We have studied quantum coherence and interference phenomena in a quantum dot (QD)-metallic nanorod (MNR) hybrid system. Probe and control laser fields are applied to the hybrid system. Induced dipole moments are created in the QD and the MNR, and they interact with each other via the dipole-dipole interaction. Using the density matrix method, it was found that the power spectrum of MNR has two transparent, states and they can be switched to one transparent state by the control field. Ultrafast switching and sensing nanodevices could be produced using this model.
We study theoretically the dipole-dipole interaction and energy transfer in a hybrid system consisting of a quantum dot and graphene nanodisk embedded in a nonlinear photonic crystal. In our model, a probe laser field is applied to measure the energy transfer between the quantum dot and graphene nanodisk, while a control field manipulates the energy transfer process. These fields create excitons in the quantum dot and surface plasmon polaritons in the graphene nanodisk which interact via the dipole-dipole interaction. Here, the nonlinear photonic crystal acts as a tunable photonic reservoir for the quantum dot, and is used to control the energy transfer. We have found that the spectrum of power absorption in the quantum dot has two peaks due to the creation of two dressed excitons in the presence of the dipole-dipole interaction. The energy transfer rate spectrum of the graphene nanodisk also has two peaks due to the absorption of these two dressed excitons. Additionally, energy transfer between the quantum dot and the graphene nanodisk can be switched on and off by applying a pump laser to the photonic crystal or by adjusting the strength of the dipole-dipole interaction. We show that the intensity and frequencies of the peaks in the energy transfer rate spectra can be modified by changing the number of graphene monolayers in the nanodisk or the separation between the quantum dot and graphene. Our results agree with existing experiments on a qualitative basis. The principle of our system can be employed to fabricate nanobiosensors, optical nanoswitches, and energy transfer devices.
We have investigated the second-harmonic generation (SHG) and dipole-dipole interaction in a quantum dot and metallic nanoparticle hybrid system. A strong probe field is applied to create two-photon absorption in the quantum dot and metallic nanoparticle. SHG photons and SHG surface plasmon polaritons are emitted by the quantum dot and metallic nanoparticle, respectively. Induced dipoles are created in the quantum dot and the metallic nanoparticle due to two-photon absorption and hence both systems interact with each other via the dipole-dipole interaction. It is found that SHG signals produced by the quantum dot and nanoparticle are enhanced by the dipole-dipole interaction and also that the SHG signal can be switched on and off by applying a control field. The theoretical findings of this paper are supported by recent experimental studies. The present hybrid system can be used to fabricate nano-sensors and all-optical nano-switching devices.
Metallic nanohole arrays (NHAs) with a high hole density have emerged with potential applications for surface-enhanced Raman spectroscopy (SERS) including the detection of analytes at ultra-low concentrations. However, these NHA structures generally yield weak localized surface plasmon resonance (LSPR) which is a prerequisite for SERS measurements. In this work, a compact three-dimensional (3D) tunable plasmonic cavity with extraordinary optical transmission properties serves as a molecular sensor with sub-femtomolar detection. The 3D nanosensor consists of a gold film containing a NHA with an underlying cavity and a gold nanocone array at the bottom of the cavity. These nanosensors provide remarkable surface plasmon polariton (SPP) and LSPR coupling resulting in a significantly improved detection performance. The plasmonic tunability is evaluated both experimentally and theoretically. A SERS limit of detection of 10-16 M for 4-Nitrothiophenol (4-NTP) is obtained along with 28 distribution mapping of the molecule on the 3D plasmonic nanosensor. This results in an 29 improved SERS enhancement factor (EF) of 10 6 obtained from a femtolitre plasmonic cavity 30 volume. The tunability of these sensors can give rise to a potential opportunity for use in optical 31 trapping while providing SERS sensing of a molecule of interest. 32
We have developed a theory for the photoluminescence (PL) and scattering cross section of a core–shell hybrid, where the core is the metallic nanoparticle and the shell is made of an ensemble of quantum emitters. A probe field is applied to calculate the scattering cross section of the core–shell hybrid. The surface plasmon polariton field in the metallic nanoparticle is calculated by solving the Maxwell equations in the quasi-static approximation. Dipoles are induced in the ensemble of quantum emitters because of the probe field and surface plasmon polariton field. Therefore, the dipole of one quantum emitter interacts with dipoles of other quantum emitters in the ensemble, and hence, there is the dipole–dipole interaction (DDI) between quantum emitters. We discovered an anomalous DDI, which is induced by the surface plasmon polaritons. It is shown that the strength of the DDI can be controlled by the surface plasmon polariton frequency, and it plays a dominant role in the phenomenon of the PL and scattering cross section. The surface plasmon polariton field can also interact with excitons of the quantum emitters via the exciton-surface plasmon polariton interaction. Using the density matrix method, the PL and scattering cross section are evaluated. It is found that the spectrum of the PL and the scattering cross section splits from one peak into two peaks mainly because of the strong coupling between the excitons and anomalous DDIs. It means that the PL and scattering spectrums can be switched ON (one peak) and OFF (two-peaks). This finding is consistent with the experimental data of the PL and scattering cross section of the J-aggregate and silver core–shell hybrid. We have found that the splitting and height of the two peaks can be increased or decreased by controlling mainly the strength of the anomalous DDI. The anomalous DDIs can be controlled by applying an external pulse pressure and pulse control laser. Hence, the present findings can be used for fabricating nanosensors and nanoswitches for applications in nanotechnology and nanomedicines.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.