Numerical Simulation Of Plasmon-Exciton Coupling In Core-Shell Structure And Its Application

Local surface plasmon resonance is the phenomenon of the interaction between light and matter with special properties,because of collective oscillation of free electrons driven by light.With the development of nanotechnology,more and more researches and applications focus on it.Plasmon-exciton coupling is one of the special physical phenomena based on the strong interaction between LSPR and excitons and is of interesting optical properties.It creates a new state with the characteristics of both LSPR and excitons.Its energy level is hybrid like Rabi splitting.Therefore,it is promising with a wide range of applications and large research value.First,the properties of LSPR of Ag and Au shell are investigated numerically by generalized Mie theory.Compared with LSPR of Ag and Au nanoparticle with same size,they show longer wavelength and narrower FWHM,which means that their LSPR can be modified easily by the size of the nanoparticles.The specific properties make metal shell structure more suitable for plasmon-exciton coupling.Subsequently,optical cross sections of TDBC@Ag core-shell nanoparticles are calculated by generalized Mie theory as well.It shows the two obvious splitting peaks changing with the energy of LSPR in optical cross sections,which are anti-crossing.Numerical calculations confirm seriously that the plasmon-exciton coupling is in the strong coupling regime.Simultaneously,the properties of plasmon-exciton coupling based on Au shell's LSPR and a virtual exciton material are investigated.These numerical results demonstrate metal @exciton core-shell nanostructures are able to realize strong coupling.Furthermore,a novel ratiometric sensor based on the strong coupling of the coreshell nanostructure is designed to detect the change of local refractive index by the ratio of splitting peaks' intensity.Compared with traditional LSPR sensors,it is of high sensitivity and strong anti-interference.In addition,the detective device based on it is simpler.Finally,strong coupling base on Ag nanoprisms core and TDBC shell is realized in experiments briefly.The response of the strong coupling for analyte is not same as the numerical results.However,it shows the sensitivity of strong coupling which demonstrates that sensors based on strong coupling are viable.