Investigation Of Exciton-polariton Modes Based On The Coupling Between F-P Microcavities And Surface Plasmon Polaritons

There has been extensive interest in the use of nanostructures to control light-matter interactions.Currently,coupling between photons and excitons has become a major research topic for many groups.In particular,in strongly coupled and super strongly coupled states where the energy exchange rate is higher than the energy dissipation rate of the system,excitons and photons can be mixed to form new quasiparticles with both photon and exciton components,namely excitation-polarization excitons(EP).It is a half-exciton-half-photon quasiparticle formed by the strong coupling of photons and excitons,which combines the properties of excitons and photons and has a wide range of applications in quantum dynamics,solar cells,sensors and the development of optoelectronic devices.The photonic component in EP can be provided by a variety of nanostructured confined optical modes,for example,Fabry-Pérot(F-P)microcavities and Surface Plasmon Polariton(SPP)are often used as a platform for studying EP.The properties of the SPP are easily influenced by the thickness and material of the metal film,so that the EP generated by mixing the SPP with excitons can be flexibly tuned by the material and geometrical parameters of the nanostructure.Currently,the vast majority of studies on EP in F-P microcavities focus only on the F-P optical mode of the microcavity,while SPP-based EP is mostly performed on single-layer metal films.In fact,F-P microcavity structures can also support SPP modes,and new optical modes can be generated by coupling between F-P and SPP modes.In this thesis,we dispersed the organic dye molecule TDBC(1,1’-diethyl-3,3’-bis(4-sulfobutyl)-5,5’,6.6’-tetrachlorobenz imidazolocarbocyanine)into polyvinyl alcohol(PVA)to study the exciton leap between the TDBC molecule and the optical modes of strong coupling.We designed and prepared an F-P microcavity supporting both the F-P mode and the SPP mode,placed the TDBC/PVA film in the F-P cavity,and systematically observed and studied the EP mode formed by the strong coupling of the F-P mode,the SPP mode and the exciton leap through variable-angle reflectance spectroscopy and fluorescence spectroscopy.The three-layer Ag-TDBC/PVA-Ag structure was prepared on a glass substrate by magnetron sputtering and spin coating,and the reflectance/transmission/fluorescence spectra of the samples were characterized by a self-assembled angle-resolved spectroscopy test system under P-polarized(TM mode)and S-polarized(TE mode)incident light,respectively.The experimental results show that the strong coupling between the F-P mode,the SPP mode and the exciton leap forms three exciton/photon hybrid states,including two almost dispersionless modes;by adjusting the thickness of the TDBC/PVA layer,the strong coupling between the three can be effectively regulated,significantly changing the peak position and height of the EP reflection spectral peaks.The experimental results agree well with the numerical simulations of the transmission matrix method(TMM),further confirming the strongly coupled state of the system and the spectral nature of the EP modes.Using a simple F-P microcavity structure as a platform,the study in this thesis demonstrates the richness of the EP modes produced by the strong coupling of two optical modes with exciton leaps simultaneously.Compared to the strong coupling of a single optical mode with exciton leap,the EP in this thesis has unique spectral properties,such as different dispersive properties for modes excited with incident light of different polarization states,as well as the excitation angle of the F-P mode being outside the critical angle of total reflection.Compared to the strong coupling of a single optical mode with exciton leap,the EP in this thesis has unique spectral properties,such as different dispersive properties for modes excited with incident light of different polarization states,as well as the excitation angle of the F-P mode being outside the critical angle of total reflection.The EP in this thesis combines the advantages of the F-P mode and the SPP mode,which improves the strength of coupling to exciton leaps while allowing more flexible means of modulation of the EP mode,and is a good contribution to the fundamental physical research related to EP as well as to the development of applied technologies such as sensors.