RESUMEN
Strong plasmon-exciton coupling, which has potential applications in nanophotonics, plasmonics, and quantum electrodynamics, has been successfully demonstrated by using metallic nanocavities and two-dimensional materials. Dynamical control of plasmon-exciton coupling strength, especially by using optical methods, remains a big challenge although it is highly desirable. Here, we report the optical introduction and manipulation of plasmon-exciton-trion coupling realized in a dielectric-metal hybrid nanocavity, which is composed of a silicon (Si) nanoparticle and a thin gold (Au) film, with an embedded tungsten disulfide (WS2) monolayer. We employ scattering and photoluminescence spectra to characterize the coupling strength between plasmons and excitons in Si/WS2/Au nanocavities constructed by using Si nanoparticles with different diameters. We enhance the plasmon-exciton and plasmon-trion coupling strength by injecting excitons and trions into the WS2 monolayer with a 488 nm laser beam. It is revealed that the emission intensities of excitons and trions with respect to the reference WS2 monolayer can be modified through the change in the coupling strength induced by the laser light. Interestingly, the coupling strength between the plasmons and the excitons/trions can be manipulated from weak to strong coupling regime by simply increasing the laser power, which is clearly resolved in the scattering spectra of Si/WS2/Au nanocavities. More importantly, the plasmon-exciton-trion coupling induced by the laser light is confirmed by the energy exchange between excitons and trions. Our findings indicate the possibility for optically manipulating plasmon-exciton interaction and suggest the practical applications of dielectric-metal hybrid nanocavities in nanoscale plasmonic devices.
RESUMEN
A strong light-matter interaction is highly desirable from the viewpoint of both fundamental research and practical application. Here, we propose a dielectric-metal hybrid nanocavity composed of a silicon (Si) nanoparticle and a thin gold (Au) film and investigate numerically and experimentally the coupling between the plasmons supported by the nanocavity and the excitons in an embedded tungsten disulfide (WS2) monolayer. When a Si/WS2/Au nanocavity is excited by the surface plasmon polariton generated on the surface of the Au film, greatly enhanced plasmon-exciton coupling originating from the hybridization of the surface plasmon polariton, the mirror-image-induced magnetic dipole, and the exciton modes is clearly revealed in the angle- or size-resolved scattering spectra. A Rabi splitting as large as â¼240 meV is extracted by fitting the experimental data with a coupled harmonic oscillator model containing three oscillators. Our findings open new horizons for constructing nanoscale photonic devices by exploiting dielectric-metal hybrid nanocavities.
RESUMEN
Simple systems in which strong coupling of different excitations can be easily realized are highly important, not only for fundamental research but also for practical applications. Here, we proposed a T-shaped gold nanorod (GNR) dimer composed of a long GNR and a short GNR perpendicular to each other and revealed that the dark quadrupole mode of the long GNR can be activated by utilizing the dipole mode excited in the short GNR. It was found that the strong coupling between the dipole and quadrupole modes can be achieved by exciting the T-shaped GNR dimer with a plane wave. Then, we demonstrated the realization of strong dipole-quadrupole-exciton coupling by placing a T-shaped GNR on a tungsten disulfide (WS2) monolayer, which leads to a Rabi splitting as large as ~299 meV. It was confirmed that the simulation results can be well fitted by using a Hamiltonian based on the coupled harmonic oscillator model and the coupling strengths for dipole-quadrupole, dipole-exciton and quadrupole-exciton can be extracted from the fitting results. Our findings open new horizons for realizing strong plasmon-exciton coupling in simple systems and pave the way for constructing novel plasmonic devices for practical applications.
