further, identifying the lowest polariton mode as SP-states dressed by excitons in the vicinity of $k=0$, we examine conditions allowing for the polariton quantum phase transition. While the system is formally a 1D array, we show that …
We study strong coupling between plasmons in monolayer charge-doped graphene and excitons in a narrow gap semiconductor quantum well separated from graphene by a potential barrier. We show that the Coulomb interaction between excitons and plasmons result in mixed states described by a Hamiltonian similar to that for exciton-polaritons and derive the exciton-plasmon coupling constant that depends on system parameters. We calculate numerically the Rabi splitting of exciton- plasmariton dispersion branches for several semiconductor materials and find that it can reach values of up to 50 - 100 meV…
Two-dimensional transition metal dichalcogenides (TMDCs) have recently become attractive semiconductor materials for several optoelectronic applications, such as photodetection, light harvesting, phototransistors, light-emitting diodes, and lasers. They are particularly appealing because their bandgap lies in the visible and near-IR range, and they possess strong excitonic resonances, high oscillator strengths, and valley-selective response. Coupling these materials to optical nanocavities enhances the quantum yield of exciton emission, enabling advanced quantum optics and nanophotonic devices…
We propose a system of highly efficient photoemitters comprising metal-dielectric (plasmonic-excitonic) multilayered structures. In the proposed structure, the absorption in the excitonic layer is greatly enhanced through quantum interference between the split modes arising from the coupling of the layered excitons and the plasmons sustained by the metallic layer. Furthermore, the large interaction volume between surface plasmons and excitons causes exciton superradiance, which results in the extremely efficient photoemission. This finding indicates the possibility of designing highly efficien…
Hyperbolic exciton-plasmon polaritons in MoS$_2$/MoOCl$_2$ van der Waals heterostructures
Universidad Politécnica de Madrid（马德里理工大学）；Instituto de Sistemas Optoelectrónicos y Microtecnología, Universidad Politécnica de Madrid（马德里理工大学光电子与微技术研究所）；Departamento de Ingeniería Electrónica, E.T.S.I de Telecomunicación, Universidad Politécnica de Madrid（马德里理工大学电信工程学院电子工程系）
We study theoretically the in-plane electromagnetic response and the exciton-plasmon interactions for an experimentally feasible carbon nanotube (CN) film systems composed of parallel aligned periodic semiconducting CN arrays embedded in an ultrathin finite-thickness dielectric. For homogeneous single-CN films, the intertube coupling and thermal broadening bring the exciton and interband plasmon resonances closer together. They can even overlap due to the inhomogeneous broadening for films composed of array mixtures with a slight CN diameter distribution. In such systems the real part of the r…
We report on the resonant coupling between localized surface plasmon resonances (LSPRs) in nanostructured Ag films, and an adsorbed monolayer of Rhodamine 6G dye. Hybridization of the plasmons and molecular excitons creates new coupled polaritonic modes, which have been tuned by varying the LSPR wavelength. The resulting polariton dispersion curve shows an anticrossing behavior which is very well fit by a simple coupled-oscillator Hamiltonian, giving a giant Rabi-splitting energy of ~400 meV. The strength of this coupling is shown to be proportional to the square root of the molecular density.…
A doped graphene layer in the integer quantum Hall regime reveals a highly unusual particle-hole excitation spectrum, which is calculated from the dynamical polarizability in the random phase approximation. We find that the elementary neutral excitations in graphene in a magnetic field are unlike those of a standard two-dimensional electron gas (2DEG): in addition to the upper-hybrid mode, the particle-hole spectrum is reorganized in linear magneto-plasmons that disperse roughly parallel to $ω=v_F q$, instead of the usual horizontal (almost dispersionless) magneto-excitons. These modes could b…
We investigate the impact that light-forbidden exciton transitions have in the near-field population dynamics and far-field scattering spectrum of hybrid plasmon-emitter systems. Specifically, we consider a V-type quantum emitter, sustaining one dipolar and one quadrupolar (dipole-inactive) excited states, placed at the nanometric gap of a particle-on-a-mirror metallic cavity. Our fully analytical description of plasmon-exciton coupling for both exciton transitions enables us to reveal the conditions in which the presence of the latter greatly alters the Purcell enhancement and Rabi splitting …
The near-field interaction due to a strong electromagnetic field induced by resonant localized plasmons can result in a strong coupling of excitonic states or formation of hybrid exciton-plasmon modes in quantum confined structures. This coupling can be strengthed by designing a system with its vibronic states resonant to the energy of the driving field induced by the localized plasmon excitation. Silver nanoislands nucleated on molybdenum disulfide (MoS2) is an ideal platform for such interaction. The influence of localized plasmons (LSP) on the formation and dissociation of excitons due to r…
