Study On The Interaction Between Silver Nanostructures And Excitons And Its Modulation

The integrated optical path has the characteristics of strong electromagnetic interference resistance,high integration,fast transmission speed,and strong confidentiality.It has extremely broad application prospects in the fields of quantum switches,quantum logic gates,quantum memories,and all-optical communication.However,traditional optical devices cannot break through the optical diffraction limit.Surface plasmons polaritons (SPPs),which are formed by the interaction between free-electon and light,are a kind of electromagnetic waves bounded on the metal-insulator interfaces.They can confining the light far below the diffraction limit and greatly enhance the local electromagnetic field,make them ideal candidates to enhance the interaction between light and realize integrated photonic devices.This thesis mainly studies the interaction between silver nanostructures and excitons.The main research contents of this thesis are as follows:1.The composite nanostructures of silver nanowire@SiO2@quantum dots was synthesized by chemical synthesis,and a fluorescence intensity and lifetime scanning system was established.The system was used to scan the hybrid nanowires,and the two-dimensional two photon excitation fluorescence (TPEF) intensity distribution and decay rate of the hybrid nanowires were obtained at different excitation light polarizations.By adjusting the polarization of the excitation light parallel or perpendicular to the axis of the hybrid nanowire,the TPEF intensity map of the quantum dots on the hybrid nanowire presents different surface plasmon mode distribution and their decay rate are different under different polarization conditions.The TPEF intensity and decay rate of quantum dots are depend on the polarization of incident light.The decay process of the TPEF of quantum dots is modulated by the local surface plasmon mode and transmission surface plasmon of the hybrid nanowire Fabry-Perot cavity mode.The experimental results show that the intensity of TPEF and lifetime depend on the polarization of incident light.The decay process of TPEF is divided into slow and fast processes.The two processes are caused by the interaction of quantum dots with the propagating surface plasmon and localized surface plasmon modes.In the case of two different excitation polarization,the energy in the hybrid nanowire is converted to each other in the form of photon-plasmon-exciton-plasmon-photon.2.This thesis derive the scattering cross sections of the coupled system described by three coupled harmonic oscillators.Subsequently,a nanosystem in which the silver nanoprism is strongly coupled to the J-aggregates molecule and WS2 is proposed.The scattering spectrum of the coupled system obtained by numerical simulation using the finite-difference time-domain (FDTD) methods,the scattering spectra of this system have two splits.The scattering spectra are split into upper,middle,and lower plexciton branches.The position of the splitting is near the position of the absorption peak of the J-aggregates molecule and the WS2,respectively.Fit the numerical simulation results through three harmonic oscillator coupling models,and the results are consistent with the numerical simulation results.We also studied the effects of the thickness of the silver nanoprism,the thickness of the J-aggregates layer,the temperature,and the molecular oscillator strength on the scattering spectrum of the system,and discussed the different results.3.This thesis propose a hybrid nanostructure in which silver nanorings are strongly coupled to J-aggregates molecules and WS2.In this system,J-aggregates molecules are organic Frenkel excitons,and WS2 are inorganic Wannier-Mott excitons.We obtained the extinction spectra of the system and the strong coupling anti-crossing curve of the system through FDTD numerical simulation,and fitted the extinction spectrum and anti-crossing curve of the system with three coupled harmonic oscillator models.The fitted extinction spectra is consistent with the numerical simulation results.By fitting the anti-crossing curve,we get the ratio of exciton and surface plasmon modes in this strong coupling system,and analyze the strong coupling behavior of organic excitons,inorganic excitons and local surface plasmons in this system.Finally,the effects of temperature and molecular oscillator strength on the strong coupling of the system are studied.