Theoretical Study On The Strong Coupling Between Surface Plasmon And Matter

As hybrid modes involving with electron oscillations inside the metal and the oscillation light field on the surface of the metal,the surface plasmon has the near-field characteristics.This makes its light field component be con-fined in dimensions smaller than the free space wavelength of light at the same frequency,which makes plasmon an important role in nano-optics.Recently,strong coupling between surface plasmon and emitters,which can exist at Nor-mal temperature with a small mode volume,has broad application prospects and become an active topic of research.It has been reported that various type of emitters,like J-aggregates molecules,dye molecules and quantum dots,can be used in tIhe strong coupling regime.In this paper,we combine theoreti-cal calculation with FDTD numerical simulation method to analysis the strong coupling between the surface plasmon excited in the Kretschmann configura-tion and the molecules of J-aggregates in the dielectric layer.Specific research contents are as follows:First,we excited the surface plasmon on the interface of the metal and the dielectric doped with J-aggregates molecules in the Kretschmann config-uration.The reflectance spectrum is obtained by theoretical calculation and FDTD simulation.By the appearance of Rabi splitting in reflectance spectrum,we confirm the occurrence of strong coupling.In order to study how various parameters of the configuration and the lorentz model which is used to discribe the permittivity of the J-aggregates molecular on the strong coupling influence the strong coupling,we use the method of control variable and get the con-clusion of each parameter's influence on the strong coupling.Besides,as the total reflection of incident light must exist on the surface of the prism while the surface plasmon is excited using Kretschmann configuration,we focus on the variation of Goos-Hanchen linear shift which is influenced by the strong coupling.Through the simulation and theoretical analysis,we found that there are two maxima at the frequency positions corresponding to the two peaks of Rabi splitting.At these two situations,strong coupling leads to the highest sur-face plasmon conversion efficiency,which proved the correlation between the linear shift and the strong coupling.Then we summarized the influence of each parameter on this linear shift.Then,we proposed a 5-layers structure based on the design of Kretschmann configuration.A layer of metal and a layer of prism are added symmetrically on the other side of the dielectric layer,which have the same thickness with their mirror image respectively.The structure of silver-dielectric-silver sand-wiched in two prisms is formed.The incident light excites the surface plasmon on the metal-dielectric interface at one side of this configuration.Then SPPs strongly coupled with the emitters inside the dielectric part and then decoupling into light at the other interface of the dielectric-silver The reflectance spectrum and transmission spectrum were obtained by using both theoretical calculation and FDTD simulation.The Rabi splitting can be found in both spectrum which proved the existence of strong coupling.Since the transmitted light is gen-erated by the discoupling of the surface plasmon polaritons,we find that the transmission angles,which generated by the incident light of different wave-lengths,is alwayTs the same as the resonance angle of surface plasmon.The result is verified by FDTD simulation,so the transmission Angle can be con-troled by the structural parameters.By comparing the reflectance spectrum and transmission spectrum at different coupling intensities,we found that as the in-creasing of the coupling intensity,Rabi splitting increases and the transmittance and reflectance goes decreasing.We can control the intensity of strong coupling inside silver-J aggregates-silver structure by change the parameters of the con-figuration and the lorentz model which discribe the permittivity of J-aggregates molecules.The frequencies produced by Rabi splitting can also be controled by this method.This makes our configuration can have potential use in the area of quantum network,optical switch and surface plasmon sensor.