We investigate plasmon-emitter interactions in a nanoparticle-on-a-mirror cavity. We consider two different sorts of emitters, those that sustain dipolar transitions, and those hosting only quadrupolar, dipole-inactive, excitons. By means of a fully analytical two-dimensional transformation optics approach, we calculate the light-matter coupling strengths for the full plasmonic spectrum supported by the nanocavity. We reveal the impact of finite-size effects in the exciton charge distribution and describe the population dynamics in a spontaneous emission configuration. Pushing our model beyond…
Transition metal dichalcogenide (TMD) monolayers are direct bandgap semiconductors that feature tightly bound excitons, strong spin-orbit coupling, and spin-valley degrees of freedom. Depending on the spin configuration of the electron-hole pairs, intra-valley excitons of TMD monolayers can be either optically bright or dark. Dark excitons involve nominally spin-forbidden optical transitions with zero in-plane transition dipole moment, making their detection with conventional far-field optical techniques challenging. Here, we introduce a new method for probing the optical properties of two-dim…
Understanding the physics of light emitter in quantum nanostructure regarding scalability, geometry, structure of the system and coupling between different degrees of freedom is important as one can improve the design and further provide controls of quantum devices rigorously. The couplings between these degrees of freedom, in general, depends on the external field, the geometry of nano particles, and the experimental design. An effective model is proposed to describe the plasmon-exciton hybrid systems and its optical absorption spectrums are studied in details by exact diagonalization. Two di…
We investigate the propagation of surface plasmons (SPPs) in a thin layer of copper surrounded by copper oxide Cu$_2$O. It is shown that particularly strong excitons in Cu$_2$O can have considerable impact on plasmon propagation, providing many opportunities for plasmon-exciton and plasmon-plasmon interactions. It is demonstrated that by the use of sufficiently thin metal layer, one can excite the so-called long range plasmons (LRSPPs) which can overcome the inherently high ohmic losses of Cu as compared to usual plasmonic metals such as silver. Analytical results are confirmed by numerical ca…
We develop the analytic theory describing the formation and evolution of entangled quantum states for a fermionic quantum emitter coupled to a quantized electromagnetic field in a nanocavity and quantized phonon or mechanical vibrational modes. The theory is applicable to a broad range of cavity quantum optomechanics problems and emerging research on plasmonic nanocavities coupled to single molecules and other quantum emitters. The optimal conditions for a tri-state entanglement are realized near the parametric resonances in a coupled system. The model includes decoherence effects due to coupl…
The multi-scale computational method of combining first-principles calculation and finite element electromagnetic simulations is used to study plasmon-enhanced interlayer charge transfer (ICT) exciton of 2D lateral and van der Waals MoS2/WS2 heterostructure with 2H phase. The weak ICT excitons are observed in the 2H lateral and van der Waals MoS$_2$/WS$_2$ heterostructures. Theoretical results reveal the physical principle of plexciton resulting from strong coupling between plasmonic and ICT exciton. The weak CT exciton can be strongly enhanced by metal plasmon, can provide a new way to observ…
Plasmonic structures are known to support the modes with subwavelength volumes in which the field matter interactions are greatly enhanced. Coupling between the molecular excitations and plasmons leading to formation of plexcitons has been investigated for a number of organic molecules. However, plasmon-exciton coupling in metal semiconductor structures have not experienced the same degree of attention. In this work we show that the very strong coupling regime in which the Rabi energy exceeds the exciton binding energy is attainable in semiconductor cladded plasmonic nanoparticles and leads to…
When a two-level quantum dot and a plasmonic metal nanoantenna are resonantly coupled by the electromagnetic near field, the system can exhibit a Fano resonance, resulting in a transparency dip in the optical spectrum of the coupled system. We calculate the nonlinear response of such a system, for illumination both by continuous-wave and ultrafast pulsed lasers, using both a cavity quantum electrodynamics and a semiclassical coupled-oscillator model. For the experimentally relevant case of meV thermal broadening of the quantum-dot transition, we predict that femtosecond pulsed illumination can…
We review the latest theoretical advances in the application of the framework of Transformation Optics for the analytical description of deeply sub-wavelength electromagnetic phenomena. First, we present a general description of the technique, together with its usual exploitation for metamaterial conception and optimization in different areas of wave physics. Next, we discuss in detail the design of plasmonic metasurfaces, including the description of singular geometries which allow for broadband absorption in ultrathin platforms. Finally, we discuss the quasi-analytical treatment of plasmon-e…
The phase delay of a local electric field, being well-known in plasmonic nanostructures, has seldom been investigated to modulate the plasmon-exciton interaction. Here, with the single-particle spectroscopy method, we experimentally investigate the phase effect in plasmon-exciton coupling systems consisting of monolayer WSe2 and an individual gold nanorod. The local plasmon phase delay is tuned by adopting various nanorods with different resonant energies respective to the exciton. We find that the local plasmon phase delay between the excitons and the plasmonic modes is as equally essential a…
Active control of light-matter interactions in semiconductors is critical for realizing next generation optoelectronic devices, with tunable control of the systems optical properties via external fields. The ability to manipulate optical interactions in active materials coupled to cavities via geometrical parameters, which are fixed along with dynamic control with applied fields opens up possibilities of controlling exciton lifetimes, oscillator strengths and their relaxation properties. Here, we demonstrate electrical control of exciton-plasmon polariton coupling strength of a two-dimensional…
We investigate the dynamics of photon echo exhibited by exciton-plasmon systems under strong coupling conditions. Using a self-consistent model based on coupled Maxwell-Bloch equations we investigate femtosecond time dynamics of ensembles of interacting molecules optically coupled to surface plasmon supporting materials. It is shown that observed photon echoes under two pulse pump-probe sequence are highly dependent on various material parameters such as molecular concentration and periodicity. Simulations of photon echoes in exciton-plasmon materials reveal a unique signature of the strong ex…
The radiative decay of quantum dot (QD) excitons into surface plasmons in a cylindrical nanowire is investigated theoretically. Maxwell's equations with appropriate boundary conditions are solved numerically to obtain the dispersion relations of surface plasmons. The radiative decay rate of QD excitons is found to be greatly enhanced at certain values of the exciton bandgap. Analogous to the decay of a two-level atom in the photonic crystal, we first point out that such an enhanced phenomenon allows one to examine the non-Markovian dynamics of the QD exciton. Besides, due to the one dimensiona…
Strong exciton-plasmon interaction between the layered two-dimensional (2D) semiconductors and gap plasmons shows a great potential to implement cavity quantum-electrodynamics in ambient condition. However, achieving a robust plasmon-exciton coupling with nanocavity is still very challenging, because the layer area is usually small with conventional approaches. Here, we report on a robust strong exciton-plasmon coupling between the gap mode of bowtie and the excitons in MoS$_2$ layers with gold-assisted mechanical exfoliation and the nondestructive wet transfer techniques for large-area layer.…
Resonant optical excitation was used to create a macroscopic non-equilibrium ensemble of dark excitons with unprecedentedly long lifetime in a two-dimensional (2D) electron system placed in a quantizing magnetic field. Exotic three-particle and four-particle states, plasmarons and plasmon-exciton molecules, coupled with the surrounding electrons through the collective plasma oscillations are engineered. Plasmarons and plasmon-exciton molecules are manifested as new features in the recombination spectra of non-equilibrium systems. Magnetoplasmarons and magnetotrions in a two-dimensional Hall in…
The plasmon-mediated manipulation of light-matter interaction in two-dimensional atomically transition-metal dichalcogenides (TMDs) critically depends on the design of plasmonic nanostructures to achieve the maximum optical field in TMDs. Here, a metal-isolator-metal Salisbury-type perfect absorber was fabricated to serve as a generator of the localized surface plasmons. The significant photoluminescence (PL) enhancement up to 60-fold was observed experimentally in the monolayer (ML) MoS2 on the top of this gold plasmonic hybrid nanostructures. Furthermore, the PL linear polarization can appro…
We present a model for exciton-plasmon coupling based on an energy exchange mechanism between quantum emitters (QE) and localized surface plasmons in metal-dielectric structures. Plasmonic correlations between QEs give rise to a collective state exchanging its energy cooperatively with a resonant plasmon mode. By defining carefully the plasmon mode volume for a QE ensemble, we obtain a relation between QE-plasmon coupling and a cooperative energy transfer rate that is expressed in terms of local fields. For a single QE near a sharp metal tip, we find analytically the enhancement factor for QE-…
Strong coupling of two-dimensional semiconductor excitons with plasmonic resonators enables control of light-matter interaction at the subwavelength scale. Here we develop strong coupling in plasmonic nano-gap resonators that allow modification of exciton number contributing to the coupling. Using this system, we not only demonstrate a large vacuum Rabi splitting up to 163 meV and splitting features in photoluminescence spectra, but also reveal that the exciton number can be reduced down to single-digit level (N<10), which is an order lower than that of traditional systems, close to single-exc…
Hybrid systems of excitons strongly coupled to localized surface plasmons supported by metallic nanoparticles define a new approach to control light-matter interactions. Here, we report exciton-plasmon coupling in two-dimensional (2D) semiconductors, such as MoS2 and WS2, hybridized with silver nanoparticles. Prominent photoluminescence enhancement in monolayer MoS2 was observed with localized surface plasmon resonance (LSPR) tuned to the exciton resonance. By tuning the excitation energy, the contributions from near field enhancement and radiative emission rate enhancement via Purcell effect …
We study theoretically optical response of WS2 monolayer located near periodic metal nanostructured arrays in two and three dimensions. The emphasis of simulations is on the strong coupling regime of excitons supported by WS2 and surface plasmon-polaritons supported by various periodic plasmonic interfaces. It is demonstrated that a monolayer of WS2 placed in a close proximity of periodic arrays of either slits or holes results in a Rabi splitting of the corresponding surface plasmon-polariton resonance as revealed in calculated transmission and reflection spectra. The nonlinear regime, at whi…
Exciton harvesting is demonstrated in an ensemble of quantum emitters coupled to localized surface plasmons. When the interaction between emitters and the dipole mode of a metallic nanosphere reaches the strong coupling regime, the exciton conductance is greatly increased. The spatial map of the conductance matches the plasmon field intensity profile, which indicates that transport properties can be tuned by adequately tailoring the field of the plasmonic resonance. Under strong coupling, we find that pure dephasing can have detrimental or beneficial effects on the conductance, depending on th…
Manipulating strong light-matter interaction in semiconductor microcavities is crucial for developing high-performance exciton polariton devices with great potentials in next-generation all-solid state quantum technologies. In this work, we report surface plasmon enhanced strong exciton-photon interaction in CH3NH3PbBr3 perovskite nanowires. Characteristic anti-crossing behaviors, indicating Rabi splitting energy up to ~ 560 meV, are observed near exciton resonance in hybrid semiconductor-insulator-metallic waveguide cavity at room temperature. An exciton-photon coupling strength enhancement f…
We study plasmon-exciton interaction by using topological singularities to spatially confine, selectively deliver, cotrap and optically probe colloidal semiconductor and plasmonic nanoparticles. The interaction is monitored in a single quantum system in the bulk of a liquid crystal medium where nanoparticles are manipulated and nanoconfined far from dielectric interfaces using laser tweezers and topological configurations are spatially colocated with a plasmonic gold nanoburst particle in a topological singularity core, its fluorescence increases because blinking is significantly suppressed an…
Transport properties of a single plasmon interacting with a hybrid system composed of a semiconductor quantum dot (SQD) and a metal nanoparticle (MNP) coupled to one-dimensional surface plasmonic waveguide are investigated theoretically via the real-space approach. We considered that the MNP-SQD interaction leads to the formation of a hybrid exciton and the transmission and reflection of a single incident plasmon could be controlled by adjusting the frequency of the classical control field applied to the MNP-SQD hybrid nanosystem, the kinds of metallic nanoparticles and the background media, r…
Just as photons are the quanta of light, plasmons are the quanta of orchestrated charge-density oscillations in conducting media. Plasmon phenomena in normal metals, superconductors and doped semiconductors are often driven by long-wavelength Coulomb interactions. However, in crystals whose Fermi surface is comprised of disconnected pockets in the Brillouin zone, collective electron excitations can also attain a shortwave component when electrons transition between these pockets. Here, we show that the band structure of monolayer transition-metal dichalcogenides gives rise to an intriguing mec…
The formation of pulses of surface electromagnetic waves in a metal/dielectric interface is considered in the process of cooperative decay of excitons of quantum dots distributed near a metal surface in a dielectric layer. It is shown that the efficiency of exciton energy transfer to excited plasmons can be increased by selecting the dielectric material with specified values of the complex permittivity. It is found that in the mean field approximation the semiclassical model of formation of plasmon pulses in the system under study is reduced to the pendulum equation with the additional term of…
